2017 Fall Meeting
Advanced composite materials: new production technologies, unique properties, new applications
It is hard to represent our life without composite materials which for today take one of the main place in such application areas as aviation, transport, space, construction and building field, ecology, sport, biomedicine, electronics, energy sector, including renewable energetic, and etc. Variation of the nature of components, using of nanocomponents and nanoadditives to the materials of matrix and to the reinforcement component, development of new production technologies and new kinds of reinforcements including textiles, fibers, meshes and etc. allow to create materials with given unique complex of service characteristics for different applications, including extreme performances. All these materials will be in the main focus of symposium activity in 2017 year.
For advanced composites materials based on metal, ceramic, polymer matrix and reinforced by various particles, fibers, textiles, meshes modified by nanocomponents of different nature which traditionally used in aeronautic, energy sector, automobile, space and transport industry, ecology, machine building, construction sector, biomedicine and electronics the task of creating of materials with given complex of service parameters ensuring their safety and reliability became more and more actual. Production of composite materials with given complex of service parameters together with decreasing of their sizes and costs of their production allow essentially widen their functionalities and find the new ways of their application. So the task of creation of composite materials and complex structures on the base of them using modern methods and materials for their joining will be the key topic of proposed symposium. Modern methods of modeling for advanced ceramics, composites and complex structures production, micro-and macrostructure and forecasting of the physical and chemical properties allow successfully decide such kind of tasks. The results of several FP7 projects concerning new methods of production, testing and applications of composite materials reinforced by carbon fibers and carbon structures and metal and ceramic composites for thermal protection system for space applications will be presented at proposed symposium. Special time will be devoted to innovative research, to the questions of technology transfer and international cooperation in the field of advanced ceramic and composite materials.
Hot topics to be covered by the symposium:
Fundamental study, modelling of technology processes, structure and properties, including phase equilibrium diagrams for multicomponent systems
- Production technologies for advanced composites powders and their properties, including various kinds of nanoadditives and their influence upon service properties of final product
- Production technologies for composites coatings and their properties, including multilayer coatings and their new regulated functionalities
- Production technologies for bulk composites and their properties, including novel sintering technologies for complex compounds and structures
- Complex ceramic and composite structures for extreme performances with special attention for materials for aviation and space applications
- Nanoceramic and nanocomposites: peculiarities of their structure and properties
- Novel techniques for advanced ceramic and composite materials characterization
- Novel areas of application of advanced ceramic and composites, including space, transport, biomaterials, micro- and nanoelectronic, constructional ones
- Results and perspectives of international cooperation in the field of creation of advanced ceramic and composite materials
Tentative list of invited speakers:
- Kervalishvili Paata (Tbilisi,Georgia)
- Gogotsi Yurii (Drexel University, USA)
- Fragge Nahum (Bersheva, Israel)
- Inaki Fagoaga (San-Sebastian, Spain)
- Konstantinova Tatiana (Donetsk, Ukraine)
- Tedenac Jean-Claude (Montpelier, France)
- Sanin Anatolii (Dnipro,Ukraine)
- Shemet V (Jülich, Germany)
- Nazarchuk Zinovii (Lviv, Ukraine)
Tentative list of scientific committee members:
- Zgalat-Lodzynsky Ostap (Kiev, Ukraine)
- Uvarova Iryna (Kiev, Ukraine)
- Vishnyakov Leon (Kiev, Ukraine)
- Ilyushchenko Aleksandr (Minsk, Belorussia)
- Panin Victor (Tomsk, Russian Federation)
- Hipke Thomas (Chemnitz, Germany)
- Pakiela Zbigniew (Warsaw,Poland)
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Composites on the base of oxide ceramic : Dr. Iryna Bilan
Authors : M. Sokol, B. Ratzker, S. Kalabukhov, N. Frage
Affiliations : Ben-Gurion University of the Negev
Resume : High pressure (up to 1 GPa) spark plasma sintering (HPSPS) technique allows to fabricate nanostructured (20-30 nm) polycrystalline ceramics at relatively low temperatures with short sintering time. The specimens obtained by HPSPS technique display a unique combination of optical and mechanical properties, comparable or even better than the best results reported in literature for a two-stage fabrication process (pressureless sintering followed by hot isostatic pressing or vacuum sintering). Our recent experimental results on densification of polycrystalline transparent magnesium aluminate spinel (PMAS) and yttria stabilized zirconia (YSZ) has raised some fundamental questions related to microstructure evolution, densification and grain growth kinetics. Furthermore, for the first time, the minimal grain size (of about 40 nm) where a Hall-Petch relation is valid was established and an inverse Hall-Petch correlation was clearly observed for ceramics with grain size less than 30 nm. In addition, an abnormal behavior of the Young modulus of these specimens was found. Nanocrystalline materials may be considered as being microstructurally heterogeneous, comprising building blocks (i.e., crystallites) and regions between adjacent building blocks (i.e., grain boundaries). The volume fractions of crystallites and grain boundaries depend on the average grain size of the materials. For extremely low grain sizes, such as 10 nm, the volume fraction of grain boundaries is between 40 to 50%. The presence of large amounts of grain boundaries in nanostructured materials is crucial for many of their properties. Therefore, it is reasonable to expect that a critical grain size at which the Hall-Petch relation remains valid does exist. The present work focuses on the understanding of sintering behavior during HPSPS process and on clarification of the grain growth mechanism. A model explaining the effect of grain size on the mechanical properties was developed and will be discussed.
Authors : Y. Brodnikovskyi(1), I. Brodnikovska(1), L. Kovalenko(2), D. Brodnikovskyi(1), I. Polishko(1), O. Vasylyev(1), A. Belous(2).
Affiliations : 1 ) Frantcevych Institute for Problems of Materials Science, Natl. Acad. of Sci. of Ukraine, 3 Krzhizhanovskyi Str., Kyiv, 03860, Ukraine; 2) Vernadsky Institute of general and inorganic chemistry, Natl. Acad. of Sci. of Ukraine, 32/34 Akademika Palladina Ave., Kyiv, 03142, Ukraine.
Resume : Solid oxide fuel cell (SOFC) is an electrochemical device which directly convert chemical energy of a fuel (H2, CnHm etc.) and air (O2) into electricity and heat. Zirconia stabilized with 8-mol% Y2O3 (8YSZ) is the state-of-the-art electrolyte material for SOFC applications. Despite the extensive use of 8YSZ for SOFCs, within the past decade zirconia stabilized with 10-mol% Sc2O3 and 1-mol% CeO2 (10Sc1CeSZ) has garnered much attention as one of the best ionic conductors for intermediate temperature SOFCs (600-700°C, IT-SOFCs) . The electrical conductivity of ScSZ is higher than that of 8YSZ practically by one order of magnitude over the entire temperature interval 600-800 ºC [1,2]. The one of the main challenges among its wide application is relatively high price of Scandia. Last decade much efforts are focused on elaboration of alternative of 8YSZ electrolyte to reduce SOFC operation temperatures till 600°C. It should widen selection of the materials for SOFC system application and allows to reduce its whole price. The present work is devoted to creation of the composite zirconia electrolytes from nonionized powders of 10Sc1CeSZ and 8YSZ. The aim of the work is to enhance electrical conductivity of the traditional 8YSZ electrolyte by combination with 10Sc1CeSZ what should help to decrease SOFC operation temperature. Mechanical behavior, electrical and structural properties of 10Sc1CeSZ-8YSZ electrolytes were studied. It was found that the composite ceramic provides much higher electrical conductivity at 600°C than 8YSZ does. Moreover, usage of 10Sc1CeSZ-8YSZ ceramics allows to reduce Scandia consumption comparing with pure 10Sc1CeSZ. 10Sc1CeSZ-8YSZ ceramic is promising material for IT-SOFC application.
Authors : Y. Mordekovitz, S. Hayun
Affiliations : Ben Gurion University of the Negev
Resume : Today, the use of green renewable energy and its storage and conveyance are of utmost importance, placing the field at the center of technological and scientific inquiry. Of the sustainable energy carriers known to date, reduced reactive gases (i.e. H2 or CO, or a mixture thereof) are the most promising. Such gases are produced by way of molecular gas (i.e. H2O or CO2) reduction/splitting. Cerium dioxide (CeO2, ceria) is a remarkable material with a unique set of properties, such as a chemically active surface and high ionic conductivity, which allow it to play a significant role in the thermal reduction (splitting) of these gases, thereby reducing the enormous energy requirements of the process. Still, the poor thermal stability of CeO2 hinders its ability to perform at high temperatures. To resolve this issue, the use of dopants has been suggested. In the present talk, the effects of TiO2 on thermal stability and surface activity of doped ceria will be discussed. TiO2 has been shown to contribute to the thermal stability of ceria by hindering its coarsening thus retaining large surface area up to 800 oC. Moreover, the photocatalytic properties of TiO2 show a promising path to enhance the hydrogen production by using the TiO2-CeO2 system.
Authors : Mahdi Halabi-1, Amit Kohn-2, Shmuel Hayun- 1
Affiliations : 1-Ben-Gurion University of the Negev, Beer-Sheva , Israel; 2- Tel Aviv University, Ramat Aviv, Tel Aviv
Resume : Segregation of defects to the surfaces and interfaces of ionic materials result in the formation of a space-charge potential (SCP). SCP is studied extensively for its critical role on functional properties. Although significant theoretical advances have been achieved, the experimental evidence in nanocrystalline ionic materials is indirect. Therefore, in this work, the electrostatic potential distribution in nano-scale grains of non-stoichiometric MAS (MgO∙0.95Al2O3 and MgO∙1.07Al2O3 ) was measured by off-axis electron holography and compared to the distribution of cations and defects in this material as measured by electron energy-loss spectroscopy. In this manner, we studied the roles of composition, grain size and applied electric field on the formation of a space-charge region. We quantitatively demonstrated that regardless of grain size, the vicinity of MgO∙0.95Al2O3 grain boundaries presented an excess of Mg+2 cations, whereas the vicinity of MgO∙1.07Al2O3 grain boundaries included an excess of Al+3 cations. The degree of structural disorder (i.e., the inversion parameter, i) indicated that as-synthesized MAS were significantly disordered (i between 0.37 and 0.41), with values decreasing toward equilibrium ordering values following annealing (i between 0.27 and 0.31). The application of an external 150 Vcm-1 electric field during annealing further enhanced lattice ordering (i between 0.16 and 0.19). Such variations in the distribution of cations and defects should determine the SCP. However, using these measurements to calculate the SCP was not possible due to the wide range of values reported for formation energies of defects (0.82-8.78 eV). Consequently, we correlated local ionic ordering with electrostatic potential in non-stoichiometric MAS. The magnitudes of the SCP in both MgO∙0.95Al2O3 and MgO∙1.07Al2O3 decreased following annealing from -3.4±0.3V and +2.0±0.2 V to -2.0±0.2 V and +1.6±0.1 V, respectively. Such results underscore the importance of comprehensive nanometer scale characterization of the chemistry and electrostatic potential and providing a comprehensive understanding of defects in complex oxides.
Composites on the base of metals and ceramics : Prof. M.Szafran
Authors : Asaf Levy-1, Aslan Miriyev-2, Amy Elliott-3, Suresh Babu-4, Nachum Frage-1
Affiliations : 1-Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel; 2- Department of Mechanical Engineering, Columbia University in the City of New York, New York, NY, USA; 3-Manufacturing Demonstration Facility, Oak Ridge National Laboratory, Knoxville, TN, USA; 4-Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN, USA
Resume : Functionally graded ceramic-metal composites (cermets) exhibit wide range of properties, controllably altered throughout a single material piece. One of the long standing challenges has been the inablility to fabricate cermet parts with complex geometries. The present work demonstrates a novel integrated approach for fabrication of fully dense complex-shape graded TiC/steel composites by 3D-printing of TiC preforms and subsequent free infiltration with molten carbon steel. Thermodynamic analysis allowed to predict the final composition of the phases and design composites with tailored properties. Gradient in hardness of the composites was achieved by using titanium carbide with different stoichiometries (TiCx), which provides different carbon contents in the steel across the printed part during an infiltration, and hence- different properties of the steel after solidification and heat treatments. The microstructural characteristics of the graded cermets and the effect of the composition on hardness gradient after the heat treatment are discussed in details. The suggested approach opens the door for a wide range of advanced cermet applications in tooling, wear, aerospace and ballistic fields.
Authors : D. Ebner, M. Bauch, T. Dimopoulos
Affiliations : AIT-Austrian Institute of Technology, Center for Energy, Photovoltaic Systems, Giefinggasse 2, 1210 Vienna, Austria
Resume : Transparent electrodes (TEs) are materials that combine a high transmittance while simultaneously providing a high conductivity and are key components in modern optoelectronic applications, e.g. flat panel displays, photovoltaics or flexible electronics. In the current work composite TEs based on an ultrathin Cu layer, embedded between two dielectric layers, are optimized by simulations and experiments. Firstly, different dielectrics are screened in a simulation algorithm for maximizing the transmittance of the trilayer in a broad spectral range (400-900 nm). Based on this, sputtered TEs were developed with the Cu layer on TiOX-coated glass and with an Al-doped ZnO (AZO) layer deposited on top. Experimental optical spectra deviated significantly from the simulated ones for Cu films below 7.5 nm, due to increased absorption caused by the Cu island-like growth. Increasing the sputter power suppresses the film’s island-like morphology, reducing the optical losses and obtaining agreement with the simulated spectra. The figure of merit is superior to previously reported Cu-based TEs, with an average transmittance of 0.80 and minimum sheet resistance of 6.5 Ω. Deposition of the designed trilayer on flexible PET substrate shows reduced performance due to the rough growth of TiOX on PET. Performance can be partially restored by utilizing an additional AZO-buffer layer. Finally, simulations have shown that the trilayer design optimized with air as medium remains practically unchanged in the case of implementation in a hybrid perovskite solar cell of inverted architecture.
Authors : R. Al-Gaashani 1,2, Md. Anower Hossain 1, Fahhad H. Alharbi 1, Abdelbaki Benamor 3, Abdelhak Belaidi 1, Belabbes Merzougui 1, and N. Tabet 1
Affiliations : 1-Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, Doha, Qatar 2-Physics Department, Faculty of Education, Thamar University, 87246 Dhamar, Republic of Yemen 3-Gas Processing Center, Qatar University, PO Box 2713, Doha, Qatar
Resume : Cuprous oxide (Cu2O) and core-shell Cu2O@Cu nanocomposites have been synthesized by a facile wet-chemical approach using aqueous solution of copper (II) sulfate (CuSO4), L-ascorbic acid (C6H8O6) and potassium hydroxide (KOH). The short synthesis time of one minute and the effects of solvent temperature on the crystal structure, morphology and optical properties of the synthesized nanocomposites have been studied. The structural and optical studies showed the nanoparticles prepared at room temperature is phase pure crystalline Cu2O material with band gap energy of 2.08 eV. The morphological studies of the samples prepared at solvent temperatures of 40 oC, 60 oC, and 80 oC showed the core-shell nature of the synthesized Cu2O@Cu nanocomposites where the core Cu2O nanoparticles were encased with the elemental Cu nanocrystallites. The X-ray diffraction and X-ray photoelectron spectroscopy (XPS) studies confirm the increase of Cu content in the Cu2O@Cu nanocomposites with the increase of solvent temperatures from 40 oC to 80 oC. The compositional analyses of the core-shell Cu2O@Cu nanocomposites showed the oxidation of the Cu shell and/or Cu2O core.
Authors : M. Parco-1, I. Fagoaga-1, O. Grigoriev-2, L. Silvestroni-3, I. Neshpor-2, G.Zhunkovskiy-2
Affiliations : 1-Fundacion Tecnalia Research &Innovation, Spain; 2-Frantsevich Institute for Problems of Materials Sciences, Ukraine; 3-Institute of Science and Technology for Ceramics, Faenza, Italy
Resume : In modern constructions of gas-turbine engines ultra-high-temperature ceramics (UHTCs) are in contact with refractory alloys and metals. The use of ZrB2- based ceramics and its coatings in contact with refractory alloys and metals at high temperatures can be substantially limited by the degradation of both ceramics and alloys. That is why the investigation of contact interaction in “ceramics-liquid alloy” systems is very important. In the research the investigation of contact interaction of ZrB2 with melted Ni, Cr, Ni-Cr and Nb alloy has been carried out. It has been shown that at interaction in these systems the process of contact melting takes place by the mechanism which is characteristic for the eutectic systems. The eutectic alloy wets the surface of the boride with a wetting contact angle close to 40 °, 50° and after interacting with it with the formation of more refractory compounds, disappears. The phase composition of the interaction products depends on the ratio of the components in the alloy and the temperature. It comprises double and triple compounds, based mainly on the crystal lattices of zirconium borides and chromium, or Ni5Zr and Ni7Zr2 intermetallides. As the interaction takes place by the eutectic systems mechanisms the application of ZrB2-refractory alloy composition is limited by the eutectic temperature (1000-1200°C). The ways of ZrB2-based ceramics protection and increasing the operating time by the creation of barrier layers have been investigated.
Authors : V.Rud, Y.Povstyana, I.Saviuk, L.Samchuk
Affiliations : Lutsk National Technical University
Resume : In connection with the development of modern technology to traditional ceramic products in recent years include more stringent requirements, thus necessitating the creation of new materials with specified physical and chemical properties. Most promising in this respect are porous ceramic materials that have long life, environmental safety, resistance to household effects, mechanical strength, ease of use and low cost. Porous ceramic materials obtained, usually by SHS are characterized by high porosity and low mechanical strength due to their brittleness. The most interesting material is a porous cermet, because of the unique combination of physical and mechanical properties of metals and ceramics. Metal has a wide range of porosity and permeability relatively high strength, high conductivity, thermal and corrosion resistance. Porous metal-ceramic materials, as a rule, receive by powder metallurgy methods. Metal-ceramic materials have several advantages that allow you to expand the scope of their application. The advantages of cermet materials include first of all a wide range of porosity and permeability, a sufficiently high strength, insensitivity to shock loads. Sintered porous materials obtained by pressing and sintering metal powders and inorganic compounds. For the manufacture of porous sintered filter material assignments apply nesterina and spherical powders of metals and alloys, metal, fiber, clay, and various fillers. Sintered samples regardless of the type of blowing agent have a high hardness, fracture toughness and strength. Using the developed technology of production of sintered products can be achieved in various physical-mechanical and strength characteristics. For porous ceramic materials in the first place come such properties as thermal and chemical stability, mechanical strength. It is the high performance of these properties will provide the versatility and possibility of chemical and thermal regeneration of the filters that are reusable. Because of this, as well as resource and energocascade technologies, such materials are competitive in comparison with existing materials of similar purpose.
Advanced methods of composite production : Dr. Iryna Bilan
Authors : Mikolaj Szafran, Aleksandra Kedzierska-Sar, Emilia Pawlikowska
Affiliations : Warsaw University of Technology
Resume : Colloidal chemistry is recently used in processing of high-quality ceramic elements and composite materials. There exist shaping methods based on colloidal suspensions in fabrication of high performance materials including ceramic-metal and ceramic-polymer composites. Authors are going to present the results of studies on the application of new water-soluble dispersants and monomers which are used in the preparation of different colloidal suspensions of high stability and low viscosity. The amphiphilic macromonomers, due to the proper ratio of the hydrophilic to hydrophobic fragments, play the role of not only an internal plasticizer, but they also modify the adhesion of such binders to the ceramic powder particles and substrates. The authors elaborated the composition of suspensions based on ceramic and metallic powders like nickel and tungsten in the preparation of ceramic-metal composites by slip casting, gelcasting and subsequent sintering. The role of the colloidal chemistry in ceramics will be discussed on the basis of ceramic-polymer composites designed for the electronic devices working at the sub-THz frequencies. These studies were financially supported by the Warsaw University of Technology, Faculty of Chemistry and by National Science Center of Poland (grant number 2014/13/N/ST5/03438).
Authors : Guoxin Hu, Li Wang, Qingqing Zhang, Kena Zhang, Feng Gao*
Affiliations : State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an, 710072, P.R. China
Resume : Ba0.6Sr0.4TiO3/PVDF (BST/PVDF) composites with high dielectric constant and flexibility as well as high dielectric tunability and low process temperature, are highly desirable for applications to produce tunable capacitors, dielectric filters, phase shifters, and other tunable electronic devices. While some key issues constrained its development and applications are still not clear. In this work, BST/PVDF dielectric functional composites connected with silane coupling agent KH550 were fabricated via tape casting followed by hot pressing method. The effects of hot pressing parameters, micromorphology, and particle size of the BST powder on the microstructure and dielectric properties of the composites were studied. A dielectric tunability theoretical model was proposed. The relationship between micromorphology, particle size, and shape factor of the BST powder with the dielectric tunability of BST/PVDF composites were discussed.
Authors : Paulina Wiecinska, Emilia Pietrzak, Natalia Prokurat
Affiliations : Warsaw University of Technology, Faculty of Chemistry, Department of Chemical Technology, 3 Noakowskiego St., 00-664 Warsaw, Poland
Resume : ZTA (zirconia toughened alumina) composites have been prepared by gelcasting followed by pressureless sintering. ZTA composites combine the advantageous features of Al2O3 (high Young modulus and hardness) and ZrO2 (notable fracture toughness and bending strength). Gelcasting belongs to the so called colloidal processing which allows to fabricate near-net-shape ceramic parts without using high pressure apparatus. Gelcasting combines the traditional shaping from ceramic slips with polymer chemistry. The aim of research was to obtain ceramic suspensions having homogenous distribution of zirconia particles in alumina matrix and thus to achieve greater uniformity of the composite after sintering. As organic monomers able to polymerize in the ceramic slurry commercially available as well as synthesized compounds based on acrylates were used. The concentration of the ZrO2 equalled 5-20vol%. Different rheological properties of alumina-zirconia slurries have been observed for each monomer what had a crucial influence on the properties of green bodies. Vickers hardness, fracture toughness and microstructure of obtained ZTA composites is going to be discussed. The project has been financially supported by the National Science Centre Poland (Agreement No. UMO 2014/15/D/ST5/02574)
Authors : Pianpian Chang, Keping Chen, Shuen Liang, Chunrong Tian*, and Jianhua Wang
Affiliations : Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, P. R. China
Resume : Cyanate ester (CE) foams are highly thermal resistant and flame retardant, so they are promising for heat insulation in high temperature environment. However, the knowledge on chemical structure-property relationship of CE foams was little to date. Herein, CE foams with different chemical structures were prepared by using bisphenol A dicyanate ester (BADCy), bisphenol E dicyanate ester (BECy), and tetramethyl bisphenol F dicyanate ester (TBFDCy) as monomers, through a two-step process. Rheological tests were performed to investigate the optimal conditions for the preparation of these foams. The results of scanning electron microscopy (SEM) showed that the foam cells are nearly spherical in foams from TBFDCy and BADCy, and oval in foam from BECy. The thermal properties of the three CE foams were studied by methods of dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetry (TG) / differential thermogravimetry analysis (DTG). The glass transition temperatures (Tg) obtained from DMA tests are 274, 264, and 241 oC for the foams from TBFDCy, BADCy, and BECy, respectively, which are apparently higher than that tested by DSC method. The Tg, compressive properties, and thermal stabilities of the foams are improved after the introduction of alkyl-substituent groups to the same aromatic ring of –OCN functionality, and the chemical structure–property relationship is explained according to the monomer chemical structures.
Authors : A. Fainleib1, V. Bershtein2, O. Grigoryeva1, K. Gusakova1, D. Kirilenko2, O. Starostenko1, P. Yakushev2
Affiliations : 1 Institute of Macromolecular Chemistry of the National Academy of Sciences of Ukraine, 02160 Kyiv, Ukraine; 2 Ioffe Institute, RAS, 194021 St.-Petersburg, Russia
Resume : High performance Cyanate Ester Resins are used in aerospace structures as matrices for carbon-, glass- or organic-containing composites, adhesives, coatings, encapsulants. Three series of high performance polymer subnano- and nanocomposites have been synthesized by polycyclotrimerization of Cyanate Ester Resins (CER) in the presence of ultralow amounts of (1) epoxy-POSS, (2) amino-MMT, and (3) combination of tetraethoxysilane (TEOS) and ?-aminopropyltrimethoxysilane polymerized to SiO2 by sol-gel method. Hybrid thermally stable densely cross-linked polycyanurate (PCN) network containing the chemically incorporated nano- or subnanometer-sized silica-based units were synthesized at high temperature. The most substantial positive impact on PCN dynamics, thermal and mechanical properties was attained at ultralow nano- or subnanofiller contents, e.g., 0.025 - 0.1 wt.%. It was revealed that the modifier particles sizes in the best composite samples were 1-3 nm for ECH-POSS, 2 to 3-nanolayer stacks and individual nanolayers for PCN/amino-MMT series, and the SiO2 nodes of subnanosize (0.5-1.0 nm) were formed in the best samples for PCN/SiO2 composites obtained using sol-gel method. The pronounced effect of constraining dynamics in the nano- and subnanocomposites was confirmed by increasing Tg by ~500, the displacement of the onset of glass transition range by 800 to higher temperatures; increasing activation energy and motional event scale in the glass transition, increasing modulus by ~ 60% at room temperature and its multifold rise at high temperatures. Thus, the upper temperature limit for application of these valuable high temperature materials may be substantially increased in this way.
Production and properties of composites based on nitride and carbide ceramics : Dr.Paulina Wiecinska
Authors : B. Ratzker, M. Sokol, S. Hayun, S. Kalabukhov, N. Frage
Affiliations : Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Resume : Silicon nitride (Si3N4) is a very important structural ceramic, with good combination of mechanical properties at ambient and high temperatures, excellent wear resistance, thermal shock and corrosion resistance. There are several processing routs for fabrication of fully dense Si3N4, including pressure-less sintering (with sintering aids), hot pressing and hot isostatic pressing. In the present study, High-Pressure SPS (HPSPS) was used to fabricate single phase α-Si3N4 by sintering at relatively low temperature (1350°C) with typical sintering additives (Y2O3, Al2O3) and LiF. Density of produced samples increased significantly with applied pressure and full consolidation was achieved for the specimens sintered under 500-650 MPa. The obtained silicon nitride displayed high hardness (~1600-1800 HV2) and good fracture toughness (~6 MPa•m1/2). It was established that even small amounts of LiF (2%) have a considerable effect on the consolidation of the silicon nitride powder with sintering additives, such as Y2O3 and Al2O3. It was suggested that LiF dissolves in the liquid phase, which consists of oxide additives and silica on the surface of the silicon nitride powder significantly improves wetting at the oxide/silicon nitride interface. Improved wetting allows for a homogeneous distribution of the oxide melt within the sintered body and enhanced its densification.
Authors : Fang Ye, Litong Zhang, Xiaowei Yin, Yongsheng Liu, Laifei Cheng, Chengyu Zhang
Affiliations : Northwestern Polytechnical University, Xi’an
Resume : A novel Si-C-N ternary ceramics were prepared by chemical vapor infiltration/chemical vapor deposition (CVI/CVD) from SiCl4–C3H6–NH3–H2–Ar precursor system. The as-received Si-C-N ceramics were composed of amorphous Si3N4 matrix and crystalline SiC nano-particles (with a homogeneous size of 5 nm) uniformly distributed in the amorphous matrix. This distinctive microstructure made Si-C-N ceramics not only maintain a high mechanical property but realize a low dielectric constant and a high dielectric loss, which led to a minimal electromagnetic reflection coefficient of -42.6 dB, ranking the best level in the already-reported high-temperature structural and wave-absorbing ceramic materials by CVI/CVD. After that, SiC fibers reinforced Si-C-N matrix composites (SiC/Si-C-N composites) were designed and prepared, and their properties were investigated. Also SiC/Si-C-N composites possess a good mechanical property combined with a promising wave-absorbing ability based on the modulus matching and electromagnetic matching between fibers and matrix.
Authors : N.Chekan,Y.Auchynnikau,I.Akula,Y.Eysymont
Affiliations : Yanka Kupala State University of Grodno Physico-Technical Institute of the National Academy of Sciences of Belarus
Resume : The morphology and structure of the surface layers of the Al-Ti-N covers formed on the steel surface are considered. The nature of the mutual influence of the layers on the distribution of active centers and the energy of interphase interaction is established. A model is formulated that makes it possible to carry out an analytical description of diffusion processes under conditions of contact chemical reactions. The distribution of inclusions in the structure of coatings is obtained by numerical methods. The kinetic features of diffusion processes and their dependence on the layer thickness and temperature are determined. The supply of a potential displacement of -50 V to the substrate leads to the formation of a strong texture in Al-Ti-N films and extremely high compressive stresses, and, therefore, to an increase in the lattice period in the direction of the normal to the surface, which affects the strength characteristics of the coatings under investigation.
Authors : Chengyu Zhang, Fang Ye, Yongsheng Liu, Mei Li, Dong Han
Affiliations : Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an 710072, P. R. China
Resume : Continuous fiber reinforced silicon carbide matrix composite(C/SiC)is an important thermo-structural material with excellent advantages, such as high temperature resistance, high specific modulus, oxidation resistance and erosion resistance. The creep behavior of the high-temperature structural materials is one of the most important mechanical properties. In this paper, the creep induced strengthening of the composite was carried out in vacuum. The microstructural damage and residual stress were studied to primarily reveal the creep strengthening mechanism. The composite could be strengthened by the creep at 1400-1600 oCwhere smaller stress and higher temperature was applied to avoid significant damage matrix. The matrix cracking stress(σmc)of the composite is improved. Larger σmc can be achieved when the material was exposed to greater stress during the creep strengthening process.The residual stress distribution and interfacial shear stress can be modified by the creep strengthening treatment for the 2D-C/SiC composites. The compressive stress in carbon fiber change to the reverse, that is, tensile stress, for of the crept composites. Meanwhile, the tensile stress in the SiC matrix become to be compressive stress. The larger compressive stress in the SiC matrix can be produced as the creep stress (or temperature) increase at the same creep temperature (or stress).
Authors : Kryachek V.M., Ragulya A.V., Chernyshev L.I., Gudymenko T.V., Fedorova N.Ye.
Affiliations : Frantsevich Institute for Problems of Materials Sciences
Resume : It is known that the most effective methods for the production of nanostructured nitrides are methods of intense plastic deformation (torsion under quasi-hydraulic pressure or uniaxial compression, all-round forging, equal-channel angular pressing), which allow creating a nanostructure and preventing grain growth during consolidation. Good results can be obtained by activation of the sintering process by the following the additives Al2O3, Y2O3, Yb2O3, ZrO2, SiO2. One of the new ways of nanopowder consolidation is the technology of sintering at a controlled rate of compaction, which allows significantly limit the growth of grains and preserve their nanocrystalline state. The results for using of the plasma sintering, microwave, solar sintering, electrophysical methods are presented. It was shown that processing of nitride billets with the help of microwaves leads to accelerated heating and decreasing of the sintering temperature by 200-400 ° C .In particular, during electric discharge (spark-plasma) sintering, for TiN powder (average diameter ~ 50-150 nm), the nanostructure of the material with a crystal size of up to 100 nm is saved up tosintering temperature of 1200 ° C. SHS technology allow to product the high strength nitrides. Sintering in a solar furnace of Si3N4 powder (particle size 20-30 nm) with additions of Y2O3, Al2O3, AlN at a temperature of 1500-1550 оС made it possible to obtain a dense nanoscale structure and high mechanical properties in the material (higher than for free sintering and hot pressing)
Poster session 1 : Dr. Iryna Bilan
Authors : Dmytro Brodnikovskyi -1, Mykola Gadzyra - 1, Volodymir Galyamin - 1, Oleksandr Vasylyev -1, Andryi Ivasyshyn - 2
Affiliations : 1 - Frantsevich Institute for Problems of Materials Science of NASU, Krzhizhanivsky str. 3, 03680, Kyiv, Ukraine; 2 - Karpenko Physico-mechanical institute of NASU, Naukova str. 5, 79060, Lviv, Ukraine
Resume : Solid oxide fuel cells (SOFCs) have recently attracted a lot of attention, owing to their high efficiency, low pollution and relatively flexible fuel choice (CnHm, H2, Co etc). SOFCs are electrochemical energy conversion devices that directly convert chemical energy of fuel and oxygen into electricity and heat. Interconnects are one of the most important parts of the energy system based on SOFC. The main role of interconnects is to connect single cells in SOFC stack, to multiply the SOFC electrical power and to separate the oxidant and fuel gases. At present chromium-forming ferritic stainless steels (20-25 vol.% Cr) are considered as the most promising interconnect materials for intermediate temperature SOFC (600-800°C), due to their conductive oxide scale, appropriate thermal expansion and low cost. However, two major challenges are associated with ferritic stainless steels. There are long term oxidation at the SOFC operating conditions and poisoning of the porous cathode by Cr evaporation, which would lead to a significant upsurge in cell resistivity and as a result SOFC performance degradation. Present work is focused on elaboration of Ti in-situ composites for SOFC application. This material should help to avoid the problems associated with ferritic stainless steels and to improve SOFC stack portability by reducing of its whole weight. Under this work Ti in-situ composite was manufactured and studied for mechanical behavior and electrical conductivity before and after exposure in hydrogen at 600°C. It was found that the strength of Ti-Si-C in-situ composite after three hours of exposure in hydrogen at 600°C was not decrease. The strength of the material in the initial state was 55.8 MPa, and after exposure in hydrogen - 57 MPa. Exposure in hydrogen slightly increased the electrical resistance of the samples from 1.2 × 10-6 to 1.25 × 10-6 Ohm∙m, still remains relatively low. Thus, Ti in-situ composites are quite promising for SOFC’s power systems application and require further investigation.
Authors : G. Akimov1, A. Novokhatska1, L. Kovalenko2
Affiliations : 1. Donetsk Institute for Physics and Engineering named after O.O.Galkin of NASU, Nauky Av. 46, Kyiv, 03680, Ukraine 2. Vernadsky Institute of general and inorganic chemistry of NASU, Akademika Palladina Av. 32/34, Kyiv, 03142, Ukraine
Resume : We present the results of a study of the conductivity at temperatures from 750 to 950 K and microstructure of ceramics of 10 mol.% Sc + 1 mol.% CeSZ + 1,5 mol.% Bi2O3, and 10 mol.% ScSZ + 1,5 mol. % Bi2O3 doped by 1,0 mol. % Al2O3 and 2,0 mol. % Al2O3 compositions. All powders were prepared by co-precipitation methods. The introduction of 1.5 mole% of Bi2O3 was to ensure liquid-phase sintering and reduce the sintering temperature to 1300 ° C. The billets were made using cold isostatic pressing with a pressure of up to 800 MPa and sintered at 1300 ° C for 3 hours. The study of the microstructure of ceramic samples showed that the introduction of aluminum oxide leads to a significant increase of grain size. It’s found that the introduction of 1,0 mol.% Al2O3 increases total conductivity compared to 10 mol.% Sc + 1 mol.% CeSZ + 1,5 mol.% Bi2O3 ceramics, and the introduction of 2,0 mol.% Al2O3 reduces the conductivity of the electrolyte of ScSZ + 1,5 mol.% Bi2O3 almost 1,5 times. It’s found for the first that the activation energy of the grain boundary conductivity decreases and the activation energy of the grain volume increases in the ceramics of 10 mol.% ScSZ + 1,5% mol.% Bi2O3 + 2,0 mol.% Al2O3 composition. Perhaps this is due to the appearance of insulating layers of Al and Bi in the border region of the grain formed during liquid-phase sintering at a temperature of 1300 °C, which leads to an increase in resistance, but also contributes to a small reduction in the energy barrier for the grain boundary.
Authors : Gulcihan Guzel Kaya, Elif Y?lmaz, Huseyin Deveci
Affiliations : Selcuk University, Chemical Engineering
Resume : In recent years, hybrid composites that generally consist of single matrix and two or more fillers have become important among advanced materials in various fields such as automotive, spacecraft, construction and marine applications . Organic/inorganic hybrids can improve mechanical, thermal, chemical resistance and water sorption properties in addition to cost reduction . While agricultural wastes are utilized as inexpensive fillers with decreasing environmental pollution, inorganic additives can be also offered to provide further developments in the properties of composite materials . In this study, epoxy hybrid composites were prepared with the addition of different weight of kaolin (0.5, 1, 2, 3, 5 wt%) to fixed weight of 3 wt% bean pod. Morphological, mechanical, thermal and water sorption properties of the composites were investigated with different analyses and tests. Morphological analyses showed uniform distribution of hybrid filler in epoxy resin. The maximum tensile strength was achieved for the composite including 2 wt% of kaolin as per tensile test. Decomposition temperatures and char residue of the composites exhibited an increase with increasing kaolin content. The composite filled with 5 wt% kaolin had lowest water sorption percentage as 0.87%. In the light of these results, it can be said that sustainable hybrid composites with enhanced properties were successfully produced.  Jawaid, M., Abdul Khalil, H.P.S., Abu Bakar, A., and Noorunnisa Khanam, P., 2011, Chemical resistance, void content and tensile properties of oil palm/jute fibre reinforced polymer hybrid composites, Materials and Design, 32, 1014-1019.  Flynn, J., Amiri, A., and Ulven, C., 2016, Hybridized carbon and flax fiber composites for tailored performance, Materials and Design, 102, 21-29.  Saba, N., Paridah, M.T., Abdan, K., and Ibrahim, N.A., 2016, Effect of oil palm nano filler on mechanical and morphological properties of kenaf reinforced epoxy composites, Construction and Building Materials, 123, 15-26.
Authors : Tyshchenko Ja. S., Lakiza S. M., Dudnik E. V.
Affiliations : Frantsevich Institute for Problems of Materials Science NAS of Ukraine
Resume : The systems Al2O3-TiO2-Ln2O3, where Ln = (Y and Er) include binary compounds with pyrochlore (Ln2Ti2O7), garnet (Ln3Al5O12), perovskite (LnAlO3), monoclinic (Ln4Al2O9) structures, rhombic structure (tieilite Al2TiO5), who have found or even find application as functional and structural materials. In the system Al2O3-TiO2 compound Al2TiO5 was found, with unique abnormally low thermal expansion coefficient comparable with that for SiO2. This allows creating a number of materials for automotive industry, tough ceramics, catalyst carriers, wear- and corrosion-resistant ceramics etc. on its basis. Low strength and sintering ability of tieilite put forward the task for creating composite materials with its participation. Binary systems TiO2-Ln2O3 are promising for creation of multi-component composite materials with strength determined by several strengthening mechanisms. Adding of a third component to these systems allows adjusting various materials properties as by changing their chemical composition within the constant phase composition, and due to the new eutectics not found in the binary systems. Such materials can increase the number of new eutectic composite materials, for example, in a number of systems Al2O3-TiO2-Ln2O3. Phase equilibria in the Al2O3-TiO2-Ln2O3 systems (Ln = Y and Er) were studied for the first time in the temperature range 1400 C-2440 C. Predominantly eutectic interaction was established in these systems and coordinates of new two-phase and three-phase eutectics w-ere determined for the first time. It opens the possibility of creating new structural and functional materials by directional solidification of eutectics.
Authors : Jeong Yun, Ki Seung Kim, Ji Hoon Seo, Seung Woo Lee
Affiliations : School of Chemical Engineering, Yeungnam University, Korea
Resume : A variety of techniques for the determination of heavy metal ions have been investigated intensively in the literature including spectroscopy, chromatography, electrophoresis, and fluorescence detection.[1,2] Sensing technologies for cations have become very important for both biological and environmental applications. in response, a large class of cation sensors based on coordination chemistry has been developed. Several are selective for both alkali and alkaline earth metals, such as lithium, sodium, potassium, zinc, calcium and magnesium, in which detection is necessary to monitor and regulate a number of cellular functions. Heavy metal cations such a lead and mercury have also been studied, due to their deleterious effects on biological system. In addition, there are several other environmental concerns were prepared by diazotization reaction. The molecular structures of azobenzene were analyzed by means of Fourier transform nuclear magnetic resonance (FT-NMR), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope(FE-SEM) and UV-visible spectroscopy. Azobenzene based nanomaterials successfully detected Cs, Cu, Fe(II), Fe(III) and Sn ion. The observed color was changed from red to violet.
Authors : Kwan ho Mun, Deok gi Hong, Seung woo lee*
Affiliations : School of Chemical Engineering, Yeungnam University, Korea
Resume : The thermal conductivity along the out-of-plane direction in polyimide (PI) blend films containing amorphous Boron Nitride (BN) was investigated. PI blend films composed of a sulfur-and a fluorine-containing PI were prepared via spin-coating and thermal curing of precursor solutions containing BN. Microphase-separated structures with ‘‘vertical double percolation (VDP)’’ morphology were spontaneously formed in the films, in which two phases were separately aligned along the out-of-plane direction, and BN were preferentially interacted in the sulfur-containing PI phase. The blend film exhibits 350% enhancement of thermal conductivity at 25 vol% of BN, whereas only 90% enhancement was observed in the monophase PI film containing homogeneously dispersed BN. These results indicate that the VDP structure with selective incorporation of BN functions as an effective thermal conductive pathway.
Authors : Kiho Kim, Seokgyu Ryu, Hyun Ju, Dabin Park, Jooheo Kim
Affiliations : School of Chemical Engineering & Materials Science, Chung-Ang University
Resume : In this study, we developed a highly thermally conductive PPS composite containing boron nitride (BN) as a thermally conductive ceramic filler. (3-Aminopropyl) triethoxysilane was doped onto the surface of hydroxyl-functionalized BN using a simple sol–gel process. The modified BN particles were embedded in a PPS matrix via a melt mixing process using a twin extruder to form BN-Si composites. The maximum thermal conductivity 3.09 W/m·K was exhibited by the surface-modified BN-Si containing 60 wt%. This value was 116% higher than the thermal conductivities of the pristine BN and PPS matrix, respectively. The surface-treated composites also showed an improved storage modulus because of an improvement in the interfacial adhesion and interaction between the BN filler and the PPS matrix.
Authors : O. Otychenko*, O. Sych, N. Ulyanchych, T. Tomila, L. Protsenko, O. Budylina, I. Uvarova, M. Demyda*
Affiliations : Frantsevich Institute for Problems of Materials Science, NAS of Ukraine, 3 Krzhyzhanovsky Str., Kyiv 03680, Ukraine *National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", 37 Peremogy Ave., Kyiv 03056, Ukraine
Resume : It is well known that hydroxyapatite (HA) is chemical analog of the bone tissue mineral component. HA seems to be the most suitable material for bone engineering. However, the risk of bone infection is a serious trouble associated with bone filling and replacement. In resent years, the results of HA studies as drug carriers for antibiotics, cytostatics, acetylsalicylic acid, indomethacin, hormones have a big interest. The adsorption activity of HA different nature: (biogenic HA ?Osteoapatyt Keramichnyi?® (Ukraine) and synthetic stoichiometric and nonstoichiometric HA ?Biomin G?® (Ukraine) with particle size of < 50 ?m) towards methylene blue have been studied in the present work. The materials were examined by SEM (RE?-106I microscope, Ukraine), XRD analysis (Ultima IV Rigaku diffractometer, Japan) and IR spectroscopy (FCM 1202 Fourier spectrometer, Russia). The specific surface area was evaluated by heat desorption of nitrogen according GOST 23401-90. Saturation of HA powder with the methylene blue performed according GOST 4453-74 using a water solution of methylene blue with a concentration of 1500 mg/l. HA powder was immersed into the solution for 45 min (250 ml of the solution per 1g of the powder) and than centrifugated (CLK-1, Russia). The methylene blue concentration on the HA powder was determined by photometric analysis (FEK-56M, Russia). It was established that adsorption activity of biogenic and synthetic HA is similar and equal to 106-108 mg/g despite to the significant differences of specific surface area (10.8 and 90 m2/g, respectively). It could be connected to the own nanoporous structure of biogenic HA. All materials are perspective as drug delivery systems in medicine.
Authors : Y. NAIDICH, M. GRIGORENKO, E. CHERNIGOVTSEV
Affiliations : I, M. Frantsevich Institute of Problems of Materials Science NAS of Ukraine (IPMS NASU)
Resume : Taking into account a perspective to realize astronauts flight to the Mars planet ("Mars one" project) and already known composition of the atmosphere of this planet (based on carbon dioxide), we considered a possibility to realize some metallurgical processes of the open type (synthesis, casting of metal alloys, brazing-joining of metals etc.) which may be also important e. g. for the installation-repairing works. Using developed by us vacuum?gas installation we performed some ground-based experiments on melting and casting of copper and some its alloys (in particular, Cu-Ag (72%, Cu-Ni), also Ag, Pb in the atmosphere imitating ?martian? conditions. Metal meltings were carried out in a chamber of vacuum apparatus equipped with pumping and CO2 leak-in means under the CO2 pressure of 0,1-0,01 atm. Thus metal/alloys ingots of a rather good quality having clean bright surfaces were obtained. Also some experiments on wetting of steal, Ni, ceramic supports by Cu-Ag (72%) alloy, Ag, Cu were performed. Data obtained may serve as evidence of possibility to realize some metallurgical technologies in the atmosphere of Mars. Apparently a range of metals used having higher affinities for oxygen may be extended later on e.g. at the expense of getters.
Authors : Lays Dias Ribeiro Cardoso, Marinés Chiquinquirá Carvajal Bravo Gomes, Djoille Denner Damm*, Vladimir Jesus Trava-Airoldi, Evaldo José Corat
Affiliations : Instituto Nacional de Pesquisas Espaciais - INPE, Avenida dos Astronautas, 1758, CEP 12227-010. São José dos Campos - SP, Brazil
Resume : Carbon fiber (CF) based composite materials are largely used in industries that need high strength, light and stiff materials, especially aerospace industry. But advanced composite materials has low interlaminar shear strength; grafting carbon nanotubes (CNTs) on carbon fiber is a promising mean to enhance mechanical properties of advanced composites. We grafted CNTs on carbon fiber surface after a thermal-chemical vapor deposition (TCVD) treatment with hexamethyldisiloxane (HMDSO). This innovative thermal treatment with HMDSO enabled a uniform and dense growth of CNTs on CF. The HMDSO modifies chemically the CF surface and changes its superficial energies. The growth method preserves the mechanical properties of CF, usually damaged by CNTs deposition by other methods. The HMDSO thermal treatment is performed for only one minute and the CNTs growth for five minutes, using a floating catalyst (ferrocene). It is a fast CVD process that can be applied in a large scale production line. Results from tensile strength of fiber tows test showed that the tensile strength of fiber tows was maintained after CNTs growth, and the mode I interlaminar fracture toughness of unidirectional composite test showed that the CNTs increases the energy release rate of composite. CF was characterized using scanning electron microscopy, X-ray photoelectron spectroscopy and a goniometer.
Authors : Justyna Zygmuntowicz; Aleksandra Miazga; Agata Baczyńska; Katarzyna Konopka
Affiliations : Warsaw University of Technology Faculty of Materials Science and Engineering 141 Woloska Str. 02-507 Warsaw Poland
Resume : The presented work focuses on the quantitative description of the molybdenum particles in alumina matrix. The prepared Al2O3-Mo composites have been fabricated via a centrifugal slip casting technique. This method allows to fabricate the graded distribution of molybdenum particles in the hollow cylinder composites. The horizontal rotation axis was applied. Aqueous based slurries (with 50 vol.%; 40 vol.% content of solid phase) containing alumina and molybdenum powder (10 vol.%) were tested. The obtained samples were characterized by X-ray diffraction studies (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS). Quantitative stereological analysis of the microstructure was conducted using scanning electron microscopy (SEM). The results of quantitative description of microstructure allowed determining the differences between the locations molybdenum particles in composites obtained via centrifugal slip casting. This work was financially supported by the Faculty of Material Science and Engineering Warsaw University of Technology (statute work).
Authors : A. Novokhatska1, G. Akimov1, L. Kovalenko2
Affiliations : 1. Donetsk Institute for Physics and Engineering named after O.O.Galkin of NASU, Nauky Av. 46, Kyiv, 03680, Ukraine 2. Vernadsky Institute of general and inorganic chemistry of NASU, Akademika Palladina Av. 32/34, Kyiv, 03142, Ukraine
Resume : We present the results of a study of the phase compositions and microstructures, electroconductivity at temperatures from 50 to 500 K of ceramic samples of 10 mol.% Sc + 1 mol.% CeSZ (electrolyte) – (Nd0.67Sr0.33)1-xMn1+xO3 (cathode) composites depending on the content of excess manganese (x=0; 0.2). The powders of cathode and electrolyte materials were mixed in equal proportions, compacted to the billets and sintered at 1000 °C for 3 hours in the air. The study of the X-ray data and SEM images of ceramic samples showed that the introduction of excess manganese in cathode material leads to preservation of phase compositions and uniform grain growth for both materials of composite. It’s found that in a sample with x=0.2 the first stage of sintering was realized which is confirmed by sample shrinkage when the sample with x=0 was remained a powder body. This behavior has affected the electroconductive properties of the samples. It’s found that the sample with excess manganese has a electroconductivity twice more than the sample without excess manganese in all temperature range. Moreover the activation energy of conductivity for sample with x=0.2 is 0.38 eV which is almost two times less than for x=0 (0.52 eV). This is due to the fact that the excess manganese located on the surface promotes a sintering and forming of grain boundary that leads to reduction in the energy barrier for charge carriers.
Authors : Raiya Kuze, Akiyoshi Otake, Soya Nakano, Kmihiro Yamanaka, and Hirohisa Taguchi
Affiliations : Department of Electrical and Electronic Engineering, School of Engineering, Chukyo University
Resume : In this study, we present the formation mechanism and heat dissipation characteristics of a Cu dendrite (CuD) deposited on an Al/Zn substrate. The CuD has a three-dimensional fractal structure with a maximum thickness of 200 μm, and its surface area is over 200 times larger than that of the reference sample. The mechanism of CuD formation was as follows. CuDs were precipitated on the Al / Zn substrate surface where Cu could not be plated. An Al / Zn substrate was introduced as a cathode into the supersaturated CuSO4 solution to forcibly precipitate Cu crystals on the substrate surface. At this time, Zn crystal grains separated from the Al / Zn substrate surface under the influence of sulfide ions, and Cu granular crystals precipitated in the separated Zn. Cu granular crystals grew along the direction of the C axis in the form of stacking on this Cu granular crystal. In the vicinity where the C axis crystal growth of the Cu crystal exceeded a thickness of 100 μm, a Cu plate crystal started forming from the Zn microcrystals separated at the early stage of formation of the Cu granular crystal, and CuDs having the three-dimensional fractal structure were considered to be constructed. In addition, the CuDs have an enormous surface area and show a strong heat radiation effect. The heat dissipation rate of CuDs was –2.0 °C/s (reference sample: –1.2 °C/s). We also showcase a high-performance heat pipe that was fabricated with this structure.
Authors : Piotr Pietrzak , Grzegorz Matyszczak , Karolina Pietak , Michal Wrzecionek , Daniel J. Jastrzebski , Slawomir Podsiadlo 
Affiliations :  Faculty of Chemistry, Warsaw University of Technology, ul. Noakowskiego 3, 00-664 Warsaw
Resume : This study researches and shows possibility to synthesize kesterite nanoparticles composite with cheap and abundant metal e.g. Nickel. Kesterite nanoparticles have been prepared in organic solvent, using metal salts and sulfur, and later subjected to electroless chemical bath in aqueous solutions of appropriate chemical compounds. The resulting composites were analysed for use as photoactive materials for photovoltaic. Samples were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and spectrophotometry UV-Vis-NIR.
Authors : Yevhen Yashchyshyn, Konrad Godziszewski
Affiliations : Warsaw University of Technology, Institute of Radioelectronics and Multimedia Technology
Resume : Sub-terahertz frequency range is becoming increasingly important due to a large number of applications. The most common applications are radars, high data rate communication systems, spectroscopy or security scanners. Development of electronic devices operating at sub-THz frequencies requires new advanced ceramic or composite materials. Therefore, precise determination of electromagnetic properties of materials is required for both designers and manufacturers of electronic systems. There are many characterization methods of materials in sub-THz range, however all of them have some limitations. For this reason we developed a new frequency-domain measurement technique based on the standing wave concept. This method makes it possible to characterize every dielectric by using only the measured complex reflection coefficient without accurate information about the thickness of dielectric sample. Complex permittivity can be determined fast and easily based on simple data processing of raw measurement results. This is important especially in manufacturing process of materials when constant characterization is needed. The mathematical model of the method was formulated and uncertainty analysis was performed. Precision of the proposed method is comparable to other quasi-optical methods presented in the literature. For verification of this technique several measurements of different dielectrics, including composites and ceramic materials, were made.
Authors : Bo Min Kwak, The Thien Ho, Younghwan Kwon
Affiliations : Department of Chemical Engineering, Daegu University, Gyeongsan, Gyeongbuk 38453, Republic of Korea
Resume : Porous polymeric composites are widely used in many applications for their properties of lightweight, superior thermal insulation, high energy/sound absorbing abilities, low thermal conductivity, and large compressive strains. The hollow thermoplastic microspheres are spherical plastic particles consisting of a polymer shell encapsulating a hydrocarbon gas. When the gas inside the shell is heated, it increases in pressure and the thermoplastic shell softens, resulting in a dramatic increase in the volume of the microspheres. Researcher used these microspheres for various high-performance structural foam materials. In this study we study the thermal insulation and thermomechanical properties of polymeric composites prepared using polymeric expanded and hollow glass microspheres, respectively. A one-step bulk UV-irradiated polymerization was used to prepare polymeric composites. This study carries out comparative research on porous polymeric composites filled with expanded organic and hollow glass microspheres. Theoretical analyses and experimental measurements of thermal conductivity are instructional for the exploitation and application of these composites. The thermal conductivity of these materials is measured by THB method and compared with theoretical prediction. Tensile and compression tests have also been carried out for both composites. Details of the synthesis, thermal insulation and thermomechanical characterization are presented in this study.
Authors : A. Dauletbekova1, Z. Baimukhanov1, A. Kozlovskiy2, A. Usseinov1,2, A. Akilbekov1, M. Murzagaliev1 E. Zhurkin1, R. Nauryzbayeva1
Affiliations : 1L.N. Gumilyov Eurasian National University, Astana Kazakhstan 2Institute of Nuclear Physics AB, Astana, Kazakhstan
Resume : Amorphous silicon oxide layer with 700 nm thickness was formed by the thermal oxidation method of silicon substrate. Latent SHI tracks in SiO2 layer were created by irradiation of Xe ions (E=200MeV, Φ = 108 - 109 cm-2). After etching of ion tracks in 1% water solution of hydrofluoric acid (HF) at 300K, a precipitation of Zinc was performed by electrochemical (ECD) method at room temperature. Morphology of SiO2/Si structures surface before and after precipitation was examined on SEM and AFM. Frontal surface and cross-section studies showed filled nanochannels. The formation regime of nanocrystals of zinc oxides in the track template is developed. The changes in luminescence and photovoltaic characteristics of deposited samples were investigated. The X-ray diffraction analysis made it possible to monitor the obtained structures. For a detailed study of nanocrystals synthesis at atomic level, an analysis of absorption processes of various impurities on the oxides surfaces was carried out using computer simulation methods. The energy band structure of pure/doping surface was modeled, where total and partial density of states (DOS) signatures of surface host atoms and impurity atoms was computed. Also, the effective charges on atoms and chemical bounds have been estimated using the Mulliken population analysis.
Authors : Yeongkwon Kang, Younghan Song, Hyungsup Kim, Bong-Gi Kim
Affiliations : Department of Organic and Nano System Engineering, Konkuk University, Seoul, Korea
Resume : Polymers having high thermal conductivity have been of great interest because of the necessity of heat management in electronic devices evolving into miniaturization and complex. In order to overcome this issue, thermally conductive composites have been actively developed. However, because of poor thermal conductivity of bulk polymers, the preparation of composites still require excessive amount of thermal conductive fillers causing deterioration of processability including the issue of manufacturing cost. The main reason resulting in low thermal conductivity of bulk polymers is mainly due to the presence of defects such as polymer chain ends, entanglement, random orientation, void and impurities. Thus, to minimize those defects in polymer matrix, two different polymers showing a thermotropic liquid crystalline behavior were designed and their thermal conductivity was compared depending on processing temperature. The liquid crystalline nature of obtained polymers was characterized with differential scanning calorimetry (DSC) and polarized optical microscopy (POM), respectively. Both polymers exhibited decent level of thermal conductivity (0.4 W/m·K – 0.5 W/ m·K), but TBPC10 containing a longer space (decyl) between mesogenic units seems to provide better property than TBPC8 having a relatively short spacer (octyl). To correlate the distinctive thermal conductivity between TBPC10 and TBPC8, the melt viscosity of liquid crystalline state of each polymer was measured and correlated with their crystallinity. Based on obtained results, it was concluded that liquid crystalline polymers could be an efficient platform to regulate unexpected defects in a polymer matrix, offering high thermal conductivity via well-organized polymer assembly including high crystallinity.
Authors : Photoredox Catalysts/Photoinitiators with Unique Thermally Activated Delayed Fluorescence Property: Structure/Reactivity/Efficiency Relationships and Use in LED 3D Printing Systems.
Affiliations : a Institut de Science des Matériaux de Mulhouse IS2M ? UMR CNRS 7361 ? UHA, 15, rue Jean Starcky, 68057 Mulhouse Cedex, France. b Laboratoire de Matériaux, Catalyse, Environnement et Méthodes analytiques (MCEMA-CHAMSI), EDST, Université Libanaise, Campus Hariri, Hadath, Beyrouth, Liban. c Laboratoire de Physicochimie des Polymères et des Interfaces LPPI, Université de Cergy-Pontoise, 5 mail Gay Lussac, Neuville-sur-Oise, 95031 Cergy-Pontoise Cedex, France d Aix Marseille Univ., CNRS, ICR UMR 7273, F-13397 Marseille, France.
Resume : This paper is devoted to the effect of a thermally activated delayed fluorescence (TADF) property in new photoinitiators/photoredox catalysts. Four carbazole derivatives A1-A4 exhibiting a TADF character are synthesized and proposed for the time as high performance visible light photoinitiators/metal free-photoredox catalysts, in the presence of an amine or/and an iodonium salt, for both the free radical polymerization (FRP) of (meth)acrylates and the cationic polymerization (CP) of epoxides upon visible light exposure using Light Emitting Diodes LEDs @405nm, @455nm and @477nm. Interestingly, the impact of the substituent effect on the excited state lifetimes and therefore on the photoinitiating ability of a series of substituted carbazoles was clearly evidenced and examined. Upon bromination of the carbazole core, clear effects on the excited state lifetimes and light absorption were demonstrated, enabling to tune the initiator performance. Excellent polymerization initiating abilities are found and high final monomer conversions are obtained. The use of these novel carbazole based systems in photocurable cationic formulations for LED projector 3D printing is particularly outlined. TADF molecules allow a more efficient reaction from the excited singlet state as a result of their prolonged lifetimes i.e. this effect is well highlighted through a comparison with previously published none-TADF metal-free photoredox catalysts. A full picture of the involved photochemical mechanisms is also provided. Carbazoles exhibiting a TADF character paves the way towards metal-free photoredox catalysts active in both oxidative and reductive cycles with efficiency on par with those of the traditional metal-based photoinitiators.
Authors : Seongjun Moon, Kyung Jin Lee*
Affiliations : Department of Chemical Engineering and Applied Chemistry, College of Engineering, Chungnam National University, 99 Daehak-ro (st), Yuseong-gu, Daejeon, 305-764, Republic of Korea
Resume : Many researchers have attracted the electrospinning process because the process can use polymeric most polymeric materials as its processing materials such as PAN, PVA, and PMMA. Although the method has these advantages, however, the practical uses of the method could not be found in industrial fields due to its lower productivity than other spinning methods. Thus, some researchers have tried to increase the production rate of the electrospinning system via multi-needle electrospinning and needleless electrospinning. Despite of these efforts, it is also hard to use these methods for industrial fields due to morphological destruction of the spun nanofiber, which was induced by electrical interferences between the needles and limited selection of materials. Therefore, in order to overcome these limitations, we introduced the syringeless electrospinning system using helically probed rotating cylinder (HPRC). The HPRC has conductive rod on its cylindrical structure, and the probed conductive rods were located on the cylinder helically. The rotating cylindrical structure impregnating several needles on surface are connected with DC power supplier, and the polymeric solution is located under the rotating object. As the positive voltage are applied on the needles and the rotating drum is rotated with desired rpm, polymer droplet was formed on end of each needles, and Taylor cones are generated on each needles when positive voltage is applied. The helical placement of the conductive rods help to reduce the electrical interferences between the rods effectively and it can provide clear morphology of nanofibers. Furthermore, we obtained the clear morphology of nanofibers with increased producing rate in lower supplied voltage using various polymers and some polymeric solutions that was hard to use for general electrospinning
Authors : Chang-Ho Lee1,2 , Chan-Hwa Hong1 , Joon-Min Lee1 , Jeong-Jin Park1 , Ho-Yeol Choi1 , Hyuck-In Kwon2 , and Woo-Seok Cheong1*
Affiliations : 1Electronics and Telecommunications Research Institute (ETRI), Korea 2Department of Electrical and Electronics Engineering, Chung-Ang University, Korea
Resume : We developed the rainbow-free cell pattern of single layer capacitive touch screen panel (TSP) using oxide/metal/oxide (OMO) multilayer electrodes. The rainbow was made by the reflection of light at the metal side between line patterns. In order to remove the rainbow, we optimized the cell-patterns by using TSP simulator(ANSYS Q3D extractor), and developed one-step etching process. Finally, we successfully fabricated OMO based-7 & 10 inch rainbow-free single layer capacitive touch screen panels with multi-touch function.
Authors : Paula Lada. Monika Zagórska. Aleksandra Miazga. Katarzyna Konopka
Affiliations : Warsaw University of Technology, Faculty of Materials Science and Engineering
Resume : The main objective of producing ceramic- metal composites is an improvement of the fracture toughness of the brittle ceramic matrix. Classical methods of powder metallurgy (such as isostatic or uniaxial pressing) are not capable of fabrication complex-shape elements. For this reason, colloidal processes are recently willingly applied in manufacturing of ceramic matrix composites. In the present work Al2O3/10 vol. % Mo composites were prepared by aqueous gelcasting process and sintering in an argon atmosphere. Selected physical properties and phase composition have been described. The microstructure of green and sintered samples was examined with a scanning electron microscope. Molybdenum particles were uniformly distributed in the ceramic matrix. The composite after sintering was characterized by a density higher than 95% of theoretical density. The performed studies have confirmed the possibility of application of the gelcasting method to produce an alumina-molybdenum composites.
Authors : V.V. Malyshev, A.I. Gab, T.V. Stetsyuk
Affiliations : University "Ukraine", IPMS NASU
Resume : The thermodynamic analysis of the decomposition potentials of boron, chromium, molybdenum, and tungsten compounds showed that metals are more electropositive than boron by 0.5-0.8 V. The depolarization value of boron deposition onto chromium (molybdenum, tungsten) metal surface is not more than 200 mV, therefore synthesis of their borides is possible only in the kinetic regime. Electrochemical synthesis of borides of molybdenum and tungsten was carried out from a molten mixture of NaCl-Na3AlF6-Na2MO4(MO3)-B2O3 (where M is Mo, W). In these systems, both individual refractory metal boride phases (higher MB4) and mixtures of phases, including lower borides M2B, MB, MB2, M2B5, were isolated depending on the melt composition and electrolysis parameters. Electrochemical synthesis of chromium borides was carried out from a molten mixture of NaCl-Na3AlF6-K2CrO4-B2O3. Depending on the composition of the melt and the electrolysis parameters, individual Cr2O3, Cr2B, CrB, CrB4 phases as well as mixtures thereof were obtained.
Authors : Barbara Lasio1, Francesco Torre1, Roberto Orrù1, Giacomo Cao1, Marcello Cabibbo2, Francesco Delogu1,*
Affiliations : 1 Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, via Marengo 2, 09123 Cagliari, Italy 2 Dipartimento di Meccanica, Università Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, Italy * firstname.lastname@example.org
Resume : Metal matrix composites (MMCs) consist of the heterogeneous combination of two or more constituents.  The metal forms the matrix within which the other constituents are dispersed as fillers. Although the individual constituents maintain their distinct physical and chemical natures, the dispersion of materials to various extents and at different length scales can result in enhanced properties and performances compared to those exhibited separately by the constituents [2, 3]. Therefore, MMCs represent an important case study for meeting the demand of replacing critical raw materials in future technology. While showing promise for advanced technological applications in several fields, MMCs also raise fundamental challenges for the current understanding of structure-property relationships. In this respect, there is still considerable room for experimental and theoretical investigation . Based on above-mentioned considerations, the present work addresses the fabrication of MMCs by mechanical processing. In particular, Cu-graphite powder mixtures have been subjected to mechanical processing by ball milling under inert atmosphere to induce mutual dispersion of the constituents . Then, powder has been consolidated by spark plasma sintering, and the obtained pellets subjected to nanoindentation to investigate the variation of mechanical properties with milling time and graphite content. References  J.W. Kaczmar, K. Pietrzakb, W. Włosińskici, 2000, Journal of Materials Processing Technology, 106, Pp 58–67.  F. Delogu, G. Gorrasi, A. Sorrentino, 2017, Progress in Materials Science, 86 Pp 75-126.  L.Y. Chen, J.Q. Xu, H. Choi, M. Pozuelo, X. Ma, S. Bhowmick, J. M. Yang, S. Mathaudhu, X. C. Li, 2015, Nature, 528 Pp. 539-549.  S. Garroni, S. Soru, S. Enzo, F. Delogu, 2014, Scripta Materialia, 88, Pp 9–12.  P. Baláž, M. Achimovičová, M. Baláž, P. Billik, Z. Cherkezova-Zheleva, J. M. Criado, F. Delogu, E. Dutková, E. Gaﬀet, F. J. Gotor, R. Kumar, I. Mitov, T. Rojac, M. Senna, A. Streletskiikl, K. Wieczorek-Ciurowam, 2013, Chemical Society Reviews, 42 Pp 7571-7637.
Authors : A.V.Paustovski (1), B.M.Rud (1), V.E.Sheludko (1), E.Ya.Telnikov (1), N.I.Siman (1), P.S. Smertenko (2), V.V. Kremenitski (3), Yu.I. Bogomolov (3)
Affiliations : (1) Frantsevich Institute for Problems of Materials Science of NASU, 3 Krzhyzhanovsky Str., 03680, Kyiv, Ukraine (2) V.Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 45 Prospekt. Nauki, 03028, Kyiv, Ukraine, email@example.com (3) Technical Centre of NAS of Ukraine, 13 Pokrovskaya Str., 04070, Kyiv, Ukraine, firstname.lastname@example.org
Resume : Technology for formation of current-conducting composite films is proposed. The first type of composite was the film material based on the thermostable polyamide with nickel boride and the second one was the film system ?binary filler + polymer matrix? where the mix of carbon nanofiber and nickel boride was chosen as the filler at various percentage ratios. The films were prepared on a dielectric (glass) substrate by screen-printing of composite pastes with a pre-dispersed filler followed by forming at 80 oC with subsequent drying at 150 o? until constant weight. The film thickness was about 70-80 ?m. The laser radiation with nano- and microsecond pulses with energy range 0.2-0.6 J was also used for the samples treatment. The surface morphology and some electrophysical properties of Ni3B-based thick composite films were studied by SEM, AFM, CVC and temperature techniques. The microstructure of the samples cross-section with Ni3B shown the uniformly distributed granules with size between 01 ?m and 5 ?m at the bottom of the samples. The formation of this layer was caused by sedimentation of dispersed filler to the substrate. At the same time carbon nanofiber in the second type of samples was distributed uniformly among all layer. The laser treatment of the first type samples in the nanosecond ranges with energy about 0.6 J is established to promote the linearity of current-voltage characteristics due to structurisation of conducting phase. The R(T) dependence is obtained and the temperature resistance coefficient is determined; the latter is positive and its value is. The temperature coefficient of resistance for the second type film was established to change from plus 1,67×10?3 o??1 to minus 1,074×10?3 o??1 while introducing carbon nanofiber.
Authors : M. Guziewicz1, R. Kruszka1, K. Golaszewska1, J. Dyczewski 2, K. Pagowska1, M. Kozubal, M. Mysliwiec3, A. Laszcz1, A. Czerwinski1
Affiliations : 1 Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw, Poland 2 Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland 3 Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw, Poland
Resume : Great application potential in power devices offered by wide bandgap semiconductors – GaN and SiC, is currently dependent on the development of adequate systems of metallization. Problems with devices operating at high current densities refer both to the reliability of contact metallization, interconnections in the area of semiconductor structures, as well as to connections with electrical terminals for packaging. Prototypical high power systems apply Au or Pt in order to protect interconnections from oxidation. A new type of interconnections could be based on Cu due to higher electrical and thermal conductivity, and considerable lower material price than for precious metals. Appropriate metallization for power devices should ensure stabile electrical resistivity after long-term thermal and electrical stresses. Both Au and Cu interconnections have to apply a diffusion barrier layer to protect a specific contact metallization from intermixing with outer metal. Moreover, Cu films require a thin coating against oxidation at elevated temperature. Looking for the best diffusion barrier layer to be working in interconnections we compare electrical and diffusion barrier properties of thin TiSiN, TaSiN, RuSiN and NbTiN films in contact with Au or Cu metallization. The films were deposited by magnetron sputtering methods. Barrier properties were studied by RBS, XRD and SEM methods. The film containing Si are amorphous. Improved films have been applied in Au or Cu interconnections. Cu oxidation risk was blocked by thin Ni-based glassy films or 50 nm thick SiN coating formed by ALD. Fabricated interconnections were stressed at temperature up to 300 C deg. and current density of 5 MA/cm2. Resistance of the Cu interconnection was intact after ageing in air at 250oC for few hundreds of hours, but increased resistance was observed for the Au interconnection.
Authors : E. Ionash, H. Dilman, S. Hayun, M. Sokol, N. Frage
Affiliations : Ben-Gurion University of Negev, Beer-Sheva, Israel
Resume : B4C powder compacts were infiltrated with molten Si, which reacts with the boron carbide particles resulting in the formation of novel SiC phase. The infiltration process takes place under vacuum 10-4torr at 1450-1500?C with a holding time that does not exceed 20 min in order to prevent significant Si evaporation. Under these conditions only a limited amount of Si is involved in the interaction and therefore, the fraction of new-formed SiC is also limited. We suggest to apply an additional thermal treatment of infiltrated composites under special atmosphere, which prevents Si evaporation. As a result of prolonged treatments for 24-120h at 1600?C the fraction of the residual Si decreased from about 20 to 10 vol% and a significant increase in Young modulus and hardness was achieved. HRSEM, HRTEM, EDS analysis were applied to characterize the composition and microstructural features of the infiltrated composites. The heat-treated composites display unique microstructure consisting of extremely thin SiC plates within boron carbide grains. Boron carbide changed its stoichiometry and dissolved of about 8at% of Si. The presence of boron (up to 14 at%) within SiC plates was also detected. The mechanism of the interaction between boron carbide and molten silicon will be discussed.
Authors : H. Hayun-1, C. Churi-2, Y. Gelbstein-1
Affiliations : Ben-Gurion University of the Negev-1; NRCN-2
Resume : The current research is focused on zirconium tungstate addition to YSZ solid electrolyte and its effect on the performance of the fuel cell. Zirconium tungstate is known for having a negative thermal expansion whereas YSZ expands considerably with temperature. Lower thermal expansion in the electrolyte may result in better compatibility to perovskite-type cathodes and a shorter starting time. Cubic YSZ with 20 at.% Y and 1 at.% W was synthesized using the sol-gel method, from yttrium nitrate hexahydrate, zirconium oxynitrate hydrate and tungstic acid dissolved in ethanol. The resulting powder was heat treated at 400-1200 °C for 2 hours to achieve crystallinity. It was found that the complete crystallinity was achieved at 1200 °C. XRD results show a single cubic phase after the powder was air quenched. In addition, the thermal diffusivity was determined using Laser Flash Analysis (LFA), the thermal expansion using Thermomechanical analysis (TMA).
Authors : B. Ratzker, M. Sokol, S. Kalabukhov, N. Frage
Affiliations : Ben-Gurion University of the Negev
Resume : SPS apparatus keeps growing steadily in popularity due to its excellent sintering capabilities. The data output of the SPS system includes temperature, applied pressure, relative punch displacement (RPD) and electric pulse parameters (i.e., voltage, mode of current, frequency, etc.). In principle, the SPS apparatus is a high temperature dilatometer and can be used for the investigation of mechanical properties of ceramics at high temperatures. The accuracy of RPD measurements (about 1 µm) is suitable for high temperature experiments, such as creep. We have successfully demonstrated that the apparatus can be applied as a high-temperature creep testing machine for advanced ceramics. Using high-pressure SiC SPS tooling, creep experiments were performed on alumina (in the temperature range of 1125-1250°C under 80-120 MPa) and magnesium aluminate spinel (in the temperature range of 1100-1200°C under 120-200 MPa). Apparent activation energies and stress exponent values were determined, Q=454, n=1.9-2.1 and Q=387-526, n=1.9-3.5 for alumina and spinel, respectively. The apparent activation energy for spinel decreased with applied stress, while the stress exponent decreased with temperature. The observed creep behavior (i.e creep parameters Q and n) in the tested regime as well as microstructure evidence of deformed samples (such as grain boundary cavities and equiaxed grains) fits the creep mechanism of grain boundary sliding accommodated by dislocation climb or glide and are in good agreement with the reported data.
Authors : M. Sokol, S. Kalabukhov, N. Frage
Affiliations : Ben-Gurion University of the Negev
Resume : Most types of passive laser Q-switching materials developed in the last two decades are based on transition metals cations like Co2+, V3+, or Cr4+ as an active dopant. For infrared lasers in the 1.3–1.7 m range, especially for lasers exploiting the 3I13/2→ 4I15/2 emission, passive Q-switches based on Co2+ doped MgAl2O4 spinel are an efficient solution. Methods of the fabrication and optical properties of Co2+ doped MgAl2O4 single crystals or glass-ceramics have been widely studied and discussed in literature. Conventional fabrication methods are expensive and time consuming. Recently, SPS and HIP have been successfully applied to fabricate polycrystalline transparent Co doped MgAl2O4. The SPS process is very fast and may be carried out at relatively low sintering temperatures, however, it doesn’t always provide a desired transmittance of ceramics. Prolonged treatments in the SPS apparatus lead to a massive interaction between graphite tooling and MgAl2O4. We suggested that a combination of a short SPS process and additional HIP treatment may make available the fabrication of the transparent ceramic with improved optical properties. In the present study, transparent Co2+ doped MgAl2O4 spinel was fabricated by SPS consolidation followed by and HIP treatment. It was established that HIP treatment significantly improved transparency of the ceramic in a wide range of wavelengths, especially, in a range, which is relevant for Q-switching. Nonlinear absorption was demonstrated and the ground and excited state absorption cross sections were estimated. The positive effect of the HIP treatment on the optical properties is related to an elimination of extremely fine porosity and to the location of Co ions at Mg2+ sites in the spinel ionic structure. The experimental results indicate that the fabricated specimens can be used as a passive laser Q-switching material.
Authors : Lee Shelly, Shmuel Hayun
Affiliations : Ben-Gurion University of the Negev
Resume : With the growth in energy demands, especially for sustainable fuels, hydrogen production from water using thermochemical methods, can be very beneficial. Nowadays, CeO2 is very popular in many oxidation/reduction cycle processes. Recently Idriss1 showed, using temperature programmed desorption (TPD) experiments, that solid solution compositions of Ce1-xUxO2 and specifically Ce0.75U0.25O2 enhances the hydrogen production efficency in comparison to the pure oxides. Thus, the understanding of the interaction between water vapor and Ce1-xUxO2 is essential. The effect of different Ce1-xUxO2 compositions on water vapor interaction will be presented. Three nano-sized Ce1-xUxO2 compositions (x= 0.25, 0.5, 0.75) were synthesized using non-aqueous sol-gel method with oleylamine as a surfactant and diphenyl-ether as an aging agent, under vacuum. The XRD and TEM analysis confirm that the resulted powders are a homogenous solid solution with fluorite structure and crystalline sizes smaller than 7 nm, while after heat treatment (H.T.) to 1000o C (in Ar) the crystalline size grew to ~30 nm. The water vapor interaction with the Ce1-xUxO2 surfaces was studied, using a custom combination of gas dosing system and micro-calorimeter and X-ray photoemission spectroscopy (XPS) analysis. The water adsorption data indicats that with increasing amount of U the coverage decreases in comparison to pure ceria and adsorption enthalpies are lower with the exception of the Ce0.75U0.25O2 composition. XPS analysis after water adsorption experiments shows that the oxidation states of the cations changes where some uranium cations are reduced and the cerium cations are oxidized Ce3+Ce4+.
Authors : O. Rahamim, S. Hayun, H. Dilman, N. Frage
Affiliations : Ben-Gurion University of the Negev
Resume : Melt infiltration is one of the attractive techniques to fabricate ceramic–metal composites with a wide range of mechanical properties. If molten metal wets ceramic particles free infiltration approach may be applied. It was established experimentally that the wetting angle in the TiB2-carbon steel (0.7wt.%C) system of about 20° at 1450°C is adequate for free infiltration. Thermodynamic analysis of the interaction between TiB2 and molten steel was performed and its results were taken into account to determine parameters of the infiltration process. SPS-processed TiB2 preforms with 30vol% porosity were successfully infiltrated with molten 1070 steel at 1450°C under 10-4 torr vacuum. The infiltrated composites were heat treated at 900°C and quenched in oil. The Young modulus (of about 500GPa) didn’t change after quenching, while hardness value increased form 1500HV to 1900HV for infiltrated and thermal treated composites, respectively. The effect of thermal treatment on the hardness value was attributed to the microstructural changes in steel matrix.
Authors : A.Ovsienko,V.Rumyantsev,S.Ordanyan
Affiliations : Virial Ltd
Resume : Our research was aimed to achieve a lightweight boron carbide-based structural material with improved performance via reaction bonding technique (RB). Nanosized carbon black powder (surface area ~100 m2/g) and boron carbide particles with different particle sizes were used as raw materials to achieve maximum powder packing density during forming. Trial batch of samples was formed by automatic double-sided uniaxial pressing under 40 MPa. Solution of phenolic resin in ethanol was used as a binder. Upon forming the samples were dried to remove residual ethanol and siliconized in a vacuum furnace at the temperature of 1500 ºС. 5 wt.% boron carbide particles were added to the silicon powder bed to inhibit the reaction of boron carbide particles with silicon melt. During powder premixing, nanosized carbon black particles are homogeneously distributed on the surface of the boron carbide particles to form nanosized grains of secondary silicon carbide in the final microstructure upon siliconization, thereby reinforcing the silicon matrix, and bonding the boron carbide grains into a continuous skeleton . Lower siliconization temperature effectively inhibits grain growth of the secondary silicon carbide, which retains mostly nano or submicron grain size, leading to improved parameters of the final material. XRD results show that the processed nanostructured composite material comprises four phases: initial В4С, solid solution B12(C,Si,B)3, β-SiC, and residual Si. Conclusions: 1. The paper describes the technique developed to process lightweight nanostructured boron carbide-based composite material via reaction bonding, as well as the results of characterization of the structure and parameters of the processed material; 2. Russian Patent is granted for the results of our research.
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Polymer based composites reinforced by fibers (FIBRALSPEC project results) : Dr. Iryna Bilan
Authors : S.D. Pandita, C. Madueke, Z. Zhang, H. Dong, G. Simmonds, G. Monaghan, K. Trompeta, V. Markakis, C.A. Charitidis.
Affiliations : a. School of Metallurgy and Materials, University of Birmingham, United Kingdom b. ANTHONY, PATRICK & MURTA EXPORTAÇÃO, Portugal c. GLOBALSAFEGUARD LTD, United Kingdom d. School of Chemical Engineering, National Technical University of Athens, Greece
Resume : Rapid development secure emergency shelter (RDSES) provides a temporary to a semi-permanent building for leisure, construction and humanitarian assistance. The shelter must be water and weather proof. The shelters can be assembled in a short period of time.The stackable shelters can be transported efficiently and stored externally for prolonged periods without additional maintenance. FibralSpec, an EU funded project, investigates the design of the RDSES shelter. The initial design of the RDSES shelter was made out of glass fibre reinforced polymer (GFRP), whose weight was approximately 500 kg. Stronger and lighter fibres such as carbon fibres are expected to reduce the weight of the initial RDSES design without losing mechanical properties. This paper will present the selection of the composite materials for the RDSES shelter. Carbon fibres, glass fibres, flax (natural) fibres in forms of woven fabrics were used as the reinforced materials. Epoxy was used as matrices. Hybrids of synthetic (carbon or glass) fibres and flax fibres were also considered for the shelter materials. Sandwich composites with Polypropylene (PP) honeycomb core will be investigated to increase the shelter thickness and hence to maintain bending properties without adding excessive weight. The composites and sandwich composites were manufactured via hand lay-up and vacuum bagging techniques. The bending properties of composites were measured by conducting three-point bending tests. The physical properties such as density of and the water absorption properties of composites will be reported. The water absorption properties of the composites will be studied by applying Fick’s diffusion law. The life cycle assessment (LCA) of the composites produced for the RDSES shelter will also be conducted by using LCA software, GaBi 6. Finally, the effects of the waste treatment of composites containing fibres as reinforcing materials will be assessed via SimaPro 9 software, in order to reveal possible environmental burdens that can arise after the end-of-life of the RDSES shelter.
Authors : Zhenxue Zhang 1, Santiago Corujeira Gallo1, Xiaoying Li1, Hanshan Dong1, Despoina Batsouli 2, Dimitrios Dragatogiannis 2, Costas Charitidis 2
Affiliations : 1 The School of Metallurgy and Materials, University of Birmingham, Birmingham UK 2 Research Unit of Advanced, Composite, Nano Materials & Nanotechnology, School of Chemical Engineering, National Technical University of Athens
Resume : The interface properties of fibre and resin often influence significantly the performance of all types of composites, such as failure mode and fracture toughness. Normally, push-in and push-out tests were carried out under continuous loading until a debonding or failure is detected; however, the creep behaviour under a load lower than the critical load is also very important to determine the interfacial strength and the mechanical strength between the fibre and the resin. The nano-creep behaviour and time-dependent properties of a commercial carbon fibre reinforced composite were investigated using a novel environmental instrumented nano-indentation machine. The mechanical properties such as indentation hardness, reduced modulus, indentation displacement and indentation creep of the composite were evaluated by means of the Oliver-Pharr method. The tests were carried out at different testing conditions in terms of loading rate, peak load, hold time, atmosphere (different humidity) and temperature (room temperature, 50, 80 and 100°C). Two different diamond indenters (Berkovich and cone indenter) were used in the push-out tests. The cone indenter had some advantages over the Berkovich indenter in terms of extended range of displacement before interference with the surrounding resin. A single fibre needs a critical load/stress to be pushed out under the continuous loading mode, and the critical load is strongly linked to the thickness of the composites sample, the location of the fibre in the resin and other environmental factors such as temperature. It was found that the fibre becomes difficult to be pushed-out at elevated temperature; the displacement and creep rate are both reduced with the increase of temperature due to the resistance caused by the expansion of the fibre and the resin. Key words: Creep, carbon fibre, push-out, push-in, nano-indentation This work has received funding from the EU FP7 Project “Functionalized Innovative Carbon Fibres Developed from Novel Precursors with Cost Efficiency and Tailored Properties” (FIBRALSPEC) under Grant Agreement No. 604248.
Authors : Pravin Jagdale*1, Aamer Abbas Khan1, Dimitrios Dragatogiannis2, Stavros Anagnou2, Kostas Mpalias2 Iryna Husarova3, Yevheniia Tishchenko3, Alberto Tagliaferro1, Costas Charitidis2
Affiliations : 1Department of applied science and technology (DISAT), Politecnico di Torino, Torino-Italy-10129. 2RNanolab, National Technical University of Athens, School of Chemical Engineering, Athens-Greece-15780. 3Yuzhnoye State Design Office, Dnipro, Ukraine.
Resume : Epoxy resin is one of the most important organic matrices in composite industry and finds application in demanding sectors due to excellent mechanical strength, thermal stability, and chemical resistance. Various fillers are used in epoxy composites in order to alter their chemical and mechanical properties. Glass transition temperature (Tg) is an important and critical property in composite product designing. Tg is not an isolated thermodynamic transition. The mobility of the polymer chains increases significantly over this temperature. Polymerisation chemistry, degree of curing and filler properties in composite varies the Tg value. Carbon fibre in epoxy composite can alter the chemical and mechanical properties at the expense of Tg. In addition, it is also interesting to know the impact of surface modified carbon fibres in epoxy for altering the Tg of composite. The thermal study was focused on epoxy composite filled with commercial and in-house produced carbon fibres prior and after plasma surface modification. Thermal properties of the composite are analyzed by Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA). The modified and unmodified carbon fibres in composite shows changes in thermal behaviours of composite. Tg of composite altered. Thermal degradation in TGA shows enhanced thermal stability of composite than plain epoxy. Reference: • B. Qi, S. R. Lu, X. E. Xiao, L. L. Pan, F. Z. Tan, J. H. Yu, Enhanced thermal and mechanical properties of epoxy composites by mixing thermotropic liquid crystalline epoxy grafted graphene oxide., eXPRESS Polymer Letters Vol.8, No.7 (2014) 467–479 • Chen J., Taylor A. C.: Epoxy modified with triblock copolymers: Morphology, mechanical properties and fracture mechanisms. Journal of Materials Science, Vol. 47, (2012) 4546–4560. This work has received funding from EU FP7 Project “Functionalized Innovative Carbon Fibres Developed from Novel Precursors with Cost Efficiency and Tailored Properties” (FIBRALSPEC) under Grant Agreement No. 604248.
Authors : Vyshniakov L.-1,Bilan I-1.,Vishnevsky L.-1,Vasilenkov Yu.-1, Mpalias K.-2, Anagnou S.-2, Koumoulos E.-2, Dragatogiannis D.-2, Charitidis C.-2
Affiliations : 1-Frantsevich Institute for Problems of Materials Sciences;2-National Technical University of Athens
Resume : Polymer based composites reinforced by weft-knitted fabrics produced from various kinds of fibers are very promising materials and an interesting object of study due to their new multifunctional properties. In the framework of FP7 FIBRALSPEC project (grant agreement 604248) carbon fibers from PAN precursors had been produced in National Technical University of Athens and weft knitted fabrics for reinforcement of polymer based composites had been manufactured in Institute for Problems of Materials Sciences of Ukraine. The main principles of processing of such kind of fibers had been applied. The glazing on the base of PVA had been proposed and fibers with glazing had been produced in a pilot line for production of carbon fibers with enhanced properties established in IPMS. The main principles of production of combined weft-knitted fabrics had been developed and analyzed. Combined weft-knitted fabrics containing caprone and glass yarns had been proposed. Their main physical and mechanical properties had been evaluated. Epoxy resin (Huntsman type) composites reinforced by weft knitted fabrics had been manufactured. In the case of unidirected arrangement of four layers in composite ratio of binder to reinforcement part was equal 29:71. Tensile and bending strength had been evaluated. Investigations of screening properties (protection from electromagnetic radiation) had been made.
Authors : A. Potapov, I. Husarova, V. Kovalenko, А. Samusenko, I. Derevyanko, O. Romenskaya
Affiliations : Yuzhnoye State Design Office
Resume : Existing production needs increasingly stringent requirements for advanced materials properties to widen their applications within more harsh and extreme conditions with simultaneous search of cost efficient production processes. The investigation of the modification impact of initial carbon materials on operational characteristics of products were targeted. Yuzhnoye is the end-user of modified carbon fibers to be used in its own production. Application of different modified materials is the road to introduce advanced materials with additional (comparing to initial) functional properties without having losses in structural integrity. Advanced carbon fibers have wide application area thanks to its unique properties and allow solving complicated tasks in material science and technologies independently from their current possibilities limits. Main task is the adaptation of gained experience to the development of the innovative demonstrators. Namely, here the demonstrators mean model cases of “cocoon” type that are used for engines cases, fuel and cryogenic vessels. Application of such cases allows increasing mass to energy characteristics of aerospace vehicles. Therefore, based on standard techniques the model cases of “cocoon” type should be produced based on materials before and after modification. The simulation of operation loads should be applied in accordance to developed test procedures. The key point is their comparative estimation of strength and mass characteristics of structure with enhanced properties of modified carbon composite material. The studies are carried out in the frame of Horizon-2020 Grant Agreement №685844 (H2020 NMP-22-2015).
Methods of enhancing of service properties of polymer based composites: part 1 : Dr. Iryna Bilan
Authors : Teresa Gatti, Nicola Vicentini, Enzo Menna
Affiliations : Department of Chemical Sciences, University of Padova
Resume : We exploit organic functionalization of carbon nanostructures (CNSs), such as fullerenes, single and multi-walled carbon nanotubes (SWCNTs, MWCNTs) and graphene-based materials (GBMs) to achieve improvements in their dispersion in organic media, i.e. solvents and polymer phases. This last aspect is particularly appealing for the production of polymeric nanocomposites with potential uses as stimuli-responsive smart materials in several applications, ranging from optoelectronics to sensing and biomedicine . We recently mainly focused on the diazotization process, commonly referred to as Tour reaction, to produce functionalized CNS derivatives, which can be employed as nano-fillers for polymer phases, improving the homogeneity of the dispersion and the physical properties of the final nanocomposite. The 1,3 dipolar cycloaddition of azomethine ylides to double bonds in CNSs (also called Prato-reaction) is another functionalization process of which we often make use. Specifically, we targeted photovoltaic (PV) applications, by combining functionalized CNSs with semiconducting polymers and nanomedicine (particularly tissue engineering) by combining functionalized CNSs with bio-compatible polymers. In the field of non-conventional PV, we focused on Perovskite Solar Cells (PSCs), contributing to the development of new materials for both hole  and electron transporting layers . Within the nanomedicine field, we proposed and tested new bio-compatible scaffolds for the growth and differentiation of neuronal cells in vitro [4,5]. We are currently exploring also possibilities of in vivo testing, with focus on peripheral nerve regeneration. We will therefore report here on our most relevant results in the aforementioned fields. References:  For a review on the topic see: T. Gatti et al. Eur. J. Org. Chem. 12, 6500 (2016).  T. Gatti et al. Adv. Funct. Mater. 26, 7443 (2016).  P. Topolovsek et al. submitted paper  N. Vicentini et al. Carbon 95, 725 (2015).  G. Scapin et al. Nanomedicine 11, 1929 (2016).
Authors : Kazuaki Sanada
Affiliations : Toyama Prefectural University
Resume : Thermally conductive polymer composites offer new possibilities for the thermal management in electronic devices. An approach of current interest to improve the thermal conductivity of polymer composites is the addition of hybrid nano and micro fillers with high thermal conductivity. The objective of this paper is to study the effective thermal conductivity of the composites with nano and micro fillers. The nano fillers used were carbon nanotubes and alumina nanowires, and the alumina and boron nitride particles with different shape and size were selected as the micro fillers. The random close-packed structures of micro fillers were obtained using packing simulations, and finite element analyses were performed to predict the composite thermal conductivity. In addition, experimental measurements of the thermal conductivity of the manufactured polymer composites were carried out by using a steady-state method. The microstructure of the composites was also examined using a scanning electron microscope. The results showed that the addition of nano fillers to the matrix significantly increased the thermal conductivity of the composites with close-packed structure of micro fillers.
Authors : Paulina Latko-Duralek , Kamil Dydek , Anna Boczkowska [1,2]
Affiliations : 1Technology Partners Foundation, ul. Pawi?skiego 5A, 02-106 Warsaw, Poland 2 Warsaw University of Technology, Department of Materials Science and Engineering, ul. Wo?oska, 02-507 Warsaw, Poland
Resume : Carbon Fiber Reinforced Polymers suffer from poor electrical properties, therefore there is a great interest in increasing their conductivity and simultaneously increasing the mechanical performance. One of the ideas is to introduce carbon nanotubes or graphene into CFRP by different routes. However, many of the approaches successfully tested in laboratory conditions do not fulfill the specifications in the industrial scale given by their end-users. Within Horizon 2020 EU program, the project with acronym PLATFORM is tasked with development of new types of nano-enabled products which could be easily applied in industrial environment (www.platform-project.eu). Untill now, pilot lines which produce three types of nano-enabled products such as buckypapers, CNT treated prepregs and CNT-doped veils have been successfully manufactured. Such products differ in manufacturing approach, properties and possible application area. All of them contain carbon nanotubes and therefore can be applied to increase CFRP electrical and mechanical properties. One example of nano-enabled products are CNT-doped veils developed by SME located in Poland (www.tmbk.pl). These nonwovens are produced by melt-blown process, which allows to obtain thin and lightweight materials with high flexibility. The usage of CNT-doped veils as interlayers in CFRP met the end-users expectations related to easy handling and fitting to specific process parameters such as melting range and compatibility with other used materials. It was revealed that CNT-doped veils can indeed increase the electrical conductivity of CFRP through the laminate thickness. However, the level of improvement is strongly affected by process conditions and the measurement technique. The research leading to these results has received funding from the European Union Horizon 2020 Program under Grant Agreement n° 646307 with title ?Open access pilot plants for sustainable industrial scale nanocomposites manufacturing based on buckypapers, doped veils and prepregs?.
Authors : A. Fainleib, O. Grigoryeva
Affiliations : Institute of Macromolecular Chemistry of NASU
Resume : The nanofilled polymer composites are more efficient and economically sound in comparison with conventional polymers or polymer blends, because they are characterized by significantly enhanced complex of physical-mechanical properties, even at very low content of nanofiller due to its specific chemical or physical interactions with polymer matrix at the nanoscale. High performanceCyanate Ester Resins (CERs) based thermosetting polymers (polycyanurate networks, PCNs) exhibit high glass transition temperature (Tg> 250oC), excellent preservation of physical-chemical properties at elevated temperature, low dielectric constant (ε ≈ 2.5 ÷ 3.2) and water adsorption, therefore theyare commonly used in structural aerospace composites, in electronic insulating applications, as adhesives [Fainleib A., Bardash L., Boiteux G., Grigoryeva O. in book “Advances in progressive thermoplastic and thermosetting polymers, perspectives and applications”, eds. Mamunya Ye., Iurzhenko M., ch.10, p.379-424, 2012]. In this work the thermostable polymer nanocomposites in situ synthesized from different CERs and multi-walled carbon nanotubes (MWCNTs) have been investigated, and asignificant effect of ultra-low content of the nanofiller on physical properties of the nanocomposites have been fixed.It has been found that addition of even 0.2-0.3 wt. % of MWCNTs provides increasing up to 90 % of tensile strength for the nanocomposites studied, improving stability to thermal-oxidative destruction. Varying MWCNTs content allows controllingtheirproperties from isolator to conductor.
Methods of enhancing of service properties of polymer based composites: part 2 : Dr. Iryna Bilan
Authors : Keping Chen, Chunrong Tian, Shuen Liang, Xiaolin Wang
Affiliations : Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang
Resume : Dispersibility of filler in polymer matrix and interfacial interaction are challenging for producing high performance polymer nanocomposites. In this study, thermoplastic polyurethane (TPU) nanocomposites incorporated with graphene nanoplatelet (GNP) and polydopamine functionalized GNP (PDA-GNP) were prepared by in situ polymerization. The influence of polydopamine (PDA) interfacial layer on the microstructures, morphology, thermal and tensile properties of TPU nanocomposites was investigated by small-angle neutron scattering (SANS), scanning electron microscope (SEM), dynamical mechanical analysis (DMA) and mechanical test. It was demonstrated that PDA-GNP exhibited homogeneous dispersion without aggregation in TPU matrix. Compared with pure TPU, the tensile strength, strain at break and toughness of TPU/PDA-GNP with as low as 0.5 wt % PDA-GNP increased by 313%, 16% and 279%, respectively. This individualized phenomenon was attributed that the interfacial covalent bonding between PDA-GNP and TPU resulted in well interfacial compatibility and specifically associated with the microstructure of TPU matrix.
Authors : Vadym Stavychenko, Svitlana Purhina, Lina Smovziuk, Vadym Shevtsov, Pavlo Shestakov, Anna Pavlenko
Affiliations : National aerospace university "KhAI"
Resume : Despite advanced mechanical characteristics, low electric conductivity of polymeric composites limits their application in aerospace and other areas. Two basic approaches, which are widely used to solve this problem, are disperse conductive particles incorporation into polymer matrix and conductive elements (metallic wires, meshes, foils) introduction into composite structure architecture. Both these approaches have their pros, cons and limitations. As an alternative, authors propose to increase electric conductivity of composites through generation of thin metallic conductive layer on the reinforcement (fibre, fabric, prepreg) surface by cold spray. This method is low-cost and can be realized as continuous production of conductive prepregs on an industrial scale. Efficiency of proposed method in terms of electric conductivity improvement and mechanical characteristics variation was experimentally validated for glass and carbon fibre reinforced samples with 1.5, 3.2 and 8.4 % content of copper particles. Specifically, CFRP samples conductivity was reduced from 78?10-6 ??m up to 1.65?10-6 ??m and is comparable with some metallic alloys conductivity. Three-point bending test results demonstrated negligible influence on composites bending strength, which varies within experimental data scatter. Additionally, samples microstructure analysis demonstrated that copper particles contact with carbon fibres, which guarantee transversal electric conductivity.
Authors : Sunil Kapadia1, Enrico Sowade1, Kalyan Yoti Mitra1, Reinhard R. Baumann1,2
Affiliations : 1Department of Digital Printing and Imaging Technology, Technische Universität Chemnitz, Germany 2Fraunhofer Institute for Electronic Nano Systems, Department of Printing Functionalities, Chemnitz, Germany
Resume : Inkjet printing technology for the last decade is growing tremendously and has been attracting several research related activities in the field of printed electronics. The technology offers numerous advantages e.g. deposition accuracy in micrometer range, additive process, high digital flexibility towards processing of patterns, low material consumption at R&D scale and industrial relevant up-scaling nature etc. In this work, we report on all inkjet-printed thin-film transistors (TFTs) and their performance regime. The inkjet-printed TFTs are manufactured using (a) Poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) PEDOT:PSS and silver (Ag) as conductor materials for developing the source, drain and gate electrodes; (b) a cross-linked poly(4-vinylphenol) cPVP as gate dielectric; (c) Dimethylchlorosilane-terminated Polystyrene was introduced as a polymeric inter-layer to improve the charge transport mechanism between the source and drain electrodes, and semiconductor interface; and (d) a polymer based amorphous semiconductor FS0096 from Flexinks inc. All the mentioned functional material inks were deposited using a piezo-electric assisted DoD inkjet printer Dimatix Material Printer 2831 and print-head cartridges offering 10 pL drop volume (under ambient condition). The main focus of this research work, is to represent the difference in the TFTs performance regime when the fundamental materials for developing a TFTs e.g. the source and drain electrodes are varied using Ag and PEDOT:PSS, in combination with and without the implementation of a polymeric inter-layer i.e. Dimethylchlorosilane-terminated Polystyrene for better charge transport. The fabricated TFTs containing the polymeric interlayer over the printed source and drain electrodes provide a superior interface for the deposition of the organic semiconductor layer by passivating it, which in return also improves the molecular structure / assembling of the semiconductor material once they are deposited. This can lead into an improved charge transport mechanism and hence high electrical performance (e.g. higher source-drain current, high charge mobility, low threshold voltage etc.) from the inkjet-printed TFTs. This present work demonstrates a drastic variation in the performance of the TFTs that can be implemented for developing organic circuitry for various applications.
Authors : A. Fainleib, K. Gusakova, O. Melnychuk
Affiliations : Institute of Macromolecular Chemistry of the National Academy of Sciences of Ukraine, 02160 Kyiv, Ukraine
Resume : Structural materials for aviation application are often exposed to extreme operational conditions, especially to high temperatures. The applicability of carbon plastics used in engines depends on the heat resistance of polymer matrix used as binder in composite material. Sometimes such materials have to withstand the temperature up to 300 ºC and even higher. The novel high temperature resistant densely crosslinked polymer matrix is formed by step-by-step curing in temperature range from 220 to 300 ºC of the mixture of polyfunctional epoxide and polyfunctional aromatic nitrile in the presence of specific initiators, catalysts and fillers. The final copolymer network contains highly thermally stable heterocycles in matrix chemical structure: triazine, isoindoline, phthalocyanine, oxazoline. Controlling the components ratio, type and amount of the additives and temperature/time schedule allows regulating physical-mechanical and thermal properties of the carbon plastics obtained. The glass transition temperature of the polymer networks obtained varied from 240 to 400 ºC (DSC data), the temperature of 10% mass loss varied from 400 to 500 ºC (TGA data). The average value of flexural strength at standard conditions was 837 MPa, and 285 MPa at 300 ºC (the retention of strength ? 34 %). The average value of tensile strength at standard conditions was 890 MPa, and 806 MPa at 180 ºC (the retention of strength ? 91 %), and 690 MPa at 250 ºC (the retention of strength ? 78 %). Tensile modulus was 95330 MPa at standard conditions and 96660 MPa at 180 ºC. The average value of compression strength at standard conditions was 504 MPa, and 316 MPa at 180 ºC (the retention of strength ? 63 %), and 142 MPa at 300 ºC (the retention of strength ?28 %).
Authors : Vyshniakov L.R., Varchenko V.T.,Moroz V.P.,Morozova V.N.,Prokhorov A.A
Affiliations : Frantsevich Institute for Problems of Materials SCiences of NASU, Ukraine
Resume : Technical decision for useful recycling of the wastes from mechanical treatment (milling, drilling, turning) of structural carbon plastics had been proposed. Such kind of wastes are powdered small dispersive particles consisting from carbon fiber fragments and wastes of epoxy resin. The collection and storage of this waste requires the costs of environmental measures, so their utilization and the following using are of great interest today. Structure and composition of such wastes had been described. It was proposed to sort these wastes in correspondence with their sizes (sieving through a sieve) and use these products for production of so called secondary composites. Taking into account peculiarities and forms of the carbon fiber fragments (high modulus, high strength) the most simple way of their using - introduction to polymer binder in correspondence with technology of the production of polymer composites reinforced by dispersive particles. Technology of the production for secondary polymer based composites with the content of fillers of 6 wt.%,12 wt.% and 18 wt.% had been proposed. Tribological properties of secondary composites had been tested at special stand M-22. The results of measurements showed that addition of the wastes of carbon plastics essentially increases wear resistance of secondary composites not only in air but also in water environment. The optimal value of concentration of additives had been determined. It is equal 18 wt.%. This amount of additives ensures the decreasing of the wear and temperature in the working zone of friction unit. It allows to recommend secondary polymer composites for their using as advance materials for loaded sliding bearings and dispersive wastes of mechanical treatment of carbon plastics as an effective additive for wear resistant friction materials. The work had been performed under the financial support of FP7 FIBRALSPEC project (grant agreement 604248)
Authors : Beata Kalska-Szostko1, Urszula Klekotka1, Dariusz Satu?a2
Affiliations : 1Institute of Chemistry, University of Bialystok, Ciolkowskiego 1K, 15-245 Bialystok, Poland 2Faculty of Physics, University of Bialystok, Ciolkowskiego 1L, 15-245 Bialystok, Poland
Resume : Magnetite nanoparticles and its derivatives such as maghemite, hematite, and doped ferrites with Co, Mn, or Ni can be efficiently prepared by various chemical methods. These compounds in nanoparticles form can be used as a base for heterogeneous nanocomposites. Presence of magnetic nanostructures plays important role in manipulation and properties. Besides that different compounds can be attached to their surface, for improving their functionality. In our case, obtained particles have a mean diameter varing from 11 to 16 ± 2 nm and were modified to improve their magnetic properties and chemical activity. Surface of proposed nanoparticles was functionalized with ?COOH, ?NH2, -OP, -SH, etc. groups to obtain active linkers. Presence of active groups is crucial for further reactions leading to nanocomposites fabrication. In the following step functionalized nanoparticles can be connected with third particles (catalyst, biological particles (lipids, enzymes, DNA, etc.) or other nanostructures (nanowires, nanotubes, fullerenes)) or reactive surfaces. Characterization of the pristine nanoparticles and effective composites was done by TEM, XRD, and Mössbauer spectroscopy. The effect of the obtained nanocomposites can be monitored by FTIR, Raman spectroscopy. Authors acknowledge COST MultiComp Action CA15107. The work was partially financed by EU founds via project with contract number POPW.01.03.00-20-034/09-00, POPW.01.03.00-20-004/11-00 and by NCN founds (2014/13/N/ST5/00568).
Methods of enhancing of service properties of polymer based composites: part 3 : Dr. Iryna Bilan
Authors : Wonbo Shim, Sungjin Han, Jinhyeok Jang, Minchang Sung, Woong-Ryeol Yu*
Affiliations : Department of Materials Science of Engineering and Research Institute of Advanced Materials, Seoul National University
Resume : The adhesion properties of adhesive between polymer and metal are becoming more important due to the increasing demand on carbon fiber-reinforced plastic/steel hybrid composites for the automobile parts. The adhesion properties such as failure strength, fracture toughness and failure mode are known to be dependent with temperature and strain rate. To analyze those adhesion properties at various strain rates and temperature, time-temperature superposition principle is used through the shift factors, which are obtained from dynamic mechanical analysis. The failure strength and fracture toughness are measured at various temperature and strain rate using a butt joint test, lap shear test, double cantilever test and end notched flexure test. By using time temperature superposition, it is shown that the failure strength and fracture toughness increase as the strain rate increases. In addition, the failure strength and fracture toughness at very high deformation rate and low deformation rate can be predicted where experimental data is unobtainable. A viscoelastic model that can account for the influence of strain rate and temperature on the adhesion properties is developed in this work.
Authors : Renata Porebska, Artur Siwek, Dariusz Bednarowski, Robert Sekula
Affiliations : ABB Corporate Research Center, Cracow, Poland
Resume : For the polymer bearings concept different approaches have been applied. At the beginning the computer simulations were done. In order to understand how the heat is dissipated by the bearing system a thermal simulation was performed. A structural simulations using ABAQUS was done to investigate contact area and for better define computational model for thermal analysis. The heat is generated on the contact area between the polymer bearing and the shaft.In order to reduce the amount of generated heat, friction-reducing coatings were applied on the shaft. Taking into account all the requirements and the conclusions drawn from thermal simulations three materials for bearings were selected. Two polymeric materials with very low coefficient of friction and good wear and heat resistance. Most of polymers are very good thermal insulators therefore bimetallic bearings were tested too. During each tribological test, temperature inside bearings, friction force, ambient humidity and temperature were measured. The tests were performed at a load in the range of 1,4 to 1,7 kN and rotation speed from 50 to 300 RPM. Comparing the obtained results, the best combination is bearing made of fluoropolymer with shaft covered by ‘diamond like carbon’ coating.
Authors : A. Szeremeta-1, A. Molak-1, S. Pawlus-1,2, J. Koperski-1
Affiliations : 1-Institute of Physics University of Silesia,Katowice,POland; 2-Institute of Physics University of Silesia, Chorzow,Poland
Resume : The electrical properties of two component composite of epoxy-glue and Bi-Mn-O ceramics, containing 66 wt.% Bi-Mn-O, were studied. Reference samples were Bi-Mn-O ceramics with sillenite structure and epoxy-glue. Secondary electron images and backscattered electron images were collected for the epoxy and the epoxy-Bi-Mn-O samples. Scanning electron microscopy showed homogenously distributed Bi-Mn-O powder in the epoxy matrix. It has been detected that the Bi-Mn ratio was different from the nominal value. Moreover, structure of the samples was determined with use of the XRD measurement in 300–450 K range.The electric impedance was measured for frequencies f = 40 Hz – 1 MHz in the 180 – 440 K range. It was analysed with use of electric permittivity e*(T,f) and modulus M''(T,f) representations. The tested epoxy-Bi-Mn-O sample exhibited low dielectric losses. The samples of epoxy-Bi-Mn-O composite show several electric conductivity relaxations. The dominating one is related to activation energy Ea= 0.6 – 1.0 eV, varying with temperature range. Therefore the Vogel Fulcher-Tammann relationship was applied for relaxation times obtained from modulus M''(T,f) representation. The other processes were not resolved clearly. The relaxation times were discussed in framework of the polymer-ceramic particle interfacial layer model
Authors : Alexandra S. M. Wittmar, Qian Fu, Mathias Ulbricht
Affiliations : Lehrstuhl für Technische Chemie II, Universität Duisburg-Essen, 45141 Essen, Germany and CENIDE – Center for Nanointegration Duisburg-Essen, NETZ – NanoEnergieTechnikZentrum, 47057 Duisburg, Germany
Resume : The presents work expands our previous studies related to cellulose processing with room temperature ionic liquids and simultaneous integration of functional nanoparticles towards photocatalytically active and easily recyclable nanocomposite porous films based on a renewable matrix material. Porosity can be tuned by the selection of phase separation conditions for films of casting solutions of cellulose in ionic liquids or their mixture with an organic co-solvent. TiO2 nanoparticles confer to the nanocomposite photocatalytic activity while the Fe3O4 make it magnetically active. The co-doping of TiO2-cellulose composite with Fe3O4 nanoparticles did not diminish the photocatalytic activity of the final composite which can be easily separated from solution with a magnet. By Fe3O4 doping, the composite temperature can be homogenously increased by exposure to a high frequency alternating magnetic field. For an optimal thermal response in magnetic field the magnetite nanoparticles have to be homogenously dispersed within the polymer matrix. The preparation method for the casting solution has been found to play an essential role for the fabrication of nanocomposite materials in which the functional nanoparticles are homogenously dispersed in a non-agglomerated form. Besides the presented flat porous sheet nanocomposites, by non-solvent induced phase separation processes similar photocatalytic and magnetic porous cellulose nanocomposites can be shaped also in spherical form.
Authors : Chiara Berlangieri (a), Giovanna Poggi (a), Sergio Murgia (b), Maura Monduzzi (b), Luigi Dei (a), Piero Baglioni (a), Emiliano Carretti (a)
Affiliations : (a) Department of Chemistry ?Ugo Schiff? & CSGI Consortium, University of Florence, via della Lastruccia, 3 - 50019 Sesto Fiorentino (Florence), Italy (b) Department of Chemical Science, University of Cagliari, CNBS and CSGI, ss 554 bivio Sestu, 09042 Monserrato (CA), Italy
Resume : The development and characterization of a new family of water based gel-like systems containing hydroxypropyl guar gum (HPG) with borax as crosslinker are presented in this contribution. In the formulation glycerol is introduced as plasticizer, and its role is broadly investigated. The effect of the components on the structure, on the viscoelastic behavior of the system and on the activation energy related to the relaxation process has been investigated by means of rheology, Nuclear Magnetic Resonance (NMR) and Small Angle X-ray Scattering (SAXS) [1-2]. Results indicated that the mechanical properties of the systems can be tuned by varying the amount of each component; 11B-NMR and 1H-NMR measurements highlighted the role of glycerol in the crosslinking mechanism, with the formation of a glycerol-borate complex. The characterization approach is used to identify the best formulation, in the view of a future application in the field of cultural heritage conservation, in particular for the cleaning of surfaces of historical and artistic interest . The main goal is to obtain a system adaptable to the roughness typical of surfaces of many artifacts. The best formulation was used for preliminary cleaning tests on a stucco artifact deriving from the decorations of La Fenice theatre, in Venice. The tests suggest a promising efficacy in selective cleaning of the surface and make these materials particularly interesting in the field of restoration.  T. Coviello, P. Matricardi, F. Alhaique,R. Farra, G. Tesei, S. Fiorentino, F. Asaro, e-XPRESS Polym. Lett. 2013, 7, 733.  Y. Cheng, K.M. Brown, R.K. Prud?homme, Biomacromolecules, 2002, 3, 456.  I. Natali, E. Carretti, L. Angelova, P. Baglioni, R.G. Weiss, L. Dei, Langmuir, 2011, 27, 13226.
Poster session 2 : Dr. Iryna Bilan
Authors : Naidich Yuriy V., Poluyanskaya Valentina, Sydorenko Tetiana
Affiliations : I.Frantsevich Institute for Problems of Materials Science of National Academy of Science of Ukraine
Resume : In this work for the production of strong brazed ceramic joints the wetting and contact interaction on interface of tin dioxide - binary metal melts (Ag-Cu, Ag-Sn, Cu-Sn, Cu-Ni) were studied. The wettability of ceramic surface was carried out by sessile drop method in vacuum at T = 1270 - 1370 K. It was shown that the most of investigated alloys (Ag-Cu, Ag-Sn, Cu-Sn) are not wetting of ceramic substrate (the contact angles are about 70 - 110 deg.). It's not enough for brazing such material. For using this binary metal melts we need to add adhesion active component, for example, Ti. However, Cu-Ni system can be used for brazing and metallization of tin dioxide ceramics: the contact angle for Cu-5Ni is 40 deg., for Cu-15Ni - 22 deg. The microstructure of ceramics-metal interface was studied. The optimal conditions for brazing and metallization of tin dioxide ceramics by Cu-Ni fillers were defined.
Authors : Naidich Y.V., Gab I.I., Stetsyuk T.V., Kostyuk B.D.
Affiliations : Frantsevich Institute for Materials Science Problems of National Academy of Sciences of Ukraine
Resume : The structure and morphology of metallic nanofilms deposited onto solid surfaces of inorganic and organic materials has been extensively studied. At the same time significant scientific interest is the investigation of metallic nanofilms deposited onto liquid surfaces of various organic and inorganic materials. In this paper we investigated the morphology of aluminum and tungsten nanofilms (ie, one of the lightest and one of the heaviest materials) with thickness of 5 150 nm deposited by electron-beam sputtering onto castor and diffusion oils surfaces, and also onto indium and tin metal melts surfaces. It is established that the metallic nanofilms of aluminum and tungsten deposited onto indium and tin melts were continuous and during last solidification the surfaces relief of these materials and all defects in their crystallization were replicated. When very thin tungsten and aluminum nanofilms (5 10 nm) were deposited onto liquid organic materials (castor and diffusion oils), the films were not yet continuous and were individual conglomerates that were at a considerable distance from each other. With an increase in the thickness of the tungsten film up to 100 nm on the same surfaces, it was already continuous though it was considerably corrugated. The aluminum film onto liquid organic surfaces was continuous though it was slightly corrugated already at film thickness of 50 nm and with increasing its thickness up to 100 nm the film became strongly corrugated, while maintaining its continuity. Thus, the possibility of thin films depositing even heavy metals onto liquid surfaces was shown and their morphology was investigated.
Authors : Tsukrenko V.V.; Ruban A.K.; Redko V.P.; Dudnik E.V.
Affiliations : Frantsevich Institute for Problems in Materials Science
Resume : Tetragonal Zirconia-based ceramics are characterized by high strength, fracture toughness, corrosion resistance and bioinertness. The CoO additive provides bright blue colour of ceramics and makes them promising cutting tools. It was investigated the influence of synthesis method on the variation of physicochemical properties (phase and chemical composition, morphology, specific surface area, primary particles size) of nanocrystalline powders in the ZrO2-Y2O3-CeO2-Al2O3 system after heat treatment up to 1300 C. Starting powders were synthesized by hydrothermal synthesis in an alkaline medium and combined method of hydrothermal synthesis/mechanical mixing. It was determined that CoO reduced the temperature of low-temperature phase transformation F-Zr2-T-Zr2 and neutralized the Al2O3 influence on this transformation regardless of the synthesis method and manner of CoO introducing.
Authors : Zhuravlev V.S., Sydorenko T.V.
Affiliations : I.Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine
Resume : A thermodynamic analysis of the contact interaction of Tantalum with aluminum nitride, alumina and silica was carried out. Expected compositions of interaction products in investigated systems were determined. The wetting of Tantalum with Cu-Ni melts was studied. It was show that the Nickel addition to the Copper melt contributes to the intensive wetting of Tantalum (the contact angle at 1423 K decreases from 75 deg until full spreading). Strong brazed Tantalum compounds with aluminum nitride and alumina-ceramics VK 94-1 were received. The bending strength is more than 60% from the strength of the brazed ceramic. The microstructure of brazed joints has been studied too. The positive role of Nickel in the formation of the brazed seam was fixed. It was show that the use of Ta foil as a ductile interlayer between brazed nonmetallic and metallic materials with significantly different thermal expansions has been perspective.
Authors : Krasovskyy V. P., Vishnyakov L. R., Krasovskaya N. A., Kochanyy V. A.
Affiliations : Frantsevitch Institute for Problems of Materials Science of NASU 3, Krzhyzhanovsky str., 03142, Kyiv, Ukraine
Resume : Realization of effect of Removal of an electric current allows to regulate process of removal of thermal and electric energy from a place of defeat of Cu-net by a lightning. This effect depends on a construction and properties of soldered knots of net. Wetting of wire surface by solder at creation of a wire net construction has great value. The studying wetting of compact materials on the base of pure Cu and bronzes (tin, beryllium, aluminum) by the low temperature alloys on the basis of Sn at 250–450 °C have been carried out. The sessile drop method with “capillary purification” method was applied. At wetting of bronzes by Sn–Ag–Cu solder showed the big activity in comparison with alloys Sn, Sn–Pb, Sn–Bi. Results on wetting of Cu and bronzes substrates by O-2 (Sn– ~99,95%), Sn–Pb (Sn–61 mass%), SAC (Sn–3,2% Ag–0,7% Cu), CASTIN (Sn–2,5% Ag–0,7% Cu–0,5% Sb) and Sn–Bi alloys showed, that Cu and beryllium bronze by alloys are wetted better. Sn–Ag–Cu solders were used for metallization and soldering of Cu-net construction. The Cu wire by thickness of 0.1 mm has been metallized, and the net with cells soldered in knitted-soldered construction was produced. Electrical resistance of О-2, SAC, Sn–Bi and Sn–Pb alloys as well as specific surface resistance of knitted-soldered copper net has been determined. It was established that metallization of Cu wire and soldering the knots of net influence on value of specific surface resistance of knitted-solder copper net essentially.
Authors : Krasovskyy V. P., Krasovskaya N. A.
Affiliations : Frantsevitch Institute for Problems of Materials Science of NASU 3, Krzhyzhanovsky str., 03142, Kyiv, Ukraine
Resume : The alloys on the basis Ti, Zr, Nb, V are used, as the welding alloys for soldering different ceramic materials, as structural materials, and recently, as amorphous metal materials. However isothermal melting and homogenisation of such alloys were impossible. For following reasons Ti, Zr, V, Nb- containing alloys have high activity in a contact to the majority of standard refractories. Earlier we studied wetting of CaF2, BaF2, MgF2, SrF2 by metal alloys. The anomalous phenomenon – non-wetting at high temperatures and abnormal inertness effect of fluorides to contact with aggressive alloys with large contents of Ti, Zr, V, Nb have been established. It allows, to use refractory fluorides as refractory for manufacturing products from them (crucibles, cups), which can be used for melting and homogenization of chemically aggressive alloys. At melting of such alloys in fluoride crucibles it has been established, that due to the big differences in factors of temperature expansion (factor for fluorides on much more than factor for metals) a mechanical compression of an alloy, which is cooled, in crucible occurs. It results to destruction of the crucible. To resist to such phenomenon and taking in attention the wetting of fluorides by such alloys (the big contact angles) we have suggested to use for melting and homogenization of such alloys the crucibles, which are disassembled. The crucible will consist of several parts. Such crucibles it is possible to use a plenty of times.
Authors : E.L.Vishnyakova,L.M.Pereselentseva, L.R.Vyshnyakov, V.A.Kokhany
Affiliations : Frantsevich Institute for Problems of Materials Sciences
Resume : Composite films on the base of thermoplastics filled by carbon nanoparticles are interesting for production of electro conducting polymer materials. The results of investigations of carbon nanoparticles (nanoplates) produced from pine chips by means of carbonization and following milling as a filler of electroconductive composites are presented. Their sizes in plane are from 0,1 µm till several tens of microns and their thickness is not exceed 100 nm. The values of electrical conductivity of nanoplates which had been measured according to original method are about 10-2 ? 10-3 Ohm cm. Introduction of nanoparticles to polyethylene matrix had been performed by means of joint mixing of polyethylene granules and preliminary produced carbon nanoparticles in planetary mill. The values of the content of carbon nanoparticles were equal 0,1; 0,5 and 1mass.%. Optimal values of milling duration and concentration of carbon nanoparticles in composite had been determined on the base of the results of the measurements of electrical conductivity and strength of the produced films. Presented results allow to consider planar carbon nanostructured particles produced from plant raw materials as a perspective filler for electro conducting polymer based composite films.
Authors : J. Iwanaga, Y. Osakabe, K.Yamasoto, S. Munetoh, O. Furukimi
Affiliations : Kyushu University
Resume : A novel power generation with no temperature difference has been performed by using polycrystalline Ba8AuXSi46-X clathrate with p-n junction. The sample was sintered with a powder consisted of n-type Ba8Au4.5Si41.5 clathrate and p-type Ba8Au5.5Si40.5 clathrate powder layers by using a Spark Plasma Sintering method. The sintered sample was cut to contain the interface of two layers for power generation without temperature difference at 27-500 °C. Electric voltage can be observed around 2.0 mV at 500 °C. Samples of Ba8AuXSi46-X (X = 4.0, 6.0) and Ba8AuXSi46-X (X = 4.8, 5.2) were also prepared in the same way. The generated voltage under uniform temperature increases with difference of the Au chemical composition. This power generation mechanism needs a material with a wide band gap n-type, a narrow band gap intrinsic semiconductor, a wide band gap p-type semiconductor junction. The electrical properties of the Ba8AuXSi46-X clathrate dramatically change depending on the Au composition. The generated voltage can be observed by heating and the voltage increases with difference of Au composition between n- and p-type semiconductors. The novel electric power generation is anticipated to improve the energy conversion efficiency compared to Seebeck effect because electric power can be obtained only by raising the temperature with no temperature difference.
Authors : Serhiy Ivanchenko, Saide Umerova, Dmytro Baranovsky, Andriy Ragulya
Affiliations : Frantsevich Institute for Problems of Materials Science NASU, Krzhizhanovsky str., 3, 03680, Ukraine, Kyiv-142
Resume : During casting a suspension in a thin layer, the tape surface can be fractured because of suspension collection into drops due to poor wetting of the lyophobic surface of the carrier. There are several ways to solve this problem: change the chemical composition of suspension to improve the wetting or use of substrate without lyophobic coating. Of particular interest is the method of eliminating defects when both methods are unacceptable. For suspension creation as solid phase was used BaTiO3 nanopowder produced by «Nanotechcenter» (ua) with a particle size of 20 - 25 nm. As the organic binder was used a polymer solution of polyvinyl butyral (PVB) with molecular weights from 40 000 to 75 000 g/mol in organic solvents ethanol and butanol. Dibutyl phthalate was used as the plasticizer. In this work was used the suspension of the following composition: the concentration of the polymer solution from 5 to 10 wt. %, The ratio of polymer plasticizer: 2:1, ratio of powder polymer solution: 1:2. TTC-1200 tape casting machine where used to obtain tapes. Improvement of suspension wetting angle was acquired by its pre-cooling. Cooled to 5ºC suspension shows a reduction of wetting angle to the substrate by 7º. Roughness criteria of the tape obtained from pre-cooled suspension with a temperature of 5 °C were: Rz = 85 nm, Ra = 24 nm. The average thickness was 350 nm and tapes show good continuously. Roughness criteria of the film obtained from the suspension with a temperature of 25 ºC were: Rz = 110 nm, Ra = 43 nm. The average thickness was 900 nm and a tape was strongly fragmented. The obtained data shows that pre-cooling of suspension is not only improved continuously of the tape on the lyophobic carrier, but also reduce the thickness and roughness of the film.
Authors : Chengjing Xiao; Da Zhang; Liang Chen; Tao Wei; Zaiqin Wang
Affiliations : Changjiang River Scientific Research Institute of Changjiang Water Resources Commission
Resume : Metakaolin based geopolymer matrix composites reinforced with different volume fractions of high-modulus short polyvinyl alcohol(PVA) fibres (PVAf/geopolymer composites) were prepared and the mechanical properties, fracture behaviour and microstructure of as-prepared composites were studied and correlated with fibre content. The results show that short PVA fibres have a great strengthening and toughening effect at low volume percentages of fibres (1.5and 2 vol.%). With the increase of fibre content, the strengthening and toughening effect of short PVA fibres reduce, possibly due to fibre damage, formation of high shear stresses at intersect between fibres and strong interface cohesion of fibre/matrix under higher forming pressure. The property improvements are primarily based on the network structure of short PVA fibre preform and the predominant strengthening and toughening mechanisms are attributed to the apparent fibre bridging and pulling-out effect. This composite was expected to be used as a coating to protect reinforced concrete against corrosion.
Authors : Oleg Tolochko, Tatiana Larionova, Marina Rakovskaya, Sergey Kotov, Alexey Shamshurin
Affiliations : Oleg Tolochko, Material Science and Technology/Institute of Metallurgy, Mechanical Engineering and Transport, Peter the Great Saint-Petersburg Polytechnic University, St.Petersburg, Russia; Tatiana Larionova, Material Science and Technology/Institute of Metallurgy, Mechanical Engineering and Transport, Peter the Great Saint-Petersburg Polytechnic University, St.Petersburg, Russia; Marina Rakovskaya, Material Science and Technology/Institute of Metallurgy, Mechanical Engineering and Transport, Peter the Great Saint-Petersburg Polytechnic University, St.Petersburg, Russia; Sergey Kotov, Material Science and Technology/Institute of Metallurgy, Mechanical Engineering and Transport, Peter the Great Saint-Petersburg Polytechnic University, St.Petersburg, Russia ;Alexey Shamshurin, Material Science and Technology/Institute of Metallurgy, Mechanical Engineering and Transport, Peter the Great Saint-Petersburg Polytechnic University, St.Petersburg, Russia.
Resume : Multilayer reaction films are used in the technology of permanent connection of various materials. For transformation of solder from a solid to a liquid state used a heat effect of exothermic reaction of formation of intermetallic compounds. As initial materials were used powders of aluminum and nickel. The mixing of the pure powders was carried out in the gravity type mixer for 4 h. Mechanical activation was provided in a planetary for 5 min at 600 Rev/min in argon-gas area. The obtained micrograph of the initial powder compound showed that the particles of aluminum powder are spherical in shape with an average particle size from 5 to 10 μm, the nickel particles were smaller and have had a spongy structure. As a result of mechanical activation produced large composite particles, with a diameter about 800 μm. The product of the reaction of combustion of the tape obtained by rolling of the initial compound is the totality of phases AlNi, Al2Ni3. As a result of combustion of the tape obtained by rolling of mechanically activated mixtures formed a single phase structure corresponding to the equilibrium phase AlNi. Thus, the mechanically activated powders by rolling the obtained multilayer reactive foil, with the effect of SAF, with the onset temperature of exothermic effect, at least 50 ºC lower than in strips of similar composition made by multiple rolling. Indirect estimates in the received samples, the interlayer distance is in the range from 40 to 120 nm, which is comparable to multi-layer foils made of magnetron sputtering. The proposed method is cheaper than average and significantly exceeds their performance.
Authors : Celina M. Miyazaki, Marco A. E. Maria, Daiane Damasceno Borges, Cristiano F. Woellner, Douglas S. Galvao, Antonio Riul Jr
Affiliations : Applied Physics Department, University of Campinas - UNICAMP, Campinas-SP 13083-959, Campinas-SP, Brazil UNESP – Univ Estadual Paulista, Bauru, SP, Brazil; Universidade Federal de São Carlos – DFQM, Sorocaba, SP, Brazil
Resume : The use of scalable methods to build-up graphene-based nanostructures endowing advanced functional properties are highly desirable for practical applications. Achieving a large area coverage of pristine graphene is still a major limitation for the applicability of this material. As an alternative, in this work, we present a graphene based polymer composite soluble in water promising to be exploited in energy storage, electrodes fabrication, selective membranes and biosensing. Graphene oxide (GO) was produced by the traditional Hummers´ method being further reduced in the presence of poly(styrene sulfonate) sodium salt (PSS), thus creating stable reduced graphene oxide (rGO) nanoplateles wrapped by PSS (GPSS). Molecular dynamics simulations were performed to better understand the interactions between PSS molecules and rGO nanoplatelets, with calculations supported by FTIR analysis. The simulations elucidate the GPSS self-organized structure governed by intermolecular forces without chemical adsorption. The formation of the soluble GPSS permits the fabrication of high quality layer-by-layer (LbL) films with polyalillamine hydrochloride (PAH) without hindrance electronic properties of rGO. Raman and electrical characterizations corroborated the successful modifications in the electronic structures from GO to GPSS after the chemical treatment, resulting in (PAH/GPSS) LbL films four orders of magnitude more conductive than (PAH/GO).
Authors : N. Lysunenko (1), O.Vasylyev (1), V. Mokiychuk (2)
Affiliations : (1) Frantsevich Institute for Problems of Materials Science of NASU, Krzhizhanivsky Str., 3, 03680, Kyiv, Ukraine (2) National aviation university, Kosmonavta Komarova, 1, Kyiv, 03058, Ukraine
Resume : Solid oxide fuel cell (SOFC) is a device for production of electrical energy from chemical reaction between oxygen and hydrogen, which react via solid / ceramic electrolyte. These fuel cells provide many advantages over traditional energy conversion systems including high efficiency, reliability, modularity, fuel variety, and very low levels of emissions. Quiet, vibration-free operation of SOFCs also eliminates noise usually associated with conventional power generation systems. SOFC hold the greatest potential of any fuel cell technology with low cost ceramic materials. SOFCs operate at relatively high temperature (600-900 °C). This high temperature gives them extremely high electrical efficiencies, and fuel flexibility, both of which contribute to better economics, but it also creates engineering challenges. The goal of the study was to compare electrical properties of different SOFC made along different technological approaches and tested at the same conditions. To date, two types of SOFC have been compared, namely, fuel cells used fabricated with tape casting technique at Frantsevich Institute for Problems of Materials Science (IPMS), and the second one those are available commercially. The electrochemical performance of the cells was tested at temperatures between 600 and 800 °C using humidified pure hydrogen (~5%) in a mixture with argon (~95%) as a fuel and air as an oxidant. The obtained data demonstrate much better performance of the SOFC newly developed; they will be used for structural optimization of SOFCs and their manufacturing route.
Authors : V.V. Malyshev1, D.B. Shahnin1, T.V.Stetsyuk2
Affiliations : 1University "Ukraine", 23 Lvivska St., 03115 Kyiv, Ukraine 2IPMS NASU, 3 Krzyzanowski St., Kyiv 03680, Ukraine
Resume : During cathode codeposition of metals with molybdenum (tungsten) from oxide tungstate-molybdate melts, the following factors are the key: the difference between the standard electrode potentials of the alloy components; the similarity of their crystal lattices; the rate of mutual diffusion of the alloy components atoms. With closeness of the standard electrode potentials values (Eo < 0.2 B) of the coprecipitated metals and with similarity of their crystal lattices (Mo-W case), the cathodic process proceeds under conditions close to equilibrium. In this case, it is possible to obtain continuous deposits of components alloy throughout the entire composition range. With Eo > 0.2 B and different types of crystal lattices (Mo(W)-Ag(Cu) cases), the cathodic process occurs under conditions far from equilibrium. In this case, the formation of deposits of three types: spongeous, deposits of one component sprouted by dendrites of other component, and acicular. With Eo < 0.2 B and different crystal lattices (Mo(W)-Ni(Co) cases), the cathodic process occurs, as in the first case, under conditions close to equilibrium. In this case, it is possible to obtain continuous deposits of intermetallic compounds. With Eo > 0.2 B and crystal lattices of the same type (Mo(W)-Re case), the cathodic process occurs under conditions far from equilibrium. In this case, inadherent powdered deposits are usually formed.
Authors : Viacheslav Syrovatka
Affiliations : Frantsevich Institute for Problems of Materials Science of NASU
Resume : In many cases, the functionality of the product is determined by the properties of their surface. Having strengthened the surface layer, it is possible to increase the service life of shafts, bearings, cutting tools and other products, which are affected by intensive wear, by an order of magnitude. Wear resistant coatings are used in the aerospace industry, nuclear power, automotive industry, in the manufacture of tool materials. The usage of coatings can increase the life of products by several times, saving costly and scarce metals. Any structural obstacles arising on the path of the moving dislocations, increase the strength limit of the material, but also reduce the fracture toughness, and vice versa. Overcoming this contradiction, it can be made a composite material that combines sturdy, solid inclusion with plastic, viscous, crack-resistance matrix. The created powder materials can be successfully used for process of wear-resistance coating. The affinity of the chemical compositions of the base and the coating creates good conditions for ensuring between them a strong adhesion - one of the most important conditions for high working capacity of the product. In this regard, the development of iron-containing wear-resistant coatings for aerospace components made of iron alloys seems to be relevant and promising. Comparative studies of the resistance to abrasion of detonation coatings based on iron aluminides have shown that the coating with an intermetallic matrix structure with inclusions of solid phases in the form of oxides has the highest indices. The lowest resistance to abrasion wear has a coating whose microstructure base represents a two-phase mixture of relatively soft intermetallic phases. Thus, the issue of ensuring the working capacity of iron alloys in various engineering constructions can be successfully solved by using coatings from mechanically synthesized powders based on the Fe-Al system. The proposed method of detonation spraying of these coatings with the optimal choice of the technologic parameters provides good adhesion of the obtained coatings, that can be easily verified by visually analyzing the coatings partially worn down to the main material by the flow of abrasive particles. The transition from the base to the coating has the smooth nature, there is no step, which indicates a high adhesion strength, capable of retaining the coating until it is completely worn with abrasive particles.
Authors : D.B. Shakhnin, V.V. Malyshev, I.I. Gab
Affiliations : University "Ukraine", IPMS NASU
Resume : Co-precipitation of molybdenum (tungsten) and nickel from oxide tungstate-molybdate melts is a typical case of electrodeposition of alloys, the components of which have different types of crystal lattices and close values of electrode potentials. Addition of a molybdenum (VI) oxide to a nickel-containing tungstate melt reveals a wave of reduction of the dimolybdate ion. The difference of the deposition potentials of nickel and molybdenum is 0.090-0.115 V at 1173 K. Electrodeposition was carried out at cathode current densities 0.05-0.1 A/cm2 within the temperature range 1123-1173 K. Concentrations of MoO3 and NiO were varied within 0.025-1.0 and 0.05-1.5 mol. %, respectively. At various ratios of MoO3 and NiO concentrations, it is possible to deposit continuous layers of MoNi, MoNi3, and MoNi4 intermetallides. The regularities described above are also characteristic for the deposition of tungsten-nickel alloys.
Authors : A.I. Gab, V.V. Malyshev, I.I. Gab
Affiliations : University "Ukraine", IPMS NASU
Resume : Experimental electrochemical measurements and thermodynamic calculations have made it possible to construct the relative and absolute acidity (basicity) scales for tungstate-molybdate melts of different cationic and anionic compositions. The most basic ones were melts containing NaBO2, Na3PO4, Na2CO3, Na2MoO4, and Li2CO3, the most acidic ones containing Na2S2O7, MoO3, Na4P2O7, Al2(MoO4)3, WO3, Al2(WO4)3, Na2B4O7. These scales are used to determine the relative acidity (basicity) of oxyanions or other particles exhibiting acid-base properties and to predict the structure of melts based on tungstates and molybdates, the composition of cathode products, and the nature of electrode processes and equilibria in these melts. To check quantitatively the reversibility of platinum-oxygen electrodes, the EMF of electrochemical chains in halide oxide and oxide melts were measured.The pre-logarithmic coefficients of the experimental dependences of the platinum-oxygen electrode potential on the concentration of oxygen ions correspond to the Nernst equation. Additional evidence was the absence of hysteresis in micro-polarization measurements. The stability and reproducibility of the potentials were also proven experimentally.
Authors : D.S. Korablov, Yu.M. Solonin
Affiliations : Frantsevich Institute for Problems of Material Sciences, NAS of Ukraine Krzhyzhanovsky str., 3, Kyiv, 03680, Ukraine
Resume : Hydrogen storage alloys are well known as a group of new functional intermetallics, which can reversibly absorb/desorb significant amount of hydrogen at ambient conditions. Over last decades, AB5-type rare eath-based hydrogen storage alloys have been widely used commercially as negative electrode materials in NiMH batteries. However, AB5-type intermetallic compounds suffer from relatively low discharge capacities (~320 mAh/g) that does not meet growing requirements for high energy and high power NiMH batteries. In recent years, a new family of AB3-type Mg-containing alloys with higher electrochemical capacity and good rate dischargeability was developed. These alloys are considered as the promising electrode materials for high performance NiMH batteries though the cycle stability and the overall electrode properties of AB3-type alloys still have to be improved. The electrode performances correlate closely to the composition homogeneity and phase homogeneity of the alloys, thus the development of suitable preparation techniques for homogenous alloys is essential. In the course of this research, experimental setup for the obtaining of alloys using the method of powder sintering in Ar gas was created. It includes the unit for gas drying and purification, which is crucial for the elimination of the possible oxidation during sintering. Thermal treatment of powder mixtures cold pressed in tablets was carried out in quartz reactor pre-filled with purified argon. The heating in La-Mg-Ni system was conducted stepwise, primarily to 630 – 650 °C aiming at introduction of Mg into the alloy followed by heat treatment in the temperature range of 850 – 1050 °C. Preliminary results suggest formation of non-stoichiometric compounds in the studied system that inspires further research.
Authors : Satoshi Kurumi, Ken-ichi Matsuda, Kaoru Suzuki
Affiliations : Department of Electrical Engineering, College of Science and Technology, Nihon University
Resume : In this study, we have attempted to develop a plasma-assisted pulsed laser ablation (PLA) technique to obtain functional particles in liquid. Oxygen atmospheric-plasma (AP) particles as oxidation agents were generated using barrier dialectic-discharge system. AP particles were ejected to liquid as a reaction solution for PLA. A laser target dipping in the liquid was ablated by focused laser beam (Nd: YAG laser, wavelength: 355 nm or 1064 nm) irradiation. Functional particles were produced by a chemical reaction of ablation plumes with the liquid including AP particles. Just after the ablation, a drop of water containing fine particles was casted onto a metal grid plate for transmission electron microscope observation. We have observed the existence of many nano-particles (diameter: below ~ 50 nm). Crystallizations of them were measured by X-ray diffraction method.
Authors : Kuda O.A., Bykov O.I., Pinchuk N.D.
Affiliations : Frantsevich Institute for Problems of Materials Science of NASU, 3 Krzhyzhanovsky Str., Kiev, 03142, Ukraine,
Resume : Composite materials based on hydroxyapatite are widely used for bone tissue engineering. There is evidence of a positive effect of the presence of strontium in osteoplastic materials in the case of a Ca/Sr certain ratio. To examine the effect of the addition of Sr2+, a study was made by introducing it into the material composition based on biogenic hydroxyapatite and sodium silicate glass phase (85/15 % wt.). The strontium was introduced into the composition in an amount of 1% wt. Composite materials were obtained at sintering temperatures of 500 and 780 °C and a sintering time of 1 hour. The effect of additions of glass phase and strontium affect changes in the crystal lattice of biogenic hydroxyapatite was investigated with the help of X-ray phase analysis. Changes in the parameters of the crystal lattice (periods a and c) occur even at a temperature of obtaining composites of 500 °C. When strontium oxide is added, the crystal lattice changes in the periods (004), (211), (202) and the relative intensity I(202)/I(211) increases, which indirectly confirms the partial replacement of calcium ions by strontium ions in the structure of biogenic hydroxyapatite. Also the behavior of composites in vitro in physiological solution was studied.
Authors : Olena Poliarus, Jerzy Morgiel, Oleksandr Umanskyi, Piotr Bobrowski, Maciej Szczerba, Oleksiy Kostenko
Affiliations : Frantsevych Institute for Problems in Materials Science National academy of Sciences of Ukraine, Kyiv, Ukraine; Institute of Metallurgy and Materials Science Polish Academy of Sciences, Krakow Poland
Resume : The work is devoted to investigation of composite powders formation methods influence on the structure and functional characteristics of the NiAl-CrB2 plasma-sprayed coatings The serial powders of NiAl intermetallic compound and chromium diboride have been used as basic materials for the experiment. The NiAl-15 (30) wt. % CrB2 composite powders for coatings deposition were obtained by three different technologies: by conglomeration of mechanical mixture of initial powders on the organic binder; hot pressing technique and sintering in vacuum of a mixture of the initial components with following briquettes grinding to powder with a particle size -100 70 microns. The results of friction surfaces structure investigation after wear testing have shown that the method of powder particles obtaining, using a hot-pressing technology or sintering, is the most appropriate. Coatings made of powder mixtures, which were obtained due to this technology, showed less areas with damages of materials. It was investigated that enrichment of the diborides additives content in the intermetallic coating to 30wt. % leads to wear rate of coating increasing, because coating becomes more brittle. Refractory particles (diborides) pulling out from the coating and amount of abrasive in friction zone increases, thereby increasing the wear rate of coating. It was established that the additives of borides into intermetallics leads to the formation of oxide tribo-films which further behaves as solid lubricant that prevents the adhesive seizure of contact surfaces and improves wear resistance of tribo-couple.
Authors : I. V. Brodnikovska, I. M. Brodnikovskyi, M. M. Brychevskyi
Affiliations : Frantsevich Institute for Problems of Materials Science of National Academy of Sciences of Ukraine, 3 Krzhizhanovskoho St., 03680, Kyiv, Ukraine
Resume : The aim of our work was to compare the ionic conductivity of conventional 8YSZ and promising 10Sc1CeSZ electrolytes for solid oxide fuel cells (SOFC) obtained from the widely used commercial powders as well as to establish the factors which make the main contribution to the resistance and activation energy of ceramics obtained under identical technological conditions. 10Sc1CeSZ electrolytes were obtained from three different types of 10 mol.% Sc2O3 – 1 mol.% CeO2 – 89 mol.% ZrO2 powder (1 – VMMC, Ukraine; 2 – DKKK, Japan; 3 – Praxair, USA). The admixtures percentage was about 0.01 wt.% – for the type 1 (mainly silica and alumina) and type 3 (mainly silica and titania); and 0.001 wt.% – for the type 2 of the powders. 8YSZ electrolytes were obtained from the 8 mol.% Y2O3 – 92 mol.% ZrO2 made by Tosoh, Japan. After 24 h milling and 30 MPa pre-pressing the samples were sintered at 1400 °С in the air. The grain size of all three types of the 10Sc1CeSZ ceramics was about 0.5-1 μm. All the 10Sc1CeSZ and 8YSZ samples had ionic conductivity not lower (0.019-0.059 S/cm at 600°C) and activation energy not higher (0.88-1.07 eV) than its known from the literature. It was shown that grain boundary conductivity prevails in YSZ electrolytes due to the higher association enthalpy of the grain at temperatures below 560°C which depends on the dopant size. In 10Sc1CeSZ electrolytes the charge transfer passes mainly through grains: the main contribution to the grain boundary resistivity in technically pure materials (type 1 and 3) is given by the SiO2 segregations at the grain boundaries; and grain-to-grain contacts – in highly pure materials (type 2). Grain boundary resistivity of the type 1 samples was two times higher than the type 3 samples due to the presence of Al2O3 admixtures and its scavenging effect for the SiO2 segregations known for its conductivity diminishing.
Authors : O.M. Poliarus, O.P. Umanskyi, O.A. Bondarenko, K.M. Galtsov, S.M. Chernega, V.Yu. Chernatska
Affiliations : Frantsevich Institute for Problems of Materials Science National Academy of Sciences of Ukraine (IPMS NASU), Kyiv, Ukraine; National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine
Resume : The development of modern technology requires the creation of new materials that will resistance in the damaging water environments conditions. That is why there is a need to create new composite materials that guarantee the reliability and the appropriate level of functional properties including in corrosive environments. Particularly acute is now the problem of hydropower equipment parts protection (water-turbine engines blades) from hydro-abrasive wear and cavitation. In this work as a matrix for new composites creation selected intermetallic NiAl and NiTi, as well as reinforcing additives - chromium borides. These borides are resistant to corrosion and cavitation wear. The complex researches of developed composite materials on cavitation and hydro-abrasive resistance were conducted. Cavitation studies of starting materials and developed composites from them were performed using an ultrasonic disperser for 30 hours. As working environment a tap water was used. Steel was used as reference material. It is shown that the surfaces structure of intermetallics and the developed composites after tests in all cases without special mechanical damages. The original NiTi material is characterized by the presence of local single damage sites. In addition, as a result of the tests carried out, it can be concluded that for this material the effect of cavitation is expressed in the etching of the material surface under study. At the same time, grain boundaries begin to appear. The remaining materials at this stage of the study are characterized by the absence of any visible structural changes. In contrast to the above materials for the steel sample, after 2 hours of testing, there are areas of surface damage in the form of ulcers or shells. After 6 hours of cavitation, the whole surface under investigation contains separate foci of failure, which is associated with the production of the ferrite phase of this material. The structure and hydro-abrasive resistance of NiAl and NiTi intermetallides , as well as developed composites materials NiAl (NiTi) -15% CrB2 and NiAl (NiTi) -30% CrB2 after the tests for 20, 40 and 80 hours were studied. Tap water was also used as the working medium; silicon carbide was used as an abrasive material. It is shown that the surfaces structure of the initial intermetallides and the developed composite materials is characterized by the absence of the sites of material destruction. The effect of the impact is the polishing of the materials surfaces. The surface of such materials after the tests practically does not wear out compared to steel.
Authors : May-Show Chen (1,2), Pei-Jung Chang (3), Chin-Yi Chen (4), Yi Hu (5), Mazurkiewicz-Pawlicka Marta (6), Teobald Kupka (7), and Chung-Kwei Lin (3,8,*)
Affiliations : (1) Department of Dentistry, Taipei Medical University Hospital, Taipei, Taiwan; (2) School of Oral Hygiene, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan; (3) Research Center of Digital Oral Science and Technology, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan; (4) Department of Materials Science and Engineering, Feng Chia University, Taichung, Taiwan; (5) Department of Materials Engineering, Tatung University, Taipei, Taiwan; (6) Faculty of Chemical and Process Engineering ,Warsaw University of Technology, Warsaw, Poland; (7) Faculty of Chemistry, Opole University, Opole, Poland; (8) School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan
Resume : Mineral trioxide aggregate (MTA), mainly consisting of Portland cement and bismuth oxide, is a commonly use dental filling material. Within MTA, bismuth oxide serves as the radiopacifier and canal filling effect after clinical treatment can be revealed. In the present study, hafnia was used to replace certain amount of bismuth oxide by using either sol-gel process followed by post heat treatment or spray pyrolysis method. The structural and morphological properties of the so-prepared bismuth/hafnium oxide composite powder was examined by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The optimum composite composition was added with Portland cement and then mixed with deionized water to investigate its solidification characteristics. Experimental results showed that, by using bismuth/hafnium oxide composite powder, a significant improvement in radiopacity can be noticed. The best radiopacity performance can be observed with 10 mol.% hafnia addition. The heat-treated sol-gel composite powder exhibited a radiopacity of 6.26 mmAl. Whereas spray pyrolyzed composite powder exhibited a radiopacity of 6.41 mmAl, that is the highest in the present study.
Authors : Pranab Biswas1*, P V Rajeswari2, Cristina Gaspar1, Ivan Shtepliuk3, Andrii Tencha3, Rositza Yakimova3, Rodrigo Martins1, Luís Pereira1 and Volodymyr Khranovskyy3
Affiliations : 1Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa and CEMOP/UNINOVA, Caparica, Portugal. 2Department of Physics, Gayatri Vidya Parishad College of Engineering (A), Madhurawada, Visakhapatnam 530048, Andhra Pradesh, India. 3Department of Physics, chemistry and Biology (IFM); Linköping University, Linköping58183, Sweden *E-mail: email@example.com
Resume : In this study, we developed a novel ?green? nanocomposite based on graphene oxide (GO) and titanium dioxide nanoparticles (TiO2 NPs) with targeted application in a memory devices. GO was synthesized by using the conventional solution method (Hummers? method) followed by surface modification by ?green? reductants. While TiO2 NPs were synthesized using green chili plants as the bio-mass precursor for the NPs. Nanomaterials were studied by complimentary techniques: NPs demonstrated the average size of 10 - 20 nm and their optical absorption spectra revealed a sharp absorption around 385 nm corresponding to an optical bandgap of TiO2 ~3.22 eV. The X-ray diffraction pattern confirmed a dominating anatase phase, primarily textured along (101). Raman spectra of GO has demonstrated both D and G bands, as well as 2D line, peculiar for 2D carbon materials. The presence of carbonyl (40%), carboxyl (17%), epoxy (3%) and oxygen substitution functional groups was identified and quantified on GO surface using XPS spectroscopy. It is observed, that upon reaction of GO with diverse ?green? reductants (Glucose, Vitamin C and Caffeic Acid) the surface chemistry and functional groups availability on graphene surface is modified differently, affecting its properties. . The memory effect of ?green? nanocomposite is investigated as a function of GO to TiO2 NPs ratio. In order to fabricate a simple resistive switching memory device, Pt (90 nm)/Ti (10 nm) metals were deposited by using e-beam evaporation technique. The devices (Pt/Ti/GO-TiO2/Pt/Ti) with 2:1, 1:1, and 1:2 ratios of the component materials were screen-printed and characterized by using current-voltage (I-V) sweeping. The switching properties were varied significantly with the changing components ratio, which proves the potential of the novel green nanocomposites for nonvolatile resistive memory devices for future printed electronics, smart labels, RFID tags etc.
Authors : Nae-Man Park, Ji-Young Oh, Sooji Nam, Seong-Deok Ahn, and Jeong-Ik Lee
Affiliations : Electronics and Telecommunications Research Institute
Resume : Pressure sensors can generate signals under certain pressures and operate in a manner, namely, signal transduction. This prominent feature enables the successful application of pressure sensors in personal electronic devices, artificial intelligence and industrial production applications. The rapidly advancing electrical sensing techniques and organic electronics have contributed to significant progress in the development of flexible pressure sensors, which possess unique advantageous properties such as outstanding flexibility, low cost, and compatibility with large-area processing techniques. In particular, many flexible pressure sensors based on organic materials have been fabricated, and their sensing capacities even surpass human skin, the largest sensory organ with thousands of specialized pressure-sensing receptors. Through large-area integration of flexible devices, active sensing matrices have been fabricated which tend to be ideal candidates for electronic skin (e-skin) applications. Here, we introduce a simple pressure sensor structure of Al/parylene which is easily fabricated on a large area and applicable for flexible or wearable sensor networks. The sensing properties such as sensitivity, limit of detection, linearity, and response time are discussed.
Authors : V.Kokhany, I.Chernyavsky, L.Vyshniakov
Affiliations : Frantsevich Institute for Problems of Materials Sciences, Ukraine
Resume : In lightning protection panels consisting from layered carbon plastic protection of the material from the action of electrical charges of lightning and Joule heating is realized due to number of dissipative processes. Usually it is considered removal of electrical charges from the place of injury through the meshes or grooved foils at the surface of carbon plastic into earthing (winding energy systems) or into oncoming stream (aviation). Additional mechanism of energy dissipation which can be technically realized by introduction of carbon nanoparticles into epoxy binder (situated between carbon fibers) and creation of conducting dielectric had been considered. The level of electrical conductivity can be regulated by changing of the concentration of carbon filler and using of prepreg technology of carbon plastic production. By arranging into the panel the laminate layers filled by carbon nanoparticles it is possible to absorb the part of lightning energy by heating of carbon plastic. In that case it is necessary to avoid the essential heating which can cause composite local burning and electrical arc in the air space of the blade. The proposed method is based on the using of mutual influence of the parameters of the surface resistance of carbon laminate and the electrical conductivity of the volume of the composite matrix. The example of the calculation of electrical conductivity of layered carbon plastic reinforced by carbon nanoparticles with enhanced resistance to the local burning due to lightning had been presented
Authors : A.Maznaya, A.Neshpor, A.Brovko, L.Yaschenko
Affiliations : Scientific and production company of composite materials
Resume : Composite construction for protective ceramic elements from reaction sintered silicon carbide and polymer supports based on glass fabric TG-660. Epoxyurethane oligomers with polyoxypropylene (ПЭУ-1) and oxytetramethylene (ПЭУ-7) fragments with hardener of anhydride type had been synthesized. For various ratio oligomer:hardener angle tangent of mechanical losses, dynamic elastic modulus and losses modulus had been measured. It was shown that polyepoxyurethanes may be used as damping compositions and optimal composition for polyepoxyurethane is the composition with 5 wt. parts of hardener. Ceramic-polymer composites with supports based on polyepoxyurethane matrixes are characterized by the high values of impact resistance under small outbarrier deformation (not more than 10 mm). In ceramic-polymer composites with discrete structure (on the base ofceramic elements of cylinder forms) polyepoxyurethane matrixes showed the high level of physical and mechanical properties and adhesion to ceramic, increased values of life cycle and decreasing of the weight of protective constructions
Authors : O.Grigoriev, T.Ludvinskaya, I.Neshpor, V.Panashenko, T.Mosina, M.Vasilkovskaya, A.Zubarev, I.Kozak
Affiliations : Frantsevich Institute for Problems of Materials Sciences, Ukraine
Resume : The influence of preliminary mechanical activation (MA) of 80 vol.% ZrB2–15 vol.% α-SiC–5 vol.% B4C raw mixture in a high-energy activator for 15, 30, 60 and 120 minutes on its structural-phase state has been studied. X-ray diffraction analysis of the initial powders and milled (activated) products showed a broadening of the diffraction lines profile with an increase in the mixtures grinding time, that indicates the nanocrystalline structure of the polycrystals (Scp-10 m2/g). The microstructural analysis (by SEM "JEOL") showed the formation of nanostructured particle agglomerates with an increase in MA time. Chemical analysis of MA products showed the iron presence in mixtures, the amount of which increases with grinding time and was 3.55, 4.66; 5.31 and 5.09 wt.%,respectively. Hot pressing of MA mixtures was carried out in graphite molds without a protective atmosphere. In order to study the formation of the ceramics structure at hot pressing, mixtures of 80%vol. ZrB2– 15% vol. α-SiC– 5% vol. B4C system after MA were hot pressed under isometric conditions in two regimes: 1– at 2100 °C for 5 min. and 2 –at 2150 °C for 15 minutes. The calculated density values (ρ, g/cm3) increased with the increasing of MA time, sintering temperature and duration according to theregimes, for regime1: 4.61, 4.90, 4.90 and 4.52 g/cm3; and for regime 2:4.84, 5.11, 5.15 and 5.43 g/cm3. A similar regularity was found for σbend, which average value for the regime1 is 350 MPa, and for the regime 2 it is 468 MPa.The structure of hot-pressed samples from mechanically activated mixtures of 80 vol.% ZrB2–15 vol.% α-SiC–5 vol.% B4C system shows more uniform phases distribution and fine-grained structure in comparison with the same samples without MA.
Authors : O.Grigoriev, T. Ludvinskaya, I.Neshpor, V.Panashenko, T.Mosina, M.Vasilkovskaya, V.Subbotin, I.Berezhynsky
Affiliations : Frantsevich Institute for Problems of Materials Sciences, Ukraine
Resume : It is very difficult to obtain nonporous and fine-grained ZrB2 pure ceramics by hot pressing. The study of the processes of ultra-high temperature ceramics (UHTC) formation, which combines the stages of carbothermal reduction of ZrSiO4, the synthesis of ZrB2 and SiC at hot pressing in the ZrB2-B4C-ZrSiO4-C system has been carried out. Thermodynamic calculations of ZrSiO4 interaction reactions depending on the carbon content in the mixtures (1 to 8 mol) were carried out in the temperature range of 1000-2000ºС. Calculations showed that the most complete decomposition of zircon ZrSiO4 to ZrO2 and SiO2 with the formation of ZrC and SiC should proceed by the ZrSiO4 + C reaction at carbon content of 4-8 moles at about 1750ºC. The optimal conditions for reactive hot pressing sintering of the ZrB2-B4C-ZrSiO4-4C composition in temperature range of 1970-2150ºC at duration of 5-30 minutes has been developed. Herewith, the obtained material has uniformly distributed fine-dispersed ZrB2 and SiC phases, according to the microstructural and X-ray phase analysis, with high density and strength characteristics (ρ = 5.29 g/cm3 and bend = 594.12 MPa.). Apparently, when the ZrSiO4 decomposes into ZrO2 and SiO2, the reaction of 2ZrO2 + B4C+3C = 2ZrB2 + 4CO(g) occurs with the formation a secondary ZrB2. Herewith, SiO2 is reduced to SiC. Combining the carbothermal synthesis of nano-SiC at hot pressing promotes the formation of composites with uniform components distribution and allows to avoid the additional stages such as obtaining a highly disperse SiC powder, mixing and co-grinding of the powders.
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Production and properties of metal based composites : Prof. M.Szafran
Authors : I. Husarova-1, N. Brodnikovskiy-2, A. Potapov-1, I.Derevyanko-1, T. Manko-1
Affiliations : 1-Yuzhnoye State Design Office; 2-Frantsevich Institute for Problems of Materials Sciences of NASU
Resume : The creation of reusable aerospace vehicles that come back to the Earth after the flight task accomplishment will significantly decrease the cost for insertion of cargos to the orbit. Today there are dozens of projects dedicated to reusable transportation aerospace systems at different development stages with diverse structural schemes. The most promising are two stages systems (German project “Zinger”, French project “Hermes”) that possess acceptable exploitation characteristics when using first stages with wings in order to come back to the starting place as a plane. One of the main issues during the creation of reusable flight vehicles is creation of heat-resistant and heat-protective materials and structures. The analysis of thermal operational modes shows that the most problematic are surfaces, which operational temperatures lay in a range of 850 ˚С to 1200 ˚С. The siliconized carbon-carbon composite materials, high-temperature ceramic and heat-resistant metallic alloys can be used in the above-mentioned temperature range in air environment. The most perspective materials are heat-resistant alloys with low-density and high specific performances, while metals are the most reliable structural materials. The advantages of metals are conditioned by their ability to plastic flow and self-reinforcement. Based on analytical review of scientific research results it was defined that one of the most perspective materials are multicomponent alloys based on niobium with high mixing entropy and aging nickel alloys that represents the alloy Ni-Cr-Тi-Аl. The target of this work is creation of aging nickel alloys and alloys based on niobium with high mixing entropy. As a result of performed study, two casting alloys were created - 56Nb-10Cr-10Al-16Ti-5Mo-2Zr-1Si and Ni-20Cr-3Al-2Ti and their properties were investigated within the temperature range of 20 ˚С -1200 ˚С. The work performed based on Grant Agreement № 607182 within the Seventh Framework Programme (FP7/2011-2014), “Light TPS”.
Authors : Jyotsna Dutta Majumdar1, A. Kumar1, S. K. Roy1, and I. Manna1,2
Affiliations : 1Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, W. B. - 721302 2. Indian Institute of Technology Kanpur, U. P.
Resume : In the present study, DC-sputter deposition (of Ti-6Al-4V) followed by nitriding (by plasma nitriding and plasma ion implantation) have been adopted for developing ultra-fine nano-nitride dispersed surface on AISI 316L stainless steel substrate. Followed by sputtering and nitriding, a detailed characterization of the surface (in terms of microstructure, phases and bond strength), and its mechanical properties (nano-hardness, Young?s modulus and coefficient of friction) have been carried out. The microstructure of the sputtered Ti-6Al-4V consists of very fine particulates of alpha in the form of clusters. Plasma nitriding and nitrogen ion implantation of the sputter deposited titanium lead to formation of ultra fine white precipitates of titanium nitrides dispersed in the ? matrix. The adhesion property of the coating has been evaluated through nano-scratch testing. An enhancement in bond strength has been observed after nitriding which is attributed to nitride formation and with a maximum adhesion strength observed due to ion implantation because of a higher depth of penetration of nitrogen and finer nitride formation. The maximum improvement in Nano-hardness and Young?s modulus after nitrogen implantation is due to the presence of nitrogen in solid solution and formation of nitrides.
Authors : Alok Bhadauria, Lavish K. Singh and Tapas Laha
Affiliations : Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India
Resume : Aluminium matrix composite reinforced with different weight percentage of functionalized graphene nano platelets (GNPs; 0, 0.25, 0.5, 1.0 wt%) were fabricated via semi-powder metallurgy method and spark plasma sintering. Microstructural characterization was conducted via field emission scanning electron microscopy equipped with electron dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy. Tensile properties of the nanocomposites were also evaluated. Atomic force performed on the (GNPs) showed that GNPs were having less than 10 layers of graphene. Al-0.5 wt% functionalized GNP composites showed homogeneous dispersion in Al matrix and no chemical reactions were seen at the interfaces between Al and GNPs. The tensile test revealed 33% increment in yield strength of Al-0.5 wt% GNPs. Further, increase in GNPs concentration (1.0 wt%) resulted in decrease in tensile properties attributed to agglomeration of GNPs present in Al matrix. The roles of strengthening in composites were discussed with different possible strengthening mechanisms. Detailed fractography cariied out on the nanocomposites indicate a change of fracture mode from ductile to brittle with increase in the amount of GNPs. Keywords: Graphene nano platelets; Al matrix composite; Tensile properties; Spark plasma sintering; Strengthening mechanism
Authors : D. Dutta Majumdar1, 3, D. P. Mondal2, M. Ghosh3, H. Rao, and A. Roy Choudhury3 and J. Dutta Majumdar1
Affiliations : 1Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur 721302, India. 2Advanced Materials and Processes Research Institute, Council of Scientific and Industrial Research, Bhopal 462064, India. 3Indian Institute of Engineering, Science, and Technology, Howrah, India
Resume : The present investigation, a detailed study of wear behavior of titanium based foam developed by powder metallurgy route has been carried out. Titanium based foam has been developed by powder metallurgy route using cenosphere, NaCl and NH4CO3 as space holders under optimum processing conditions. Followed by processing, a detailed characterization of the microstructure and phase of the composite has been carried out. The wear behaviour of the samples has been evaluated by fretting wear testing unit against WC ball at varied applied load of 10 N and 20 N and an oscillating frequency of 10 Hz. The detailed objectives include understanding the role of space holders on the characteristics (microstructure, phase, composition, porosity) and wear behavior of the foamed coupons. Finally, the mechanism of wear has been investigated through a detailed observation of the post wear microstructures.
Authors : Seyed Reza Elmi Hosseini, Zhuguo Li
Affiliations : Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Resume : The fiber laser welding of Ti64 alloy to SS 304 by some pure intermediate layers were developed. The scope of this research is to improve the joint strength of materials pair by usage of composite interlayer sheets. The microstructure and fracture characteristic of the joints were analyzed by OM, SEM, EDS and X-ray diffraction. The intermetallic compounds were observed in the Ti/weld interface, and the joints all fractured at the Ti/Filler interfaces. In order to estimate the area which intermetallic phases formed in the weldment, the microhardness experiments were done on the cross section of each sample. First, laser welding done by pure Cu which laser positioned at the interface of titanium and stainless steel achieved joint strength of 227 MPa. In order to strengthen the joint strength of the weld, the pure nickel and vanadium sheets added to the copper which then showed the strength raised about 31 % and 51 %, respectively. The best value for cross-weld tensile strength of the joints was up to 343 MPa, recovering 51 % of titanium alloy strength. All experiments performed at the same laser power.
Functional bioceramics : Dr.Paulina Wiecinska
Authors : O. Sych, A. Iatsenko*, T. Tomila, Ya. Yevych, S. Korichev, M. Demyda*
Affiliations : Frantsevich Institute for Problems of Materials Science of NAS of Ukraine, 3, Krzhyzhanovsky Str., Kyiv 03680, Ukraine *National Technical University of Ukraine ?Igor Sikorsky Kyiv Polytechnic Institute?, 37, Peremogy Ave., Kyiv 03056, Ukraine
Resume : Development of modern highly-porous biomaterials for bone tissue engineering has been based on the enhanced knowledge of materials science and the way these materials interact at cellular and tissue levels. Highly porous glass-ceramics based on biogenic hydroxyapatite and SiO2-Na2O glass with addition of Aerosil® and sodium hydroxide solution have been prepared by foam replica method at sintering temperature 900 °?. The samples were examined by optical microscopy (binocular stereo microscope MEIJI Techno, Japan), XRD analysis (DRON-3M computerized diffractometer, Russia) and IR spectroscopy (FCM Fourier spectrometer, Russia). The compressive strength was determined by a uniaxial compression using a universal machine (Ceram test system, Ukraine). Experiments in vitro were carried out to estimate bioresorption of materials, in particular their solubility in the physiological isotonic solution (0.9 % NaCl water solution) at 36.5±0.5 °?. According to the XRD results it was established that during sintering, the hydroxyapatite phase (??5(??4)3(??), JCPDS No. 9-432) of biogenic hydroxyapatite in the glass-ceramics was not changed, which was confirmed by IR spectroscopy results. Prepared samples are characterized by a permeable macrostructure with total and open porosity of 85 and 80 %, respectively, and a compressive strength of 0.4 MPa. Based on in vitro experiments it was established that the bioresorption rate of glass-ceramics is equals 0.11 wt.%/day. Prepared highly-porous materials are promising for replacement of defective cancellous bone tissue in surgery. The publication contains the results of studies conducted by President?s of Ukraine grant for competitive projects No. F70/17295 of the State Fund for Fundamental Research
Authors : A. Dabrowska, R. Innocenti Malini, F. Spano, R. M. Rossi
Affiliations : Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, CH-9014, St. Gallen, Switzerland
Resume : Human skin is an advanced functional material, playing a variety of vital functions in everyday life. Skin properties, structure and performance are all influenced by many internal and external factors, of which the level of hydration seems to dominate. Water on human skin arises from sweating and sweat accumulation or from external factors, such as rainfall or increased air humidity. Due to the presence of keratin, the stratum corneum (SC, horny layer of skin), is able to take up water leading to significant adjustments of its properties. Water uptake causes swelling of the cells within the SC, increasing its thickness and decreasing the surface roughness of skin. Moreover, water acts as a strong plasticizer on human skin and leads to a vast decrease in the SC stiffness (Young’s modulus drops from the GPa to the MPa range). Smoother and easier deformable hydrated skin exhibits higher real contact area with other materials and, as a result, higher friction-coefficient values. Here we propose a new bio-mimicking composite skin model, consisting of an elastomeric, pressure-triggered sweating system and a water-responsive layer, composed of gelatine and textile. The skin model undergoes the same skin-specific changes caused by prolonged water exposure; it swells, smoothens, softens and follows the same changes in the frictional behaviour. A water-responsive, pressure-triggered sweating skin model can be applied instead or next to the conventional in vivo investigations focused on the influence of various atmospheric conditions and sports activities on skin properties and frictional behaviour. Moreover, it can act as a suitable system to better understand the influence of water on human skin properties and performance.
Authors : M. Sopronyi-1, N.Mihailescu-1, A. Ficai-2, C. Ristoscu-1,C.N. Mihailescu-1, L.Floroian-3, M. C. Chifiriuc-4, I.Negut-1, I.N. Mihailescu-1
Affiliations : 1-1National Institute for Lasers, Plasma and Radiation Physics; 2-Politehnica University of Bucharest; 3-Romania Transilvania University of Brasov; 4-University of Bucharest
Resume : Nowadays, intense research is focused on the development of “smart implants” based on biodegradable metallic materials. We report a new type of thin films obtained from two independent materials collected on a single biodegradable metallic substrates by Combinatorial Matrix Assisted Pulsed Laser Evaporation (C-MAPLE) technique. The coatings were obtained using a KrF* excimer laser source (λ = 248 nm, τFWHM ≤ 25 ns). The aim of this study is to enhance the cellular adhesion of surrounding tissue to the biodegradable substrate by finding the optimal ratio between tow biocompatible metamaterials: Ligning to Chitosan. The obtained coatings preserved their initial composition, as demonstrated by physical-chemical analyses: Optical Florescence Microscopy, Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma mass spectrometry (ICP-MS). Electrochemical measurements, impedance spectroscopy and in vitro immersion tests were conducted to evaluate the corrosion resistance of the uncovered and covered biodegradable metallic substrates into physiological fluids. In vitro assay revealed that the obtained thin films are non-cytotoxic. The antimicrobial effect of the covering layers was tested against S. aureus and E. coli strains, involved implant associated infections. The deposited films where monitored over a timeframe of 8 and 24 hours, to monitor the antimicrobial evolution of the two bacteria, and the according ration between lignin and chitosan. The results proved that C-MAPLE method allow for the fabrication of efficient shield barriers against corrosion, biofilm formation and contamination with bacteria.
Authors : V. Zinchenko, S. Pavlinchuk
Affiliations : V. Bogatsky Physico-Chemical Institute of NAS of Ukraine,
Resume : The problem of creating suitable materials for prostheses used in the damage of bone tissue is acute permanently. There are various types of materials which are proposed for these purposes: a) inactive materials (some metals, for example Ti, Ta); b) bioinert materials (oxides, particularly, ZrO2, Al2O3), and c) bioactive materials (apatites, for example, Calcium hydroxylapatite (CaHap) or fluoroapatite (CaFap); phosphate or mixed phosphate-silicate glasses; other phosphates). The use of composites in which the bioactive material (CaHap or CaFap, for example) is combined with inactive or bioinert one to obtain a bioactive implant with high mechanical strength and durability reveals most promising. The studies of synthesis of nano-composite including CaFap, from one hand, and alumina, Al2O3 – from another – are carried out. Earlier we developed an essentially new way of synthesis of CaFap in saline melt (NaCl-KCl) at moderate temperature (700°C). At the synthesis of CaFap as initial Ca – containing components CaCO3, CaO, CaF2, and P – containing component NaPO3 were used. To avoid possible hydrolysis, the process is better carried out in an inert atmosphere (argon). The XRDA data suggested formation of well crystallized product. The washed out in water powders consist of nano-scale particles associated into the stick-like aggregates of various sizes. To obtain the nano-composite of CaFap and alumina in a weight ratio of 2 : 1 as initial components Ca10(PO4)6F2 and Al(OH)3 (the last is an industrial product) were taken. The synthesis of the composite CaFap – alumina was performed by solid – state route. Initial butch (mixture of powders) was pressed into pellet and sintered in three stages for 2 hours at each of them: stage 1 – 650°C, stage 2 – 1000°C, and stage 3 – up to 1350°C. After each stage the tablets were ground and pressed again. Thus we obtained rather strong tablets of white (with light gray tint) color.
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Multifunctional composites and their service properties: part 1 : Dr. Iryna Bilan
Authors : PingAn Hu; Jia Zhang; Xiana Wang
Affiliations : Research Centre for Micro/nanotechnology,Harbin Institute of Technology
Resume : High scalability and conductive fibers have important application prospects in the field of wearable devices. Using multi-scale structure coordination gain principle, we first proposed a imitation shell nano scale and micrometer screw structure combined with building materials, the micro is nano scale clay brick layer structure, the secondary structure is helical structure of the micron scale. The combination of these two kinds of structure gives the fiber with high elongation and high mechanical strength, so it has high toughness. In helical fibers into luminescence cadmium selenide (CdSe) quantum wires and found that the helical fibers in non polarized light under the excitation of a polarization of polarized light, polarized light (left-hand or right-hand) type is determined by the spiral direction of the fiber, the polarized light intensity can be regulated by mechanical deformation of helical fibers. References: (1)J Zhang, W Feng, H Zhang, Z L Wang, H A Calcaterra, B Yeom, P A Hu*, N A Kotov, Multiscale deformations lead to high toughness and circularly polarized emission in helical nacre-like fibers, Nature Comm, 2016, 7,10701 (2)X N Wang, Y F Qiu, W Cao, PA Hu, * Highly Stretchable and Conductive Core–Sheath CVD Graphene Fibers and Their Applications in Safe Strain Sensors, Chem. Mater, 2015, 27 (20), pp 6969–6975 (3)Z Ma, Y Qiu, H Yang, Y Huang, J Liu, Y Lu, C Zhang, PA Hu* Effective synergistic effect of dipeptide-polyoxometalate-graphene oxide ternary hybrid materials on peroxidase-like mimics with enhanced Performance, ACS Appl Mater Inter, 2015, 7(39), 22036-45
Authors : Seung Hwan Lee, Seunggun Yu, Woo Nyon Kim, Soon Man Hong, and Chong Min Koo*
Affiliations : Seung Hwan Lee; Seunggun Yu; Soon Man Hong; Chong Min Koo Materials Architecturing Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, Republic of Korea Seung Hwan Lee; Woo Nyon Kim Department of Chemical and Biological Engineering, Korea University, Seoul, 136-713, Republic of Korea Chong Min Koo KU-KIST Graduate School of Science and Technology, Korea University, Anam-ro 145, Seongbuk-gu, Seoul 02841, Republic of Korea
Resume : We demonstrate facile strategy to develop polymer composites with unusually enhanced electronic and thermal conduction behaviors via 3-dimensional (3D) Cu hollow networks. The composites with efficient Cu conduction pathway were easily prepared through the electroless plating of Cu on expanded bead (EBCu), followed by conventional thermal compression with polymer matrix. The EBCu/polycaprolactone (PCL) composites revealed excellent electromagnetic interference effectiveness (EMI SE) of 88 dB at 8 GHz as well as thermal conductivity of 5.1 W m-1 K-1 despite the extremely low Cu content of 6.8 vol%, resulting in decreased density of composites. Especially, the EMI SE and thermal conductivity values were rapidly increased with the decrease of density, because the increased EBCu content contributed to not only decreased density of composite but also formation of efficient Cu conduction pathway with low percolation threshold of 0.034.
Authors : Yan-Jun Wan, Peng-Li Zhu, Shu-Hui Yu, Rong Sun, Ching-Ping Wong, Wei-Hsin Liao*
Affiliations : Yan-Jun Wan, Wei-Hsin Liao. Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China; Peng-Li Zhu, Shu-Hui Yu, Rong Sun. Center for Advanced Materials, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Ching-Ping Wong. Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China.
Resume : Electromagnetic pollution and electromagnetic interference (EMI) caused by electrical and electronic equipment have increased substantially with the rapid development of information technology. Electronics and their components with higher power, smaller size and faster operative speed emit the unwanted electromagnetic waves, which not only lead to malfunctioning and degradation of electronics but also threaten human health and the surrounding environment. EMI shielding has become the effective method and key technology to protect human and environment from the negative effects, which is of great importance in both fields of the civil and military. In addition to high-efficiency EMI SE, being light weight and flexible are another two key factors for EMI shielding materials, especially in areas of aerospace, modern aircraft, communication, flexible electronics and wearable devices. In our previous work, super elastic and ultralight graphene/cellulose fiber hybrid aerogel with excellent EMI shielding effectiveness (SE) was developed , and the effect of graphene aerogel pore size on EMI SE of epoxy composites was investigated . In present study, large-sized graphene sheets (LG) and doping strategy were employed to fabricate lightweight and flexible graphene paper with exceptional EMI shielding performance. Compared with the smaller sized ones, LG with fewer defects and more conjugated carbon domain size as well as better alignment result in higher electrical conductivity and strength of graphene paper. The iodine doping further improves the carrier density of LG by formation of triiodide ("I" _"3" ^"-" ) and pentaiodide ("I" _"5" ^"-" ) through charge transfer process without deteriorating the mechanical property, thus leading to superior EMI shielding effectiveness (SE). The EMI SE of iodine doped LG film with thickness of 12.5 μm is up to ~ 52.2 dB at 8.2 GHz, which is much higher than that of undoped LG with the same thickness (~ 47.0 dB). More important, the improvements in EMI SE is contributed to the SE absorption, while the SE reflection is almost unchanged. The mechanisms of improved EMI shielding performance as well as mechanical property were investigated and discussed. The present study provides a facile way to fully develop graphene in lightweight and flexible EMI shielding materials and devices. References:  Wan Y-J, Zhu P-L, Yu S-H, Sun R, Wong C-P, Liao W-H. Ultralight, super-elastic and volume-preserving cellulose fiber/graphene aerogel for high-performance electromagnetic interference shielding. Carbon. 2017;115:629-39.  Wan Y-J, Yu S-H, Yang W-H, Zhu P-L, Sun R, Wong C-P, Liao W-H. Tuneable cellular-structured 3D graphene aerogel and its effect on electromagnetic interference shielding performance and mechanical properties of epoxy composites. RSC Advances. 2016;6(61):56589-98.
Authors : Chunhua Zhu, Limin Li
Affiliations : Institute of Chemical Materials, China Academy of Engineering Physics
Resume : Stretchable conductors which can retain high conductivity under substantial stretching and bending deformation can enable a wide variety of new applications in electronic skins, sensors, and deformable capacitors. Three different types of stretchable conductors with excellent properties were fabricated. The binary conductive network structure was constructed based on cotton or PU sponge which had an interconnected and junction-free macro-porous structure as the skeleton to support the two dimensional AgNWs network, leading to excellent electrical and mechanical properties. During the fabrication of stretchable conductors, polydopamine was used to enhance the adhesion between the conductive nanomaterials and polymer to construct the high conductive network. The dip-coating or pre-strain methods were explored to tuning the microstructure of nanocomposites, which controlled the resistance of nanomaterials. The as prepared composites showed high electrical and mechanical properties. Moreover, the excellent conductance is maintained up to 1000 stretching or bending cycles. The significant electromechanical properties was also demonstrated by a simple stretchable circuit composed of a light-emitting diode (LED) and stretchable conductor during bending, twisting or stretching.
Authors : K. Shportko1*, L. Revutska1, O. Paiuk1, J. Baran2, M. Wuttig3, A. Stronski1, A. Gubanova4 and E. Venger1
Affiliations : 1. V. Lashkaryov Institute of Semiconductor Physics of NAS of Ukraine, Kyiv, Ukraine; 2. W. Trzebiatowski Institute of Low Temperatures and Structure Research of PAS, Wroclaw, Poland; 3. Institute of Physics (IA), RWTH Aachen University, Aachen, Germany; 4. Kamianets-Podilsky National University, Kamianets-Podilsky, Ukraine.
Resume : Amorphous chalcogenides are widely used in infrared optical elements, acousto-optic and all-optical switching devices, holography recording media, etc. Chalcogenide alloys that exhibit remarkable contrast in their electrical and optical properties between the amorphous and crystalline states are promising for data storages. We focused on the several amorphous Ge-Sb-Te and Ge-As-Se alloys with systematic increase of the Ge-content. Raman spectroscopy has been employed to investigate the compositional dependencies in the vibrational properties of selected materials. Raman spectra of Ge-As-Se samples showed that the backbones of the studied samples consist of AsSe3/2 pyramidal units, edge- and corner-shared GeSe4 tetrahedral units. Systematic compositional changes of characteristic constituent Raman bands’ intensities showed that Ge-As-Se samples contain different nanophases whose concentration is changing along chosen compositional cross-section. Systematic compositional changes in Ge-Sb-Te alloys result in the evolution of the observed Raman bands. The shift of the strongest band in the Raman spectra of studied alloys can be interpreted in the term of the interplay of its component bands’ intensities. Obtained compositional trends in the intensities of Raman bands may enable one to predict vibrational properties of other amorphous Ge-Sb-Te alloys along the studied compositional line.
Authors : P.S.Smertenko (1), T.Ya.Gorbach (1), N.M.Roshchina (1), V.V.Naumov (1), M.G.Dusheiko (2), G.Wisz (3), A. Ubelis (4)
Affiliations : (1) V.Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 45 Prospekt. Nauki, 03028, Kyiv, Ukraine, firstname.lastname@example.org (2) National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, 56 Peremogy Avn., 03680, Kyiv, Ukraine (3) University of Rzeszow, aleja Tadeusza Rejtana 16C, 35-001, Rzeszow, Poland, email@example.com (4) University of Latvia, 19 Raiņa bulvāris, Rīga, LV-1586, Latvia, firstname.lastname@example.org
Resume : Organic-inorganic hybrids are one type of the variety of composite materials. We propose the self-organization (SO) and self-assembly (SA) approach for formation of such hybrids. SO and SA layers are potential objects for photovoltaics, optoelectronics, biosensing, as well as gene and drug delivery applications due to: (i) unique properties of both the isolated molecule and self-organized molecular assemblies or aggregations; (ii) the combination of a high absorption coefficient of organics and good Si transport properties; (iii) hybrid compatibility with well explored Si planar technology. Our approach is based on the next innovations: (i) low-cost ecological bio- or synthetic organic compounds; (ii) room-temperature process of molecular self-organization and assembly for 2D structures; (iii) simple technology of chemical bath deposition from aqueous solution. At the first time we used heterocyclic amines for self-organization of organic layers on nanostructures silicon substrate. We used heterocyclic amines: thiamine diphosphide, b) clonidin, c) metamizole sodium, d) procainamide, e) sulfacil sodium. The morphology of self-organized films had a wide variety of morphology: net-like, ring-like, fibers, stars etc. New knowledge about the mechanisms of self-organization of organic molecules on the surface of inorganic materials during the formation of hybrid organic-inorganic structures allow the better understanding of many processes, such as the passivation of surface, changing of the charge trap states, influence of chemicals on the energy level alignment, altering the work function of surfaces, direction for the charge carriers injection and extraction, control of the organic layers morphology.
Multifunctional composites and their service properties: part 2 : Prof. M.Szafran
Authors : Hwan-Jin Jeon
Affiliations : Department of Chemical Engineering and Biotechnology, Korea Polytechnic University, 237. Sangidaehak-ro, Siheung-si, Gyeonggi-do 15073, Republic of Korea.
Resume : The development of complex nanopatterned three-dimensional (3D) structures with high resolution, high aspect ratio, high areal density and tunable features from a soft template is one of the most important challenges in high performance nano-devices such as opto-electronics, display devices and nanobiotechnology. To date, several approaches, which include nanoimprint-, block copolymer-, interference lithography and electrodeposition have been suggested to fabricate 3D 10nm scale patterned materials. However, they have serious problems such as high process cost and difficulty of resolution / large area. In this study, we introduced a new patterning technique, named “secondary sputtering lithography (SSL)”, that enables the fabrication of 10 nm-scale 3D patterned nanostructures with high aspect ratios over large areas by utilizing secondary sputtering phenomena during conventional ion-etching process. This innovative method we have developed utilizes the angular distribution of target particles by ion-beam bombardment, which leads to deposition of target materials on side-walls of patterned polymers. We have fabricated a variety of complex 3D patterns with ultrahigh-resolution, including lines, hole-cylinders and cup shaped structures. In addition, this approach can create the nanopatterned ITO surface without greatly decreasing the electrical and optical properties of the surface, since our SSL technique is a one-step process that simultaneously etches and deposits materials without any further surface treatments and deposition processes. Also, based on the secondary sputtering phenomenon, we have successfully fabricated the nanopatterned ITO layers with sub 20nm high resolution and high aspect ratio for liquid crystal devices without a conventional polymer alignment layer fabrication process. Accordingly, the new, secondary sputtering lithography approach will serve as a new technique for fabricating complex nanoscale patterns with 10nm scale ultrahigh resolution, 3D structures and high aspect ratio.
Authors : Damian Lukawski, Agnieszka Lekawa-Raus, Filip Lisiecki, Krzysztof Koziol, Alina Dudkowiak
Affiliations : Damian ?ukawski, Alina Dudkowiak, Faculty of Technical Physics, Poznan University of Technology, Poland; Agnieszka Lekawa-Raus, Faculty of Mechatronics, Warsaw University of Technology, Poland; Filip Lisiecki, Institute of Molecular Physics, Polish Academy of Sciences, Poland; Krzysztof Koziol, Pembroke College, Cambridge, UK;
Resume : Carbon nanomaterials (CNMs) has recently found applications in terms of superhydrophobic coatings. Here we propose the novel use of large-scale produced multiwall carbon nanotubes, graphene nanoplatelets, and carbon black as hydrophobic agent in wood technology applications. We present simple methods of CNMs deposition via drop casting and dip coating, using CNMs dispersed in organic solvent and aqueous solution. The quality of coating was investigated by fluorescence microscopy and scanning electron microscopy, which showed that even a small amount of multiwall carbon nanotubes or graphene nanoplatelets creates a homogeneous coating onto wood surface. The contact angle measurement gave the results of 145° for the best samples, which confirmed that their surface is superhydrophobic. Moreover, we proofed that the developed method increases hydrophobicity independently on porosity or chemical composition of various woods. Finally, we developed a model describing superhydrophobic properties of wood coated with carbon nanomaterials. Acknowledgements D.?. and A.D. would like to thank National Science Centre, Poland for funding (project no. 2015/19/N/ST8/02184).
Authors : Da Zhang*, Chengjing Xiao, Liang Chen, Tao Wei, Zhen Li, Zaiqin Wang
Affiliations : Changjiang River Scientific Research Institute, 289# Huangpu Street, Wuhan, 430010, China
Resume : Chemical grouting technology is an effective means to deal with the foundation defects and leakage. However, most gels of the chemical grouting materials have poor toughness, and are easily broken under external force. Nanocomposite hydrogel has excellent mechanical properties and toughness, but the viscosity of its slurry is high and the permeability is poor. In this paper, the surface of clay-nanosheets was modified with different ions and organic molecules to improve its dispersion in aqueous solution. The rheological property and gelation process of clay-nanosheets crosslinked organic-inorganic composite chemical slurry were researched. Furthermore the internal structure, mechanical properties and strength of solid sand body of gels were characterized and analyzed. The permeability characteristics of organic-inorganic composite chemical grouting materials was studied by the penetration test in several sand media. The paper presents a theoretical and technical basis for the application of clay nanosheets based nanocomposites hydrogels in foundation treatment by chemical grouting.
Authors : M. Parco-1, I. Fagoaga-1, O. Grigoriev-2, L. Silvestroni-3, I. Podcherniaeva-2, I. Neshpor-2, G.Frolov-2, V. Kisel-2, Y.Evdokimenko-2
Affiliations : 1-Fundacion Tecnalia Research &Innovation, Spain; 2-Frantsevich Institute for Problems of Materials SCiences, Ukraine; 3-Institute of Science and Technology for Ceramics, Faenza,Italy
Resume : ZrB2-15 MoSi2 and ZrB2-3SiC-5 WC corrosion-resistant plasma coatings have been deposited by shrouded plasma method on a specially designed equipment on carbon-carbon composite material (СССM) of 50 × 24 × 5 mm. The coated samples were subjected to a supersonic flow of combustion products of air-fuel and oxygen-fuel mixtures impact. The coatings thickness was 0.4-0.7 mm. At the maximum mode (maximum surface temperature of the coatings), the flow stagnation temperature was 2100 ° C, the flow stagnation pressure was 0.45 MPa. The determining surface temperature in the tests was 1470 ± 10 ºС, the maximum temperature - 1692 ºС. The test conditions differed in these two series by the concentration of oxygen in the gaseous medium, i.e. with the intensity of oxidation processes and thermal stresses outside the heat spot, caused by different diameters of the jet - the source of heating. The surface temperature in the tests was kept at 1600°C for 200 sec at one heating cycle. The test results in both cases correlate well with each other. It is established that the mechanism of these compositions coatings destruction is different. The preferential destruction of the ZrB2-15 MoSi2 coating takes place outside the heating spot and is related to thermal stresses caused by high temperature gradients under local heating conditions at the accepted test scheme. The material demonstrates high thermal-erosion resistance and preservation of the integrity of the coating during the whole test period without breaking down for 600 sec. The destruction of ZrB2-3SiC-5 WC coating in the tests has the character of the material layer by layer taking away (thickness ~ 50 μm) in the heating spot. In this case, the destruction occurs before the complete removal of the coating for 500 sec. For comparison, two tests of C/C-SiC substrate were carried out under the same heating conditions. Herewith, the determining surface temperature was increased to 1660 ° C (due to the СССM higher value of radiation coefficient - its measured value was = 0.85) at a total duration at two heating cycles of 234 sec. As a result of the tests, the linear removal of the СССM was not less than 0.5 mm, and its surface on the whole area of the heating spot was damaged to a depth of at least 0.5 mm. The damage has the character of the carbon matrix "washing away" while maintaining the reinforcing framework. Under the conditions of thermal erosive action of combustion products of air-fuel mixture of supersonic flow with a temperature of 2100 ° С, the tested UHTC coatings are appeared to be rather promising increasing the lifetime of the CCCM up to the beginning of the surface destruction for no less than 20 minutes for ZrB2-15 MoSi2composition and for 12 minutes for ZrB2 - 3 SiC - 5 WC composition.
Authors : M. Nedielko1, V. Chornii2, O. Alekseev2, S. Nedilko2, S. Revo2, V. Scherbatskii2
Affiliations : 1) E.O. Paton Electric Welding Institute of NASU, 11, Bozhenko st., 03680-Kyiv, Ukraine; 2) Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska st. 01601- Kyiv, Ukraine
Resume : Polymer based, particularly micro/nanosized polymer composites, now are under intensive studies as their perspectives spread from paper electronics to forensic examination and eco-friendly sorbents. This work was devoted to fabrication and study of the set of ?cellulose-oxide? micro/nanocomposite materials. So called cool-pressing procedure was used to produces the composite materials of the ?ceramics-like? morphology. Several sets of the composite samples both (un-doped) and embedded with inorganic oxide dielectric micro/nanoparticles (complex oxide vanadates, phopspates or zirconia) were prepared and studied. Morphology of the pure and doped micro/nanocellulose, structural and physical properties of the samples were studied and various experimental techniques were used to do it. Morphology of the samples was studied using optical and electronic microscopy tools. The morphology showed both grains of the cellulose and the luminescent particles of complex oxides. Temperature dependences of the specific capacity and dielectric losses tangent were measured in -100 ? 1000C temperature range when frequency of electric field varied from 1 to 100 kHz. As result, components of the complex dielectric permittivity, ?*, ?0 conductivity and other relaxation parameters were evaluated. Luminescent characteristics of starting and doped samples were taken, analyzed and compared with the data concerning free oxide particles. Measured characteristics and properties are of great importance for possible applications of mentioned composites in various fields.
Multifunctional composites and their service properties: part 3 : Dr. Iryna Bilan
Authors : M. Elkady, M. Khorolskiy, A. Sanin
Affiliations : Ph.D researcher, Dnipro National University, Ukraine; Ph.D, associated professor Dnipro National University, Ukraine; D.Sc, professor, head of department of manufacturing engineering of launch vehicles, Dnipro National University, Ukraine
Resume : Nowadays, one of the most important materials are elastomeric materials and their products. These materials are playing a serious role in almost types of machines. Once, there is no common material could be used for manufacturing details for any working conditions. Science researches are doing their best to promote technical properties. It is known that elastomeric materials products which ensure the capacity of many aggregates of rocket and space equipment that can be operated in extreme conditions. Definitely it involves high heat resistance materials for solid propellant rocket motors that must withstand high temperatures. Nowadays, a special rubber produced by various rubber fillers which have different activities is using as internal thermal insulation material. At the same time, their heat-shielding properties need to be improved. One of methods for improving protective properties of rubber composite materials is using carbon nanotubes (CNTs) as filler. CNTs structure makes ability for creating more effective heat resistance coating of rubber composite. According to our estimation vulcanizates with CNTs as an active filler will improve heat-shielding properties such strength and elastomer properties, abrasion and tear resistance. Moreover, the thermal insulation coating volume in solid rockets is substantial and density of CNTs does not exceed 1400 kg/m3 . These properties of CNTs make them auspicious to be used as filler. As well it can be used for reducing the structure net weight of solid propellant rocket.
Authors : Kenshi Matsumoto1, Ryota Sato2, Thang Thuy Trinh2, Noritsugu Sakuma3 and Toshiharu Teranishi2
Affiliations : 1Department of Chemistry, Graduate School of Science, Kyoto University Kitashirakawa Oiwake-cho,Sakyo-ku, Kyoto 606-8502, Japan; 2Institute for Chemical Research, Kyoto University Gokasho, Uji, Kyoto 611-0011, Japan; 3Higashifuji Technical Center, Toyota Motor Corporation 1200 Mishuku, Susono, Shizuoka 410-1193, Japan
Resume : Exchange-coupled nanocomposite magnets (NCMs) composed of hard and soft magnetic phases can be applied in various fields such as electronic vehicle motors. Although maximum energy product ((BH)max) of NCMs are expected to become higher than that of neodymium magnets, it is difficult to create high-performance NCMs because a coercivity (Hc) of NCMs easily decreases with the increase of the volume fraction of the soft phase. In fact, we succeeded in synthesizing highest-performance L10-FePd/Fe NCMs by the reduction-diffusion of Pd/?-Fe2O3 heterostructures, however the Hc could reach only 9.01% of a theoretical value. Therefore, we need to unravel how the Hc of NCMs can be improved. Here we demonstrated that an optimum phase-segregation fashion enable L10-FePd/Fe NCMs to obtain higher Hc and (BH)max. Statistical analysis of first-order reversal curves (FORCs) clearly showed that the Hc of NCMs decreased with the change from a core-shell to a dimer structure. It was also suggested by FORC analysis and micromagnetic model that the change of Hc with tuning the grain size of L10-FePd phase and the volume ratio of NCMs depended only on the different phase-segregation fashion. Thus, we revealed the necessary conditions for synthesizing NCMs with high Hc and succeeded in fabricating higher-performance L10-FePd/Fe NCMs with 26.5% Hc of a theoretical value. This research was supported by "Development of magnetic material technology for high-efficiency motors" commissioned by NEDO.
Authors : C. Pettenkofer
Affiliations : Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
Resume : The electronic properties of interfaces in semiconductor devices are crucially dependent on the detailled atomic structure of the contact plane. Most studies on solar cell interfaces are carried out on technologically prepared interfaces. In this study we start from idealized single crystalline interfaces prepared by MBE, MOMBE, ALD etc. under very well defined UHV conditions and investigated in situ by UPS, XPS, LEED, STM and XPEEM. In particular we report on our attempts to model the junction in chalcopyrite thin films by well defined interfaces to clarify the influence of grain boundaries, lateral inhomogenities and chemical variations across and aside the contact plane. Chalcopyrites of the Type CuYX2 (Y=Ga, In;X=S,Se) were grown by MBE as single crystalline samples in various orientations and were studied by surface analytical tools like XPS, UPS, LEED, STM and XPEEM in situ. Especially the application of synchrotron radiation in photo emission experiments is an extremely powerful tool to gain insight into the morphology and structure of hetero contacts. In a single deposition experiment it is possible to determine the band alignment, band bending, chemical reacted interfaces and their crystalline structure with high accuracy. By following the development of the contact phase to ZnO, ZnSe, ZnS step by step in an UHV environment, all properties of the interface are determined on an atomic scale with high resolution. Beside the formation of an ordered vacancy compound of the absorber the existence of various interfacial layers are detected and their influence on the parameters of a cell is discussed.For CuInSe2 the formation of Cu poor interface layers is observed by SRXPS by the formation of the interface to ZnSe buffer layers. The development of Cu-poor surface phases was discussed by Zunger et al. and is here detected unambiguously. To determine the band alignment valence band spectra have to be recorded to obtain the valence band onset. Here we will show that the right value can only be obtained by using synchrotron radiation as the correct position of the valence band in k-space has to be determined at the Γ-point.Further details on interface properties will be given by presenting XPEEM results on energy converting interfaces.
Authors : I. Polishko, Y. Brodnikovskyi, D. Brodnikovskyi, B.Vasyliv*, V. Podhurska*, O. Vasylyev
Affiliations : Frantsevich Institute for Problems of Materials Science of NASU, 3 Krzhizhanovskyi Str., Kyiv, 03860, Ukraine *Karpenko Physico-Mechanical Institute of NASU, Naukova str. 5, 79601, Lviv, Ukraine
Resume : Solid Oxide Fuel Cell (SOFC) is a promising device for obtaining alternative energy. SOFC based on anode substrate is the most common configuration. Because of that anode should provide mechanical stability of whole cell. Since the main electrochemical reaction of fuel oxidation is occurred on the anode side, it should have enough porosity (>25%) to facilitate the supply of fuel and remove by-products from reaction site. These requirements impose difficulties on material choice. Typically, anodes are making from NiO and 8YSZ powders mixture. However, in this case it is difficult to provide uniform phase distribution in anode structure, which can cause decrease in anode performances. This problem can be solved via manufacturing of highly porous zirconia skeleton and its further impregnation with nickel salt. The present work is devoted to elaboration of highly porous zirconia skeleton made from 3,5YSZ. Using of 3,5YSZ instead of 8YSZ should allow to provide required mechanical strength with increasing porosity. The porosity of 3,5YSZ skeletons was ensured with different amount of a pore-former (starch) 10-, 16-, 22-, 29-, 42-, 51-, 58-, 64-, 69-vol. %. Influence of porosity on mechanical strength of 3,5YSZ skeletons was studied. It was found that replacement 8YSZ with much stronger 3,5YSZ is acceptable for anode-support ceramic skeleton fabrication. Addition of 51-vol.% of starch provides in 3,5YSZ skeletons open porosity 38% and mechanical strength of 92 MPa.
Authors : V.Liopo, Y.Auchynnikau, V.Gubanov
Affiliations : Yanka Kupala State University of Grodno
Resume : In introduction questions of use of micas and influence of heat treatment on their physicomechanical characteristics are considered. In the main part influence of extent of hydration of crystals of natural micas on the provision of clusters of the inverse lattice 00l is investigated. Carried out by methods of computer model operation studying of crystals of natural micas of two types consisting of layers with sizes of d1?10 blocks ? and d2?14 ?. These blocks correspond to phlogopite (d1) of vermiculite (d2). D1 and d2 blocks form the mixed layer crystals. If concentration of one of phases exceeds value 0,7, then on a x-ray monocrystal diffractogram there are reflexes only of this phase. If concentration are in an interval 0,3÷0,7, then on a diffractogramreflexes of both phases are found. In all cases, except monolayer structures, diffractions of 00l-clusters of the inverse lattice around their ideal provisions are observed. Questions of influence of a charging condition of mica on electret characteristics of fluorinated coverings are considered. For the fluorinated coverings formed on a surface mica substrates depending on substrate type electronic or dipole polarization is shown. The coverings of the fluorine containing oligomer formed on the juvenile surfaces of mica are nanoelectret since the size of charging areas on the surface of mica is commensurable with nanosizes, and this charging mosaic leads to essential changes in physical characteristics of coverings in comparison with coverings of the fluorinated oligomers formed on inert substrates. Existence of an electret state in coverings of fluorinated oligomers, has to have significant effect on the tribochemical reactions happening on a demarcation of couples of sliding friction modified by fluorine containing oligomer.
Ceramic based composites: production and properties : Dr. Iryna Bilan
Authors : Olena R. Andrievskaya (1, 2), Aleksandr I. Bykov (1), ?lga V. Chudinovich (1), Oksana A. Kornienko (1), Yuriy V. Yurchenko (1)
Affiliations : 1-Frantsevich Institute for Problems of MAterials Sciences of NASU; 2-National Technical University of Ukraine ?Igor Sikorsky Kiev Polytechnic Institute?
Resume : Systems with lanthana, yttria and rare-earth oxides are perspective for the development of transparent ceramics, laser and other optoelectronic components, ceramics for the intermediate temperature solid oxide fuel cells with high ionic conductivity. Alternatively to cubic garnets, the transparent ceramic matrices based on rare earth oxides and their compounds are considered perspective for advanced laser systems. Solid solutions based on La2O3-Y2O3 system (such as LaxY2-xO3, where x=0.05÷0.20) doped with lasing additives (Nd, Eu, Sm, Tb, Er, Yb) have been subject of research. Many excellent characteristics were achieved for these laser media, but all of them did not result in breakthrough as compared to garnets. High symmetry cubic crystals, the non-cubic anisotropic crystals attract interest to be more effective laser matrices than their isotropic competitors because they enable to harvest excitation energy randomly from all surrounding, but emit monochromatically mostly in one selected direction. The fabrication of laser-grade anisotropic ceramics through the conventional particulate processes is not realistic because of resulting randomly oriented grains and grain boundaries and additional optical scattering. Fabrication of transparent polycrystalline ceramics from non-cubic materials requires precise crystal orientation control so that optical scattering losses at the grain boundaries are prevented. In present work, first the phase relations and solid solutions based on ordered perovskite phase like LaYO3 and C-type cubic solid solutions in the systems La2O3-Y2O3-Ln2O3 (Ln = Nd, Eu, Yb) at 1500, 1600 °C in air in the whole concentration range were studied. The phase compositions were studied by XRD, microstructural phase and electron microprobe X-ray analyses. The study of solid state reaction of Nd2O3 and Y2O3 at 1500, 1600 °? showed that three types of solid solutions based on hexagonal A-Nd2O3, monoclinic B-Nd2O3 and cubic ?-Y2O3 in the Nd2O3-Y2O3 system are formed. These solid solution fields were separated by the two-phase fields (A + B) and (B + C). The boundaries of the homogeneity fields for the solid solutions based on A-Nd2O3, B-Nd2O3 and ?-Y2O3, as well as lattice parameters for solid solutions were determined. The refined solubility of Y2O3 in A- modification of Nd2O3 is about 4 mol % at 1500, 1600 ?C. The solubility of Nd2O3 in cubic ?- modification of yttrium oxide attain ~28 mol % at 1500 °? and ~30 mol % at 1600 °?. The lattice parameters of the C phase varies from ? = 1.0604 nm in pure Y2O3 to ? = 1.0715 nm (1500 °C) and 1.0718 nm (1600 °?) in two-phase sample (B + C), containing 30 mol % Y2O3. The solubility of Y2O3 in monoclinic neodymia attains 20-45 mol % at 1500 °? and 21-50 mol % at 1600 °?. The lattice parameters of the B phase varies from ? = 0.6368, b = 0.4085, ? = 0.6710 nm, ? = 81.64 in two-phase sample (A + B), containing 15 mol % Y2O3 to ? = 0.6897, b = 0.4139, ? = 0.6678 nm, ? = 95.63 in two-phase sample (? + ?), containing 50 mol % Y2O3 (1500 °?) and from ? = 0.6615, b = 0.3615, ? = 0.6708 nm, ? = 75.94 in two-phase sample (? + ?), containing 20 mol % Y2O3 to ? = 0.6936, b = 0.3638, ? = 0.6659 nm, ? = 80.45 in two-phase sample (? + ?), containing 50 mol % Y2O3 (1600 °?). In the ternary system La2O3-Y2O3-Nd2O3, the continues solid solutions based on A-Nd2O3, B-Nd2O and ?-Y2O3 (1600 °C), as well as LaYO3 (1500 ??) were revealed. Acknowledgements: This work was supported by SFFR Ukrainian-Belarus joint R&D project, No. F73/111-2016 (2016-2017) and Ukrainian-Indian joint R&D project, No. ?/128-2015-2017.
Authors : V.F. Zinchenko(1), O.V. Mozkova(2)
Affiliations : 1-A.V. Bogatsky Physico-Chemical Institute of NAS of Ukraine, Odessa, Ukraine; 2-State Enterprise for Special Instrument Making "Аrsenal", Kyiv, Ukraine
Resume : Film-forming materials (FFМ) are used as initial substances for obtaining thin-film coatings by so-called PVD (Physical Vapor Deposition) method most often. In a CVD (Chemical Vapor Deposition) method the coating is formed in a course of gaseous reactions between volatile components on the substrates. Earlier we developed CVD composite on the basis of system Ge-ZnS. The calculated value of conditional temperature (Tc=TP≈1.33Pa) for the composite (590°С) is much lower, than for both ZnS (820°C) and for Ge (1410°C). Thus, according to XRDA, the nano-composite type coating is obtained though the initial materials being microcrystalline. It makes possible to improve essentially optical and operational (especially, mechanical durability) parameters of coatings and to expand domain of transparency of Ge up to the border of a visible range of a spectrum. The materials evaporating and condensing in a similar way are named CVD-composites. Ge-Sb2S3 composite makes it possible obtaining coatings with much higher mechanical durability in comparison with a coating produced from pure Sb2S3. Other CVD-composites as FFМ on the basis of binary compounds are investigated also, namely: Ge-ZnSe, Ge-Sb2Se3, Ge-In2Se3, Ge-EuS, Ge-EuSe, Ge-ZnO, Ge-GeO2, and Ge-SnO2. Their considerable part has shown also a high level of optical and operational parameters of coatings. It is proposed to expand series of FFМs of CVD-composite type, using complex chalcogenides as one of components, for example systems: Ge-ZnIn2S4, Ge-MnIn2S4, Ge-EuIn2S4, Ge-EuIn2Se4, Ge-YbIn2S4, Ge-YbIn2Se4 etc
Authors : M.Vasilkovskaya, L.Krushinskaya, G.Makarenko, I.Uvarova
Affiliations : Frantsevich Onstitute for Problems of Materials SCiences of NASU, Ukraine
Resume : The combination of titanium diboride with silicides of groups iV-VI metals makes it possible to produce materials with high heat resistance, wear resistance, hardness, tribological properties and good fracture toughness. In the present work, the method of mechanochemical synthesis, which, in contrast to the method of mechanical mixing of corresponding borides and silicides, makes it possible to obtain a uniform distribution of different phases in the nanosized state, is used. The composite nanosized powders of boride-silicide systems were prepared by the mechanochemical synthesis method. The features of the phase composition and structure of the obtained powders with a particle size of 40–70 nm were studied. The initiating effect of TiB2 on the formation of silicide phases in the process of simultaneous mechanosynthesis was shown. The obtained electrolytic coatings of the composition Ni–TiB2–MoSi2 showed high wear resistance under sliding friction conditions and can be recommended for the hardening and restoration of the surfaces of machine components and mechanisms.
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