Advanced Materials Research Vol. 1040

Abstract: Linear and nonlinear components relation in integral index of friction (D) for tribosystem dependence on hydrophilic properties of metal fillers (M=Cu, Al, Ni) has been considered. Metal fillers (M=Cu, Al, Ni) have been modified in surface layer with quaternary ammonium compounds. It was found that systems with Cu-based fillers had sufficiently high and stable linear component. The best antifriction properties of tribosystem correspond to metal filler with maximum nonlinear component in D = f(a) dependence, where a is adsorption of water.

Abstract: Deformation processes of the α-titanium specimens moving through the channels of the die for two loading schemes: equal channel angular pressing (ECAP) and channel pressing through the channel of variable form (CVF) are investigated. Schemes of dynamic pressing in case the block is extruded at high speed through the channel of the die due to the pressure of the punch or the pressure of powder gases were analyzed. The problem is solved by the smoothed particle hydrodynamics method (SPH) within the framework of elastoplastic continuum.

Abstract: Plastic flow localization behaviour has been investigated in commercial Zr alloys used in the nuclear power industry. The type of deformation localization pictures corresponding with the stage preceding material fracture is described. Proposed is a method for assessing the reserve ductility of the metal subjected to deformation in rolling of thin-wall Zr alloy tubes by examining the local strain patterns.

Abstract: Using Co₃₅Ni₃₅Al₃₀ (at.%) single crystals the effects of crystals axis orientation and ageing at 673 K for 0.5 h in free state on superelasticity responses in compression are investigated. Ageing of these single crystals is found to result in strengthening of the high-temperature В2 phase and L1₀ martensite, twofold increasing of temperature interval of SE response and weakening of the orientation dependence and improving the cycle stability of superelasticity response. In [011]- and [123]-oriented single crystals the values of the stress hysteresis decrease a nearly threefold as compared to the quenched state. The combination of high-strength [001] crystal axis orientation and precipitation of coherent nanoscale particles leads to the best stability of SE response in aged Co₃₅Ni₃₅Al₃₀ single crystals.

Abstract: The paper presents the results of experimental investigation of formation microstructure and properties of ultra high molecular weight polyethylene (UHMW-PE), modified by ceramics А1₂О₃ particles by different particle size and method of obtaining.

Abstract: Superelastic biocompatible metallic materials Ti-22Nb-6Zr and Ti-22Nb-3Ta-3Zr (at %) were produced. Vacuum arc remelting (VAR) with manual control allowed to produce high‑purity alloys. X-ray fluorescence spectrometry (XRF) results showed that one remelt was not enough to obtain homogeneous Ti-Nb-Ta-Zr ingot. Ti-Nb-Zr and Ti-Nb-Ta-Zr alloys were remelted 3 times and turned upside down after each remelting. Scanning electron microscopy (SEM) with micro X‑ray spectral analysis showed that chemical composition of the alloys coincided with nominal chemical composition. SEM results also showed that the alloys were mostly homogeneous. Recommendations for optimization of VAR in terms of producing high-purity homogeneous superelastic titanium alloys were elaborated.

Abstract: Frequency dependences of transmission and reflection coefficients, dielectric permeability of composite materials with the various content of carbon fillers (technical carbon, graphite) in polyurethane varnish in ranges of frequencies 26–40 GHz and 110–260 GHz are experimentally investigated. It was found that composite material 0.4 mm thick with 4–5 % graphite mass content has a transmission coefficient of less than minus 7 dB in the whole investigated range of frequencies and can be effectively used in devices of protection from electromagnetic radiation.

Abstract: In this paper electromagnetic properties of composite materials based on polymethylmethacrylate and multiwall carbon nanotubes (MWCNTs) are investigated. Carbon nanotubes are received with application of various types of catalysts and have various structural parameters. Calculation of dielectric permeability of the synthesised materials is carried out. Dependence of electromagnetic properties of composite materials on concentration and structure used multilayer carbon nanotubes is shown.

Abstract: The abrasive wear of pure UHMWPE as well as one filled with nanoand microparticles (fibers) were investigated. It was found that abrasive wear resistance of microcomposites (containing AlO(OH) and Al₂O₃ microparticles) can grow up by 16-18 times in comparison with pure UHMWPE depending on the strength and size of the filler as well as abrasive grit. Nanofillers (AlO(OH) and carbon nanofibers (CNF) as well as SiO₂ and Cu nanoparticles) as opposed to microfillers can improve abrasive wear resistance of UHMWPE in a significantly less degree (up to 50 %). Abrasive wear resistance of nanocomposites weakly depends on the type of filler and is defined by the polymeric matrix (permolecular) and counter-face abrasive grit. The comparative analysis of the wear mechanisms of UHMWPE based micro-and nanocomposites under abrasive wear (fixed abrasive particles) and dry sliding friction is carried out.

Abstract: The construction of a metal-supported fuel cell has been recently generating a growing interest among the designers of solid oxide fuel cells. The present work is aimed at solving the problem related to high-temperature sintering of fuel cell NiO/YSZ anode on the porous metal substrate functioning both as a supporting structure and a reliable current collector. Hence, its irreversible oxidation during high-temperature sintering should be avoided. NiO/YSZ layers were applied on porous metal samples by a screen-printing technique and sintered in reducing and inert atmospheres, as well as in vacuum. The obtained layers were studied by means of scanning electron microscopy and X-ray phase analysis. It was shown that a temperature of 1000°С does not ensure a substantial sintering of Ni and YSZ granules in a reducing atmosphere. Under the sintering temperature above 1230°С in an inert atmosphere and vacuum, the nickel oxide dissociation and its massive agglomeration are observed. The conditions of NiO/YSZ layer vacuum sintering were experimentally determined which provide a high-grade sintering of nickel cermet granules without Ni agglomeration, disturbance of homogeneity in the formed anode layer, and the metal substrate oxidation.