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Quartzite is a mountain igneous sedimentary rock formed by fusion of quartz sand with other minerals. The volume of its consumption is increases constantly. For this reason resolution of the problem of the feasibility of developing a new formation or a new site (lode) of an existing quartzite deposit depends directly on its properties. This is especially true for the use of quartzite in the metal industry where it is exposed to high temperature. As a rule studying properties of quartzite for water absorption, open porosity and apparent density is performed at room temperature. Macro and microstructures are studied before and after calcining at 1450°C using optical microscopes that make it possible to conduct X-ray phase analysis.

Pb10 – xPrx(GeO4)2 + x(VO4)4 – x (x = 0, 1, 2, 3) apatites have been prepared by solid-state reactions via sequential firing of appropriate oxide mixtures (PbO, Pr2O3, GeO2, and V2O5) in air in the temperature range 773–1073 K. Their unit-cell parameters have been determined as functions of temperature by high-temperature X-ray diffraction measurements, and the linear and volume expansion coefficients of Pb7Pr3(GeO4)5(VO4) have been calculated. The heat capacity of the synthesized Pb10 – xPrx(GeO4)2 + x(VO4)4 – x (x = 0, 1, 2, 3) compounds with the apatite structure has been determined by differential scanning calorimetry in the temperature range 350–1050 K. The cp(T) curves of the samples with x = 1, 2, and 3 have been shown to have extrema (in particular, peaks at 701, 917, and 1018 K for the x = 3 sample) due to phase transitions. The experimental Cp(T) heat capacity data have been used to evaluate the thermodynamic functions of the synthesized apatites.

Comprehensive investigations into Cu–ZnO (nano) and Cu–TiN (nano) copper-based materials by standard methods in combination with metallographic and electron microscopy investigations using energy-dispersive and thermal analyses make it possible to identify stable correlation relations between the content of nanoparticle additives, microstructural parameters, and mechanical-and-physical properties of pseudoalloys. Process procedures of increasing the distribution uniformity of modifying additives of ZnO and TiN nanoparticles over the pseudoalloy bulk excluding their conglomeration are developed and substantiated. Novel original methods of nanoparticle introducing into a matrix material in the form of a master alloy made of Cu–Al–ZnO or copper powders coated with TiN nanoparticles are proposed. A high specific surface and reactivity of nanopowders make it possible to lower the ceramic phase in electrocontact materials (down to 2.0–3.0% instead of 10–15% when compared with known commercial brands). This results in the conservation of the main properties characteristic of the matrix material (copper) such as thermal and electrical conductivity at a rather high level, while the general level of physicomechanical characteristics (hardness, strength, and wear resistance) and operational properties of composite pseudoalloys simultaneously increases. The main characteristics of copper-based composite materials are as follows: electrical resistance (ρ = 0.025 μΩ m), bonding strength to the contact support material (σ ~ 2 MPa), and dispersed ceramic phase inclusions. They reduce the electroerosive wear (up to a factor of 2.5) when compared with conventional materials.

We have made investigations of the phase formation and microstructure on the ceramics obtained from a starting nanopowder mixture with the weight ratio ZnO : TiO2 = 4 : 1. Ceramic is obtained at different sintering temperatures, namely, 948, 1223 and 1473 ?. Using the characterization methods of electron microscopy, energy dispersive microanalysis and X-ray diffraction phase analysis it has been shown that the ceramics structure is consisted of two dispersed phases of Zn2TiO4 and ZnO with the grain sizes being in range 0,5-1 ?m. It has been found also that, at ceramic`s sintering temperature of 1223 ?, the solid phase interactions are completed with the structure ZnO : Zn2TiO4 ? 1 : 1,5 phase ratio.

This paper introduces a new concept of coated fine carbides modified by nanoparticles Al2O3, ZrO2 (inhibitors) as the starting method for improved hardmetals. The study involved computational and experimental methods to determine functional relationships between the parameters of microstructure, sizes, volume content of additives of nanoparticles and properties (transverse rupture toughness, hardness, fracture toughness) of the heterophase hardmetal composites. Factors having a positive influence on the structure of hardmetals are the decrease in the average size and contiguity of carbide grains due to SPS-consolidation and ultrasonic activation during mixing. The study of microstructural parameters by scanning electron microscopy in a combination with x-ray phase analysis indicates high statistical homogeneity of the relative distribution of nanoparticles (inhibitors) in the cobalt binder between carbide grains and the formation of nanostructured inclusions in hardmetal composites.

The multi-method investigation of Cu–ZnO (nano), Cu–TiN (nano) copper-based materials using standard mechanical testing methods along with metallographic, electron-microscopic research using energy-dispersive and thermal analysis allowed to identify stable correlative relationships between the content of nanoparticle additives, microstructure parameters and mechanical-and-physical properties of pseudoalloys. Processing technologies are suggested and justified to improve the uniform distribution of ZnO and TiN modifying nanoparticle additives over the pseudoalloy volume eliminating their conglomeration. The paper proposes novel original methods of nanoparticle introduction to the matrix material as master alloys of Cu–Al–ZnO or copper powders coated with TiN nanoparticles. High surface area and reactive capacity of nanopowders provides for reduced ceramic phase in electrocontact materials (down to 2,0–3,0 % instead of 10–15 % compared with known commercial ones). In this way, general properties typical for matrix materials (copper), i.e. heat and conductivity, remain significantly high, and at the same time, the general level of mechanical-and-physical properties of composite pseudoalloys such as hardness, strength and wear resistance as well as their operational properties is increased. Main properties of copper-based composites include resistivity (ρ ~ 0,025 μΩ·m), strength of bonding to Тугоплавкие, керамические и композиционные материалы 20 Известия вузов. Порошковая металлургия и функциональные покрытия  4  2017 the contact support material (σ ~ 2 MPa), dispersed ceramic phase inclusions that reduce electroerosive wear (2,5 times) in comparison with conventional materials.

The continual approximation of the ground state of the discrete Frenkel–Kontorova model is tested using a symmetric algorithm of numerical simulation. A “kaleidoscope effect” is found, which means that the curves representing the dependences of the relative extension of an N-atom chain vary periodically with increasing N. Stairs of structural transitions for N ≫ 1 are analyzed by the channel selection method with the approximation N = ∞. Images of commensurable and incommensurable structures are constructed. The commensurable–incommensurable phase transitions are stepwise.

The ground state of a periodic elastic atomic chain in a periodic potential has been investigated. The tensile strain and potential energy of the chain have been found as functions of the disproportion parameter. Exact solutions differ from those found in the continuous approximation by the P symmetry and smaller regions of commensurate phases.

The influence of nanoparticles additives on the hard metals properties has been investigated. Nanoparticles introduced into a binder of average size decrease the metal interlayer and therefore increase the strength of binder and composite as a whole. The reduction of the carbide grain average size was found as well (owing to nanoparticles blocking influence on re-crystallization). Besides, the internal thermotension and adhesion wear decrease at high speed cutting (especially for stainless steel) in comparision with base hard metals. The test results display that the modification through ultrafme particles enables to improve the main properties: wear resistance – 1.6 - 2 - fold; fracture toughness – 1.8 - 2 - fold; transverse rupture toughness - at 25 - 50%; tool life – 1.3 - 4 - fold.

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.

The laws governing the formation of residual stresses in copper oxide nanoparticles in the process of their direct plasma-chemical synthesis in a low-pressure arc discharge plasma are studied. Correlation dependences of the residual stress and the magnetization of nanoparticles on the pressure of the gas mixture of 10% O 2 + 90% Ar are presented. The problems associated with the bifurcation of the magnetization curves during cooling in zero (ZFC) and non-zero (FC) magnetic field, non-equilibrium behavior, relaxation of magnetization and magnetic viscosity of the obtained CuO nanoparticles are discussed.

Results are presented from a study of the phase composition of spent quartzite lining from a crucible-type industrial frequency induction furnace. The study is performed by the methods of x-ray analysis. The lining that was examined contained quartzite, boric acid, and electrocorundum. Different regions of the lining were identified and their phase composition was determined along with the changes in the lattice parameters of the components of each region’s phases.

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала. Abstract—The structure of natural crystalline and cryptocrystalline graphites from deposits of Krasnoyarsk krai is investigated by means of XXray structural analysis using a D8 Advance diffractometer (Bruker, Germany). The variations in types and parameters of the crystal lattice due to the mechanical activation or mechanical synthesis of the material are revealed and the optimal activation modes of graphite at which they occur are established. The influence of the treatment time on the structural parameters of both types of graphites is considered. It is shown that their physicochemical properties are improved at the optimal activation duration due to the variation in the type and lattice parameters as well as amorphization of the crystal structure.

The effect of temperature on the change in quartzite crystal lattice interplanar distances of industrial purity (IChT) used in lining induction and crucible furnaces is studied by x-ray-phase analysis (XPA). A regularity is revealed for changes in interplanar distance. A curve is plotted for these changes. The connection of changes in crystal lattice with material properties is determined, affecting induction furnace lining life.

The method of producing TiN nanopowders in the plasma of low pressure arc discharge in nitrogen atmosphere is discussed. The influence of gas pressure on nanopowder dispersion is studied. It is shown that the particles have nanometer size and a narrow particle size distribution.

Thermal effects in cathode space of low-pressure arc discharge, which contribute to the synthesis of nanopowders with an average particle size of less than 10 nm, are considered. One of the most important parameters, characterizing the cathode processes of vacuum arc, is a voltage drop across the discharge gap. All the gases demonstrate a decrease of a voltage drop across the discharge gap under the condition ofincreasing the gas pressure in the range of p = 10−3 − 1 Pa. Dissipation of energy of ions and electrons on gas molecules causes abrupt heating of the gas. Heat, coming from gas plasma, has a significant impact on evaporating material of a cathode. It can be assumed that a microdrop fraction, formed as a result of a cathode spraying in a liquid phase, will further evaporate in a superheated gas.