卷 9, 编号 4 (2018)

It was found by the Monte Carlo method that violation of the structural arrangement in alloy Cu₃Pt₅ at an increase in temperature always starts near the antiphase boundaries. The process of disordering is accompanied by the blurring of boundaries. Formation and growth of the antiphase domains of different orientation near the boundaries are observed apart from blurring.

This article presents the research results for blended cements with complex mineral additives based on thermally activated clays and carbonate rocks. The possibility to use thermally activated clays both with and without kaolinite as additive components is shown. The synergistic effect of the joint introduction of thermally activated clays and carbonate rocks is established. The efficiency of dolomite as a component of a complex additive is demonstrated.

The values of TCLE (temperature coefficient of linear expansion) of glaze and clinker brick on the basis of raw kaolin and aluminum-containing nanotechnological raw materials are established, and the mechanism of glaze formation during burn is established by IR spectroscopy and electron microscopy. During the glaze formation, phase separation of the glass takes place, which precedes the crystallization process. As a result of liquation, the glaze glass is divided into regions enriched in silica, zirconium, sodium, boron, and calcium. The study of heat-treated monoliths shows that the liquation structure is markedly reduced at temperatures of 700 and 950°C. The temperature interval of liquation is a function of the heat treatment conditions of the glaze. It is shown that the creek resistance of glazed clinker products is mainly due to the ratio of the mean TCLE of the mass and the glaze.

A comparative analysis of the physicomechanical characteristics and phase composition of Al₂₃O₂₇N₅ ceramic obtained by reaction sintering of the mixture of Al₂O₃ and AlN powders at different temperatures and pressures is carried out. The samples obtained had properties that correlated well with the published data.

Rapidly solidifed foils of Sn₃₂Bi₅₂Pb₁₆ alloy consist of liberations of tin, bismuth, and ε phase. The length of most chords of random secants located on sections of tin, bismuth, and ε-phase grains does not exceed 1 μm. The specific surface area of boundaries of grains of all phases is 2.4 μm^–1. There are clear textures of (100) tin, (\(10\overline {12} \)) bismuth, and (\(10\overline {10} \)) ε phase.

The structure of the ZhS32-VI heat-resistant alloy obtained by the method of selective laser alloying (SLA) on single-crystal substrates with the 〈001〉 and 〈111〉 crystallographic orientations is studied. It is established that the synthesized alloy inherits the 〈001〉 orientation from the single crystal of the substrate. After vacuum thermal treatment and hot isostatic pressing (HIP), the synthesized alloy has a heterophase γ + γ' + MC microstructure with the structural-phase characteristics typical of the monocrystalline ZhS32-VI alloy and shows high short-time strength values.

The key methods for polyphenylene sulfide production are discussed in this study. The mechanisms for the main and side reactions taking place during polyphenylene sulfide synthesis are presented. The effect of different factors on the course of polyphenylene sulfide production is demonstrated; these factors are found to play a crucial role in formation of polymers with linear and cyclic macromolecular structure. An efficient method for high-temperature synthesis of polyphenylene sulfide in a high-boiling point solvent is proposed. The resulting polyphenylene sulfide is characterized by high values of heat resistance, thermal stability, and melting point.

The alginate gels microstructure formation regularities that were prepared in situ in a multicomponent system were determined, and their properties were studied. To produce experimental specimens, a combination of cross-linking agents of calcium and zinc salts with inhibitors based on a denatured protein and tricalciumphosphate granules was used. The antibacterial properties of the hydrogels were studied as a function of their composition.

High-cycle fatigue of single crystals of nickel-rhenium-ruthenium-base superalloy VZhM4 with crystallographic orientation of 〈001〉, 〈011〉, and 〈111〉 within the temperature interval of 20–1000°C was investigated. Influence of the test temperature on the shape of the high-cycle fatigue curve was considered. It was found that single crystals of the alloy VZhM4 have negligible anisotropy of the fatigue limit at 1000°C on the basis of tests of 2× 10⁷ cycles.

Relaxation properties of nanocomposites based on styrene-butadiene DST-30 thermoelastoplast and detonation-synthesized nanodiamonds and nanodiamond batch mixture are investigated. Key features of the modifying effect of nanodiamond batch mixture on the complex of physicomechanical and relaxation properties of the polymer matrix are established.

In the past decades, metakaolin additives synthesized by the calcination of kaolin clays have been implemented in cement systems. Their scarcity and high cost promotes the studies on the effectiveness of thermally activated additives of common polymineral clays. This article presents the results of research on the effect of thermally activated heavy loam additives to Portland cement. It was shown that additives of 5–15% heavy loam calcined at certain temperatures in the range of 400—600°C and ground to a certain specific surface area of up to 250–500 m²/kg lead to a more significant increase in the strength, density, and water resistance of cement stone than corresponding metakaolin additives with the specific surface area of 1200 m²/kg.

This article provides an overview of the stages of occurrence and development of the manufacturing of domestic hard alloys. It describes the contribution of domestic scientists to the development of various brands of hard alloys and establishment of their production. It shows the outstanding role of G.A. Meerson in the development of the hard-metal industry.

When steel is tungstenized under the conditions of microarc heating, a diffusion layer with a thickness of 200–210 μm and a microhardness of 12.5–13.5 GPa is formed. The base of the layer is a solid solution of tungsten in iron, which contains WC, Fe₂W₂C, and Fe₇W₆ inclusions of various degrees of dispersity, including nanosized inclusions. The diffusion coefficient of tungsten in this case is 36 times higher than that in the case of furnace heating, which is explained by the influence of “electronic wind” on the atoms and ions of the diffusant.

The antifriction properties of coatings in the form of a nanocomposite of a silica layer with molybdenum disulfide nanoparticles distributed in it, whose average sizes are 70, 64, 61, and 53 nm and concentrations are 80, 73, 68, and 62 wt %, respectively, grown via plasma-chemical deposition at atmospheric pressure on a 12Cr18Ni10Ti steel, are studied. The best tribotechnical properties are established for a SiO₂ + 68% MoS₂ coating (61 nm) which possesses the most stationary friction mode and a friction force two times lower as compared to a MoS₂-free SiO₂ coating.

Powder mixtures based on calcium hydroxyapatite (HAP) and sodium salts in the amount corresponding to 25 mol % of Na₂O in the Na₂O–CaO–P₂O₅ system were studied by isothermal exposures in the range of 600—1200°C. According to XRD data, the phase composition of the samples of HAP/Na₂CO₃ after calcination included HAP, β-CaNaPO₄, and CaO. The phase composition of the ceramic samples from the HAP/Na₂HPO₄ powder mixture after calcination contained the phases of β-CaNaPO₄ and Na₄P₂O₇. The phase composition of the ceramic samples from the powder mixture of HAP/NaH₂PO₄ after calcination contained Ca₂P₂O₇, Ca₁₀Na(PO₄)₇, β-CaNaPO₄, CaNa₂P2O₇, and Na₄P₂O₇. The presence of sodium salts in the amount corresponding to 25 mol % of Na₂O in the Na₂O–CaO–P₂O₅ system provided the occurrence of liquid- phase sintering in compact preforms from the studied powder mixtures. However, the presence of the water-soluble salt Na₄P₂O₇ in ceramic samples of HAP/Na₂HPO₄ and HAP/NaH₂PO₄ after calcination imposes a restriction on the use of such materials in contact with an aqueous medium. And the presence of CaO in the HAP/Na₂CO₃ samples excludes the use of such materials as bone implants.

The influence of the physicochemical characteristics of the tempering medium on the structure of nickel samples is studied. The micromechanisms of plastic hardening and fracture of the surface layer under friction are established. The temporal changes in strength characteristics of the metal surface layer at the initial stages of friction load are determined. These strength characteristics have a cyclic character. The duration of the cycle of strength characteristics strongly depends on the tempering medium.

The ion-exchange properties of polymeric zirconium phosphate and zirconium dioxide were studied and their ion-exchange capacities with respect to pyridine bases and pyridinecarboxylic acids were determined. The ion-exchange capacities of polymeric zirconium phosphate with respect to pyridine bases and pyridinecarboxylic acids were 0.53–0.76 and 0.18–0.2 meq/g, respectively. The ion-exchange capacity of polymeric zirconium dioxide with respect to pyridinecarboxylic acids was 0.43–0.44 meq/g. Polymeric zirconium phosphate and zirconium dioxide containing 1–3% of immobilized metallic palladium particles were obtained.

The distribution of substitution alloying elements in the structure of hexagonal silicide Nb₅Si₃ of the γ-modification, which serves as a reinforcing phase of the composite, and in the Nb solid solution matrix of a high-temperature natural composite based on Nb–Si is studied. Studies were carried out on samples in a cast state and after homogenizing thermal treatment. A structural model of the γ-modification of silicide Nb₅Si₃ is constructed. On the basis of the crystal-chemical analysis of the structure of hexagonal silicide, possible causes of phase instability of the composite after thermal treatment are revealed.

The specimens of fine cementless composite binders with various contents of polymineral sand have been prepared. The relative change in surface free energy (δE_S) has been calculated for these silica-containing systems and the ultimate compression strengths of their composites have been determined. The functional relationships of the mineral fine compositions have shown high negative correlation between the compared parameters. The validity of the mathematical model for the evaluation of dispersion interaction in the composites based on fine mineral particles has been confirmed. The parameter δE_S has been recommended for the choice of the optimal composition of the mixture characterized by the maximum compression strength.