Inorganic Materials: Applied Research最新文献

This paper presents the prediction of the phase composition and properties of a high-entropy CoCrFeMnNi alloy using the Calphad method and neural networks. The study emphasizes the importance of phase composition in determining the properties of materials, separating phases into solid solutions, intermetallic compounds, mixed phases, and amorphous structures. corrosion resistance. Traditional parametric and computational approaches are discussed, the role of rules of thumb and the potential of machine learning methods, in particular neural networks, in predicting mechanical properties such as microhardness, Young’s modulus, yield and strength strengths are emphasized. The research is aimed at creating effective methodologies for designing new alloys with optimal properties, identifying hidden patterns in large data sets, and thereby improving the efficiency of predicting the properties of complex materials.

The paper considers the possibility of cationic isomorphic substitutions for controlling and changing the properties of hydroxyapatite (HA). HA was synthesized by changing the concentration of Mg²⁺, Ca²⁺ ions and adding Zn²⁺ ions at physiological pH 7.45 ± 0.05 from a model solution of synovia. It was found that the synthesis carried out with an increase in the concentration of magnesium ions leads to the appearance of a new phase—whitlockite. A large volume of the unit cell and a variety of different structural positions determine the ability of whitlockite to a variety of isomorphism. This largely serves as a source of a wide range of functional properties inherent in compounds with this structural type. Synthesis carried out with a simultaneous increase in the concentration of Mg² ions and a decrease in the concentration of Ca²⁺ ions has a huge destabilizing effect on the formation of HA and leads to the formation of new phases: whitlockite, phosphate, oxide and hydroxide of magnesium. It has been established that synthesis with the introduction of small amounts of Zn²⁺ ions (up to 12 mg/L inclusive) does not affect the phase composition of the obtained samples, the amorphousness of the solid phase and the mass of the resulting sediments increase slightly, and the size of the crystallites decreases. Synthesis of new compounds with specified physical properties and chemical composition is a relevant and practical task.

This study examines the microstructure and properties of molybdenum-containing coatings deposited by non-vacuum electron beam cladding of molybdenum and amorphous boron powder mixtures. Chromium and titanium served as alloying elements in the experiments. The resulting coatings demonstrated thicknesses of 1.5–2 mm. The Mo-B coatings with chromium additions formed chromium-alloyed α-Fe solid solution along and Fe₃B-type borides, while titanium alloying produced α-Fe solid solution and Fe₂B borides. The chromium-modified MoBCr coatings exhibited superior hardness and high-temperature oxidation resistance compared to titanium-containing variants. The microhardness increased by a factor of 2.5 relative to AISI 5140 steel base material. The oxidation resistance of MoBCr coatings improved twofold through formation of dense Cr₂O₃-based oxide films that effectively block oxygen and metal ion diffusion during oxidation processes.

Tribological tests of a composite material based on the antifriction alloy AOM20-1 were carried out. The samples were produced using reaction casting, mixing titanium particles to form a structure with intermetallic strengthening. Dry sliding friction tests were carried out at sliding speeds from 0.25 to 0.75 m/s and loads from 0.5 to 3.0 MPa. A comprehensive comparison of the tribological properties of samples and friction processes (wear intensity, friction coefficient, stability index) was used. The loading conditions under which the material demonstrates the best set of characteristics have been determined: sliding speed of 0.5 m/s under a load of 1.5 MPa.

Using the Plasma Focus PF-5M device, damageability, erosion, and structural changes in the surface layers of tungsten single-crystal samples caused by exposure to pulsed electron beams are studied in comparison with pulsed irradiation by combined flows of helium ions and helium plasma with the following parameters: power density q_e = 5 × 10⁸ W/cm² for electrons; q_ipl = 1 × 10⁸ W/cm² for ion-plasma flow; pulse duration τ_e = 20 ns and τ_ipl = 50 ns, respectively; and the number of pulsed impacts N = 15. It is shown that, in the implemented irradiation mode, the melting of tungsten surface layer by ion-plasma flows occurs over the entire irradiation area and is noticeably stronger than by electron beams, the impact of which leads to very weak melting of individual local areas of the surface, which are island-like in character. After ion-plasma impact on the tungsten single crystal, a wavelike surface relief is formed, which contains blisters with undestroyed shell domes, microcracks located in mutually perpendicular directions, and pores. In the irradiated surface layer of tungsten, a transformation of the initial monocrystalline structure into a polycrystalline cellular structure is also observed. In the case of exposure of the tungsten single crystal to electron beams, two mechanisms of structural changes in the surface layer are established. One of them is related to the processes of melting and crystallization of the irradiated surface layer, which occur in its individual local areas and contribute to the formation of pores and microcracks. The second one is due to the solid-phase recrystallization process occurring as a result of thermal heating of a near surface layer deeper than the thickness of the melt, which is related to the release of energy during the scattering of the electron flow in the material. Under the influence of the resulting thermal stresses, a network of microcracks appears over the entire area of electron impact located along the slip lines of the crystallographic planes of the tungsten single crystal. The observed increased cracking of the surface layer of the studied tungsten single crystal contributes to the intensification of its erosion by sputtering and evaporation of the material under conditions of multiple radiation-thermal exposures.

Compounds of antimony(III, V) were obtained: {[2,6-(ОMe)₂C₆H₃)₃]EtSb}I, [(2,6-OMe)₂C₆H₃]₃SbO, [Sb(μ₂-O)Cl(DMSO-О)]_n, [(2,6-OMe)₂C₆H₃]₃Sb(N₃)₂, (C₆H₅)₃SbBr₂, [(C₆H₅)₃Sb(NCO)]₂O⋅C₄H₈O₂, being by potential ferroelectrics. Temperature dependences of the permittivity of the compound were studied. According to dielectric measurements, it was established that for the compound [(C₆H₅)₃Sb(NCO)]₂O⋅C₄H₈O₂ a phase transition is observed at a temperature of 164°C. The presence of hysteresis on the temperature dependence of ε' indicates a first-order phase transition.

ZnS:Cu, Br (0.005–0.01, 0.8 wt %) radioluminescent materials were synthesized for the first time from solid charge mixtures using a microwave sintering. The temperature range of zinc sulfide matrix recrystallization at microwave synthesis was determined in a range of 600–650°C. The microstructure and phase composition of the synthesized luminescent materials were studied; it was shown that at 650°C, a complete phase transformation of the ZnS matrix into a high-temperature wurtzite modification occurs. The spectral and brightness characteristics of tritium radioluminescence were obtained and compared with samples synthesized using a traditional solid-phase method.

The structural and hysteresis properties of epitaxial MgO(100)/⁵⁷Fe(50 nm)/Cr(2 nm) films grown by molecular beam epitaxy (MBE) were investigated. Changes in structural properties during annealing in the temperature range of 200–300°C were studied using X-ray diffraction, Raman spectroscopy, atomic force microscopy and Mössbauer spectroscopy. It was shown that at temperatures above 250°C, oxygen diffusion through the protective Cr layer occurs, leading to the formation of antiferromagnetic α-Fe₂O₃ oxide. The temperature dependences of hysteresis properties during annealing were determined. At an annealing temperature of 280°C, the coercive force reaches a maximum value of 190 Oe. The absence of exchange bias, evidenced by zero shift in the hysteresis loops, suggests the dominant role of low magnetic anisotropy of α-Fe₂O₃ and interface disorder in these oxidized heterostructures.

The paper presents studies on modification of a polyurethane membrane in a low-energy ion flow in an argon environment. The studies have shown the possibility of changing the surface structure and physical and mechanical properties of the polyurethane membrane.

The study investigates physical mechanisms underlying plasma-assisted modification of capillary-porous materials, such as natural leather and fur, using low-energy ion flows generated in a capacitively coupled RF discharge at intermediate pressure (13.3–133 Pa). The proposed model demonstrates that material modification occurs through three interconnected processes: interaction with low-energy ions (up to 100 eV) from the positive charge layer, ion recombination energy release, and bulk treatment effects mediated by non-self-sustained discharge inside the material’s porous structure.