Inorganic Materials: Applied Research最新文献

The detailed comparative XRD, TEM/EDS analysis of TiNi and TiNiCuZr samples revealed the formation of two isostructural B2 phases with different lattice parameters, chemical composition and microstructure. According to the experimental the lattice parameter value a_B2(TiNiCuZr) in the TiNiCuZr sample is several times higher than a_B2(TiNi) in the TiNi sample, indicating the formation of a new B2 phase. These variations in B2 lattice parameters strongly correlate with the changes in the chemical composition. The study of the electrochemical properties of the initial alloys (TiNi, Ti–Ni–Cu–Zr) in 0.9 wt % NaCl and artificial saliva showed that the TiNi alloy of binary composition exhibits significantly higher corrosion properties. In turn, the Ti–Ni–Cu–Zr alloy is prone to anodic polarization and corrosion destruction. It was found that under the same conditions of the corrosive media, the corrosion rate of the Ti–Ni–Cu–Zr alloy is ∼3.2 times higher than that of the TiNi alloys.

The development of new functional and structural materials constitutes one of the priority areas of modern materials science. Accurate knowledge of the thermal properties of systems under study is important for obtaining new effective multifunctional materials with high practical performance. In this paper, we investigate the effect of the composition of the Ni–Zr system on important thermophysical properties such as heat capacity, thermal expansion coefficient (CTE), and thermal conductivity. The temperature dependences of the thermophysical properties of polycrystalline Ni–Zr samples are considered, and the influence of structure effects on their behavior is discussed. The phase compositions of the alloys were confirmed by X-ray structural analysis. The deviation of density from the additive value reaches 5% and has a pronounced minimum at 50 at % Ni. The CTE curves of the annealed samples show two extremes at nickel concentrations of 77 and 50 at %. Deviations in the CTE values on the concentration curve are typical for samples with concentrations close to the formation of NiZr₂ and NiZr intermetallics. The temperature curves of the thermal diffusivity and thermal conductivity of Ni–Zr alloys are non-monotonically. The defective structure of polycrystalline Ni–Zr samples has a noticeable effect on their thermophysical properties.

The article presents the results of thermodynamic modeling of the behavior of Am, Pu, Cs radionuclides when radioactive graphite is heated with an atmospheric atmosphere. Using the TERRA software package, thermodynamic analysis was performed in the temperature range from 300 to 3600 K in order to determine the possible composition of the ionized, gaseous and condensed phases. It has been established that americium in the temperature range from 300 to 2200 K is in the form of condensed AmO_2(k). When the temperature rises from 2200 to 3600 K, it is in the form of gaseous Am and condensed Am₂O_3(k). Plutonium in the range of temperatures from 700 to 1200 K is in the form of condensed PuCl_3(k), PuOCl_(k) with an increase in temperature from 1900 to 3600 K in the form of gaseous PuO₂, PuO in the form of condensed PuO_2(k), Pu₂O_3(k) and ionized PuO⁺. Caesium at temperatures from 600 to 900 K is in the form of condensed CsCl_(k) and gaseous CsCl as the temperature rises from 1300 to 1700 K in the form of ionized PuO⁺. The main reactions within individual phases and between condensed, gaseous and ionized phases are determined in this work. Calculations of the equilibrium constants of their reactions have been carried out.

In this work, the methods of scanning electron microscopy and transmission electron microscopy to study the deformation refinement of copper grains from 200 μm to 50 nm in a 20 mm workpiece’s cross section were used. A grain refinement pattern during the transition of the copper structure from mesolevel (d ≥ 250 nm) to the microlevel (d < 250 nm) after drawing and two, six, and eight passes of the ECAP along the Вс route at room temperature was proposed. It was shown that when shear bands intersect at an angle of 45°, grains in the form of rhombuses or hexagons with a width of 500–800 nm are separated by subgrains with a width of 150–250 nm with their own structure of nano bands with a width of 50 nm, and submicrograins of 50–100 nm. After 8 passes ECAP, high-angle grain boundaries of hexagons were formed at the location of triple grain junctions as a result of primary recrystallization. The scheme of deformation grain refinement was changed as follows. After two ECAP passes, microbands with a cellular structure 100–200 nm wide with an apex angle of 45° were formed. This herringbone-like shear bands were formed. After six ECAP passes, a banded and “lattice” structure was formed at the places of multiple intersections of shear bands, with rhombohedrons forming in the center. After eight ECAP passes, the resulting grain refinement pattern consisted of fragmented shear bands of 400–500 nm wide and shear bands of 300 nm wide located at an angle of 45°.

This study demonstrates the results of incorporating granulated filler into quartz glass-based slurry to intensify the forming process. The use of porous granules reduces ceramic product forming time by more than half. The introduced granules serve a reinforcing function while improving workpiece density uniformity, minimizing slurry stratification rial properties were investigated and compared with those obtained via alternative manufacturing technologies.

To reduce porosity and enhance the density of vibro-cast materials, a study was conducted to evaluate the effects of a polycarboxylic acid-based superplasticizer, Kratasol PK, produced by JSC “Pigment.” Compatibility assessments were performed using high-alumina cement and KR-0 silica. The results demonstrated a significant reduction in water demand for the molding mixture, enabling the production of materials with increased density and reduced porosity. The use of this deflocculant resulted in a decrease in the water requirement of the molded mass to 5.7%.

The influence of homogenization annealing on the structure and properties of aluminum heat-resistant ALTEK alloys is studied. The 2Cu_1.5Mn and 3Cu₂Mn alloys are homogenized at 450°C (30 h) followed by hot and cold rolling to a thickness of 1 mm and heat treatment at 300–500°C (3 h). It is found that homogenization annealing allows achieving higher specific electrical conductivity (SEC) compared to non-homogenized alloys owing to the earlier onset of decomposition of the aluminum solid solution. However, a decrease in strength characteristics is observed: after annealing at 300°C, the tensile strength decreases to 25%, while non-homogenized alloys demonstrate higher thermal stability—their strength decreases by 3% compared to the cold-rolled state. This phenomenon is most likely due to the fact that homogenization promotes the growth of Al₂₀Cu₂Mn₃ particles, which makes the latter less effective in inhibiting the processes of recovery and recrystallization. For the 2Cu_1.5Mn and 3Cu₂Mn alloys, after annealing at 400°C (3 h), the following properties are obtained: tensile strength is 215 and 201 MPa, conditional yield strength is 79 and 81 MPa, relative elongation is 16.4 and 19.2%, and SEC is 27.7 and 28.6 MS/m.

Experimental data on the patterns of electrophoresis of a colloidal silver solution in an aqueous dispersion medium and the parameters of metal particles deposited at the cathode have been obtained. It was found that no coagulation occurred during electrophoresis. The silver particle size increases at the cathode itself due to diffusion processes. As a result, the silver particles at the cathode surface have a significant thickness, far from the monolayer of atoms. The rate of Ag accumulation at the electrode decreases with increasing duration of electrophoresis. While the rate of movement of colloidal particles to the electrode remains constant. The formation of a coating on the electrode surface is a heterogeneous process consisting of a kinetic act. This act is the adsorption of colloidal silver particles and the growth of the latter by diffusion. During electrophoresis, the particles approach the electrode and are adsorbed on it under the action of significant Coulomb forces. When estimating the growth rate of colloidal particles on an electrode, it should be borne in mind that the diffusion coefficients for nanoscale bodies are orders of magnitude greater than for a large amount of matter. In the initial periods, silver particles are deposited at the nickel cathode, and then on the surface of the silver released earlier. The patterns of deposition are changing including the act of adsorption of colloidal silver particles at the electrode. It has been experimentally established that the mass of the substance isolated at the cathode, depending on the amount of electricity passed, is approximated by a straight line in accordance with Faraday’s law. The proportionality coefficient for electrophoresis of a colloidal Ag solution under experimental conditions is an order of magnitude higher than the electrochemical coefficient for silver. It is shown that there is an increase in the amount of Ag at the electrode with an increase in the concentration of the colloidal solution. This illustrates the increasing role of molecular diffusion in the electrophoresis process.

This paper is concerned with the corrosion behaviour of the high nickel TiNi alloy in coarse-grained and ultrafine-grained states in solutions of acids of different molarity. In addition, an analysis of the corrosion products on the surface of the samples after the test was carried out using X-ray photoelectron spectrometry. The results of the X-ray photoelectron spectrometer showed that no corrosion products were found during the tests in HCl solutions of different concentrations. The spectra of oxygen in the C=O compound, titanium in the TiO₂ compound and nickel are observed on the surface.

The corrosion behavior of copper (M1) samples in the as-received state, after recrystallization and after structure optimization based on grain boundary engineering was investigated using polarization tests in a specially non-aerated 0.1 M NaCl solution. The general view, morphology, chemical and phase composition of the corrosion products formed on the samples surface during polarization tests were investigated using scanning electron microscopy, energy dispersive and X-ray diffraction analysis. It was established that optimization of the structure in two thermo mechanical treatment modes—TMT I and TMT II—leads to a consistent increase in the overall corrosion resistance of the samples compared to the recrystallized state of copper. The increase in corrosion resistance of copper is consistent with increase in the proportion of special twin boundaries resistant to corrosion and a decrease in the proportion of random high-angle boundaries susceptible to corrosion during TMO I and TMO II. The features in the cathode region of the polarization curve and in the general view and morphology of the corrosion products for copper samples after TMO II allow us to assume a qualitative change in the nature of their overall corrosion in comparison with other studied samples.