Inorganic Materials: Applied Research最新文献

The influence of a thin-film copper coating deposited by magnetron sputtering on a sample of the VT6 titanium alloy is studied at the running-in stage in a friction pair of the VT6 titanium alloy and ShKh-15 steel. The results are compared with a sample of the VT6 titanium alloy without a copper film. The composition of a thin copper film is studied by elements before and after wear testing using scanning electron microscopy. It is established that the VT6 alloy sample with deposited copper coating is characterized by a shorter running-in time and mass wear.

The results of experimental studies are given on the effect of the welding method of butt joints made in sheets of alloy 1565ch. The level and distribution of transverse residual stresses are investigated. It is proved that, depending on technique, fusion welding results in tensile stresses of 65–120 MPa developing in the central region of the weld. The residual compression stresses of 8–15 MPa are observed in the weld zone during friction stir welding. Annealing of welded joints at 280–300°C for 30 min completely relaxes the residual stress. The application of electrodynamic processing with an exposure time of 0.7–1.8 ms lifts the tensile stresses in the welded joints of alloy 1565chM obtained through fusion welding and forms a stable zone of compression stresses in the mixing zone of joints obtained using friction stir welding.

This paper presents the results of a study examining the effects of mechanical activation of graphite nanoparticles and heat treatment of nanocomposites on their key physicomechanical and physicochemical properties. Polyolefins such as ethylene/hexene copolymer, ethylene/butene copolymer, ethylene/propylene random copolymer, and ethylene/propylene block copolymer have been used. The objective of the study was to explore the feasibility of producing multifunctional nanocomposites based on these materials that exhibit electrical conductivity, wear resistance, strength, and satisfactory melt flowability for processing by injection molding and extrusion methods.

Scientific principles of hydrochemical dispersion of inorganic nonmetal powder materials are formulated. The effect of hydrochemical nanodispersion of quartz and chalk microparticles under the conditions of a wedging destructive action of surface-active substances and a “pseudocavitation” thermohydrodynamic action of a boiling suspension upon a fast-repeating interchange of thermal, chemical, and physical gradients generated in a coarsely dispersed system is found. A geometric model of the origination of this process is developed, and a generalized equation describing the effect of various processing parameters on the degree of hydrochemical dispersion of inorganic ceramic-forming particles is proposed. The following is determined on the basis of the investigation of the effect of hydrochemical treatment on the change in the sizes and volume fraction of dispersed quartz and chalk particles in an aqueous dispersion medium: (1) two opposite processes compete in the process of hydrochemical treatment, namely, nanodispersion and aggregation of nanoparticles, and (2) upon long-term execution of hydrochemical treatment, the aggregates obtained in an aqueous dispersion medium are broken down to nanoobjects, increasing the fraction of nanoparticles in the dispersed system.

Temperature dependences of shear modulus and internal friction are studied in the range from 130 to 600 K for Cu–Ni, Ti–Ti₅Si₃, and EP678–Me₃Al metal laminate samples. In the initial state of samples, at temperatures below room temperature, a peak in internal friction and a stepwise change in the shear modulus are observed. After high-temperature annealing, these features disappear. Possible mechanisms for this observed behavior are discussed.

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.