Inorganic Materials: Applied Research最新文献

Zirconium dioxide nanoparticles obtained by arc deposition at low pressure with variable oxygen content in the gas mixture are investigated in the study. The phase composition, structural characteristics, and chemical state of zirconium in the samples are confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, and electron paramagnetic resonance. The modification of the phase composition of samples, which is accompanied by a change in photoluminescent properties, is discussed. Nanopowder of ZrO₂ in the tetragonal phase exhibits intense luminescence (λ_max = 417 nm) when excited by light with a wavelength of 270 nm. As the phase composition of the nanoparticles changes to the prevailing monoclinic modification, the broad peak in the PL spectra is replaced by three distinct peaks at 376, 407, and 479 nm. For all samples, the nature of the radiation is related to the impurity states in the band gap. New energy levels are formed by oxygen vacancies and surface defects.

Using transmission and scanning electron microscopy, as well as X-ray phase and X-ray diffraction analyses, the structure and phase composition of a deposited high-speed steel R2M9 cladding on medium‑carbon steel 30KhGSA were investigated after heat treatment consisting of triple high‑temperature tempering followed by irradiation with pulsed electron beams.

This paper presents studies on the influence of wollastonite with different particle morphologies and structural characteristics on the tribological properties of polymer composite materials based on ultrahigh molecular weight polyethylene (UHMWPE). The influence of wollastonite synthesized in three systems under different conditions on the formation of the composite friction surface was assessed. It was found that the introduction of wollastonite into the matrix leads to a 3- to 6-fold increase in the wear resistance of the composite.

A method is proposed to identify the initial interval in a kinetic diagram depicting the fatigue fracture growth rate. The method takes into account the qualitative features of the experimental data used to plot the diagram.

In this study, a composite material based on a solid solution of Ti(Al, Si)₃ is obtained for the first time using the method of self-propagating high-temperature synthesis. In the volume of the synthesized material, rod-shaped hexagonal crystals of Ti₅Si₃ are formed, the internal region of which is enriched in aluminum. Hexagonal crystals are joined to each other in a reticulated structure forming a spatial framework in the shape of a “bird’s nest.”

Studies of the effect of plastic deformation by equal-channel angular pressing (ECAP) and rolling on a Zn–0.8Li–0.1Mn bioresorbable zinc alloy are conducted in the work. Eight cycles of ECAP with decreasing the temperature of the cycles from 300 to 1500°C are executed. The structure and mechanical properties upon tension of the alloy in different states are studied. The alloy in the initial state and after ECAP undergoes brittle fracture at a fracture stress of about 370 MPa. Rolling with fractional deformation per pass makes it possible to transform the structure in such a way that the ductility of the alloy increases up to 8%, while the strength reaches 530 MPa.

Main thermal and dielectric properties of hexagonal boron nitride and silicone elastomer-based composite films are described. Films consisted of up to 47 vol % of filler. Maximal thermal conductivity reached 6 W/m K (1400% improvement over neat elastomer) at thermal conductivity anisotropy level ca. 2, weakly depending on measurement temperature. Materials demonstrated excellent dielectric properties. Concentration correlations of thermal conductivity were described using modern models, as well as compared to the best published data.

This article describes the results of a comprehensive study of the physical and mechanical properties of wood (using Scots pine (Pinus sylvestris L.) as an example) at the nano-, micro-, and macroscales and shows their relationship with the anatomical structure at these levels. Size effects in wood hardness, as well as their similarities and differences between earlywood and latewood within annual rings, are identified. Using nanoindentation and scratch testing, the hardness and Young’s modulus distribution profiles are constructed, and their relationship with the structure of wood annual rings is shown. Using SEM image analysis of the cellular structure, density distribution profiles are obtained within wood annual rings, and their correlation with the distribution profiles of physical and mechanical properties is revealed. This makes it possible to use the obtained data both for solving problems in materials science and for other fields of science, such as dendrochronology and dendroclimatology.

The effect of iron stearate on the processing and physical properties of SP40KhSMF powder alloyed steel is studied in this paper. Iron stearate is introduced in amounts of 0.5, 1, 2, and 3 wt %. It is found that introducing iron stearate into the furnace charge of SP40KhSMF powder steel increases flowability and decreases bulk density. Also, iron stearate favorably affects the compressibility of blanks made of the powder mixture of SP40KhSMF steel. The highest values of density are demonstrated by the samples pressed under 800 MPa, in which the amount of introduced iron stearate is 3 wt %. In addition, it is found that introducing iron stearate into the powder mixture of SP40KhSMF steel results in a slight increase in the average particle size.

Using solid-state synthesis in the ZrO₂–SnO₂–TiO₂ system with the La₂O₃ and ZnO sintering additives, dense ceramics with a Q factor of 400, a permittivity of 34, an open porosity of 0.3%, a zirconium–tin titanate crystal size of 5–7 μm, and a closed porosity of up to 3% has been obtained. The Zr_0.8Sn_0.2TiO₄ dielectric has a sintering temperature of 1350°C, which is 200–250°C lower than the value for the commercial analogs.