Vol 10, No 4 (2019)

The study of formation of the structure of austenitic nitrogenous steel obtained from physical simulation of the processes of hot deformation with a Gleeble-3800 installation by various modes is considered in the work. The kinetics of metadynamic recrystallization within the interdeformation interval under multipass deformation implemented under different schemes is studied. As a result, it was established that, depending on the deformation scheme, the recrystallization runs with varying degree and intensity.

Temperature dependence of insulator-to-metal phase transition in VO₂ epitaxial thin films was studied in the microwave range. Biaxially textured VO₂ thin films were obtained on 3-inch sapphire substrates by the method of chemical vapour deposition (MCVD). The change in the electrical resistance with temperature reached approximately 3 orders of magnitude for the obtained films, measured in the metal-insulator phase transition region. Using a high-temperature quasi-optical setup, the microwave features of the phase transition in VO₂ thin films were studied at temperature. The hysteresis of microwave properties of the studied samples was observed in the temperature range of VO₂ phase transition.

This article describes a method of producing composite materials with an ice matrix from distilled water reinforced with plant fillers of different biological composition and morphology: coniferous needles, wood chips, cedar cone scales, cedar nut shells, luffa, and linen fibers. We studied the bending strength and strain of the composite samples and showed that the reinforcement of the ice matrix with plant fillers makes it possible to control their physical and mechanical properties by creating stronger materials as compared to ice. We identified the quantitative dependences of strength characteristics of the composite materials on the type and composition of the reinforcement component and determined the optimal variants of reinforcing ice with plant substances.

The results of studies concerning ceramics made of substituted (silver, zinc, copper, iron) tricalcium phosphate (TCP) powders are presented. It is shown that the pores in the obtained ceramics are interrelated, the size of macropores ranges from 200 to 400 μm, the size of micropores ranges from 1 to 5 μm, and there are nanopores between the ceramic grains. Such pore sizes can provide the penetration of biological fluxes and cells required for the subsequent formation and growth of new bone tissue into the ceramic matrix. According to the solubility in the physiological solution, the ceramics composed of cation-substituted TCP can be arranged in the following order: Ag ≈ Fe < Cu < Zn. According to the results of studies on the antimicrobial activity with respect to a strain of E. coli bacteria, it has been established that cation-substituted TCPs exhibit a pronounced antimicrobial activity. The highest antimicrobial activity has been shown by the samples of zinc-substituted TCP.

A biocompatible material characterized by gradient structure titanium nickelide–tantalum–biodegradable polymer layer was designed for the manufacture of medical implants. The mechanical characteristics of the material and components were studied. The structure and composition were determined by SEM and Auger electron spectroscopy. The formation of surface layers does not significantly affect the mechanical characteristics of the support; high adhesion between the layers and the support is observed.

In the present work, Mg–Ni–Mm alloys (where Mm is a mixture of rare earth metals) are studied to elaborate a chemical hydrogen source for portable energy systems based on fuel cells characterized by high gravimetric energy density used for unmanned air vehicles and robot systems. Hydrogen generation on demand by hydrolysis of metal hydrides (MgH₂, Mg₂NiH₄) is proposed for the fuel cell power supply because it is the most efficient method characterized by high hydrogen storage density, safety, and low costs of the stored energy. The influence of the composition of alloys on the hydrogen absorption properties and hydrogen generation during hydrolysis is studied.

This article presents information about the publicly available computer database of the Arctic materials created on the basis of an Internet catalog comprising the materials of the All-Russian Scientific Research Institute of Aviation Materials. The possibilities of using and appending the database are discussed along with the enhancement of its effectiveness and usefulness.

Various poly(lactic-co-glycolic acid)-based polymeric films with various molecular weights were obtained. The mechanical characteristics of these films were investigated. It was shown that the obtained polymer films do not have a short-term toxic effect on mammalian cells. The percentage of actively dividing cells on such polymer films is 1.5–3.0 times higher than when grown on culture glass, and, accordingly, the cell layer is formed faster. The obtained poly(lactic-co-glycolic acid)-based polymer films are biocompatible.

Powders for selective laser sintering based on commercial aluminum and some cast and wrought aluminum alloys as well as three experimental alloys have been prepared by atomization technique. The micromorphology of the powders is characterized by nearly spherical main particles distributed with the maximum in the region of 50 μm as well as existence of satellites. It is demonstrated that the adhesive strength between satellites and the main particle revealed by static light scattering before and after ultrasonic treatment can be attributed to peculiarities of its solidification.

The pivoting friction of ShKh15 steel over the flat surface of a prism made of R6M5 and 10R6M5-MP steel was investigated. It was proved that, in the steady wearing mode, the pivoting friction moment is steady as well. It was shown that the change in the pivoting friction moment from the load for R6M5 steel does not stay within the boundaries of one linear dependence and for the powder steel 10R6M5-MP is linear. Wear of a ball made of ShKh15 steel in the case of friction by 10R6M5-MP steel is more intense as compared with the friction by R6M5 steel, and the friction moment, on the contrary, has a smaller value. As a result, cutters made of 10R6M5-MP steel will be more effective and energy saving during cutting of ShKh15 steel.

The influence of the natural aging for ten years and the subsequent heating to 680°C on the magnitude of the strain aging effect in low-carbon microalloyed 05Mn2Nb grade steel for trunk pipelines of the X80 grade pipes has been studied. A method for the assessment of the strain aging effect by the parameters of the stress–strain curve, namely, strength increment Δσ_y on the yield plateau, change in the σ_y/σ_u ratio, and proportional elongation δ_p, has been proposed.

Results of the study of microstructure and hardness distribution of weld joints of BrKh1Tsr bronze by electron–beam welding (EBW) after welding and thermal aging are given. Thermal aging provides an increase in the hardness of weld metal up to 80% of the hardness of the base metal, while the hardness of the heat-affected zone is up to 60%.

The nature and mechanisms of the negative effect of phosphorus on the structural stability and service properties of single-crystal refractory nickel alloys are considered. It is demonstrated that the phosphorus admixture induces the appearance of low-melting phosphides. The segregation of phosphorus on phase interfaces decreases their cohesive strength and increases their diffusion permeability. Moreover, the phosphorus admixture increases the porosity, promotes the coagulation of the hardening γ' phase, and decreases the long-term and cyclic strength and the yield of suitable single crystals. The data on the physicochemical parameters (the enthalpy and Gibbs free energy of formation of phosphides and their melting and boiling temperatures and density), which simplify the selection of additives neutralizing an adverse effect of phosphorus, are systematized and generalized.