A new composite material of W–Bi2O3 system is proposed as a protection against ionizing radiation. An improved method of hot isostatic pressing for the preparation of composite materials is proposed. The duration of sintering under conditions of high pressure and temperature was 3 minutes. The study of the morphology and chemical composition of W–Bi2O3 composites was carried out using scanning electron microscopy and X-ray energy-dispersive spectroscopy respectively. The density evaluation of the obtained materials was carried out using the Archimedes’ method. The densest samples were obtained at a pressure of 5 GPa and temperatures of 25 and 500 °C, the density of which was 18.10 and 17.85 g/cm3, respectively. It is shown that exposure to high temperatures during sintering adversely affects both the microstructure and density of the samples due to the redox reaction accompanied by the reduction of Bi and the oxidation of W. The results of studying the W–Bi2O3 structure by X-ray diffraction analysis showed that all samples include the main body-centered phase W, and the presence of the WO2 phase is noted only when the sintering temperature is increased to 850 °C, which is confirmed by the appearance of reflections 111 and 22-2. Shielding effectiveness of the W–Bi2O3 composite materials from gamma radiation using the Phy-X/PSD software was evaluated. Co60 with an energy of 0.826–2.506 MeV was used as a source of gamma quanta. The simulation results were compared with the calculations for Pb and Bi. Key parameters such as linear attenuation coefficient, mean free path and half value layer are determined. The calculation results showed that the W–Bi2O3 composite surpasses Pb and Bi in its shielding properties, which makes it promising for use as a radiation shielding material.

The results of studies of the structure formation process in an iron-based antifriction composite powder material infiltrated with a copper alloy (pseudo-alloy) during thermal and high-temperature thermomechanical treatment (HTMT) are presented. It is shown that after infiltration the structure of the pseudo-alloy consists of sections of the steel skeleton with a perlite structure almost homogeneous in carbon and a small amount of cementite, sections of the copper phase located along the boundaries and at the joints of the particles of the steel skeleton, sulfide inclusions mainly in the copper phase. In the process of hardening, carbon is redistributed in the particles of the steel skeleton; a layer 2–5 µm thick with an increased carbon content is formed at the boundary with the copper phase. During HTMT, the structure is refined, a macrotexture is formed, and the thickness of the copper phase interlayers decreases, depending on the degree of deformation. The degree of deformation also affects the structure of the steel skeleton. After HTMT with a degree of deformation of 30 %, the structure consists of structureless martensite, troosto-martensite and residual austenite, and in the areas adjacent to the copper phase the carbon content is slightly lower, with a degree of deformation of 50 % – structureless martensite, 25 % more austenite content, more uniform distribution of carbon. It has been established that, due to the activation of diffusion processes during deformation during HTMT, molybdenum sulfides decompose and form iron and copper sulfides of various compositions; molybdenum alloys the iron base or forms carbide. The investigation results can be used in the development of high-strength antifriction materials for heavily loaded friction units.

In the article innovative methods of surface hardening of internal surfaces of machine parts by laser and highfrequency induction heating are presented. The relevance of applying the methods of laser and induction hardening for the internal surfaces of heavily loaded parts of quarry equipment is proved. The results of modeling and calculation of thermal and electromagnetic fields under the influence of an external electromagnetic field and laser radiation beams are presented. The original design of a complex of equipment for processing the internal surfaces of suspension parts by external electromagnetic field is described. The optimal designs of inductors with magnetic circuits made of various materials are shown. The study of the structure and properties obtained on the internal surfaces of heavily loaded suspension parts of cars, line of the BelAZ company, treated according to the optimal modes of surface induction exposure is given. The developed original technology and equipment of laser surface hardening, which makes it possible to increase the wear resistance of heavily loaded parts, is described. Data on the implementation of research results at JSC “BELAZ” – the Management Company of the Holding “BELAZ-HOLDING” for processing a wide range of heavily loaded suspension parts are given.

The paper discusses the results of an experimental study of the thermal decomposition of pyrolytic tar carried out in isothermal conditions at temperatures of 300, 350 and 400 °C. It was found that the kinetics of this process can be described using the Avrami–Erofeev equation with a variable parameter n. Analysis of the established data showed that the area of variation of this index included values from 0.415 to 1.238. The mean value of the n parameter calculated for all variants of the study was 0.694 (95 % CI from 0.605 to 0.783), and the median value was 0.639. As is known, the Avrami–Erofeev equation describes the kinetics of thermal decomposition of matter in the condensed state, determined by the nucleation process. This suggests that in the case of thermal decomposition of pyrolytic tar in the temperature range 300–400 °С this process is the limiting stage of the total process. The pyrolytic tarn decomposition rate was found to increase in the case of introduction of particles of nickel catalyst developed at the Physical and Technical Institute of the National Academy of Sciences of Belarus into the reaction zone. However, only with respect to one sample, it can be confidently stated that this is the result of the catalytic effect of applied nickel catalyst. Based on the established data, it was concluded that it is promising to use a nickel-containing catalyst in the processes of thermal decomposition of heavy hydrocarbons formed in the processes of thermochemical conversion of biomass.

The technique of poly(ethylene terephthalate) track-etched membranes (PETF TMs) modification to increase of water-in-oil emulsions separations is developed. The water-in-oil emulsions separations by using PETF TMs with regular pore geometry and pore sizes 200 and 350 nm is described in the article. PETF TMs were modified with octadecyltrichlorosilane by spin-coating method to increase their hydrophobic properties. The results of changes in the pore diameters and the contact angle after PETF TMs modification are presented. The obtained samples were characterized by AFM, SEM and gas permeability test. Chloroform–water and n-hexadecane–water emulsions have been used as a test liquid for water-in-oil emulsions separations. At an operating vacuum of 700 mbar, the specific filtration performance of chloroform: water emulsions were 51.5 and 932.0 l/(m2 ⋅ h), hexadecane: water were 46.1 and 203.4 l/(m2 ⋅ h) for PETF-200 / OTS and PETF-350 / OTS, respectively. The degree of purification of emulsions by modified membranes according to the refractive index is of 100 %. Obtained membranes can be used to separate oil-water emulsions in order to prevent the corrosion of pipelines and changes of crude oil viscosity, as well as the treatment of water purification from oil industry waste.

Methods of restoring images and properties of non-destructive testing objects based on solving inverse problems (problems of restoring distribution functions of unknown characteristics of an object based on the results of indirect measurements) are considered. Management methods are based on solving inverse problems and allow you to get the most complete information about the distributed properties of an object. The need to attract additional information imposes serious restrictions on the development of universal applied algorithms for solving incorrectly set tasks. As a rule, individual additional information is available for each specific non-destructive testing task. An effective numerical algorithm for solving an incorrectly posed problem should be focused on taking this information into account at each stage of the solution search. When solving an applied problem, it is also necessary that the algorithm corresponds to both the measuring capabilities and the capabilities of available computing tools. The problem of low-projection X-ray tomography is always associated with a lack of initial data and can only be solved using a priori information. To introduce the necessary additional information into the numerical algorithm, the methods of iterative reconstruction of tomographic images are identified as the most suitable. One of the approaches to the presentation of this kind of information is described. A practical solution to this problem will expand the scope of the X-ray tomography method.

Тhe criteria for compliance with which the properties and characteristics of clays from industrially exploited deposits of the Republic of Belarus were assessed in order to determine the possibility of their further use as part of the underlying screen of the radioactive waste disposal facility (RWDF) of the Belarusian NPP are defined. The performed experimental analysis of clay samples from 12 deposits of the Republic of Belarus showed that clays from the “Gorodnoye” deposits of the Brest region and the “Markovskoye” deposits of the Gomel region have optimal quality indicators for use as part of the RWDF engineering barrier (underlying screen). It has been established that these clay samples have high sorption properties for 137Cs and 85Sr radionuclides. The values of the degree of sorption of 137Cs and 85Sr radionuclides from an aqueous solution for the above clay samples are about 99 %, and the values of the quantitative indicator of sorption the coefficient of distribution of radionuclides – are about 104 l/kg. Over time, the fixation of 137Cs on the studied clay samples increases; as part of the underlying RWDF screen, these clays will be an effective anti-migration barrier to prevent the migration of radionuclides into the environment in the event of depressurization of radioactive waste packages.