The results of a study of the structure and physical and mechanical properties of diamond-like coatings (DLC) on sublayers of different hardness are presented. The coatings have high hardness, but at the same time they are prone to delamination and destruction due to high residual internal stresses. The fracture toughness was determined by the nanoindentation method and the energy calculation method using approach-retraction curves. Atomic force microscopy was used to study the surface structure and deformation region after nanoindentation. A change in the surface structure and roughness of DLC was established depending on the sublayer. Low roughness is characteristic of DLC on a copper sublayer. Applying а titanium sublayer leads to an increase in the elastic modulus of the DLC. The microhardness of both coatings is practically the same. AFM studies have shown two different types of DLC deformation after nanoindentation with a Berkovich pyramid. A crack on coatings with a copper sublayer propagates around the indentation print, and on an DLC with a titanium sublayer, it propagates along the edges of the indentation. It was found that the fracture toughness of DLC on a Ti sublayer is 33 % lower compared to DLC on a Cu sublayer due to a decrease in stress relaxation inside the coating. The considered coatings can be used in microelectronics for protection against mechanical damage on contacting and rubbing surfaces.

The results of studies on the production of a porous ceramic-matrix composite material C–N/SiC from silicon carbide and nitrogen-doped nanostructured carbon for subsequent use as supercapacitor electrodes are presented. The material is formed by pressing silicon carbide micropowder (1 µm) and impregnating with a solution of carbamide (nitrogen source) in phenol-formaldehyde varnish (carbon source), curing and pyrolysis in a nitrogen atmosphere. The maximum concentration of carbamide was obtained in the solution (16 wt.%) at 50 ºС with a viscosity of 134.3 mPa⋅s. Thermogravimetric analysis in nitrogen of the cured solution revealed multistage decomposition with a residual mass of C–N of 48 % at 1000 ºС. Studies of the elemental composition showed a nitrogen content of 1.4 wt.% in C–N/SiC composite (up to 7 % of C–N active mass). In the composite structure, the C–N carbon-nitrogen layer (up to 12 wt.%) distributed inside the matrix pores and covering the SiC grains is X-ray amorphous has a complex nanoscale relief with an average pore size of 1.0–1.5 nm. According to electrochemical studies, the specific capacitance of the C–N/SiC material and the C–N active layer is 16.84 and 153.2 F/g respectively, and the equivalent resistance of the test supercapacitor cell with C–N/SiC electrodes is 0.567 Ohm for samples with maximum doping. The electrodes operate according to the sorption-desorption mechanism of charge accumulation and release, which is typical for a classic supercapacitor based on a double electric layer without the presence of redox reactions on the electrodes. The influence of technological regimes of pyrolysis on the electrophysical parameters of the cell is revealed: lower values of the pyrolysis temperature and nitrogen pressure in the chamber lead to an increase of the material specific capacitance and reduction of the cell equivalent resistance. The obtained results demonstrate the possibility of utilizing C–N/SiC material for the manufacture of supercapacitor electrodes.

The assessment of existing technological solutions in the field of preparation of feedstock for potassium chloride granulation plants of silvinite processing plants of JSC “Belaruskali”, compliance of these solutions with the developed theoretical concepts and recommendations was carried out. It has been established that in the granulation departments of factories with the flotation method of enrichment at the stage of homogenization of the charge by granulation composition and humidity, and the improvement of its crystal structure, the process of particle agglomeration is not efficient enough due to the technical imperfection of the used agglomerators. At the same time, there is a significant overspending of the structure-forming reagent compared to the amount calculated in accordance with the stoichiometry of calcium and magnesium ions, which leads to excessive contamination of the finished product with sodium carbonate. To eliminate the identified drawback, it is proposed to use as an agglomeration device a turbo-blade agglomerator mixer of the TLA-080 brand manufactured by the JSC “Soligorsk Institute of Resources Saving Problems with Pilot Production”, specially designed for agglomeration of potassium chloride. It has been established that an increase in the physico-mechanical and physico-chemical characteristics of granulated potassium chloride of a processing plant with a halurgic enrichment method can be achieved by introducing the developed technology of structural agglomeration of the charge entering the granulation plants in turbo-bladе agglomeration mixers of the TLA-080 brand without the use of structure-forming reagents.

The factors that have led to the creation of the scientific direction “hydraulics of variable mass” to study the fluid movement laws in channels with permeable walls are indicated. The results of applying of the dynamics of a variable mass point for describing the flow in such pipelines are presented. It is noted unjustifiability of the second Newton’s law generalization to the case of motion of a variable mass point for hydrodynamics problems. The functionality of one-dimensional and multidimensional models of fluid motion in permeable channels based on the classical equations of fluid and gas mechanics is characterized. It is substantiated the dominance of one-dimensional models in engineering computational practice, and a number of contradictions in the description of fluid dynamics are shown (with the flow visualization). On the base of the new kinematic image (instead of the generally accepted “solid jet”, when fluid particles are separated or joined), it has been obtained a one-dimensional equation of fluid motion in a permeable channel in which the friction coefficient is an indicator of the relative magnitude of the energy dissipation of the flow. The dependence of the Coriolis coefficient on the flow regime is constructed. The structure of the friction drag coefficient of a permeable channel has been studied using the vector dimension of length. It is shown that the dissipation of the flow energy in a permeable channel is higher both during outflow and inflow of liquid than in channels with solid walls at the same flow rates. The results are in demand in the development of chemical technology devices, nuclear reactors with microfuel elements, filters and heat exchangers containing channels with permeable walls.

Using the method of applying instantaneous point sources, a solution was obtained to the problem of heat conduction during surface heating of a body in the form of a half-space by a uniformly distributed highly concentrated heat flux moving at a constant speed along a rectilinear trajectory with a different shape of the heating spot at constant thermophysical characteristics of the material. The effect of temperature loading modes and the shape of the heating spot on thermal processes in the heat-affected zone is studied. The surfaces and lines of the temperature level are constructed for different moments of time and speed loading modes in different planes of the heating zone. Time dependences of temperatures, heating and cooling rates for body points are given. The shortcomings of the methods used for linear thermal conductivity, the lack of direct consideration in the design scheme of the surface melt zone of the material do not allow one to reliably assess the effect of heat treatment modes on changes in material properties, focusing only on the level of the maximum design temperature. In this regard, the structure formation of metal in the zone of thermal action is proposed to be associated with a thermal impulse, i.e. the total thermal energy perceived by the material at a given point of the body, as well as with the effective structurization impulse introduced into consideration, which characterizes the energy spent on the process of structural transformations of the material, and the structurization time at a point and some volume of the body. The dependencies of these values on the speed of movement and the shape of the heating spot are presented. The considered approaches can be applied to various metals and alloys. The research results can be used to develop more effective methods for determining the optimal modes of surface hardening of metal products with a high-energy source.

The relevance of the work is due to the need to improve the technology of extinguishing fire with extinguishing powders based on the study of the laws of the physicochemical processes of interrupting chain combustion reactions, in particular, heterogeneous and homogeneous mechanisms of inhibition of active flame centers by powder particles. The aim of the work is to evaluate the effectiveness of non-stationary mechanisms of heterogeneous and homogeneous inhibition of active flame particles by fire extinguishing powder particles taking into account the rate of their birth, as well as to compare the contributions of each of the mechanisms to the result of fire extinguishing. Mathematical modeling of the mechanisms of heterogeneous and homogeneous inhibition of active flame particles by fire extinguishing powder particles is carried out, taking into account the rate of birth of active particles of in flame. The theoretical dependences of the rates of reactions of heterogeneous and homogeneous inhibition of active flame particles on the dispersed characteristics of powder particles, their residence time in the zone of flame and the characteristic durations of inhibition reactions are obtained. It is established that the condition for the effective recovery inhibition of active particles of flame by the mechanisms under consideration is exceeding the time of interaction of powder particles with active flame particles over the duration of inhibition processes, as well as an excess of the rate of inhibition of active flame particles over the rate of their birth. The rate of inhibition of active particles of flame depends on the particle size of the extinguishing powder, namely, the smaller the particle size of the powder, the greater the rate of inhibition. This dependence is observed explicitly for the mechanism of heterogeneous inhibition of active particles of flame and implicitly for the mechanism of homogeneous inhibition through the dependence of the rate of thermal production of metal oxide radicals of the extinguishing powder involved in this process on the size of the powder particles. The presence of two stages in the implementation of the mechanism of homogeneous inhibition of active flame particles (thermal production of metal oxide radicals of the powder substances used and the inhibition process itself) allows us to consider this mechanism of extraction of active particles longer than the mechanism of heterogeneous reduction, and, therefore, it does not significantly contribute to the chemical process of extinguishing a fire.

The influence of supply voltage on the photosignal value and signal-to-noise ratio has been studied while changing the incidence angle of optical radiation on the photosensitive surface of Ketek PM 3325, ON Semi FC 30035, and KOF5-1035 silicon photomultipliers. A scheme of the installation and a research technique are given. An installation scheme and a research technique have been given.The magnitude of the photosignal of the studied photodetectors was measured as a function of the magnitude of the overvoltage, and the signal-to-noise ratios were determined. The photosignal values of the studied photodetectors have been conducted as a function of overvoltage value, and the signal-to-noise ratios have been determined.It has been established that a flat vision angle of silicon photomultipliers depends on the photodetector supply voltage. Diagrams of changing the photosignal values from the incidence angles of optical radiation on the photosensitive surface of photodetectors have been given.It has been found that at supply voltages exceeding the breakdown voltage by no more than 1 V, the maximum deviation of the incidence angle of optical radiation on the photosensitive surface of silicon photomultipliers within a flat vision angle leads to a decrease in the signal-to-noise ratio to at least 60 % of the maximum value for KOF5-1035 and not more thant 80 % for Ketek PM 3325 and ON Semi FC 30035.The dependences of the signal-to-noise ratio on incidence angle of optical radiation on a photosensitive surface for various overvoltages have been given. The results of this article can be applied in the development and design of instruments and devices for detecting optical radiation based on silicon photomultipliers.