Mathematical models of the main characteristics of a spray atomizer have been developed, namely: dispersion characteristics that define the torch (the spray flow from the nozzle) as a certain set of particles of different sizes; distribution characteristics that reflect the profile of specific liquid flows across the torch cross-section; shape characteristics that allow determining the dimensions of the torch at a given distance from the sprayer. These characteristics have been calculated for a pneumatic nozzle and the calculation results have been compared with experimental data, which confirmed the adequacy of the developed models. Based on calculations, it was found that the spray droplet diameter distribution curve obeys the log-normal distribution, the median spray droplet diameter is 754 mu m, the most common diameter is 249 mu m. The average droplet evaporation time is about several minutes. A system of nonlinear differential equations for the motion of aerosol particles in a spray torch was obtained, which made it possible to determine its parameters. When deriving the equations, the following assumptions were made: aerosol particles have a spherical shape, the particles move at low Reynolds numbers, and the drag force is determined by the Stokes formula. As a result of the numerical solution of the nonlinear equations system, an equation for calculating the distance of a spray droplet movement in the direction perpendicular to the torch axis, which made it possible to estimate the law of the torch spray density distribution was found. The effect of the spray torch parameters (torch height and spray angle) on the type of irrigation curves was revealed. The obtained results are in good agreement with the experimental data obtained by the authors of the article, as well as with the results given in scientific sources. A technological and functional scheme for obtaining transparent conductive thin films is proposed.

It is shown that a promising method for obtaining transparent conductive oxides is spray pyrolysis, which allows to obtain films of proper quality without the use of vacuum. For the effective use of the spray pyrolysis method in order to obtain reproducible films with specified properties, it is necessary to take into account a variety of heterogeneous technological parameters that affect the quality of transparent conductive coatings. To this end, the authors have developed a model in the form of an oriented graph that displays the relationship of technological modes and quality parameters of transparent conductive coatings. The model displays parameters in the form of graph vertices, which are divided into technological and parameters characterizing the quality of transparent conductive coatings. The arcs connecting the vertices represent the properties of the coatings, and the arrows of the arcs indicate the direction from the action property to the reaction property. This model made it possible to systematize the influencing factors and offer an analytical description of the influencing parameters, reactions to them and properties of the synthesized coatings in the form of a system of differential equations. Based on the specified mathematical model of the relationship between technological modes and coating properties, a method for selecting optimal technological parameters has been developed in order to obtain transparent conductive coatings with specified properties. The technique has been tested on the example of the synthesis of a transparent conductive film of tin dioxide doped with antimony. Analysis of the factors affecting the surface resistance of coatings showed that the concentration of charge carriers significantly depends on the volume and concentration of impurities. The results of the analysis of experimental studies of the dependences of the concentration of charge carriers on the concentration of the impurity, the volume of the solution, on the thickness, the dependence of the surface resistance of the film on the thickness are presented

The aim of the work is to select the technological parameters necessary to obtain microarc oxide coatings with desired properties. The objectives of the study are: modeling the properties of coatings from the technological parameters of the process of their formation and assessing the error of modeling adequacy. For this, regression analysis methods, interpolation and approximation of functions were used. Mathematical expressions are proposed for calculating the specified coating parameters depending on the current density and the duration of the microarc oxidation process. The initial data were the results of measurements of coating parameters obtained at current densities of 8, 10, 12 A/dm2 for 180 minutes in a silicate-alkaline electrolyte, the thickness, microhardness and porosity of which lie in the range: thickness from 0 to 180 цап; porosity from 4 to 44 % and microhardness from 7 to 10 HV. It is shown that the simulation results are in good agreement with the experimental data, while the relative adequacy error does not exceed 15 %. The results obtained can be used in scientific research in the development of a digital twin of the microarc oxidation process and in industry for testing the technology of coating light alloys.

The work addresses the issues of controllability of the microarc-oxidation process. This problem is mostly due to the difficulty of analytically characterizing the heterogeneous physical–chemical processes, which are nonlinear and nonstationary, that take place during microarc oxidation. To tackle this issue, a digital twin of the process is being developed, within which an analytical model is proposed to describe the behavior of the equivalent electrical circuit of the galvanic cell during coating deposition. The proposed analytical model of the process is nonlinear and nonstationary, which is attributed to the abrupt decrease in the active resistance of the coating during dielectric breakdowns. Based on experimentally obtained current and voltage oscillograms and the proposed analytical model, parametric identification of the electrical parameters of oxide coatings is performed using the matrix-operator method on the orthonormal Walsh basis. The matrix-operator method is selected because of its applicability to solving problems with both linear and nonlinear equations, as well as stationary and nonstationary parameters and variables, along with the relative simplicity of the mathematical and algorithmic implementation of computations. The calculations result in weight functions of the electrical model of the microarc-oxidation process, reflecting the relationship between the voltage and current in the galvanic cell (coating conductivity). The mean values of the weight functions (average conductivity) decrease during coating deposition, which confirms the adequacy of the proposed model and enables its use for implementing real-time procedures for monitoring coating properties. The scientific novelty of the work lies in the possibility of the real-time control of microarc oxidation through parametric identification of the electrical parameters of coatings using the matrix-operator method.

A version of the design of a film resistor with temperature self-compensation, which makes it possible to achieve temperature coefficient of resistance values not exceeding ±5 · 10-7 in the temperature range from 60 °C to 125 °C is presented. The technology of obtaining combined resistive structures with specified obligations is considered.

Morphological studies of coatings were carried out on aluminum samples obtained by microarc oxidation. The sinusoidal current density in the anodic and anode-cathode modes was 15 A/dm(2), and the processing time varied from 120 s to 960 s. The formation of oxide coatings occurred in a silicate-alkaline electrolyte. Studies of the surface topology and mechanical parameters of oxide coatings were carried out using an SEM, a laser profilometer and a universal electrical strength meter, which, in turn, made it possible to establish a relationship between the properties of the coatings and the sample processing time. Thus, an increase in the processing time during the micro-arc oxidation of products made of valve group alloys leads to a complication of the surface morphology, as well as an increase in the size and number of pores. In addition, the coating roughness increases in the anode and anode-cathode modes. Electrical strength tests showed that all samples with the resulting coatings withstood a voltage of 600 V. Multifunctional coatings obtained using the developed technological modes are multilayer structures. They consist of a base layer with excellent adhesion, an intermediate layer with porous structure and a top layer with high porosity and actively functioning surface. The changes revealed during morphological studies are characteristic of the plasma growth model of coatings. The results of the conducted morphological studies of coatings can be implemented in the development of a digital twin of the microarc oxidation process.

Micro-arc oxide coatings of aluminum alloy AD31 samples were formed in an electrolyte containing 2 g/l NaOH and 9 g/l Na2SiO3 for 2, 4, 8, 16 min in the anode and anode-cathode modes. During the processing, the forming curve, the time dependences of the charge passed through the galvanic cell, and the optical parameters of the microdischarges were measured using the optical synchronization method developed by the authors with subsequent image recognition. The thickness of the coatings was measured using a point autofocus probe surface texture measuring instrument Mitaka PF-60, the surface morphology was studied using a VEGA3 scanning electron microscope using SBH surface topography. The elemental composition of the coatings was determined using a scanning electron microscope JSM-6610LV. The analysis of the elemental composition and morphology of the surface revealed that the inner layer of synthesized coatings consists of Al2O3, the outer layer consists of Al2O3SiO2 mullite, and the ratio of phases Al2O3 and mullite changes with changes in current density and oxidation mode. The formation of mullite is due to the presence of Na2SiO3 in the electrolyte. It is shown that with increasing processing time and current density, the thickness, roughness and porosity of coatings increase. The interrelation of the optical parameters of microdischarges with the morphology of the surface and the elemental composition of the formed coatings is substantiated; it is shown that the ratio of illuminated and non-illuminated sections of the sample surface by microdischarges can be used as a rough estimate of the ratio of electron and ion currents corresponding to microplasma and electrochemical processes. A mathematical model describing the dependence of the coating thickness on the oxidation time based on Faraday's laws for electrolysis and the results of measuring the optical parameters of microdischarges and the electrical parameters of the MAO process without taking into account microplasma processes that do not lead to an increase in the thickness of coatings is proposed. The error of adequacy of the proposed model does not exceed +/- 10 %. The results of the study can be used in the development of a digital twin of the micro-arc oxidation process.

A method for diagnostics of local stresses/strains in diamond at room temperature based on optically detected magnetic resonance (ODMR) of NV defects in a zero magnetic field using low-frequency microwave power modulation is proposed.

Transitions in a system of interacting electron and nuclear spins in color centers with S = 3/2 in a 4H-SiC crystal with the natural isotopic composition have been detected by fully optical methods at room temperature. Giant changes in the photoluminescence in a volume of about 1 μm 3 under cw and pulsed laser excitation occur in the region of the anticrossing of electron and nuclear spin levels. An optical manifestation of the flip of the nuclear spin of the 29 Si isotope with the conservation of the projection of the electron spin has been detected. All anticrossing points of the spin sublevels coupled by hyperfine interactions have been identified. This identification enables the observation of such effects in the family of quarter spin centers in other SiC polytypes.

A method for forming a nanostructured bimetallic PtNi catalyst on the surface of a solid polymer electrolyte is presented. Nickel particles, on which the bulk of the platinum catalyst is grown by chemical deposition, are obtained by magnetron sputtering. The resulting system has high catalytic activity and temporary stability.

The spin properties of transition metal dichalcogenides are of interest for applications in spintronics. Anisotropic electron paramagnetic resonance spectra in a WS 2 single crystal under optical excitation have been detected. These spectra assumingly belong to localized carriers near the valence band and reflect features of the 5 d shell of the crystal. It has been shown that the g -factor for the magnetic field perpendicular to the c ‑axis of the crystal (in-plane magnetic field) is larger than that for the magnetic field parallel to the c ‑axis (perpendicular to the layer plane), which can provide information on the type of the 5 d function. The discussed center is most likely described by the 5d(z^2 - r^2) wavefunction, which can be associated with the valence band of the crystal.

With the development of technology, protective coatings in nano and microelectronics are actively developed. Protective coatings based on metal oxides, such as aluminum oxide, titanium oxide, iron oxide, as well as ceramic protective coatings, have been actively developed. Particular attention is paid to zirconium oxide. The article presents a technological installation for obtaining coatings from metal oxides by spray pyrolysis. The installation is part of the information-measuring and control system for the synthesis of metal oxide coatings and its technological subsystem. With the help of this installation, coatings samples of zirconium dioxide with an admixture of yttrium, introduced for the purpose of stabilization, were obtained. The study results of the coating structure morphology, the features of the solution influence on the coating structure, as well as the graph model and its analytical description, used to analyze the relationship between the parameters of the technological process, electrophysical and optical parameters of metal oxide coatings, are presented.

In this work, oxide coatings on aluminum samples were obtained by the method of micro-arc oxidation at a sinusoidal current in an anode-cathode alloy with an anode and cathode current ratio of 1, with a current approximation of 10.88; 13.99; 17.10; 20.21; 23.32 A/dm2 in four electrolytes containing 0.5 g/l NaOH and 80, 90, 100 and 110 g/l Na2SiO3. An analytical description of the thickness and porosity dependence of micro-arc oxide coatings on the decrease in current, treatment time, and electrolyte components detection in the form of empirical regression formulas is obtained. Based on the obtained equations a technology for the formation of micro-arc oxide coatings with desired properties was proposed. As a result of experimental verification, the reproducibility of the technology for obtaining micro-arc oxide coatings with a thickness of 25 mu m and minimal porosity (P = 19.5%) was confirmed. The relative error of the appearance reproducibility does not exceed +/- 0.5%. The results of the study were used in the development of intelligent algorithms that underlie the digital twin of the micro-arc oxidation process.

A design and technological solution for increasing the temporal stability of gas sensors based on the nanorods-colloidal quantum dots structure is presented. For this purpose, zinc oxide nanorods oriented predominantly to the surface normal were grown by the hydro thermal method. Silicon nitride, followed by etching to the level of zinc oxide colloidal dots in an inductively coupled plasma using a gas mixture based on sulfur hexafluoride, was deposited onto the resulting structure by RF magnetron sputtering. Through accelerated aging testing, it has been found that silicon carbide protected zinc oxide nanorods exhibit greater temporal stability due to less surface oxidation resulting in a reduction in specific surface area. Silver nanoparticles with a plasmon effect were deposited onto the resulting structure by centrifugation.

Questions of raising the efficiency and controllability of the process of depositing protective microarc oxide coatings with specified properties on products made of light metals and alloys (aluminum, magnesium, titanium) are examined. An intelligent information-measurement system is developed for measuring the parameters of microarc oxide coatings which contains unique hardware, program, and information support. For the hardware support of the system a technological current source is created that specifies the technical regimes, strength and shape of the current (a sinusoidal or pulsed signal is possible) which to a great extent determines the parameters of the formed coatings. Original circuit solutions in the area of pulsed power electronics, along with modern electronic components, are used for developing the source. The technological current source has a high efficiency and provides a complete range of regulation of the parameters of the energy effect on a test sample where a coating is being formed. The developed intelligent informationmeasurement system is intended for high current measurements of the process parameters and properties of the resulting coatings; it can be used for automatic monitoring of microarc oxidation, as well as for scientific studies. Intelligent application and the knowledge bank of the system ensure intelligent choice of the optimum technological parameters of microarc processing, along with automatically controlled synthesis of microarc oxide coatings with specified properties.

The processes occurring in the structure of thin films leading to a change in the resistance of a thin-film resistor over time are investigated. The addition of a thin film to the resistor with the opposite direction of the resistance "drift" allows minimizing the effect of aging processes on the total resistance of the composite resistor. Various design options are presented that provide an opportunity to compensate for the temporary instability of a thin-film resistor, including one close to zero. Their advantages and disadvantages are shown.

The process of a heterogeneous catalytic coating formation on the ion-exchange membranes surface was studied in this work. It is determined that the use of the chemical deposition method results in a highly porous coating, but with low strength and durability. A combined method for obtaining a heterogeneous catalytic coating is proposed, which includes the formation of adsorption centers by thermal vacuum spraying and the growth of the bulk of the catalyst by chemical deposition.

A method for diagnostics of local stresses/strains in diamond at room temperature based on optically detected magnetic resonance (ODMR) of NV defects in a zero magnetic field using low-frequency microwave power modulation is proposed.