In present work, methods of in situ regeneration for the Co-Al2O3/SiO2 catalyst were studied. The activity and selectivity of the catalyst in the Fischer-Tropsch synthesis are shown, as well as the compositions of the products in different periods of its operation. Process parameters after regeneration regimes and before stabilization of catalyst activity were studied. The compositions of the products of the Fischer-Tropsch synthesis after the renovation of the catalyst are analyzed and compared with the initial ones.

Keywords: Fischer-Tropsch synthesis, heterogeneous catalysis, catalyst regeneration, synthetic hydrocarbons

The influence of the content of the zeolite component in the composition of cobalt catalysts for the synthesis of hydrocarbons on their physico-chemical properties is investigated. The catalysts were obtained by impregnation of a zeolite-containing carrier with subsequent heat treatment. The obtained samples with a concentration of ZVM zeolite of 30-70% were characterized by the methods of BET, TPR, TPD H2. The results of the analysis show that an increase in the concentration of the zeolite component of the catalyst contributes to an increase in the specific surface area, dispersion and a decrease in the recovery temperature of the deposited cobalt.

Keywords: applied catalyst, cobalt, zeolite, dispersion, specific surface area, active component, synthetic fuel, degree of reduction

The article presents the results of a study of the photoelectric response of cobalt-containing ferroelectric ceramics (1-x)Ва0.95Pb0.05TiO3+xCo2O3, synthesized at the Institute of Solid State Physics of the University of Latvia using conventional ceramic technology. Ceramics was exposed to optical radiation at room temperature. Before applying light radiation to the cellular electrode of the ceramic sample located in the measuring cell, zero current was recorded for 0.5 minutes in the absence of illumination using a high sensitivity digital electrometer. Then, the photoresponse was recorded during the time until its value remained constant (since the anomalous photovoltaic effect manifests itself in the form of constant currents flowing along the polar directions) and only then the light flux was turned off. A significant effect of the concentration of cobalt oxide on the value of the photovoltaic current is shown, which manifests itself in a decrease in the value of the stationary current with an increase in the content of the impurity of cobalt oxide. It is assumed that a possible reason for the decrease in the stationary current is deep charge traps, which is due to an increase in the cobalt concentration in the ceramic. The influence of the incident radiation wavelength, as well as the aging factor on the photoelectric response for ceramics with the highest concentration of cobalt oxide, is established.

Keywords: mobile robots, polarization, depolarization, ferroelectrics, polarization current, remanent polarization, dielectric losses, electrical load, domain structure, electrical breakdown, mechanical failure

The article presents the results of a study of the physicochemical and catalytic properties of cobalt catalysts on a mixed zeolite-containing carrier. Samples of catalysts containing 10% cobalt and from 30 to 70% high-silica zeolite ZVM were prepared by impregnation with subsequent heat treatment. Methods of IR spectroscopy, scanning electron microscopy (SEM) in combination with energy dispersion analysis (EMF) were used to study the physicochemical properties of catalysts. The catalytic properties were studied in a reactor with a fixed layer at a temperature of 240 °C, a pressure of 20 MPa, a volumetric gas velocity (OSG) of 1000 h-1, H2 / CO = 2. As a result of IR spectroscopy, the presence of Si-O, Al–OH, Co–O, etc. functional groups was detected, SEM–EMF images confirmed the uniform distribution of cobalt on the surface of catalysts. The dependences of the catalytic characteristics depending on the content of zeolite were established, the maximum activity was recorded for a sample containing 70% of ZVM zeolite.

Keywords: catalysts, Fischer-Tropsch synthesis, cobalt, zeolite, carrier, IR spectroscopy

The results of the analysis of leakage currents as a function of time in samples of polycrystalline ferroelectric ceramics solid solutions of lead titanate-zirconate with sodium and bismuth impurities under the condition of applying a constant electric field are presented. We considered batches of samples that were stored in different conditions, which led to the formation of two batches - standard and defective. The samples of the standard and defective batches differed in values of the dielectric loss tangent by several times, while other electrophysical parameters practically did not differ. To measure the patterns of current fluctuations with time in the sample, a modernized Mertz scheme was used. The electric field was changed stepwise on the sample. Current fluctuations at a constant voltage across the sample were measured during the establishment of a constant leakage current and were considered as a time series, allowing only a statistical description. Changes in the form of the dependence of the leakage current on time are determined with an increase in the electric field strength on samples with different values of the loss tangent. The exponential decline is accompanied by random jumps in the magnitude of the leakage current. It is assumed that at a higher voltage, the state of the domain regions stabilizes, resulting in current leakage under a depolarizing field, since the domain system retains its more rigid configuration.

Keywords: mobile robots, polarization, depolarization, ferroelectrics, polarization current, remanent polarization, dielectric losses, electrical load, domain structure, electrical breakdown, mechanical failure

Parameters indicating the appearance of a glass-forming molten mixture in the melts of the salt system Ca(NO3)2 - KNO3 at a molar ratio of components of 3:2 are shown. The nonlinearity of the change in frequencies and line widths in the Raman scattering spectra of the anion NO3 was detected, which indicates a structural transformation in the molten mixture that correlates with a change in the viscosity of the mixture.

Keywords: melts, nitrates of alkali and alkaline earth metals, Raman spectra, binary salt systems

The article looks into the influence of energy and optical factors on the quality of laser cutting of thick sheet metal. The authors describe the advantages of using laser cutting in production and determine further directions in the development of laser technology. The work presents an analysis of Russian and foreign scientific research and highlights the indicators that affect the quality of manufacturing parts by laser cutting. The authors present the results of an experimental study of the influence of energy and optical factors and finding dependencies in order to determine the optimal technological modes for obtaining a high quality cut. The studies and experiments carried out made it possible to determine the optimal ratio between the focal spot diameter and the waist length when using lenses with focal lengths of 200, 250, and 300 mm. Based on the data obtained, the authors also formulated technical requirements for the development of a model of a laser optical head.

Keywords: laser cutting, radiation power, optical factor, parameters, laser head, experimental study

The article presents the results of a study of the mechanism of occurrence of cracks in the material of heated cylindrical porous powder blanks being deposited. The type of cracks is classified and the role of the boundaries between the "particles" of powder on the surface of a porous workpiece as stress concentrators contributing to the formation of cracks during its deformation is noted.

Keywords: dynamic hot pressing, heating temperature, powder billet, pore, crack, sintering temperature, plasticity

The article analyzes the influence of the roughness and thermal conductivity of the processed steel on the choice of gas laser cutting parameters. The authors describe the possibilities and advantages of using gas laser cutting in production. The article presents the results of an experimental study of samples made of St3 steel of various thicknesses. An analysis of the data obtained showed that with an increase in the gas laser cutting speed, the roughness parameter increases, and the laser power has practically no effect on the roughness value. The authors also attempt to take into account the influence of the thermal conductivity of the processed material on the choice of laser cutting characteristics. It was found that in order to ensure a minimum roughness for steels with higher thermal conductivity, increased power and cutting speed should be used.

Keywords: gas laser cutting, roughness, thermal conductivity, parameters, mathematical models, experimental study

The operating conditions of polycrystalline dielectrics in external mechanical and electric fields make it relevant to study the properties of such materials and their resistance to extreme loads, which depends on the processes of polarization reversal and the dynamics of the domain structure. Based on the model of motion of domain walls and the rheological model, equations are obtained for the dependence of polarization on the applied mechanical, electrical, or simultaneous electromechanical load. It is shown that the nonlinearity of the current in the ferroelectric ceramic is due to the dependence of the coefficients of the model on the through conduction current and the current associated with the emission of charges from traps. The physical meaning of the coefficients makes it possible to use their well-known dependences on the electric field and external mechanical stresses both in the range of the linear piezoelectric effect and in the region of external loads, when linearity ceases to exist. The obtained coefficients make it possible to pass from polarization (macroscopic parameter) to domain walls (mesoscopic scale). The parameters of the model depend on the change in the domain structure and its interaction with defects; therefore, the current relaxation time in the ferroceramic is described by changing the corresponding times for 180°-domains and non-180°-domains. The model considers two polarization components: elastic and irreversible. Changes in polarization after the external action of the electric field can be explained by the movement of domain and interphase boundaries. When a critical mechanical load is applied, the domain boundaries are detached from the defects and the crack grows abruptly, and as a result, destruction occurs. The relaxation motion of domain walls with constant friction leads to the growth of cracks due to the creation of mechanical stresses. The chosen rheological model and approach, taking into account the mechanisms of motion of domain walls, will make it possible to describe the rate of polarization change using the behavior of defects (dislocations, domain walls). The model will allow from a unified point of view to describe the experimental patterns of the behavior of currents under electromechanical action.

Keywords: ferroelectric ceramics, computer simulation, rheological model, polarization current, polarization current density, domain wall, 1800-domains, not 1800-domains, mechanical load, electrical load, relaxation time

The article presents the results of studies on the influence of sintering modes on the distribution of carbon in the material of a porous powder billet used for the manufacture of a differential satellite by dynamic hot pressing. The distribution of carbon and density in the satellite material is established, recommendations for its chemical and thermal treatment are given.

Keywords: dynamic hot pressing, heating temperature, powder billet, density, satellite, sintering temperature, cementation, quenching, material property

A periodic semiconductor structure is considered, consisting of tunnel-uncoupled quantum wires (QW) based on InSb containing impurity centers. The uniform magnetic field is directed along the QW axis. For the case of light polarization transverse with respect to the QW axis in the framework of the dipole approximation, in the effective mass approximation, an analytical expression for the impurity absorption coefficient of light is obtained taking into account the dispersion of the QW radius described by the Gauss function. It is shown that on the spectral curve constructed in the Maple program, for given parameters of the QW and the semiconductor structure, there is a sequence of resonant maxima with a doublet structure. The cyclotron frequency determines the distance between the maxima in the doublet, and the frequency of the doublets on the spectral curve is determined by the hybrid frequency. With an increase in the magnetic field, the dynamics of the edge of the impurity absorption band is observed, which can be used to create detectors of optical radiation in a wide range of wavelengths and will make it possible to identify such semiconductor structures. It is also possible to obtain valuable information about the parameters of the QW and the band structure of the semiconductor from the spectral curve

Keywords: impurity absorption coefficient, quantum wire, low-dimensional semiconductor structures, impurity center

This publication is devoted to the method of applying coatings from various materials to carbide cutting tools by the method of electrospark alloying, as well as the experience of using this method in practice. The formation of the surface layer, its structure were studied, and cutting tests were carried out. It has been found that nickel and aluminum coatings are more resistant than copper and zinc coatings.

Keywords: coating, carbide, cutting tool, wear, electrospark alloying, roughness, hardness

The effect of a zeolite support on the physicochemical properties of cobalt catalysts prepared by the precipitation method and calcined at 400°C was studied. The values of the specific surface of the catalysts, the degree of cobalt reduction, and the dispersion of the metal were determined, and the presence of functional groups on the surface of the catalysts was determined by BET, TPV, TPD-H2, and IR spectroscopy.

Keywords: catalyst, cobalt oxide, hydrocarbons, dispersion, active surface

A semiconductor quantum wire (QW) containing an impurity center described in the framework of a hydrogen-like model is considered. The possibility of using InSb QW in photodetectors of infrared optical radiation is discussed. The QW is modeled as a geometrically symmetric cylinder, on the axis of which an impurity center is located at an arbitrary point, with which the origin of the cylindrical coordinate system is associated, in which calculations are performed. It is assumed that the magnetic length is much smaller than the effective Bohr radius - the case of a strong magnetic field. This approximation made it possible to make the impurity potential effectively one-dimensional and obtain analytically accurate calculation results. In the effective mass approximation, in the dipole approximation, an expression is obtained for the matrix elements of the optical transitions of an electron from the impurity ground state to the size-quantized QW states for the case of transverse light polarization and the Kane dispersion law of charge carriers.

Keywords: matrix elements of optical transitions, effective mass method, quantum wire, dipole approximation, size-quantized states

The effect of a zeolite support on the physicochemical properties of cobalt catalysts was studied on a series of samples with zeolites ZSM-5, HY, and NaX. The catalysts were obtained by precipitation followed by mixing the precipitate with a zeolite support. Their properties were characterized by BET, TPR, TPD-H2, IR spectroscopy. The results of the analysis show that the type of zeolite support affects the specific surface area, reduction of deposited cobalt, and the structural properties of the active component of catalytic systems.

Keywords: precipitated catalyst, cobalt, zeolite, dispersion, specific surface area, active component, synthetic fuel, degree of reduction

The article describes the design of an experimental equipment (sample) for determining the cohesive strength of powder coatings in inactive and aggressive environments. A method for determining the mechanical characteristics of samples with coatings is presented, as well as data from the results of testing the cohesive strength of coatings based on nickel, PN60Y40, PN40Y60, iron-aluminum, coatings of self-fluxing alloys based on nickel PGSR-2, PGSR-3, PGSR-4.

Keywords: experimental equipment, cohesive strength, gas-thermal powder coatings, physical and mechanical properties, plasma spraying

The results of the development of asymptotic expressions for the calculation of the background of internal friction at the boundaries of the General type for the limiting cases of frequency dependence are presented. Mathematical expressions are obtained on the basis of consideration of models of the border containing periodically located steps of alternating signs and the intercrystalline border of the general type consisting of parallel plane segments of the set width separated by alternating steps of identical height and cylindrical pores.

Keywords: model, boundary, internal friction background, relaxation, temperature-frequency dependence, slip rate

The results of the analysis of various models of structural defects formed at grain boundaries in metals are presented. It is shown that the resulting boundary defects should be taken into account when determining the tensile stresses on the lines of their junction. The development of ideas about the structure of defects contributes to a better understanding of the mechanism of their occurrence in crystals and a better definition of changing chemical and physical properties at the atomic level.

Keywords: defects, grain boundary dislocations, facets, microplasticity, plastic deformation, boundary geometry

The results of a theoretical and experimental study of the synthesis of GaInAsBi thin-film structures formed on InAs substrates in the field of a temperature gradient are discussed. The features of interfacial interaction in the In-As-Sb system in the presence of isovalent solvents (In, Bi) have been studied. The values ​​of the interaction parameters and the distribution coefficients of the system components are determined. Optimal technological modes for obtaining InAs-based heterostructures are presented. The properties of the surface of epitaxial layers are studied experimentally. It was found that the main control parameters are the temperature of thermomigration and its gradient. It is shown that the synthesized semiconductor materials can be effectively used in electronic devices of a new generation - electro-optical modulators and supersensitive sensor elements.

Keywords: epitaxial structure, crystallization, recrystallization, melt, segregation coefficient, organometallic compound, voltage sensitivity, near infrared range, solid solution, optical characteristic

The physicochemical properties of cobalt catalysts on a NaX zeolite support have been studied. The parameters of the specific surface area, reduction of deposited cobalt, and structural properties of the active component of catalytic systems have been determined. To establish these properties, the methods of BET, TPR, TPD-H2, IR spectroscopy were used. It is shown that the preparation procedure has a significant effect on the physicochemical characteristics of the samples.

Keywords: catalysts, cobalt, zeolite, dispersion, specific surface area of the active component

Methods of mathematical modeling of complex systems are considered. To construct mathematical models of changes in the electrical capacity of microlayers of magnetic nanofluids, the universal statistical package IBM SPSS Statistics was reasonably adopted. To optimize the construction of models, a database of the electric capacity of a cell with a microlayer of magnetic nanofluid and a program for generating a calculated model of the electric capacity of a capacitor with a magnetic nanofluid for IBM SPSS Statistics and Microsoft Excel were developed.

Keywords: magnetic nanofluid, concentration, microlayer, polarization, electric field, mathematical model, regression model

The article investigates the role of the preparation method and heat treatment in the formation of the physicochemical properties of cobalt catalysts on ZSM-5 support. Determination of the main characteristics of the samples showed that the Co/ZSM-5 I catalyst obtained by the impregnation method has the optimal cobalt dispersion and crystallite size.

Keywords: synthesis of hydrocarbons, cobalt, zeolite, preparation of catalysts, heat treatment

The results of studies of the structural and chemical properties of cobalt catalysts on zeolite HY support are presented. The samples were characterized by BET, TPR, TPD-H2, and IR-spectroscopy. It was found that these properties largely depend on the preparation method.

Keywords: Fischer-Tropsch synthesis, active surface, cobalt, zeolite, preparation method

This article presents and investigation the diffused reflection spectra of light from designed green pigments based on chromium(III) oxide, obtained by pyrochemical method by thermal decomposition of ammonium dichromate powder and hydrolytic method from chromium(III) sulfate in water-ammonia solution, as well as zinc oxide doped with cobalt, which are obtained by pyrochemical Sol-gel citrate method, with different levels of cobalt doping, obtained on the basis of silicone with the addition of obtained green pigments based on chromium(III) oxide), some commercial samples of PLA plastics are green in color and from naturally aging green leaves of grasses, trees and shrubs typical of areas with a transitional climate from mild continental to subtropical according to the Köppen classification. A comparative analysis of their diffuse light reflection spectra was performed to determine whether it is possible to partially simulate the diffused light reflection spectra from naturally aging green tree leaves with non-organic pigments or functional materials. Based on the analysis conducted, it is concluded that the studied commercial samples of green PLA plastics are categorically not suitable for simulating the spectra of diffused light reflection from green leaves. However, it is possible to create functional composite materials that can approximately imitate the spectra of diffused light reflection from green leaves of grasses, trees and bushes.

Keywords: spectroscopy, diffuse reflection, functional materials, pyrochemical sol-gel citrate method, hydrolytic methods, chromium (III) oxides, inorganic pigments