The purpose. Optimization of the sintering process of the electroerosion charge obtained by the method of dispersing waste of a tungsten-free hard alloy of the KNT16 brand, as well as the study of the composition, structure and properties of the new alloy obtained under optimal sintering conditions.

Methods. To obtain a new experimental tungsten-free hard alloy, an electroerosive charge was used, obtained by dispersing the waste of the alloy of the KNT16 brand. The consolidation of electroerosive particles was carried out using the Thermal Technology Spark Plasma Sintering system Model 25-10 (SPS 25-10). Determination of optimal parameters (optimization) of the consolidation process of the new alloy by the microhardness of sintered samples was carried out by setting up a complete factor experiment (PFE) type 23. As factors influencing the sintering process, such parameters of the SPS 25-10 installation as temperature, pressure and holding time were chosen.

Results.. In the course of the study it was found that: limit value of the optimization parameter Y (microhardness) were: 1415 HV at T = 1200°C, P = 40 MPa and t = 5 min; the new structure of the solid alloy is uniform throughout the volume, from the analysis of the microstructure shows the absence of defects such as cracks and pores chain; BVTS made on the basis of electroerosion dispersed particles of the KNT16 alloy in an oxygen-containing liquid (distilled water) contain part of oxygen. It is also established that the main elements in these new alloys are Ti, Ni and Mo; the process of EED 

of the KNT16 alloy in distilled water leads to the formation of such phases as TiC, MoNi₃, Ni₂O₃, Ni and Mo in the new experimental BVTS; the microhardness index of sintered samples by the method of SPS synthesis of electroerosion dispersed particles of BVTS brand KNT16 obtained in distilled water is 1415 HV, which corresponds to the calculated data of the optimization process.

Conclusion. The results obtained allow us to conclude that the consolidation of the electroerosion charge obtained by dispersing the waste of a tungsten-free hard alloy into a new alloy is most optimally carried out at the following parameters of the SPS synthesis system 25-10: T = 1200 ° C, P = 40 MPa and t = 5 min, which is confirmed by the results of optimization and research of the composition, structure and properties of a new experimental tungsten-free hard alloy.

The purpose of this study was to investigate the possibility of using molds reinforced with wear-resistant protective coatings applied by gas-thermal spraying methods under the influence of significant thermomechanical loads during injection molding of non-ferrous and ferrous metals.

Methods. As a base material for spraying protective wear-resistant coatings, 3X2V8F tool die steel was used, from which samples with dimensions of Ø50×10 mm were cut out. The following powder materials were used as sprayed materials: PHM, ferrochrome, PH18N9T, PH23N28M3D3T. During diffusion metallization, coatings with the above powders were applied to the surface of the samples with a plasma torch using the following technology: degreasing the surface with uyat spirit; shot blasting of the surface (to improve the quality of adhesion of the coating to the substrate); plasma spraying of the coating. The study of microhardness was carried out using a PMT-3 microhardness meter, with a load on the indenter of 50 g. Metallographic studies were carried out on a metallographic microscope MIM-8. The microstructure was detected in an etcher of the following composition: 20 ml H₂O, 20 ml HCl, 4 g Cu₂SO₄.

Results. It is shown that in the structure of the steel matrix of samples annealed in hydrogen, large martensitic needles are visible at the surface opposite to the sprayed one. As a result of the conducted studies, it was found that during the diffusion metallization of samples with plasma-dusted coatings of PC23N28M3D3T and PC18N9T powders and subsequent annealing in a protective hydrogen atmosphere, a diffusion layer is practically not formed.

Conclusion. The method of diffusion chrome plating, associated with the formation of plasma-dusted coatings, involves applying a layer of metal coating containing chromium to a steel surface by the plasma method and subsequent diffusion annealing. It is established that the saturation method has a significant effect on the initial conditions preceding the diffusion process. Therefore, the quality of coatings applied by plasma spraying has a great influence on the kinetics of the diffusion layer formation process, its structure and properties characteristics after subsequent annealing.

Purpose of research to study the effect of nitrocementation of chromium-molybdenum-vanadium steel 30X3MF in a highly active paste-like nitrogen-carbon medium on the structure, hardness and wear resistance of surface diffusion layers.

Methods. The study of nitrocementation was carried out on samples of improved chromium-molybdenum-vanadium steel 30X3MF (0.38% C; 2.7% Cr; 0.47% Mn; 0.27% Mo; 0.14% V). Nitrocementation was carried out in a paste-like medium consisting of amorphous carbon (carbon black DG 100) - 80% and potassium ferrogenide KuFe(CN)6 – 20%. Nitrocementation was carried out in a shaft laboratory furnace SSHOL-10/11 with automatic temperature control. The hardness of the samples was measured on a TP-2 (Rockwell) hardness tester, microhardness was measured on a PMT-3 microhardness meter. A metallographic optical microscope POLYLAB ML-02 and an electronic scanning microscope QUANTA 3D 200i were used for the analysis. Wear resistance tests of 30X3MF nitrocemented steel samples were carried out on a standard SMC-2 friction machine.

Results. The results of an experimental study of the nitrocementation of 30X3MF steel in a highly active paste-like medium based on potassium ferrocyanide and amorphous soot on its structure and properties are presented. It is shown that nitrocementation promotes the formation of a large number of high-hard carbonitrides in the diffusion layers, which cause a significant (several times) increase in the wear resistance of steel.

Conclusion. The proposed method of nitrocementation, in our opinion, will be very effective for increasing the durability of parts made of improved 30X3MF steel and the like, working at increased power loads in combination with abrasive wear.

The purpose. Optimization of technological parameters of the manufacturing process of antifriction alloys based on EDM lead bronze charge.

Methods. To obtain an experimental charge, an installation for grinding metal waste into metal particles suitable for industrial use was used, lead bronze grade BrS30 in the form of shavings (GOST 493-79) was used as the metal waste, distilled water was the working medium for dispersion. 6709-72 (oxygen-containing) and lighting kerosene GOST 11128-65 (carbon-containing)

The study of microhardness of workpieces of antifriction alloys was carried out on a digital microhardness tester  DM-8.

Optimization of the technological parameters of the process of manufacturing antifriction alloys was carried out according to the average microhardness of the obtained samples by setting up a complete factorial experiment of type 2³.

Results. In the course of the calculations, the optima (maximum values of the output parameter y ̂) were calculated, amounting to: for workpieces from a charge obtained in water 67.7 HV at a pressing pressure of 1500 MPa, a sintering temperature of 830°C, and a holding time of 2 h; for workpieces from a charge obtained in kerosene 52.8 HV at a pressing pressure of 1600 MPa, a sintering temperature of 850°C and a holding time of 2 hours.

Conclusion. Based on the presented results of research and calculations, it can be concluded that the microhardness of antifriction alloy blanks based on charge obtained in water exceeds by 15% the microhardness of antifriction alloy blanks based on charge obtained in kerosene. The presence of free carbon in the composition of the charge obtained in kerosene prevents the production of dense compacts and, as a result, leads to an increase in the final porosity of the workpiece and a decrease in its hardness.

The purpose. To study the process of formation of sparingly soluble hydroxides and basic salts in the cathode layer during the restoration of machine parts by electrodeposited iron coatings.

Methods. To determine the pH of the hydrate formation of ferrous electrolytes, the method of potentiometric titration with a glass electrode was adopted. The change in the course of the titration curves was recorded using an automatic high-precision potentiometric titrator ATP-02 by direct reading of pH values with an accuracy of ±0.05 units.

The pH of the cathode layer was studied using a microglass electrode. For research, an electrolyte containing 200 kg/m³ of ferrous sulfate and 150–200 kg/m³ of ferric chloride was adopted.

Results. Studies have shown that when using current densities above 30 A/dm², a decrease in the quality of coatings was noted (the appearance of a large number of cracks, local flaking upon impact). To obtain precipitation with satisfactory qualities, it is necessary to apply current densities up to 30 A/dm². An increase in the electrolyte temperature from 293 to 333 K leads to a drop in the pH of the near-cathode layer from 5.9 to 5.2 units. A change in pH in the volume of the solution from 0.3 to 1.8 units leads to an increase in pH in the cathode layer.

Also noteworthy is the rather low quality of the coatings (peeling on bending) obtained at an electrolyte pH above 1.4 units. Therefore, the best condition for electrolysis is the use of an electrolyte acidity of up to 1.4 units.

Conclusion. The study of the pH of the cathode layer of the sulfate-chloride electrolyte depending on the various additions of iron chloride and the effect of electrolysis conditions (current density, temperature and pH of the electrolyte) on the pH shift of the cathode layer showed that an increase in the concentration of iron chloride in a solution of 200 kg/m3 of sulfate reduces the pH of the cathode layer, an increase in temperature also reduces the pH of the catholyte of the sulfate-chloride solution, and an increase in the current density and pH in the volume of the solution increase the pH of the cathode layer.

Purpose of research. Expansion of technological possibilities of using the method of electrospark alloying due to the systematization and optimization of changes in the controlled electrical parameters of the process current.

Methods. To expand the technological capabilities in the formation of the executive surfaces of machine parts, a method for stabilizing the work of the electrode-tool during their electric spark alloying is proposed. The stability of the vibrating electrode-tool in the process of electric spark alloying is carried out by automatically monitoring the interelectrode gap by changing the frequency of the process current pulses. Process current impulses are formed as a result of the integrated action of two components. The first one is set directly due to mechanical vibrations of the electromagnetic vibrating electrode-tool and synchronizes the operation of the installation as a whole. The second one is formed due to the spacing in time of the synchronized control signals of the sequential discharge of all charged capacitive storages according to the algorithm - the discharge of the next one after the discharge of the previous one.

Results. It has been experimentally established that when using this method, it becomes possible to improve the quality of deposition of functional coatings by systematizing the choice of technological parameters of the process control. To implement the method, it is proposed to develop an original scheme and layout of the installation, which ensures the establishment of the influence of the operation of the components of its nodes (technological current) on the composition, structure, properties of the applied coatings.

Conclusion. Based on the experimental studies carried out, one of the ways to improve the functional properties of the executive surfaces of machine parts and mechanisms by changing the technology of using the electric spark doping method by improving the process equipment, namely, the electrical parameters of the process current pulse generator, is proposed.

Purpose. Investigation of the photoluminescence spectra of ZnS_xSe_1-x and ZnS_xSe_1-x:Mn nanocrystals and determination of the parameters of individual emission bands of ZnS_xSe_1-x:Mn nanocrystals obtained by combustion synthesis.

Methods. Characterization of ZnS_xSe_1-x and ZnS_xSe_1-x:Mn nanocrystals using photoluminescence spectroscopy.  Extraction of the parameters of individual bands due to a method based on the Tikhonov method and the derivative spectroscopy method.

Results. here is an abrupt change in the half-width of the integral photoluminescence spectrum in ZnS_xSe_1-x and ZnS_xSe_1-x: Mn nanocrystals and the signal intensity; this may be due to the crystal lattice transformation. We determined the parameters of individual photoluminescence spectra ZnS_xSe_1-x:Mn nanocrystals according to a single experimental measurement. The nature of the individual photoluminescence bands is discussed.

Conclusion. The obtained results of the dependencies can be explained by the change in the band gap of the ZnS_xSe_1-x and ZnS_xSe_1-x:Mn nanocrystals, as well as by the redistribution of the intensities of the individual bands. The difference between the integral (sum of individual bands) and experimental spectrum arises from the presence of an additional individual band of low intensity in the experimental spectrum. This individual band is located in the region of  E = 2.48 eV and is associated with the electronic transitions in Mn²⁺ ions in the ZnS lattice.

The purpose of the work: To develop an effective technology for creating microfluidic chips for studying the dynamics of magnetic fluid media with non-magnetic inclusions using controlled exposure to magnetic field sources based on permanent magnets, electromagnets, and their combinations.

Metods. To consider several methods of manufacturing microfluidic chips based on a sandwich structure using Parafilm ® film, as well as PDMS microfluidics using a standard 3D printer, ABS plastic and acetone  The experiments were carried out on installations developed on the basis of known methods and equipment for magnetic measurements and manufactured independently. Various combinations of electric coils and permanent magnets are used as sources of an inhomogeneous magnetic field.

Results. An analytical review of known methods for the production of microfluidic chips was carried out. Most of them require expensive equipment and clean rooms, but a number of them are based on the use of available consumables and do not require specific conditions. These include technologies based on Parafilm® film, as well as PDMS chips with a removable ABS frame. For each of the technologies, a series of microfluidic chips was manufactured, during the production of which technological parameters changed: temperature, pressure and sintering time, the composition of the polymer matrix and the washing technology. The optimal production technology was determined on the basis of microscopic analysis and technological tests.

Conclusion. The paper considers several technologies for the production of microfluidic devices. Optimal parameters for manufacturing chips based on Plexiglass - Parafilm ® – Plexiglass sandwich structures have been determined. An original variant of manufacturing a microfluidic device with an integrated miniature magnetic field source based on ESCARGOT technology is proposed. The results obtained can be useful for the development of devices for controlled exposure to smart materials in microfluidic chips.

Purpose. Synthesis micro- and nanometer-thick aluminosilicate films by electrochemical methods and systematically study the influence of their structural and geometrical characteristics on the band structure and photocatalytic properties. 

Methods. Thin-film coatings of aluminosilicates were obtained on an aluminum substrate by electrolysis of Na₂SiO₃ and NaOH solutions of different concentrations at constant voltage in the range from 8 V to 30 V. The surface was studied by atomic force microscopy, the specific surface area was determined by methylene blue adsorption. The width of the forbidden zone has been established by diffuse reflectance spectra.

Results. The film coatings based on high silica aluminosilicates close to the structure of MFI and FAU were obtained. It was found that the surface of the samples at 8 V voltage - globular with a diameter of globules from 500 nm to 2.5 microns, with increasing voltage - the formation of a crystal structure whose elements are parallelepipeds with the length of the edges not exceeding 250 nm. The thickness of the films varies in the range from ~1.0 µm to ~18.5 µm, and the specific surface area from ~250 m²/g to ~650 m²/g depending on the synthesis conditions. The mechanism of aluminosilicate coating formation was proposed. The narrowing of the band gap width of the aluminosilicates up to 3.10-3.32 eV has been detected.  The increase in the catalytic activity of the structures occurs with an increase in the voltage at which they were obtained, which can be explained by an increase in the specific surface area of the material and, consequently, by an increase in the concentration of active centers and the contact area with the dye molecules.  

Conclusion. The results presented in this work are of interest in studying the properties of two-dimensional objects, as well as in obtaining new functional materials based on aluminosilicates with high catalytic activity.

The purpose of the study is to analyse the mechanisms of generation of elastic waves in magnetic fluids in a constant magnetic field by applying an alternating magnetic field.  

Metods. The theoretical calculation of the dependence of the relative amplitude of the excited oscillations on the strength of the magnetizing field (constant component) is carried out under the assumption of a rigid connection between a magnetic nanoparticle and its magnetic moment (Brownian mechanism of magnetization) and the possibility of the magnetic moment to rotate independently of the particle itself (Néel mechanism of magnetization). The work provides a comparison of theoretical conclusions with previously published experimental data.

Results. In the case when the constant and alternating magnetic fields are perpendicular to each other, the function of the amplitude of the magnetoacoustic effect on the magnitude of the constant magnetic field has a linearly increasing character at first, then turns into saturation. The frequency dependence of the magnitude of the magnetoacoustic effect can exhibit several maxima. Theoretical analysis shows that the number of maxima is four (three were found experimentally). At a fixed magnetic field, the maximum value of the elastic vibrations generated in the magnetic fluid increases in proportion to the square of the frequency. In the case of parallelism of alternating and constant magnetic fields, the dominant mechanism for the generation of elastic waves is the ponderomotive mechanism. The dependence of the magnetoacoustic effect on a constant magnetic field has the form of the Langevin function.

Conclusion. The paper proposes mechanisms for the generation of elastic waves in a magnetic fluid in a constant magnetic field by applying an alternating magnetic field, which in one case is perpendicular to the alternating field, and in the other parallel to it. 

Purpose – is devoted to the study of the possibility of controlling various effects, including metallization, of carbon nanotubes using impurity boron atoms. The existing methods of carrying out substitution reactions in nanotubes of a part of carbon atoms for boron are considered. 

Methods. To analyze the current state of research on the subject, international and domestic studies in the field of modification and metallization of carbon nanotubes were compared. In order to clarify the mechanisms of metallization and determine the dependence of this process on the concentration of impurity boron atoms, the results of model experiments conducted using the density functional theory (DFT) were used. 

Results. As a result of the conducted research, it was found that the modification of carbon nanotubes with atomic boron is one of the most effective ways to control the physico-chemical properties of the studied nanoobjects. It was also found that the introduction of impurity boron atoms leads to the localization of adsorption centers near them. During the model experiment, it was also found that the electron density is redistributed in the system from metal atoms to the surface of the nanotube.

Conclusion. The totality of the described phenomena allows us to conclude that with the help of impurity boron atoms, it is possible not only to control the metallization process of carbon nanotubes, but also those electronic properties that will be important for their further use as nodes of nanoelectronic devices.

Purpose of research. Form a film structure from the BaTiO₃ colloidal system by the Langmuir-Blodgett method and characterize its polarization properties using modern nanoinstrumental methods.

Methods. Determination of the chemical structure by Raman light scattering; study of film polarization on a scanning probe microscope in the Kelvin probe microscopy mode.

Results. From a colloidal system of stabilized barium titanate nanoparticles, Langmuir–Blodgett multilayer film structures were obtained. Their chemical structure was confirmed by the method of Raman (Raman) light scattering: lines corresponding to both the tetragonal and cubic structures of barium titanate were observed, and lines caused by transverse and longitudinal optical vibrations were also found. The values of the coercive fields (624 and 1056 kV/cm) and the displacement field (216.5 kV/cm) were determined from the dielectric hysteresis. The polarization of a barium titanate nanofilm on a glass substrate with a platinum sublayer was studied by the contrast of shades in images obtained by Kelvin probe microscopy. It has been shown that platinum is the most preferable substrate material that enhances polarization. Sequential recording of areas in the form of squares (information pits) was performed at a positive and then at a negative voltage, from which the functional dependence of the residual polarization on voltage was established.

Conclusion. The Langmuir-Blodgett method makes it possible to form film structures from barium titanate nanoparticles and study their polarization properties. Using the Kelvin probe microscopy, it was possible to polarize the films with voltages of different signs and to analyze the profiles of the obtained contrast images with different polarizations on an atomic force microscope: 50:1 and 600:1 for light and dark areas, respectively.

Purpose. Determination of the dimensional characteristics, phase and chemical composition of ZnS_xSe_1-x nanocrystals with a parameter step x = 0.2, obtained by the combustion synthesis.

Methods. Characterization of ZnS_xSe_1-x nanocrystals using scanning microscopy, X-ray diffraction analysis and EPR spectroscopy obtained by the combustion synthesis.

Results. We determined the crystal lattice parameters of the synthesized ZnS_xSe_1-x:Mn nanocrystals, which were ranged from a = 5.386 Å (для х = 1) to a = 5.633 Å (для х = 0). We determined the sizes of the synthesized ZnS_xSe_1-x:Mn nanocrystals, which were ranged ranged from 50±5 nm to 80±5 nm. The dependences of the loaded charge before synthesis and the powder obtained after synthesis, microstresses and sizes of nanocrystals depending on the parameter x, fractions of cubic and hexagonal phases depending on the parameter of composition x, half-widths of narrow and wide lines of the EPR spectrum on parameter x, the resonant value of the magnetic field of the broad absorption line due to Mn²⁺ ions and the constant A of the hyperfine structure of the EPR spectra of Mn²⁺ ions on the parameter x are plotted.

Conclusion. The obtained nanocrystals are characterized by a high perfection of the crystal structure. The change in the studied dependences for ZnS_0.4Se_0.6:Mn nanocrystals and upon transition from ZnS_0.2Se_0.4:Mn nanocrystals to ZnS_0.4Se_0.6:Mn nanocrystals can be explained by the smallest size of ZnS_0.4Se_0.6:Mn nanocrystals, the simultaneous presence of almost the same amount of S and Se in the solid solution, and an increase in the role of surface phenomena at the nanocrystal boundary.

Purpose of research. We consider a problem of setting up and solution the inverse scattering problem for systems of Schrödinger equations. We consider a connected problem (in Gelfand–Levitanand- Marchenko approaches) of solution of systems of Fredholm integral equations of the second kind.

Methods. Based on the performed an analysis the setting up of the scattering theory inverse problem for radial Schrödinger equations is presented in Marchenko approach for case of a number of coupled channels with different thresholds (by the example of two channels with obvious generalization). 

Results. Specific properties of the corresponding scattering S-matrix and asymptotics of possible bound states are obtained necessary and sufficient for explicit solution of the considered inverse scattering problem and its physical adequacy. A quasirational approximation of the S-matrix elements (Pade type approximant) for the scattering theory inverse problem for system of Schrödinger type equations is presented. The obtained approximation has explicitly all the necessary and sufficient properties for solution of the considered problem. The presented approximation allows to solve the considered inverse problem (system of coupled Marchenko equations – Fredholm integral equations of the second kind analytically, in principle.  

Conclusion. Possible areas of application of the presented algorithm and developed method of numerical solution of the inverse problem of equations (systems of equations) of Schrödinger type and other similar problems. Analytical solution of the scattering theory inverse problem for the system of Schrödinger type equations with different thresholds and for case of specific kind S-matrix. Designed specific kind of S-matrix allows to approximate (interpolate) any physically adequate S-matrices. 

Purpose of research The aim of the work was to study the features of instrumental methods of qualitative and quantitative determination of ascorbic acid in a medicinal product.

Methods. For research, the drug "Asvitol" with a content of 200 mg of the main component in the form of ascorbic acid was selected as an object.

The main and auxiliary solutions were used in the work, in which distilled water obtained using an electric DEM 10 distiller acted as a medium, the pH of the solutions was determined on the pH meter of IPL-311. The process temperature was maintained using the UT-4300E ultrathermostat.

The ascorbic acid content was determined by the spectrophotometric method on the SHIMADZU VV-1800 spectrophotometer and by the method of high-performance liquid chromatography on the Agilent 1260 Infinity chromatograph. Results. The known methods of determination of ascorbic acid by the spectrophotometric method and by the method of highly effective liquid chromatography have been refined. The influence of the pH of the medium on the quantitative determination of ascorbic acid has been studied. The equation of the calibration dependence is obtained. The suitability of the Agilent 1260 Infinity chromatographic system for the analysis of the content of ascorbic acid in the preparation "Asvitol" was tested.

Conclusion. The conducted studies have shown the possibility of using both the spectrophotometric method and the method of high-performance liquid chromatography with a certain accuracy to determine the content of ascorbic acid in the drug "Asvitol".