The purpose of this work was to study the wear resistance of samples obtained by selective fusion of electroerosive Iron-Chromium-Nickel powders produced by processing metal waste.

Methods. During the research, the following equipment was used: a plant for producing electroerosion Iron-Chromium– Nickel powders – original patented; raw materials for producing Iron–Chromium–Nickel powders alloy grade 20X25H20X2; working fluid isopropyl alcohol; a plant for selective alloying original patented; equipment for studying the wear resistance parameters of an additive sample – automated friction machine Tribometer, CSM Instruments. The material of the counterbody is Stainless Steel AISI 420.

Results. As part of the task aimed at studying the wear resistance of samples obtained by selective fusion of electroerosive Chromium-Nickel iron powders produced by processing metal waste, the following has been established: the coefficient of friction of the surface of the sample under study ranges from 0.256 to 0.634; the amount of volumetric wear is 1.116 x10-5 mm3. A jump in the coefficient of friction has been experimentally established at the initial moment of tribological testing of the sample, which is associated with relatively high roughness and wear characterized by smoothing of the solid protrusions of the sample surface. It has been experimentally established that in a contacting pair, an Iron–Chromium-Nickel sample and a counterbody, both contacting surfaces wear out almost uniformly. At the same time, the width of the wear track of the test sample was about 270 microns. The relatively high wear resistance of the studied sample, obtained by selective fusion of electroerosive Iron-Chromium-Nickel powders, was facilitated by a porous defect-free structure and a relatively small grain size.

Conclusion. The data obtained will allow us to select the most rational area of practical application of the new additive material.

The purpose of this work is focused on establishing regular relationships between the electrical and operating characteristics of the experimental installation of electroerosion dispersion and the intensity of the process of forming the powder charge of steel P6M5K5 during the processing of metal waste from high-speed tools. The main attention is paid to the analysis of the influence of key parameters of electrical action on the efficiency of converting solid metal raw materials into a dispersed powder state.

Methods. Experimental studies were carried out using the author's laboratory installation of electroerosion dispersion. The production of a high–speed steel powder charge was carried out under conditions of controlled changes in the electrical parameters of the process: voltage in the range of 100-200 V, discharge capacitance in the range of 25.5-65.5 UF and pulse discharge frequency of 25-75 Hz. The geometric and temporal parameters of the process remained constant: the interelectrode distance was 120 mm, and the dispersion duration was 600 minutes. Metal waste from high-speed cutting tools, previously prepared for processing, was used as the starting material.

Results. It is established that an increase in the values of the electrical parameters of the installation is accompanied by an increase in the productivity of the process of forming a high-speed steel powder charge. A stable direct dependence of the mass of the obtained powder material on the influence of the electric capacity of discharge energy storage devices has been experimentally revealed. It has been established that the total mass of the starting materials involved in the zone of electroerosion dispersion quantitatively corresponds to the mass of the formed products of the process, regardless of the specifics of the ongoing physico-chemical, phase and structural transformations. It has been experimentally confirmed that the losses of the substance during the research do not exceed 2% of the total amount of processed material.

Conclusion. The results obtained confirm the technological feasibility of using electroerosion dispersion for the industrial production of high-speed steel powders. They can be used in the development of optimal operating modes of plants, as well as in improving the compositions and structures of powder materials in the tasks of powder metallurgy and resource-saving technologies.

Purpose. Development, preparation and research of a charge for the production of hard alloys of the W-Co system using powders obtained by electroerosion dispersion of secondary raw materials of tungsten and cobalt in a carboncontaining working medium.

Methods. The components of the electroerosion charge of a hard alloy were obtained by the method of electroerosion dispersion in a Carbon-containing medium of aviation kerosene TS-1.

The microstructure of the obtained powder particles was studied using scanning electron microscopy. The granulometric characteristics of the charge were determined using a particle size analyzer. The composition of the elements in the powder was analyzed by energy dispersive X-ray spectroscopy based on a scanning electron microscope, and the phase composition was determined using X-ray diffraction using a diffractometer.

Results. The results of the development, production and complex investigation of a powder charge for the production of hard alloys of the W-Co system intended for use in machine–building and tool manufacturing are presented. The results of studies of the morphology, granulometric composition, and phase state of powders are presented. It has been experimentally established that powder particles are spherical and elliptical. The particles of tungsten carbide powder W2C range in size from 2.26 microns to 90.72 microns with an average volume diameter of 20.2 microns and contain carbon on the surface, while the particle sizes of cobalt powder are distributed in the range from 0.9 to 63.77 microns, with an average volume diameter of 12.06 microns.

Conclusion. The experimental data obtained create a scientific and practical basis for the development of fundamentally new solid alloys, which include powdered tungsten carbide and cobalt obtained from metal waste by electroerosion dispersion. The developed charge is characterized by a high degree of uniformity and can be used for subsequent pressing and sintering of hard alloys for instrumental purposes. The presented results open up the prospect of further improvement of the composition and regulation of the structure of newly formed alloys.

Purpose. Computational and experimental substantiation of the effectiveness of electrodispersion technology for the production of Iron-Chromium-Nickel powders of regulated dispersion from metal waste of alloy H25H20 in alcohol.

Methods. To carry out the planned research, waste from the X25N20 alloy was selected in the form of 6 mm diameter and 15 mm long rod pieces. The implementation of the research objectives was based on the experimental study of the process of obtaining powder materials from X25N20 alloy waste by means of their electric dispersion in an organic liquid medium. Isopropyl alcohol (propanol-2, TU 6-09-402-87) was used as a dielectric medium. Next, the selection and justification of rational dispersion modes was carried out, followed by a study of the dispersed composition of particles formed under optimized technological parameters.

Results. As part of achieving the set research goal, the following results were obtained. The calculated value of the optimized parameter characterizing the dispersion of the powder material was determined to be 75.4 μm, with an average particle size of 75.4 μm. This value is achieved with a discharge capacitor capacity of 65.5 μF, a voltage applied to the electrodes of 200 V, and a pulse frequency of 200 Hz. Experimental verification was performed using the Analysette 22 MicroTec laser analyzer, which showed that the size range of the iron-chromium-nickel powder particles is between 0.1 and 100.0 microns, and the average volume diameter corresponds to the calculated value of 75.4 microns. It has been experimentally established that about 7% of the powder particles have a size of 0.1 μm to 1 μm. This fine-grained powder fraction is formed during the crystallization of the vapor phase of the metal ejected from the point of the pulse electric discharge. The remaining 83% of the powder particles have a size of 1 μm to 100 μm. This powder fraction is formed during the crystallization of the liquid phase of the metal waste.

Conclusion. Recycling of Iron-Chromium-Nickel alloy 20Х25Н20С2 will contribute to resource conservation, import substitution and ensuring the technological sovereignty of the Russian Federation.

The purpose ‒ to develop a model of a ferrofluid whose magnetic filler consists of nanoparticles of two shapes: spheres and prolate spheroids, which must be taken into account when describing magnetic and steric interactions; based on the proposed model, to investigate the magnetic properties of the ferrofluid.

Methods. The simulation is performed within the framework of the coarse-grained molecular dynamics approach. The ferrofluid is represented as a collection of particles of two shapes: 1) spherical, simulated using the Lennard-Jones potential, and 2) prolate ellipsoids of revolution, described by the anisotropic Gay-Berne potential. A mixed potential is introduced to model steric interactions between particles of different types. The magnetic state of an elongated particle is simulated by a chain of point dipoles oriented along the major axis of the spheroid. Thermal fluctuations in the ferrofluid are simulated by incorporating a Langevin thermostat into the system.

Results. A series of test calculations were performed on ferrofluid samples with different ratios of the two particle types but the same total volume concentration of the magnetic filler. Quasi-static magnetization curves were obtained for the samples, which showed, in particular, an increase in the magnetic susceptibility of the ferrofluid upon the inclusion of ellipsoidal particles.

Concluson. A model of a ferrofluid filled with spherical and prolate ellipsoidal particles has been proposed, with corresponding spatial potentials used to simulate their steric interactions. Test calculations on samples with different ratios of the two particle types demonstrated the functionality and physical adequacy of the developed model. The further development of the proposed approach is primarily associated with adding the capability to describe the polydispersity of anisotropic particles.

Purpose. To establish the relationship between the morphological parameters of Nickel nanofilms on GaAs substrates and their magnetic characteristics, and to determine the influence of the nanofilm growth mechanism on the formation of domain structures.

Methods. The Nickel nanofilms under study were synthesized by magnetron sputtering on GaAs substrates in an argon atmosphere. To study the evolution of the Ni nanofilm properties, a series of samples with thicknesses ranging from 5 nm to 100 nm were created. Surface morphology was studied using magnetic force microscopy in tapping mode. Based on the obtained three-dimensional images, a quantitative analysis was performed, including calculation of the arithmetic mean (Ra) and root-mean-square (Rq) roughness, statistical processing of structure size distributions, and determination of fractal dimensions. The crystalline structure of the films was studied using X-ray diffraction in BraggBrentano geometry. Analysis of diffraction patterns was used to establish the phase composition, determine the size of coherence regions using the Scherrer approximation, and assess the degree of texture of the material. Magnetometric measurements were performed, and the coercivity (Hc) and effective magnetic anisotropy (Keff) were determined.

Results. It was established that the film grows predominantly via the Volmer-Weber mechanism. At thicknesses of 40– 50 nm, the surface of the Nickel magnetron nanofilm retains its roughness, forming a labyrinthine domain structure in the form of individual islands. For a film thickness of 75 nm, the structural homogeneity increases and the spread of domain sizes decreases. At a thickness of 100 nm, an increase in domain size and a decrease in roughness are observed. Calculations of Keff and Hc showed their interrelationship and an increase in magnetic hardness with increasing thickness.

Conclusions. Domain size is linearly dependent on the nanofilm thickness. As the thickness of the Nickel magnetron nanofilm increases, the magnetic hardness of the domain structure increases.

Purpose. To investigate in detail the hydrodynamic parameters of a magnetic fluid droplet with a variable volume concentration of the magnetic phase, in a suspended state within a volume of non-magnetic liquid, under the influence of an external magnetic field with varying strength.

Methods. The experimental part of the work was carried out using an original laboratory setup with standard measuring equipment. To measure the magnetic field strength, a standard TPU-01 teslameter equipped with a precision Halleffect sensor was used, ensuring high accuracy of field registration in the working area. In addition to direct measurements, a computer simulation of the spatial configuration of the magnetic field was performed using the FEMM software package integrated into the MATLAB environment; this allowed for a detailed analysis of the spatial distribution of the magnetic field and its visualization. The processing of video data recording the dynamics of deforming magnetic fluid droplets in the surrounding non-magnetic liquid was carried out using specialized image analysis software, Digimizer, which made it possible to track changes in the geometric parameters of the droplet over time with high accuracy. The obtained experimental data were interpreted using fundamental principles of condensed matter physics and the laws of classical and magnetic hydrodynamics of viscous fluids.

Results. The results of experimental studies were obtained, which are consistent with the numerical simulation results describing the shape change of a ferrofluid droplet suspended in a non-magnetic medium, as well as its eccentricity, as functions of the magnetic phase concentration in the ferrofluid and the strength of the magnetic field generated by the solenoid. The obtained numerical simulation results and experimental data are in good agreement with each other.

Conclusion. The control of the behavior of dispersed droplets of magnetic fluid in a non-magnetic medium using a magnetic field creates the foundation for new technologies in microfluidics and "soft" robotics.

Purpose. To investigate the dynamic properties of magnetic active "raspberry"-type particles of different shapes under the influence and in the absence of an external magnetic field.

Methods. A mathematical model of ellipsoidal magnetic "raspberry"-type particles was developed for detailed simulation of translational and rotational processes of magnetic nanoparticles. Computational experiments based on this model were performed using molecular dynamics methods, followed by analysis of the obtained results.

Results. It was found that ellipsoidal particles demonstrate more complex and chaotic motion compared to spherical counterparts, especially with increasing aspect ratios and higher activation forces. The application of an external magnetic field has almost no effect on particle motion along the field direction, but it significantly reduces their velocity in the transverse direction, thus enhancing the anisotropy of motion.

Conclusion. The dynamic properties of active magnetic particles are determined by a complex interrelation between their shape, activation force, and external magnetic field, emphasizing the significance of taking into account these factors when designing colloidal systems for substance transport.

Purpose. To experimentally investigate the velocity and acceleration of water droplets rising in a volume of magnetic fluid under the influence of a non-uniform magnetic field generated by a combined magnet system, which includes a ring permanent magnet placed on top of a solenoid.

Methods. The experiments were conducted using a setup developed by the authors. Data collection was carried out employing standard measuring equipment. The magnetic field strength was recorded using a TPU-01 teslameter equipped with a Hall probe, which ensures high measurement accuracy. The magnetic field topology was numerically simulated using the FEMM finite element package integrated into the interactive MathLab environment. This software platform was utilized for the calculation, subsequent processing, and visualization of the magnetic field distribution generated by the combined magnet system. Image processing of the moving non-magnetic inclusions was performed using specialized software developed by the authors in the NI LabVIEW environment. The theoretical interpretation of the experimental data was based on the principles of condensed matter physics.

Results. During the experiments, the dependences of the coordinate, velocity, and acceleration of disperse systems based on magnetic fluid and water on the parameters of the non-uniform magnetic field generated by the combined magnet system were obtained. Computer simulation in FEMM made it possible to evaluate the field topology affecting water droplets in the bulk of the magnetic fluid and to compare the calculated data with experimental results. It was found that the experimental and theoretical results are in good agreement.

Conclusion. The obtained results demonstrate the fundamental possibility of controlling the dynamics of magnetic fluid media using the non-uniform magnetic field generated by the combined magnet system. This paves the way for the development of adjustable dispensers and systems for generating active droplets.

The objective of this study is to develop a high-voltage power supply with a power section capable of withstanding sharp current surges associated with dielectric fluid breakdown in an EHD extruder. The need to develop a high-voltage voltage source arose due to the specifics of its use. Since the final goal is to manufacture an electrohydrodynamic spraying unit for condensed matter, at this stage of research, a schematic implementation of a voltage source is presented.

Methods. Electronic circuit modeling and printed circuit board design in Multisim and Altium Designer were used to design and study the operating modes of the high-voltage power supply. An Android application for controlling the highvoltage power supply was subsequently developed. The device enclosure was designed in AutoCAD.

Results. The circuit design of the digitally controlled high-voltage power supply was developed using an ATmega328 microcontroller. A node-by-node breakdown of the device was implemented, including the power and control sections, as well as the communication and protection units. A control section circuit diagram for the high-voltage power supply was developed, capable of providing stabilized power to the microcontroller and peripherals, displaying temperature information, controlling and displaying status on an LCD screen, and communicating with external devices for monitoring and configuration. Using the specialized Multisim simulation program, the circuit's operability was confirmed: the output voltage matches the calculated value and demonstrates stable operation. The printed circuit board (PCB) layout and 3D modeling were performed using the Altium Designer integrated CAD system, in accordance with the design and circuitry features of the device being developed.

Conclusions. A high-voltage power supply circuit was developed and simulated. Experimental studies of the developed high-voltage power supply were conducted to verify its characteristics, particularly its immunity to current surges and output voltage stability.

Purpose. The main problem of the synthesis of α,β-unsaturated carbonyl compounds is their high reactivity due to the presence of active electrophilic centers. At the same time, chalcones with a wide range of pharmacological activity are included in the composition of available plant raw materials, such as flowers of sand Helichrysum arenarium, bark of white willow (Salix alba) and roots of licorice (Glycyrrhiza glabra). The purpose of this work was to consider the possibility of extracting chalcones from dry plant raw materials using an aqueous solution of ethyl alcohol.

Methods. The following methods were used in the study extraction of organic compounds; qualitative determination of compounds and spectrophotometric determination of the quantitative content of the sum of chalcones; physical and chemical methods for determining moisture content, viscosity, density, and other characteristics.

Results. The paper considers known variants of chalcon synthesis and problems in their implementation. As an alternative, the extraction of chalcones from dry vegetable matter with an aqueous solution of ethyl alcohol under conditions of continuous extraction at the boiling point of a solvent in a Soxlet apparatus and maceration at room temperature is proposed. The selected objects (sandy immortelle (Helichrysum arenarium), white willow (Salix alba), and smooth licorice (Glycyrrhiza glabra)) have a wide distribution area and are considered as affordable raw materials. The effect of the initial raw material moisture on the amount of extracted chalcones and the ratio of raw material and solvent was evaluated.

Conclusion. It has been established that both continuous extraction in a Soxhlet apparatus and maceration in the absence of stirring are suitable for extracting chalcones from dry plant raw materials. For all the types of raw materials studied in this work (flowers, roots, and bark), continuous extraction at the boiling point of the solvent proved to be more effective. The maximum amount of chalcones was extracted from the flowers of Helichrysum arenarium under conditions of continuous extraction. Based on the extraction of chalcones from the flowers of Helichrysum arenarium, it was found that the maximum yield of flavonoids is observed when the ratio of raw material to extractant is 1:10.

The purpose of this work is to study the practical application of Expancel microspheres in complex polyesters. To lighten the weight of polymer products, save polymer material, and in some cases, to increase strength, foaming technologies are used by introducing specialized chemically active foamers or pre-porous structured materials.

Methods. The following methods are used in the work: scanning electron microscopy, element analysis based on energy dispersion spectroscopy, compression testing.

Results. The work presents the practical possibility of introducing Expancel microspheres into complex polyethers by extrusion. A thermoplastic polymer material containing Expancel microspheres in amounts of 1% and 2%, respectively, was obtained. The distribution of microspheres in the synthesized polymer material was studied at the micro-level, and the force characteristics of the modified polymer materials were evaluated, as well as the mechanical properties of the obtained polymer materials containing Expancel microspheres were analyzed in comparison with the mechanical properties of the original polymer. Using non-contact atomic force microscopy, the presence of Expancel microspheres in the polymer material was demonstrated, and micrographs of thermoplastic elastomer with and without Expancel microspheres were taken and presented.

Conclusion. A comparison of the mechanical properties of the obtained polymer materials containing Expancel microspheres with the mechanical characteristics of the pure initial polymer showed that the strength characteristics of the thermoplastic elastomer modified with Expancel microspheres decrease slightly, while the residual deformation decreases by 3 to 5% under force loads, and the mass of the polymer material decreases by up to 100 g per 1 kg of pure polymer when making products from it, which allows us to recommend the use of this type of microsphere in complex polyesters.

Purpose. Comparative assessment of the sorption capacity and kinetics of the removal process of isomeric dihydric phenols – hydroquinone and pyrocatechol – from aqueous solutions using three types of non-traditional waste-based sorbents: lignocellulosic (wheat husk), protein (leather shavings), and synthetic (polyethylene).

Methods. Sorption was studied under static conditions at room temperature, varying the contact time from 5 to 30 minutes. The concentration of phenols was determined spectrophotometrically by colored complexes with iron (III) chloride. Kinetic data were processed within the framework of pseudo-first and pseudo-second order models. The main sorption characteristics were calculated: recovery degree, equilibrium sorption capacity, distribution coefficient, and rate constant.

Results. All studied sorbents demonstrated high and comparable efficiency, providing >98.5% phenol recovery within the first 10 minutes. A systematic slight advantage of pyrocatechol over hydroquinone (by 0.1–0.3%) was established, due to its higher acidity (pKa₁ = 9.45) and hydrophobicity (log Kow = 0.88). The process kinetics in all cases are satisfactorily described by a pseudo-first order model. The highest values of sorption parameters for both phenols were obtained for non-food wheat processing waste, which allows us to recommend it as the most effective material. For this sorbent, the dominant sorption mechanisms are proposed: hydrogen bonds and π-π interactions with aromatic fragments of lignin.

Conclusion. Non-food wheat processing waste is a highly effective, affordable and promising sorbent for the removal of hydroquinone and pyrocatechol from aqueous solutions, superior in a set of characteristics to leather shavings and polyethylene. The process is limited by the diffusion of the sorbate to the surface.

Purpose. Search for natural essential oils with low toxicity to humans and their individual components possessing acaricidal activity, with the aim of further identification and use as individual components of acaricidal agents; development and testing of a method for identifying components of a wide range of essential oils.

Methods. The acaricidal activity of essential oils was studied using bioassays with adult and large nymph ticks. Gas chromatography with a flame ionization detector was used to conduct a comparative analysis of the essential oil composition. Rosemary, thyme, lemon balm, clary sage, peppermint, lavender, and jasmine oils were used for the study. Results. The studies revealed varying acaricidal activity among the essential oils tested. An essential oil with the highest acaricidal activity was identified, demonstrating a strong and rapid effect on all test specimens. An analytical method was developed to determine the composition of essential oils and the release times of individual components. The composition of the essential oils tested was compared based on the release times of components obtained using a gas chromatograph. The obtained data demonstrated high consistency.

Conclusion. Rosemary oil was found to possess the most pronounced acaricidal activity of the essential oils analyzed. This, coupled with its low toxicity, makes it promising for practical use both as a component of acaricidal products and in its pure form. Melissa, clary sage, peppermint, and jasmine essential oils also demonstrated strong acaricidal activity. Gas chromatography revealed that all oils with high acaricidal activity contained compounds characterized by similar column yields.