The purpose of this study is to manufacture blanks from the charge obtained by the method of electroerosion dispersion, lead-antimony alloy - SSu3, under certain pressing and sintering parameters, to determine the effect of pressure on the density of the final blanks, as well as to find shrinkage dependencies during the sintering operation.

Methods. To perform this study, a charge of lead-antimony alloy - SSu3, obtained by the method of electroerosive dispersion, was required. The pressing process was carried out in a mold specially designed for this study on a NORDBERG N3612 hydraulic floor press in two modes under load - 2.5 and 5 t. respectively, the holding time under pressure in both cases was 10 minutes. Sintering was carried out in a graphite crucible, which was placed in an oven for heating the molds EKPS - 10, where a constant temperature of 296 degrees is maintained for 120 minutes. 

Results. Experimentally, it was found that when the force is doubled, the density of the workpiece increases by 2%, which is due to a closer interaction between metal particles. It is noted that in order to create products with greater porosity, it is necessary to reduce the pressure during pressing, and to create products with greater hardness, more pressure is needed. The difference in the color of the workpieces is due to the degree of oxidation of the charge with oxygen during the cooling of the briquettes after pressing, the compounds of the alloy elements change during its oxidation with oxygen, oxides and lead peroxides are formed, which in turn affect the chemical properties of the alloy. Gray color has a low content of oxygen oxides, and brown, up to orange, is characterized by a high content of lead peroxides.

Conclusion. The obtained results can be used for further study and improvement of the composition and structure of the alloy, as well as for the selection of optimal modes of pressing and sintering in further studies.

Purpose. Show that nitrocarburizing of KhVG steel in a highly active environment significantly increases its hardness and wear resistance due to surface modification with a large amount of carbonitrides.

Methods. For research in an induction furnace, samples with a diameter of 50 m, 8 pieces of steel KHVG, were subjected to nitrocarburizing in a highly active nitrogen-carbon medium, which would provide saturation of the surface layers of steel with carbonitrides of iron alloys with manganese and chromium.

Results. Investigation of the microstructure of modified samples from steel KhVG showed that in all modes of nitrocarburizing, a large amount of a new phase was formed in their surface layers. Inclusions of a new phase in the structure of nitrocarburized layers, as shown by the results of X-ray diffraction analysis, are carbonitrides isomorphic with cementol. The sizes of these carbonitrides vary in the range 3… 10 µm, and the microhardness - in the range Hµ 9150… 10500 MPa. The content of carbonitrides in the modified layers depends on both the temperature and the duration of nitrocarburizing.

Conclusion. The presence of carbonitride inclusions in nitrocarburized layers on the surface of parts leads to a significant increase in their hardness and wear resistance. For practical purposes, it is possible to recommend the content of carbonitrides in modified layers on the surface of parts of 50 ... 60%.

The purpose of this study was to study the characteristics of the charge obtained by electrodispersing the waste of the alloy Н20N80 in distilled water.

Methods. Electrodispersion of waste of alloy Н20N80 was carried out in a dispersant. The tasks set in the work were solved using modern equipment and complementary methods of physical materials science, including: the shape and morphology of the particle surface was studied on an electron-ion scanning (scanning) microscope with field electron emission "QUANTA 600 FEG" (Netherlands); the granulometric composition was studied on a laser particle size analyzer "Analysette 22 NanoTec" (Germany); X-ray spectral microanalysis of particles was carried out on an energy dispersive X-ray analyzer of the company "EDAX" (the Netherlands), integrated into a scanning electron microscope "QUANTA 200 3D" (the Netherlands); phase analysis of particles was studied on an X-ray diffractometer "Rigaku Ultima IV" (Japan); the microstructure of particles was studied on an optical inverted microscope "OLYMPUS GX51" (Japan) and an electron-ion scanning (scanning) microscope with a field electron emission "QUANTA 600 FEG" (Netherlands). Results. Based on the conducted experimental studies aimed at studying the composition, structure and properties of the charge obtained from the waste of the alloy X20N80 in distilled water, the high efficiency of the use of electrodispersion technology, which provides, at low energy costs, the production of new nichrome powder materials suitable for industrial use, is shown. It is noted that powder materials obtained by electroerosion of Н20N80 alloy waste in kerosene have the following characteristics: spherical and elliptical particles, agglomerates; particle sizes from 0.25 to 100 microns; the volumetric average diameter of the particles is 34.12 microns; the main elements are Fe, Ni, Cr and C; the main phases are Fe, Ni, Cr and Cr₂О₃.

Conclusion. The conducted research will allow for a gradual transition to advanced production technologies and materials through the use of progressive, environmentally friendly, low-tonnage and waste-free electro dispersion technology for the production of new nichrome powder materials from waste alloy Н20N80 in distilled water.

The purpose of this study was to conduct metallographic studies of high-strength high-speed steels based on electroerosion dispersed particles of alloy R6M5.

Methods. Electrodispersion of the R6M5 alloy waste was carried out in a metal waste disperser patented by the authors (RF Patent No. 2449859). Lighting kerosene was used as the working fluid. The fusion of the electroerosion charge was carried out in the spark plasma fusion system SPS 25-10 "Thermal Technology" (USA). The tasks set in the work were solved using modern equipment and complementary methods of physical materials science, including: the elemental composition of high-speed steels was studied on an energy dispersive X-ray analyzer of the company "EDAX" (Netherlands), embedded in a scanning electron microscope "QUANTA 200 3D" (Netherlands); the phase composition of high-speed steels was studied on an X-ray diffractometer "Rigaku Ultima IV" (Japan); The microstructure of the alloys was studied using an electron-ion scanning (scanning) microscope with field emission of electrons "QUANTA 600 FEG" (Netherlands).

Results. It has been experimentally established that high-speed steels made of electroerosion dispersed waste particles of alloy P6M5 have the following characteristics: fine-grained structure without pores, cracks and discontinuities; the main elements are Fe, W, Cr, Mo and C; the main phases are Fe₃C, Mo₂C, Fe, W, Cr.

Conclusion. A complex of metallographic studies of new high-speed steels produced by spark plasma fusion of powders obtained by electroerosive dispersion of alloy R6M5 waste in kerosene has shown high efficiency of using spark plasma fusion technology to provide high mechanical properties to high-speed steels from electroerosion dispersed particles of alloy R6M5 waste.

The purpose of the study is to determine the size and configuration of the gating system to prevent gross defects of castings associated with insufficient mold spillage when obtaining the body casting by the casting method.

Methods. The research was carried out using computer modeling of the casting process based on the finite element method and virtual engineering.

To achieve this goal, a 3D model of the casting with several variants of the gate system was built. Modeling of the casting process was carried out in the PROCAST software package, when working in which drawing defects were automatically eliminated and 2D and 3D grids were built, which allows you to take into account the casting configuration as much as possible during the modeling process. As a result of the simulation of the casting process, diagrams of filling the mold with melt were constructed and the places of possible gross defects were determined.

Results. Based on the results of computer modeling of the casting process for the body models with different configurations and sizes of the gating system, the variants of the gating system were determined to ensure the absence of gross defects associated with insufficient mold spillage. The uniformity of the casting crystallization process was also taken into account.

Conclusion. The use of modern computer modeling methods can significantly reduce the time of technological preparation of production, promptly make changes to the configuration of castings and gate systems, predict the appearance of possible defects and promptly develop measures to eliminate them. The widespread use in engineering practice of software complexes modeling various foundry processes makes it possible to improve the quality of manufactured products and their competitiveness.

Purpose of the study. Investigation of the antioxidant properties of nanodispersed solutions of ablated particles of cerium dioxide under conditions of oxidative degradation of an organic dye methylene blue during a photocatalytic reaction, depending on their size characteristics and the pH-environment of solutions.

Methods. The ablated cerium dioxide nanoparticles were characterized using scanning electron microscopy; a study was carried out in the visible and ultraviolet ranges of the absorption spectra of the samples using an optical spectrophotometer. The antioxidant activity of ablated nanoparticles in the oxidative photocatalytic reaction was studied using the example of the organic dye methylene blue, depending on the size composition of cerium dioxide nanoparticles and the pH environment of the systems. Cerium dioxide nanoparticles with pronounced antioxidant properties have been obtained by laser ablation. 

Results. Scanning electron microscopy revealed that cerium dioxide particles agglomerate in an aqueous solution. After the centrifugation process, the number of agglomerates in the upper layers of the solution with a nanometer size of the order of 10 nm increases. Dependences of the antioxidant activity of cerium dioxide nanoparticles on their size characteristics have been determined. The data obtained during the research indicate the highest antioxidant properties of solutions with cerium dioxide nanoparticles, which were centrifuged at a speed of 13400 rpm. With an increase in the pH-medium of solutions, the intensity of the process of inactivation of reactive oxygen species formed during the photocatalytic reaction increases.

Conclusion. Cerium dioxide nanoparticles ablated by pulsed laser radiation are new nanomaterials that are antioxidants capable of inactivating reactive oxygen species in oxidative processes of a photocatalytic reaction. These properties of cerium dioxide nanoparticles are determined by the content of defects of the oxygen vacancy type on their surface.

The purpose. Determination of the mechanical properties of two-layer composites surface coating hard brittle films - elastic polymer, as well as the development of mechanical testing methods.

Methods. Mechanical tests of a multilayer composite compounds without carbon nanotubes and reinforced with carbon nanotubes were carried out by the method of local loading. The dependence of microhardness Hv on the magnitude of the load and the depth of indentation is determined.

Results. The method of creating multilayer composite compounds is described. The values of microhardness for composite compounds are determined. The specificity of the standard method of mechanical testing for a multilayer composite compound is revealed. 

Conclusion. The addition of nanotubes to the polymer composite has a weakening effect, which is associated with the formation of nanotube conglomerates, around which pores are formed. It is possible to achieve a growth of strength with an increase in the dispersion of carbon nanotubes. At low loads not exceeding 1 N, the microhardness is determined by the influence of a thin and hard nanocrystalline film. Therefore, the usage of a standard scheme of mechanical tests for loads from 0.5 N to 1 N allows us to define the value of microhardness of thin composite film and polymer. If loads are more than 1.5 N, it is more correctly to say, that we define the value of microhardness of the composite film, polymer and the second nanocrystalline film. If the load increases 1.5-2 N, it is correct say, that we define the microhardness of the composite as a whole. A method for determining the micro-fracture viscosity coefficient of two-layer composite compounds based on determining the total length of cracks on a surface area S, with an imprint from the Vickers pyramid in the center, is proposed.

Purpose of the study. Determination of the dimensional characteristics, elemental, phase and chemical composition of titanium dioxide nanoparticles synthesized by the hydrothermal method using low temperatures up to 100 ° C, as well as the study of their photocatalytic activity.

Methods. Сharacterization of titanium dioxide nanoparticles synthesized at low-temperature conditions using scanning electron microscopy with an energy dispersive analysis attachment, structural chemical analysis using infrared Fourier spectroscopy to identify organic impurities, and determine efficient decarbonization methods by comparing the analysis results of samples after washing with different polar and non-polar solvents; a study of the photocatalytic activity of synthesized powders of titanium dioxide nanoparticles using the example of photodegradation of methylene blue solution depending on the concentration and the size characteristics of the particles.

Results. Titanium dioxide particles in the form of nanopowder were obtained by the hydrothermal synthesis method using low temperatures followed by washing with polar and non-polar solvents and subsequent thermal annealing. According to spectral analysis and scanning electron microscopy data, after washing with solvents and the decarbonization methods used, a decrease in impurities of carbon compounds in the substance from 68% to 4% is achieved. The synthesized particles had spherical and ellipsoidal shapes with an average size of 24 nm. The high photocatalytic activity of the synthesized nanoparticles was proved by the example of methylene blue degradation under ultraviolet radiation.

Conclusion. As a result of complex analysis by nanoinstrumental methods, titanium dioxide nanoparticles obtained by the hydrothermal method at low-temperature conditions up to 100 °C were characterized. The particles have an average size of 24 nm and a rounded shape. The efficiency of combined washing from organic impurities with polar and non-polar solvents and thermal annealing of the synthesized samples for decarbonization has been proven. Upon annealing, the anatase structure of the crystal lattice was preserved. Nanoparticles exhibit high photocatalytic activity in the photodegradation of methylene blue under ultraviolet irradiation. Acceleration of the reaction rate of photocatalysis contributes to the achievement of concentration in the solution and a decrease in their size.

The purpose of research. Study of the mechanism of Rayleigh-Lamb waves generation by the moving domain wall. Methods. The equations describing the elastic displacements generated by moving domain wall in the plate were solved by the Fourier method.

Results. For yttrium orthoferrite crystal we’ve estimated the amplitudes of Lamb waves displacement for two different cases of their generation: due to bulk and surface strains arising from the movement of the domain wall. The amplitude of displacement in an unbounded crystal has the same order of magnitude as for waves excited by surface strains - 10^-10 cm for the theoretical domain boundary thickness D₃ = 1.1·10^-6 m. The correlation between the contributions of bulk and surface mechanisms in the generation of Lamb waves by the domain wall has been determined.  

Conclusion. For development domain wall-based logic and memory devices it is necessary to fully investigate the factors that can affect the domain dynamics in magnetics. One of these factors is the braking of the domain wall on Rayleigh-Lamb waves. From the equations describing the elastic displacements in the orthoferrite crystal plate during the motion of the domain wall, we can conclude that there are two independent mechanisms of Rayleigh-Lamb waves generation - bulk and surface. The evaluation of the contributions of these mechanisms helps to consider the effect of surfaces on the domain dynamics and can be used in the future to develop magnetic memory devices based on weak ferromagnets.

The purpose of the work: to study the dynamics of the volume of a magnetic fluid levitating in an external magnetic field experiencing an oscillatory shift.

Metods. The experiments were carried out on installations developed on the basis of known methods and equipment for magnetic measurements and manufactured independently. We study samples of magnetic fluid based on magnetite Fe₃O₄ stabilized with oleic acid. Kerosene was used as a carrier fluid. 

Results. Samples of a magnetic fluid with different physical parameters are considered, and the dependence of the viscosity on the magnetization of the magnetic field is investigated. The increase in viscosity in a magnetic field upon the action of a levitating MF column on the interface can be explained by an increase in particle interactions, which lead to MF microstructuring in the near-wall layer. The microstructure of the sample and the presence of large magnetic particles exert the greatest influence on the dynamics of a magnetic fluid, which undergoes an oscillatory shift and magnetoviscous effect.

Conclusion. An assessment of the viscous magnetism effect in a thin near-wall layer of a column of magnetic fluid vibrating in a tube is made when a strong magnetic field is applied. The calculation of the viscosity value is carried out according to the formula obtained on the basis of two different theoretical approaches. The results of the work can be used to develop a method for express testing of magnetic fluid samples, as well as to develop acceleration and vibration sensors based on magnetic fluids. This method can be used to study magnetophoresis and aggregation of nanoparticles. Information on the viscous magnetic effect will be valuable for microfluidic technologies, where magnetic fluids with anisotropic particles, functionalized with various specific surfactants and flowing in microchannels, are used.

The purpose of the work is an experimental verification of additive elasticity model of magnetic fluids.  

Methods. To achieve the purpose of the work, methods of molecular acoustics and methods of systems analysis were used. Magnetic fluids are an example of microheterogenous medium. The small size of the magnetic particles dispersed in the carrier fluid compared to the ultrasonic wavelength makes it possible to apply certain findings of continuum mechanics to magnetic fluids. Thus elastic properties of magnetic fluids are described by the additive model, which is based on the assumption of the additivity of the specific compressibility of the components included in the system, wherein the specific compressibility means the product of the compressibility of a given component and its volume concentration. The work investigated magnetic fluids on a different basis and different concentrations. Samples with lower concentration were obtained by diluting the original ones. Investigations of the dispersion medium of all magnetic fluids were also carried out. The speed of sound was determined by the pulse-phase method, with the mode of multiple reflection from the receiving and transmitting piezoplates.

Results. Comparative analysis of experimentally obtained dependences of speed of light and adiabatic compressibility of MF on solid phase concentration with theoretical data obtained in the context of additive elasticity model was conducted. This analysis made it possible to estimate the adiabatic compressibility of surface-active agent of magnetic fluids - the oleic acid. It was concluded that adiabatic compressibility of surface-active agent – the oleic acid is slightly less than adiabatic compressibility of free oleic acid.

Conclusion. The conducted studies made it possible to experimentally confirm additive model of the formation of magnetic fluid elasticity экспериментально and supplement conclusions of the microheterogenous media theory.

The purpose of the study.The aim of the work was to study the kinetics of the nucleophilic substitution reaction between 7-amino-3-tert-butyl-4-oxo-8-cyano-6H-pyrazolo[5,1-c][1,2,4]-triazine and benzyl chloride.

Research methods.7-amino-1-benzyl-3-tert-butyl-4-oxo-8-cyano-6H-pyrazolo[5,1-c][1,2,4]-triazine was synthesized by the nucleophilic substitution reaction by the interaction of 7-amino-3-tert-butyl-4-oxo-8-cyano-6h-pyrazolo[5,1c][1,2,4]-triazine with benzyl chloride.

The IR spectra of the initial and obtained compounds were obtained using the Agilent Cary 660 FTIR IR-Fourier spectrometer. UV spectra were taken on a Shimadzu UV-1800 spectrophotometer and a digital STUART Melting point SMP30 device with a resolution of 0.10С was used to determine the melting temperature.

Kinetic control of the process under study was carried out by TLC (planar chromatography). During the analysis, Sorbfil PTSH-AF-V-UV chromatographic plates with high efficiency were used. The chromatograms were developed at a wavelength of 254 nm using a SORBFIL video sensor based on a lighting camera. Chromatograms were processed in the computer program "Sorbflil TLC View 1.8".

Results.The interaction of 7-amino-3-tert-butyl-4-oxo-8-cyano-6H-pyrazolo[5,1-c][1,2,4]-triazine and benzyl chloride PhCH2Cl produced a white crystalline substance with T_pl =194,6-195,2⁰C. The yield of the product was 1,1g (79% of the theoretical). When analyzing the IR spectrum of the obtained compound, the presence in its structure was revealed: 1,2,4-triazine ring (at 943 and 1096 cm^-1 peaks characteristic of the "skeletal vibrations" of the triazine ring were detected); pyrazole ring (peaks at 1591 and 1350 cm^-1), NH₂ groups (at 3202 cm^-1, a peak corresponding to the valence vibrations of the amino group was manifested), C≡N groups (peak at 2220 cm^-1), C=O groups (peak at 1702 cm^-1), groups with (4)=O (peak at 1626 cm^-1). The existence of peaks of the benzyl group is analyzed using the NIST database. Transitions were observed in the UV spectrum at 255nm (π→σ* transition of the functional group C=O) and 318 nm (π→π* transition of the aromatic system).

To determine the kinetic parameters of the reaction, the data obtained using the TLC method were processed using differential and integral methods, as well as the Van't-Hoff method. 

Conclusion. During kinetic studies, it was found that the nucleophilic substitution between 7-amino-3-tert-butyl-4-oxo8-cyano-6H-pyrazolo[5,1-c][1,2,4]-triazine and benzyl chloride has that the reaction order is 0,9, the rate constant is 0.0064 min^-1.