Resume. To develop a mathematical model of the interaction of a carbide steel coating with a steel base under conditions of the formation of a liquid phase.

Methods. The average value of the transition zone was experimentally determined using a PMT-3 device. The size of the transition zone in the carbide steel layer was determined using a MAR-2 X-ray microanalyzer.

Results. A mathematical model of the interaction of a carbide steel coating with a steel base under conditions of liquid phase formation has been developed. It is established that the distribution of carbon in the transition zone of the carbide steel layer (δL) and the steel base (δS) is described by an exponential dependence, and the above technique allows to predict the size of the transition zone with high accuracy, which confirms the corollary of the theory that when applying a layer on a base with a lower carbon content, the width of the transition zone will be greater, and the speed of the melting of the base is less. properties of coatings made of carbide steels of various compositions. High adhesion strength of coatings to the substrate after vacuum sintering has been established (for carbide steel of 10% TiC, steel Cr6V3Mo 116 MPa; for carbide steel of 40% TiC, steel Cr6V3Mo 131 MPa; for carbide steel of 40% TiC, steel Cr12Mo 220 MPa), which in combination with their high physical-mechanical properties allow us to recommend the method of plasma spraying of coatings made of carbide steels for the restoration of worn surfaces of parts and tools for various purposes.

Conclusion. The developed mathematical model makes it possible to calculate the size of the intermediate layer, as well as the diffusion coefficients of carbon in the liquid phase and in the steel base.

The purpose of this work was to conduct an X-ray fluorescence analysis of the elemental composition of tungsten, nickel and copper metal waste using an Olympus Delta portable spectrometer.

Methods. To determine the chemical composition of raw materials, samples of metal waste in the form of copper rods, tungsten rods of various diameters and scraps of nickel plates intended for recycling were examined. To determine the elemental composition of metal waste, the method of X-ray fluorescence analysis (XFA) was chosen. The X-ray fluorescence method is based on the ratio of the intensity of X-ray fluorescence to the concentration of elements in the sample. Samples irradiated with powerful X-ray tube radiation, in response, emit characteristic fluorescent radiation of atoms proportional to their concentration in the sample. This method allows us to qualitatively assess the elemental composition of complex samples without violating their physico-chemical properties with minimal time costs. The Olympus Delta spectrometer was used as an express analyzer of metals and alloys, with the help of which experimental data on the composition of metal waste of tungsten, nickel and copper were obtained.

Results. Based on the conducted studies aimed at X-ray fluorescence analysis of the elemental composition of tungsten, nickel and copper metal waste using the Olympus Delta portable spectrometer, it was found that the samples of the studied metal waste correspond to the following grades of alloys: tungsten rod made of tungsten grade VA; nickel plate made of nickel grade PNK-0T1; copper rod made of copper grade M3r.

Conclusion. The results obtained will allow further research on their processing by the method of electroerosive dispersion and reuse in the production of heavy tungsten alloys. Renovation of metal waste, including tungsten, nickel and copper metal waste, will contribute to resource conservation, import substitution and ensuring the technological sovereignty of the Russian Federation.

The purpose of this work is to develop and apply mathematical methods (Fourier interpolation) to fix the presence and evaluation of the mechanisms of wave processes developing in products made of powder stainless and heat-resistant alloys of additive technologies (SLM) during their deformation.

Methods. To fix the presence of wave processes of plastic deformation in loaded 3d technology products, samples of powder stainless steel 03X18H12M2 (analog AISI 316L) and powder heat-resistant alloy 08ХN53BMTU (analog Inconel 718), manufactured using SLM technology on a 3d printer SLM280 2.0HL, were used. The samples were subjected to uniaxial stretching (GOST 1497-84) with a constant rate of capture in air at room temperature. The lengths of the marked sections were measured using digital video recording of the loading process of the marked surface of the samples. Graphs of the dependences of local relative deformation along the length of the sample and at selected test moments were constructed. The mathematical substantiation of the existence of the wave character of the fixed functions as periodic was carried out by decomposing them into a Fourier series with subsequent interpolation.

Results. It has been experimentally established that in the volume of the studied samples of powder stainless steel type 316L and heat-resistant alloy type Inconel 718, obtained by SLM technology, when they are stretched, there is a multistage character of wave deformation reflecting the development and movement of local micro-volumes of increased plasticity (foci of localized deformation). The Fourier interpolation procedure of a complex of experimentally obtained piecewise linear functions of the dimensions of the marking grid and their local deformations confirmed their apparent periodicity, i.e. the presence of a wave character.

Conclusion. The developed technique of fixing and mathematical processing of wave deformation spectra can be used to analyze the changing parameters of the surface marking (rolling grid) of 3d products both along their length and at fixed loading times, as well as when constructing multidimensional dependencies of the marking parameters on the geometry of samples and test time.

The purpose of this study was to obtain electroerosive dispersed nickel by processing nickel waste by electrodispersing in isopropyl alcohol, as well as to study the performance of this process and the particle size of the obtained dispersed nickel.

Methods. Nickel waste in the form of plates was processed into powder by electrodispersion at an experimental electroerosive dispersion plant (RF Patent No. 2449859) in an isopropyl alcohol medium. The study of the average particle size of the obtained electroerosive dispersed nickel was carried out using a laser particle size analyzer "Analysette 22 NanoTec".

Results. For the first time, spherical nickel powders in the medium of isopropyl alcohol were obtained from industrial waste by the method of electroerosive dispersion. The parameters of the electroerosive dispersion unit necessary for the dispersion of nickel waste have been determined. A directly proportional dependence of the mass productivity of the process of electroerosion research of nickel waste dispersion on the voltage at the electrodes in isopropyl alcohol in the range of 120-220 V. has been experimentally established. The optimum for dispersing nickel waste in isopropyl alcohol is the voltage at the electrodes in the range of 200-220 V. It is established that the smallest particle size is nickel powder obtained at a voltage of 220 V at the electrodes, while the mass productivity at this value of the voltage at the electrodes is the maximum.

Conclusion. Based on the presented experimental studies of the mass and quantitative productivity of the process of electroerosive dispersion of nickel waste in isopropyl alcohol, a high efficiency of the use of electrodispersion technology for obtaining dispersed nickel powder, which is not inferior to industrially used powders in terms of average particle size, has been established. It has been experimentally established that the smallest particle size has a nickel powder obtained at a voltage of 220 V on the electrodes, while the mass productivity at this value of the voltage on the electrodes is maximum.

Purpose. Modern technologies in their development are increasingly in need of increasing the speed of processing and recording information. An alternative to semiconductor methods is magnetic memory based on changing magnetic moments. The speed of magnetization reversal is determined by the speed of motion of domain walls. The speed is maximum in weak ferromagnets. The purpose of this work is to study the effect of a magnetic wave generated by a moving domain wall on a longitudinal acoustic wave, taking into account the absorption of a magnetic wave in yttrium orthoferrite.

Methods. The equation describing the effect of a magnetic wave generated by a moving domain wall on a longitudinal acoustic wave is solved using the following methods: the slowly varying amplitude method, the perturbation theory method, and the Lagrange method.

Results. For an orthoferrite crystal, the contribution of the magnetic wave accompanying the motion of the domain wall in yttrium orthoferrite to the deformation of the amplitude of the longitudinal acoustic wave is calculated. This contribution in a bounded crystal, without taking into account the absorption of magnetic waves in the absence of the influence of acoustic waves on them, is of the order of 10-6 cm. In an unbounded crystal, the corresponding contribution, taking into account the absorption of magnetic waves, into the generation of longitudinal acoustic waves is of the order of magnitude 10^-10 cm with a theoretical thickness of the domain wall D3 ≈ 10^-6 cm.

Conclusion. To study the mechanisms of the influence of a magnetic wave generated by a moving DW on a longitudinal acoustic wave, yttrium orthoferrite was taken. Since a weak ferromagnet is characterized by a significant increase in the magnetoelastic coupling when it overcomes the sound barrier. It is this circumstance that made it possible to experimentally observe the generation of elastic displacements by a moving domain wall. To develop devices for recording and processing information based on weak ferromagnets, it is necessary to fully investigate the mechanisms that affect the dynamics of a domain wall during its motion. Such a factor is the interaction of magnetic and acoustic waves with the domain wall, which can affect the quality of information processing. The evaluation of the contributions of these mechanisms can be used to develop the element base of devices for recording and processing information based on the magnetic memory of weak ferromagnets.

Purpose. Experimentally investigate the difference between the characteristic lifetime of plasma formations in a stationary and rotating toroidal air volume under normal ambient conditions.

Methods. Experimental study of plasmoids was carried out by videotaping with a high-speed camera with subsequent frame-by-frame processing of the recording. Generation of plasmoids was performed by mechanical rupture of the plasma cord of the welding arc in the field of permanent magnets. The creation of toroidal rotation of the plasma formation in air occurs when it passes through a hole in a solid screen. Numerical estimation of mechanical forces acting on ions in the air vortex is performed by order of magnitude using experimental data.

Results. Two different in design laboratory installations for observation of plasma formations in air under normal external conditions have been created. The lifetime of such "long-lived" plasmoids in air is equal to about two milliseconds, which significantly exceeds the lifetime of a plasma-forming welding arc in the free state under the same conditions. The increase in plasmoid lifetime is considered and explained within the framework of mechanical ideas about spatial separation of heavy and light ions inside the plasma under the action of inertia forces as a result of rotational motion of air. The proposed mechanical model of the phenomenon is obviously simplified and does not take into account diffusion, recombination and other related phenomena, since the main and only difference between the observed "longlived" and "ordinary" plasmoids lies in the nature of the mechanical motion of the medium.

Conclusion: Two experimental setups allowing to generate and observe the behavior of plasma formations with a characteristic lifetime of the order of two milliseconds are created and described. The results of observations indirectly confirm a simple mechanical hypothesis about the connection between the lifetime of a free plasma formation and the rotational motion of the gas inside it.

Purpose. To propose a simple and physically reasonable way to describe basic properties of magnetoactive elastomers under the action of magnetic field and/or mechanical loading.

Methods. A phenomenological approach is developed, in the framework of which the aggregation of ferroparticles in a magnetoactive elastomer is interpreted as the appearance of an order parameter whose physical meaning resembles, although does not coincide entirely with, the number of the particles dwelling in aggregates normalized by the total number of the particles. The corresponding functional contribution to the free energy of the system is constructed in the form similar to that of the Landau-de Gennes expansion, as it is used in the theory of phase transitions. Depending on the presence of the cubic term in this expansion, the transition may develop along the scenarios of either I or II order.

Results. In a model 1D calculation it is shown that the dependences of the main characteristics of the composite, viz. magnetization and deformation, on the applied field and mechanical load, might be in a unified manner described as being entailed by the evolution of the above-introduced order parameter. A specific feature manifested by the model system is its ability to display quasi-plastic response that exists as long as the external field is on, and to get back to elastic behavior as soon as the field is switched off.

Conclusions. The results obtained are found to be in good agreement with the data obtained from the direct numerical modelling of the mesoscopic variant of the considered problem. In qualitative aspect, the discovered specific features of the rheological bahavior closely resemble the results of experimental studies om mechanical loading of magnetoactive composites consisting of a silicone rubber filled with micron-size particles of carbonyl iron.

Purpose to study the temperature dependence of the viscosity of a water-based magnetic fluid.

Method. Consists of measuring the dynamic viscosity of a magnetic fluid based on cobalt ferrite particles stabilized in water by a double layer of surfactant. Lauric acid (first layer) and a mixture of lauric acid and sodium dodecyl sulfate (second layer) were used as a stabilizer. Measurements were performed using a Brookfield DV-II+Pro rotational viscometer equipped with a coaxial cylinder system. The measuring system of the viscometer was thermostated using a KRIO-VT-12-1 thermostat.

Results. The temperature dependences of dynamic viscosity were measured for three samples of magnetic fluid based on cobalt ferrite particles of various concentrations in the temperature range 0–90C°. The obtained temperature dependences of viscosity are radically different from the temperature dependences both predicted by known theories and experimentally observed for kerosene-based magnetic fluids. According to well-known theoretical models, the ratio of the viscosity of the magnetic fluid to the viscosity of the base medium is a certain universal function of particle concentration. Different models offer different types of this feature. But it clearly follows from them that the viscosity ratio should not depend on temperature. For magnetic fluids based on kerosene, it has been experimentally established that its relative viscosity decreases with increasing temperature. However, according to the results obtained, the relative viscosity of a water-based magnetic fluid does not decrease with increasing temperature, but increases significantly. That is, the viscosity of a water-based magnetic fluid decreases more slowly with increasing temperature than the viscosity of water.

Conclusion. The observed dependencies completely contradict the known patterns, both theoretical and experimentally established for kerosene-based magnetic fluids. The results obtained may be useful for the further development of the theory of aqueous colloidal solutions with particle stabilization by a double layer of surfactants.

The purpose of this work is to experimentally study the process of decomposition of a horizontal layer of a magnetic fluid lying on a liquid non-wettable substrate into an ordered system of drops under the influence of a vertical magnetic field.

Methods. In the experiment, the studied liquids in the form of a two-layer system filling a cylindrical glass cuvette were placed on a horizontal platform in the center of the Helmholtz coils connected to a direct current source. The development of magnetic fluid layer free surface instability was monitored using a high-speed digital video camera installed at the top of the coil system.

Results. The dependence of the critical strength of the magnetic field on the thickness of the torn layer and the magnetic susceptibility of the magnetic fluid is determined. The obtained experimental data are compared with the results of existing theoretical studies of the instability of the magnetic fluid layer. Compared to the case of a solid substrate, the rupture of the magnetic fluid layer on a liquid substrate occurred at lower values of the critical field strength. In this case, the development of instability of the free surface magnetic fluid layer on a solid substrate occurs at field strengths twice as high as the instability strength of the interface of the layer on a liquid substrate.

Conclusion. The use of a liquid substrate makes it possible to break such layers of the magnetic fluid, the deformation of which on a solid substrate is limited only by a periodic perturbation of the surface. The magnitude of the critical strength leading to the disintegration of a continuous magnetic fluid layer on a liquid substrate increases with increasing thickness of this layer. An increase in the magnetic susceptibility of the magnetic fluid leads to a decrease in the critical field strength.

Purpose. To study the process of photodegradation of methylene blue under the influence of laser radiation with a wavelength of 660 nm, used for photodynamic therapy installations, for the formation of reactive oxygen species, in particular short-lived hydroxyl radicals, using electron paramagnetic resonance (EPR) spectroscopy.

Methods. The residual concentration of methylene blue during photodegradation was determined using an HR2000 spectrometer. The formation of hydroxyl groups was detected using an EPR spectrometer SPINSCAN X.

Results. Analysis of data on the photodegradation of methylene blue shows that under the influence of laser radiation with a wavelength of 660 nm, the structure of methylene blue is destroyed, manifested in the gradual discoloration of the dye solution. When trypaflavin is added to the solution, the rate of photodegradation of methylene blue slows down significantly. Analysis of ESR spectroscopy data shows that when methylene blue is exposed to a red laser, (OH’) radicals begin to intensively form in the solution. Their content increases significantly with increasing irradiation power.

Conclusion. Irradiation of an aqueous solution of the thiazion dye methylene blue by a laser source with a power of 0.3÷1 W and a wavelength of 660 nm leads to its active photodegradation. The addition of trypaflavin leads to a slowdown in the process of photodegradation of methylene blue when irradiated with red light due to the consumption of part of the generated oxygen-containing radicals for the degradation of trypaflavin. According to EPR spectroscopy data using DMPO spin traps, it has been proven that when methylene blue is irradiated with a red laser, active formation of hydroxyl OH' radicals occurs. It was found that with increasing laser radiation intensity, the amount of generated hydroxyl radicals (OH') increases significantly. The presented results may contribute to the development of effective photosensitizers for photodynamic therapy of tumor tumors.

Purpose. Performing measurements of sound velocity and density in the liquid phase of hexane isomers on the saturation line in a wide range of state parameters, including the critical region.

Methods. Using a precision pulse-phase method for measuring the speed of sound in the liquid phase of hexane isomers and their density with a pycnometer at atmospheric pressure. The paper discusses the results of precision measurements of sound velocity and density in five hexane isomers. The speed of sound was measured on the equilibrium curve in the liquid phase of isomers by the pulse-phase method in the range from -30 to their critical point. The measurement error of the speed of sound did not exceed 1 m/s. Density measurements were performed using a pycnometer at atmospheric pressure in the range from -30 to their normal boiling point with an error not exceeding 0.05%. The results of sound velocity and density measurements were used to study the character of intermolecular forces. The necessity of taking into account the non-covalent chemical interaction of molecules of the studied substances is shown.

Results. Sound velocity measurements were performed on the saturation line in the liquid phase of all five hexane isomers in the temperature range from -30 C to the critical temperature of all 5 isomers. The obtained results are used to study the features of the dependence of the energy of intermolecular forces on the parameters of the state in the field of research.

Conclusion. It is shown that the energy of intermolecular forces in marginal hydrocarbons and other simple substances is the sum of 3 terms representing: 1) the energy of the dispersive attractive forces proportional to the square of the density; 2) the energy of the repulsive forces proportional to the biquadrate of the density and 3) the energy of weak chemical non-covalent binding forces proportional to the cubic root of the density of matter.

Purpose. Study of the protective properties of ablated cerium oxide nanoparticles for cell cultures in an oxidative reaction under ultraviolet and ionizing irradiation.

Methods. Cerium dioxide nanoparticles with high antioxidant activity were obtained using laser ablation. Atomic force microscopy was used to characterize ablated cerium dioxide nanoparticles and cells incubated with cerium dioxide nanoparticles. The protective properties of cerium dioxide nanoparticles were studied after 0 (without incubation), 6and 24-hour incubation using the colorimetric MTT test method.

Results. Using laser ablation, cerium oxide nanoparticles with a maximum size of up to 50 nm were obtained. The resulting nanoparticles were incubated with BJ TERT cell lines for 6 and 24 hours. The samples were subjected to ultraviolet (UV) and ionizing irradiation in order to reveal the protective properties of CeO2 nanoparticles. Based on the results of the MTT test, it was found that incubation with cerium dioxide nanoparticles has a pronounced protective effect on the BJ TERT cell line. After UV irradiation, 6-hour and 24-hour incubation of cerium oxide nanoparticles with cell culture provides 15±5% and 20±5% more cell survival, respectively, than without particles. After ionizing radiation, the percentage of survival of cells incubated for 24 hours with cerium nanoparticles also increases by 20±5%.

Conclusion. This work shows that ablated cerium dioxide nanoparticles have a protective effect on healthy BJ TERT cells. The work shows that cerium oxide nanoparticles are promising antioxidants that can provide a protective effect for cell cultures from ultraviolet and ionizing radiation.

The purpose of this work was to continue research on the activation of quartz raw materials using alkali metal hydroxides. This paper presents a theoretical justification and practical confirmation of the physical and chemical activation of quartz raw materials by sodium hydroxide, taking into account the eutectic ratios in the Na₂O–SiO₂ system.

Methods. Quartz glass sand VS-030-B was chosen as a source of quartz raw materials; as a sodium-containing raw material flake sodium hydroxide brand TR. For the scientific basis, the phase diagram of Na₂O-SiO₂ of Berezhny was used. To study the phase composition of activated quartz sand, X-ray phase analysis was used; to study a particle of the activation product of quartz sand and sodium hydroxide, scanning electron microscopy was used. To confirm the effectiveness of the developed method, comparative pulping of sodium vitreous silicate was carried out according to the proposed method and previously known ones.

Results. A method has been developed for activating quartz raw materials with sodium hydroxide to obtain vitreous sodium silicates using a mixture of two activation products, to obtain one of which parts of quartz raw materials and sodium hydroxide are taken in an eutectic ratio, and to obtain another activation product, the remainder of quartz raw materials and the calculated minimum the amount of sodium hydroxide required to obtain a shell on a quartz grain.

Conclusion. Based on the results of comparative experimental cooking of tableted mixtures for silicate lumps using the developed method for activating quartz raw materials and using a mixture of quartz sand and sodium carbonate, the efficiency of the developed method, expressed in reducing the cooking temperature, is experimentally affected. The results of the study were issued in the form of a patent of the Russian Federation No. 2714415 "Method of preparing a charge for alkaline silicate glass".

Purpose of research. The aim of the work is to optimize the conditions for gas chromatographic determination of a mixture of eight organochlorine pesticides: aldrin, hexachlorobenzene, heptachlor, α-hexachlorocyclohexane, γ-hexachlorocyclohexane, dichlorodiphenyltrichloromethylmethane, dichlorodiphenyldichloroethane and dichlorodiphenyldichloroethylene.

Methods. For chromatographic studies of organochlorine pesticides we used a Shimadzu GC-2010Plus gas chromatograph (Shimadzu, Japan) equipped with an automatic equilibrium vapor sample dispenser NT200N, electron-capture detector based on 63Ni and quartz capillary nonpolar column "Chromatek" SPB-5 (30 m, 0.32 mm, film thickness on the basis of phenyl(5%) and dimethyl(95%) polysiloxanes 0.5 μm) with an operating temperature range of 60°C 320/340°C. The chromatograms were processed in the application LabSolutions GPC.

Results. On the basis of experimentally obtained data the optimal conditions for gas chromatographic determination and separation of eight-component mixture of organochlorine pesticides were selected, namely: the value of mobile phase flow division 1:10, carrier gas flow rate – 1.0 ml/min, two-stage temperature programmable column mode from 160 to 240°C with the rate of increase of 5°C/min. The metrological characteristics of the analysis and validation of the results of the proposed technique with the method of high-performance liquid chromatography were evaluated. Good reproducibility of chromatography results with the possibility of detection of organochlorine pesticides at the level of 10-6 – 10-5 μg/cm3 was proved. Application of Fisher's test has shown absence of significant differences in reproducibility of sampled populations the investigated methods of chromatographic analysis of COPCs are equally accurate. Extraction sample preparation of samples of real objects was proposed, the calculated extraction degrees >84% allow to recommend the technique for quantitative determination of analytes.

Conclusion. The method of gas chromatographic analysis was tested for determination of organochlorine pesticides in samples of drinking water and baby puree (Russia) by additive method. Exceeding the norms of residual contents of organochlorine pesticides in the samples of the food products under study was not detected.