The purpose. To investigate the structure and properties of sintered samples from electroerosive high-chromium powders obtained by electrodispersion in lighting kerosene.

Methods. To carry out the planned studies, 12X17 steel waste was selected as a dispersible material, which accumulates in large volumes at enterprises. 12X17 steel waste was processed at an electrodispersing plant. The electrodispersion process was carried out under the following conditions: voltage 100 V; pulse repetition frequency 120 Hz; capacity 48 UF. Lighting kerosene was used as a working fluid. The resulting powder was consolidated by the spark plasma sintering (IPS) method using the spark plasma sintering system SPS 25-10 (Thermal Technology, USA). Mechanical processing of sintered samples was carried out on an automatic high-precision desktop cutting machine "Accutom-5" and a grinding and polishing machine "LaboPol-5".

Results. It has been experimentally established that high-chromium alloys from 12X17 alloy particles dispersed by electroerosion obtained by spark plasma sintering have the following characteristics: equilibrium state with submicron and nanoscale grain; the main elements in the alloys are Fe, Cr and C; the main phases are Cr,Cr7C3 and FeCr0.29C0.06; porosity 0.27%; microhardness 555 HV0.2.

Conclusion. Based on the conducted experimental studies aimed at studying the structure and properties of sintered samples from electroerosive high-chromium powders obtained in kerosene, the high efficiency of using spark plasma sintering technology is shown, which provides a uniform heat distribution over the sample, controlled porosity and high physical and mechanical properties with a short working cycle time and grain growth suppression.

The purpose of this studyinvestigation of texture evolution during magnesium rich aluminum alloys as-cast structure workover in reversing mill. 

Methodology. As part of the studytwo cast workpieces from magnesium rich aluminum alloys 5182 and 1565 ch were rolled in a commercial reversing mill  for as-cast structure workover. Аs-cast structure formation was modeled at different Zener parameters. Samples microstructure was analyzed using Carl Zeiss Axiovert - 40 MAT optical microscope. Texture was investigated by reflection method, using X-ray diffraction meter DRON-7 in Cokα-radiation. Results. The study identified similarities and differences specific to both alloys. The major common feature of both alloys is second-phase particles based mechanism of recrystallized grains nucleation. However, significant difference consists in second phase particles-based nucleation being specific to 1565ch.Under some thermomechanical treatment modes second-phase particles based nucleation will be prevailing mechanism in 1565ch. Besides, 5182 fully recrystallizes after as-cast structure workover completion, while in 1565 ch only small metal volume recrystallizes.

Conclusion. Such factor calls for two different approaches to texture formation management for each studied alloys. In case of 5182 alloy as-cast structure shall be worked over with low Zener-Hollomon parameters with attempt to achieve max sharp cube texture. Vice versa, 1565 ch as-cast structure workover shall be performed with high ZenerHollomon parameters to eliminate pronounced texture components after recrystallization.

Purpose. Determination of the factors that have the greatest impact on the technological chain of the process of obtaining powder materials (metal granules). 

Methods. The study is based on an experimental approach and statistical analysis of the regression equation, built as a result of planning a multifactorial experiment of type 2³, which is used to find optimal conditions, build interpolation formulas, select essential factors, evaluate and refine the constants of theoretical models, select the most acceptable from a set of hypotheses about the mechanism of phenomena, etc. And also on the results of the experiment using the method of a priori ranking of factors using the coefficient of concordance and coding of natural variables. 

Results. Evaluation and analysis of the results of the experiment made it possible to establish that the most important factors influencing the efficiency of the production of powder materials are factor x₅ – rotation speed of the workpiece; factor х₁ – time of sieving and magnetic separation; factor х₆ – Power of the plasmatron. 

Conclusion. Experimental studies were carried out to vary the parameters of the main factors affecting the increase in the productivity of the technological process, the yield of suitable material and the quality of metal granules. Improving the control of the parameters of these factors (optimizing the spraying modes and improving the classification process) will allow obtaining the maximum yield of suitable material, increasing the quality of finished products (metal powders), obtaining an economic effect and improving the technical and economic indicators of the production chain of granules metallurgy. The data obtained can be used for further research, in which it is supposed to propose and implement various ways to improve the factors under study, which will optimize the technological process of pellet production. 

The purpose. The aim of this work is to develop a technique for obtaining uniform nickel films of nanometer thickness on a metal surface. Electrochemical films of nickel on copper were chosen as the object of research. The article describes a technique for determining the topography of electrochemical nickel films of nanometer thickness (40-60 nm) applied to a conductive substrate with low roughness.

Methods. A study of the roughness of the Cu substrate of the Ni film was carried out using metallographic and probe microscopes. To obtain electrochemical nickel films, a Watts solution and an installation for the production of electrochemical films by the drop method were used; To minimize the roughness of the nickel surface, we used a low current mode with an electrolysis time of 2–10 min on a copper and aluminum foil substrate. For the theoretical substantiation of the technique, an electrodynamic boundary value problem is constructed, solved by the Fourier method. 

Results. Mathematical and computer models of the distribution of the normal component of the current density at the electrolyte-metal interface have been constructed. Using the method of force tunneling microscopy, the roughness of the obtained nickel nanofilms on copper was determined. To obtain homogeneous magnetic films with a thickness of about 50 nm, the necessity of high-quality preliminary polishing of the substrate surface is shown. The conditions for the formation of a solid film of nanometer thickness are considered, and the properties of nickel magnetic films on copper are obtained. The binding energies of dimers were calculated by the methods of quantum chemistry NDDO PM3 and ab initio (HF) to assess the reactivity and the possibility of interaction of nickel atoms with surface aluminum and copper atoms. 

Conclusion. The parameters of the nickel surface roughness, which affect the operational properties of the devices, have been determined. It is shown that the formation of a nickel film on the copper surface is possible for Ni thicknesses exceeding the average substrate roughness.

Purpose. Selective laser treatment is a promising method for creation the mechanical properties of the surface layer of metal alloys. The selectivity of laser processing is manifested in the predominant effect of the shock wave and the heat front on the defective areas. As a result, mechanical stress relaxation processes occur in the defective areas, while the defect-free material does not undergo significant changes. This makes it possible to improve the mechanical characteristics of the material while maintaining its initial structural state as a whole. Further development of the method of selective laser processing requires investigation the thermal mechanism of the effect of laser radiation on defective areas. The aim of the work is to investigate the interaction of the thermal front initiated by a laser pulse with defects in the surface layer of a metal alloy.

Methods. The propagation of a thermal front in the surface layer of a titanium alloy containing a pore system was studied by the finite difference method and using computer modeling.

Results. A model of the interaction of the heat front with a system of three pores located parallel to the sample surface is proposed. The developed model can be used to identify the specifics of the interaction of the heating wave with various defects. The specificity of the thermal mechanism of the effect of short-pulse laser radiation on the pores in the surface layer of metal alloys is manifested in the distortion of the thermal front and the non-uniform heating of the material.

Conclusion. The non-uniform heating of the material manifests itself, first of all, in the defective areas and can lead to stress relaxation due to plastic deformation of the heated material. The available experimental data obtained on samples subjected to selective laser treatment indicate a simultaneous increase in the microhardness of the surface layer and resistance to crack formation in condition of local loading conditions.

Purpose of research. Determine the content and forms of components of luminescent substances with the structure of garnet and nitride on the emissive properties of white LEDs.

Methods. Electron microscopic studies were carried out in conjunction with energy dispersive and X-ray phase analyzes of powder samples, produced by LLC "Monocrystal Paste". Lighting parameters were determined using a confocal Raman and fluorescence spectrometer OmegaScope with blue laser radiation.

Results. The correlation effect of physical and mechanical characteristics on the fluorescence spectra of powder materials with the garnet and nitride structure is built, their analysis and promising approaches to improving the structure of white LEDs and the color rendering index are carried out. The theoretical calculation of the content of the red component has been carried out.

Conclusion. Offering promising characteristics such as small size, safety, long life and luminous efficiency, white LED lamps perform in a high CRI alternative to natural light, which characterizes the contrast in which objects are displayed by irradiated light. The main purpose of the LED source is to convert the blue light of an InGaN semiconductor crystal into white light over a wide frequency range. As a result of the research, the direct influence of the composition and structure of photoluminescent substances on the emissive properties of the LED has been established. Thus, by including gallium in yttrium-aluminum garnet, the wavelength of the fluorescence maximum decreases from 547 nm to 523 nm. When strontium is replaced in the nitride phosphor with calcium, the shape changes towards red, namely from 600 nm to 650 nm. With a multicomponent phosphor, including both phosphors, the LED source crosses the entire frequency range of visible radiation.

The purpose of the work is to increasing the resolution of Raman spectroscopy using the transformation of multidimensional vector-matrix correlation mathematical models for the identification of silver nanoparticles in nanostructured biological objects under conditions of information uncertainty.

Metods. The research methods are based on the mathematical apparatus of regression, multidimensional vectormatrix analysis, probability theory, namely, for the implementation of scientific tasks in this study, they are used: Raman spectroscopy; the physical effect of giant Raman scattering (SERS); statistical modeling of the random process of changing the experimental parameters of silver nanoparticles together with autocorrelation functions and interdependent parameters on the correlation matrix; vector-matrix method for modeling the equivalent radius of ellipses of the distribution of two-dimensional correlation distributions in solving the equations of recognition of silver nanoparticles on the multidimensional components of Raman spectra. Numerical implementation of mathematical models is carried out on a PC in the MathCAD Enterprise Edition 15 environment. 

Results. In the course of the study, the reliability of recognition of colloidal silver nanoparticles on polyester fibers was evaluated by the multidimensional correlation components of the Raman spectra when controlled by the polarization characteristics. It is shown that the proposed method of recognition of silver nanoparticles on the surface of textile materials gives a significant advantage in assessing the reliability of determining the modes of deposition of silver nanoparticles on fibers.

Metods. A method of mathematical modeling for the identification and control of silver nanoparticles on the surface of textile materials is proposed; a vector-matrix model of the equivalent ellipse radius of the distribution of twodimensional correlation distributions is obtained for solving the equations of recognition of silver nanoparticles by multidimensional correlation components of Raman spectra; a software implementation of multidimensional polarization correlation methods for increasing the reliability of identification of silver nanoparticles is developed. 

Purpose of research - characterization of microstructural, optical and electronic properties of synthesized samples of nanosized inorganic pigments of the composition Zn_(1-x)Co_xO (x = 0.02-0.15).

Methods. Inorganic powder pigments with the general formula Zn_(1-x)Co_xO (x = 0.02-0.15) were synthesized by the pyrochemical nitrate-urea method using crystalline hydrates of metal nitrates and urea. The initial reagents in the required stoichiometric ratio were thoroughly mixed with urea powder in a ceramic mortar and then thermolysis of the reaction mixture was carried out in ceramic crucibles with the decomposition of nitrate salts with the formation of colored green powders of varying color intensity. The microstructure of the prepared pigment powders was investigated using a JEOL JSM-7500F scanning electron microscope. The composition of the pigments was studied by energy dispersive microanalysis using an Inca X Sight EDX Spectrometer attachment. Optical diffuse reflectance spectra of synthesized pigment powders were measured on a Hitachi U-3900 spectrophotometer with a two-channel integrating sphere in the wavelength range from 300 to 900 nm.

Results. By means of particle SEM analysis of the synthesized Zn_(1-x)Co_xO pigments, it was taken into account that they are nanopowders with an average nanoparticle size from 20 to 45 nm and with varying degrees of nanoparticle agglomeration. The diffuse reflectance spectra of pigments doped with different amounts of cobalt ions in the wavelength range from 300 to 900 nm show a systematic increase in the intensity of the green color with an increase in the cobalt content. All studied samples of the synthesized pigments Zn_(1-x)Co_xO are semiconducting compounds with several direct-gap electronic transitions.

Conclusion. With an increase in the percentage of cobalt particles in the composition of the investigated green inorganic pigments with the general formula Zn_(1-x)Co_xO a decrease in reflectivity was observed in the entire investigated optical range, and especially in the range from 600 to 680 nm. The difference in color parameters for the studied inorganic oxide pigments of the composition Zn_(1-x)Co_xO is mainly associated with both a change in the fraction of chromogenic cobalt ions in them and a change in the nearest coordination of oxygen atoms in the Co-O_n coordination polyhedron, which affects the parameters of electronic transitions ion Co ⁺. The calculated color parameters in the CIE Lab color space allow you to guide the selection of the composition of Zn_(1-x)Co_xO pigments to achieve the desired color.

Purpose of research. To determine the possibility of using regenerative effluents of Na-cationite filters to obtain magnesium-enriched sodium chloride solutions 

Methods. The following methods were used in the research: physico-chemical, radiological analyses, atomicabsorption spectrometry, capillary electrophoresis; devices: beta-radiometer RUB-01P with a BJB-06P detector; gamma-spectrometer Gamma-1P; atomic absorption spectrometer KVANT-2AT; capillary electrophoresis system " DROPS”  modification "Drops 104T".

Results. Information about the biological properties of seawater and its elements has been studied. Laboratory studies have established that the concentration of calcium, magnesium, and chloride ions in regeneration effluents is several times higher than in seawater; sulfates - are many times less. The ratio of Mg²⁺/Ca²⁺ ion concentrations is: in seawater 3.95-5.03; in regenerative effluents-1.38; in fresh water-0.16-0.21 mg-eq/mg-eq/dm³. Strontium and cadmium in regeneration effluents are contained approximately at the same level as seawater. The concentration of strontium in seawater is in the Black, Barents, and Mediterranean seas, respectively: 7.7; 20.0; and 25.3 mg / dm³. The proportion of strontium in the total hardness in regenerative effluents is lower than in seawater. The total beta-activity of regenerative effluents and water of the Black Sea (near Gelendzhik) did not exceed the background values; in the area of Sochi it was 7.4 Bk/l. This is below the average level of -activity of the water of the World Ocean - 11.1 Bk/l. In the -spectra, with a relative measurement error of ± 20%, potassium-40 was detected: in seawater (Sochi) - 0.72 Bk/l; in regenerative effluents - 1.59 Bk/l. The remaining radionuclides have low activity and high measurement error.

Conclusion. Regenerative effluents of Na-cationite filters, with the lime-cationite method of softening fresh water, can be used for the preparation of magnesium-enriched wellness baths.

Purpose of the study. Study of the possibility of imparting an antimicrobial effect to cotton-based fabric at the stage of dyeing with substantive dyes as an alternative to the existing methods of finishing.

Methods. Synthesis of a substantial stilbene disazo dye containing a fragment of salicylic acid by diazotization and azo coupling reactions, confirmation of the dye structure by infrared spectroscopy and liquid chromatography with mass spectrometric detection; experimental dyeing of cotton fabric with the obtained dye; checking the obtained fabric samples for antimicrobial activity in relation to eight test strains of microorganisms.

Results. Diazotization of 4,4'-diaminostilbene-2,2'-disulfonic acid and subsequent coupling of the obtained diazo compound with salicylic acid gave the substantive dye 5,5 '- {[(E-ethene-1,2-diyl) bis (3-sulfo-4,1-phenylene) bis (diazen-2,1-diyl)]} bis-2-salicylic acid. Samples of cotton fabric dyed with synthesized disazo dye were obtained. Studies have shown that for a fabric sample treated with 5,5 '- {[(E-ethene-1,2-diyl) bis (3-sulfo-4,1-phenylene) bis (diazen2,1-diyl)]} bis-2-salicylic acid using the technology of dyeing with substantive dyes, there is no growth of colonies of pathogenic microorganisms within the boundaries of a fabric fragment in contact with a pre-seeded nutrient medium. The dyed fabric samples were treated with solutions of zinc and copper salts, the presence of metal ions recorded on the dyed fabric was confirmed by atomic emission analysis. It was found that the subsequent treatment of the dyed fabric with zinc and copper salts is not accompanied by a significant change in color and does not lead to an increase in the antimicrobial activity of the material obtained.

Conclusion. The studies have shown the potential for imparting an antimicrobial effect to cellulose fabric within the technological regime of dyeing with the obtained substantive dye. It was found that the treatment of dyed fabric with zinc and copper salts does not lead to significant changes in color and does not increase the observed antimicrobial effect.