Materials Science Forum Vol. 1040

Abstract: New requirements put forward to the modern industry to reduce harmful emissions increase the utilization rate of metal, reduce the production time of equipment, the production of components and parts from hard-to-process materials aim to introduce new technological processes. A promising technology is additive growing, which allows one to minimize the production time of unique products, to use hard-to-process alloys, for example, based on the Ni-Fe-Cr system, in their manufacture. The study was carried out by the method of mathematical planning of the experiment with subsequent processing of the results on a supercomputer. The results of the influence of the current applied to the plasma torch and the flow rate of the plasma-forming gas are presented; wire feed rates during spraying in power plants per fraction and particle size ratio in the volume of the yield of suitable. The minimum allowable yield of the product is set at 30 % with the production of fractions in the range from 40 to 140 microns. The results obtained for the Inconel 718 alloy confirmed the possibility of obtaining Ni-Cr-Fe alloy powders. The mode proposed in the work allows obtaining commodity fractions at the level of 30-35% of the mass of the sprayed feedstock. Additional tests of the mechanical properties and corrosion resistance of samples made from the resulting powder showed satisfactory results, similar to the results of tests of samples made from heat-treated alloy forgings.

Abstract: In this work, a study of the cases of destruction of the CuCrZr / 316L (N) bimetallic joint (BMJ) obtained by diffusion welding under conditions of hot isostatic pressing (HIP) was carried out. The identified defects are cracks propagating in the BMJ zone in the corner zone of the mock-ups of the heat-sink elements (HE). The analysis of the causes of destruction of the BMJ was carried out and the factors leading to the weakening of the BMJ zone are analyzed. The analysis of the thermal and stress-strain state of the HE mock-up during the manufacturing process was carried out. The study of the elements of the HE mock-up were carried out by methods of non-destructive testing (ultrasonic testing (UT)) and destructive testing (metallography; fractography; energy-dispersive X-ray spectroscopy; tensile tests). The inclusion of brittle phases in the zone of the BMJ was revealed and an assumption was made about the chemical composition of these phases. It was revealed that this line of brittle phases is a crack propagation zone in all cases of destruction of the BMJ in the HE mock-ups. The temperature range is revealed at which the effect of "ductility failure" of the CuCrZr is observed during the tensile testing of the samples.

Abstract: The behavior of С₅₆ fullerene when heated in a nitrogen atmosphere at a pressure of 10⁵ Pa was studied using computer thermodynamic modeling. The modeling consisted in a complete thermodynamic analysis of the system using the TERRA software package, which is one of the most developed and efficient ones that implements such thermodynamic calculations. Experiment temperature ranges are from 273 to 3373 К. Based on the calculated data, a graph of the carbon balance in the С₅₆-N₂ system was constructed, the ongoing physicochemical processes were described, divided into four classes: sublimation, dissociation in the gas phase, chemical reactions occurring in the gas phase, dissociation and chemical reaction in the gas phase. Temperature intervals of reactions are identified. The equilibrium constants of the reactions are calculated and described, as well as the coefficients of these constants are found using the least squares method. The temperature interval of thermal stability of the condensed C₅₆ fullerene and C₅₆ vapors is defined. This work is one of the series of works on the properties of nanoparticles, in the future it is planned to study the thermal properties of higher fullerenes. The data obtained can be used to determine the explosive and fire hazardous properties of fullerenes as a dispersed solid.

Abstract: The article deals with the determination of the efficiency of a multi-bladed tool equipped with inserts made of oxide-carbide cutting ceramics, depending on the microstructural parameters of the tool material. The microstructural parameters of the oxide-carbide cutting ceramic, which affect the performance of the tool, are proposed to be determined according to the electrical resistance of the tool material. In order to implement the method for determining the working capacity of the instrument, a basic design of the device for measuring the electrical resistance of the material of the instrument is proposed. The device for measuring the electrical resistance of ceramic plates consists of a body made of a dielectric material, with channels for supplying a conductive material and a groove for installing a case with a test sample. During the test, the channels are filled with a liquid conductive material, which fills the cavity formed by the channel of the case, the groove of the case and the plate itself under test. To ensure uniform filling of the cavity, after the introduction of the liquid conductive material, metal balls are installed into the channels, which are made in such a size as to ensure free sliding along the channel, but not to let the liquid pass into the upper part of the channel. The tested ceramic plate is installed in the walls of the removable case. The walls of the removable case include electrodes, which, when the device is in operation, are inserted into a cavity with a liquid conductive material at one end, and are connected to an ohmmeter at the other. Using a device for measuring the electrical resistance of ceramic plates, it is possible to determine the operability of the tool and guarantee its operation without rejection for a certain period of time, which was confirmed by experimental research in the milling of workpieces of machine parts made of gray cast iron. Experimental studies in multi-edge machining with cutters with different values ​​of electrical resistance of ceramic plates made it possible to plot graphs of the dependence of the quality of machining during milling on the operability of the tool and on the time of the machining process.

Abstract: The search for optimal conditions for the method of synthesis of copper (II) salts to create a unified one-step method for obtaining salts from natural raw materials was the purpose of this work. During the process of salt production, it is desirable that the product accumulates in the solid phase and is easily separated by phase separation methods. The study of the direct interaction of copper (II) oxide with acids in organic liquid media using a bead mill as a reactor and grinding agent of different nature showed that besides the usual places of localization of product that take place in practice, we can meet unusual places of localization of product, such as the surface of a foreign solid phase in the reactor zone, for example, the surface of the grinding agent, reactor elements, etc. It was found that in some cases, localization on a solid surface could be a favorable localization option in terms of the speed of the process. But it happens not always, because it requires specific methods of separation of film from surface, which can be very expensive. Often, the localization of the product on the solid surfaces is an extremely unfavorable localization option. It was found that different variants of product localization of interaction CuO with acids which were implemented in different proportions, prevented the creation of a unified method for producing salts in such systems

Abstract: Radioluminescence technologies are at the front line of the optic and electronic studies. Effective, self-contained and safe radioluminescent light sources can find their application in space industry, in medicine and in military technologies. The question of the performance improvement of the solid-state radioluminescent light sources (SRLS) without raising the included activity of working radionuclide can be solved by upgrading the phosphor crystalline structure. The electron-beam treatment for zinc-sulphide phosphors initial batch has been studied in a wide range of concentrations of the activating agent (Cu) for improving the radioluminescent performances of the phosphors, for creating the structural defects that form centers of luminescence. The changes of the phase composition were investigated under different synthesis conditions. It is revealed that electron-beam treatment of the initial batch leads to the growth of the wurtzite phase content in zinc-sulphide phosphors synthesized below the phase transition temperature. The changes of the phase content promote the spectral redistribution under the tritium beta-excitation. It is obviously the reflection of the fact of «green» luminescence centers rearrangement between the volume of the crystal and its surface. The correlations between structural configuration and performances of ionizing luminescence were found. Electron beam treatment gave the 20% increase of brightness of the radioluminescence. The achieved enhancement of luminescence performances allows the development of advanced tight-packed SRLS with minimal radioactivity and high energy-light conversion.

Abstract: The paper considers the applications of foamed glassy phosphate materials as carriers of biologically active substances. One of the advantages of phosphate materials is their ability to effectively support the life of microorganisms. This feature of phosphate glassy materials opens up the prospects for the application of microorganism strains - destructors of oil products to their foamed samples, that is, the creation of biosorbents for purification of water and soil from hydrocarbon contamination. The advantages of a biosorbent are explained by the high biological activity of microorganisms on the surface of foamed glassy phosphates and the possibility of active development of microorganisms with the simultaneous destruction of petrochemical contaminants. The use of biosorbent eliminates the problem of its utilization and regeneration, thus it is suitable for repeated use. The formation of porous glassy phosphate materials on the surface by the method of molecular layering of monolayer coatings allows obtaining chemically modified composite materials, which improves their performance characteristics such as strengthening the material structure with a simultaneous increase in the catalytic activity of biochemical processes.

Abstract: This work represents the characterization of materials surface before and after laser processing with macrophotography, optical metallography, and scanning electron microscopy before and after thermal exposure. The factors influencing the reliability of the laser-induced code readability have been determined as color and contrast. The range of stability of the code readability under thermal influence on the structural materials under study was determined, which allows improving the reliability of the laser-induced marking codes readability. The research objects in this paper were samples of the following materials: alloys based on copper, aluminum, and iron with laser-induced codes of various types applied on the surface. This work aimed to research the stability of laser-induced codes readability after thermal exposure using macrophotography, optical metallography and scanning electron microscopy on structural materials of various purposes before and after laser processing (when forming a binary matrix code). The research results obtained and presented in this article on the stability of laser-induced codes reading under thermal action on structural materials can be used in different fields of industry, when marking products of heavy, general, medium, and precision engineering, as well as for marking metal products and blank parts. The results of this research are also planned to be used for further analysis of the occurring damage, leading to reading errors due to mechanical and chemical influences. It is planned to evaluate the limit values of the parameters that determine the degree of degradation at which the encoding will be considered to have lost the recognizing ability. Requirements for the quality and permissible code damage will also be developed to ensure their reliable identification.

Abstract: In this paper, the time effect of hydrothermal synthesis on YF₃ morphology particles is considered. The work was carried out on X-ray-excited YF₃:Ce³⁺ phosphors. The synthesis was carried out by the hydrothermal method, since it avoids high temperatures leading to particle agglomeration. The first stage of research consisted in identifying the most favorable medium for obtaining the required phase and size - water or organic matter (ethylene glycol and ethanol). Research has shown that ethylene glycol has all the advantages: it prevents agglomeration, allows us to get the required phase. Hydrothermal synthesis of YF₃ samples to determine the optimal synthesis time was carried out according to the same scheme - in an organic medium of ethylene glycol without using stabilizers for 4, 8, 12, 16, 20 hours. Our study showed that it is possible to obtain a YF₃ sample that meets the necessary requirements (including nanoscale) within 16 hours, moreover, without the use of stabilizers. In parallel with the study of the synthesis duration, an experiment was carried out on the effect of various stabilizers on the properties of the YF₃:Ce³⁺ phosphors (5%). The synthesized nanophosphors possessed effective X-ray luminescence with a maximum in the region of 300 nm, which makes it possible to use them in the composition of preparations for PDT.