Кафедра медичної та біологічної фізики і медичної інформатики
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Browsing Кафедра медичної та біологічної фізики і медичної інформатики by Subject "alumina"
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Item Cutting composite material based on nanopowders of aluminum oxide and tungsten monocarbide(Sergeieva&Co Karlsruhe, Germany, 2021-02) Gevorkyan, E.; Nerubatskyi, V.; Chyshkala, V.; Morozova, O.The articale investigated properties cutting tool material of ultrapowders Al2O3 - 50 wt. % WC which have got hot pressing method and the study of their properties. To obtain cutting inserts based on aluminum oxide and tungsten monocarbide with high functional capabilities, the phase components of the initial powders are selected and their homogenized during mixing, hot pressing with the selection of optimal sintering modes with the direct passage of a high-ampere current through a graphite mold. The sintering regime has a great influence on the final properties of the ceramic material. The optimum sintering temperature of ceramics depends on the dispersion of the original powder, the presence of impurities, additives and the duration of heating. It was found that in order to reduce fragility and obtain tool ceramics with high reliability, it is sometimes necessary to exclude even the smallest porosity caused by the ingress of dust from the air.Item Revealing specific features of structure formation in composites based on nanopowders of synthesized zirconium dioxide(Eastern-European Journal of Enterprise Technologies, 2021-11-10) Nerubatskyi, Volodymyr; Chyshkala, Volodymyr; Morozova, Oksana; Gevorkyan, EdwinPeculiarities of formation of microstructure in composites based on chemically synthesized zirconium nanopowders obtained by the method of decomposition from fluoride salts were considered. Hydrofluoric acid, concentrated nitric acid, aqueous ammonia solution, metallic zirconium, and polyvinyl alcohol were used. It was established that the reduction of porosity in nanopowders in the sintering process is the main problem in the formation of high-density materials. Analysis of various initial nanopowders, their morphology, and features of sintering by the method of hot pressing with direct transmission of electric current was made. Peculiarities of obtaining the composites based on them with the addition of Al2O3 nanopowders applying the electric sintering method were considered. It was shown that the increase in the content of alumina nano additives leads to an increase in strength and crack resistance of the samples due to simultaneous inhibition of abnormal grain growth and formation of a finer structure with a high content of tetragonal phase. The influence of sintering modes on the formation of the microstructure of zirconium nanopowders has been studied for different contents of alumina additives. Electric current promotes the surface activity of nanopowders and its variable value promotes partial fragmentation of agglomerated grains thus affecting the composite structure. Physical-mechanical properties of the obtained samples, optimal compositions of mixtures, and possibilities of improving some parameters were determined. It was found that nanopowders of zirconium dioxide obtained by the method of decomposition from fluoride salts are quite suitable for the production of composite materials with high physical and mechanical properties. They can compete with imported analogs and enable obtaining of crack resistance of 7.8 MPa·m1/2 and strength of 820 MPa.Item Structural phase processes in multicomponent metal ceramic oxide materials based on the system Y–Ti–Zr–O (Y 2 O 3 –TiO 2 –ZrO 2 )(2021-03) Chyshkala, V.; Lytovchenko, S.; Gevorkyan, E.; Nerubatskyi, V.; Morozova, O.The article investigates the synthesis processes, structural characteristics and structural-phase processes in multicomponent metal-ceramic oxide materials based on the Y-Ti-ZrO system (Y2O3-TiO2-ZrO2), synthesis of ultra- and nanodisperse oxide powders of the Y-Ti-Zrsystem. O, development and improvement of methods of compaction and consolidation of materials based on them, determination of structural characteristics of oxide materials and the impact of technological processes on these characteristics. The structural-phase evolution in the production of yttrium and titanium oxides, as well as compact ceramics based on them with the structure of pyrochlorine has been studied. Samples of oxide powders were obtained and compact and consolidated ceramics with different content of pyrochlorine phase of Y2Ti2O7 oxides were made, high-temperature influence technology was optimized to increase the content of this phase in ceramic samples. It is recorded that the increase in the term of high-temperature exposure leads to an increase in the content of the pyrochlorine phase