Determining the influence of ultra-dispersed aluminum nitride impurities on the structure and physical-mechanical properties of tool ceramics

Gevorkyan, Edwin; Nerubatskyi, Volodymyr; Chyshkala, Volodymyr; Gutsalenko, Yuriy; Морозова, Оксана

doi:10.15587/1729-4061.2021.245938

Cited by 10 publications

(2 citation statements)

References 25 publications

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“…The fracture toughness K IC was determined from the indentation with Vickers’ pyramid on the polished surfaces according to the following formula [ 25 , 26 ]:

where F is the constraint factor, F = 3; H is the hardness; a is the half-diagonal of the Vickers indent; E is the Young’s modulus; and l is the length of the surface crack. The dimensions of samples made for that purpose were 13 mm × 13 mm × 5 mm.…”

Section: Methodsmentioning

confidence: 99%

Activated Sintering of Cr2O3-Based Composites by Hot Pressing

et al. 2022

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The paper presents and discusses questions on structure formation during the sintering process of Cr2O3-based composites using the hot pressing method, when a chemical reaction between the components takes place. The task was difficult because Cr2O3 decomposes when sintered at temperatures above 1300 °C. The proposed novel method allowed for interaction between aluminum and chromia, thus avoiding the decomposition of the latter. Here, ultrafine aluminum powder played the role of the active agent forming a liquid phase and reacting with Cr2O3. The appearance of the solid solutions of (Cr,Al)2O3 with different stoichiometry of Cr and Al depended on the aluminum content in the initial mixture. The solid solution significantly strengthened boundaries between composite phases, resulting in the composite material of high fracture toughness between 5 and 7 MPa m½ and bending strength of ca. 500 MPa. The best mechanical properties exhibited the cermet with 22 wt.% of the restored chromium.

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“…The fracture toughness K IC was determined from the indentation with Vickers’ pyramid on the polished surfaces according to the following formula [ 25 , 26 ]:

Section: Methodsmentioning

confidence: 99%

Activated Sintering of Cr2O3-Based Composites by Hot Pressing

et al. 2022

Self Cite

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“…Рoбoтa прoдoвжує раніше проведені дoслiджeння i бaзується нa нaукoвoму дoрoбку тa рeзультaтaх, чaсткoвo oпублiкoвaних у рoбoтaх [5,6].…”

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Feature of Increase in Energy Efficiency of High-Temperature Industrial Furnaces With Resistive Heating

Nerubatskyi¹,

Gevorkyan²,

Zinchenko³

et al. 2023

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For the sintering of ceramic products, high-temperature electric furnaces are used, which work both in a protective environment and in air. In some technological processes, for example, for the production of ceramic carriers for afterburning car exhaust gases based on SiC and Al2O3, only air furnaces are used. Silicon carbide (SiC – silicate) heaters and molybdenum disilicide (MoSi2) are used as resistive heaters in such furnaces. Due to the relatively small resource of their work, it is energetically beneficial to use the residual heat when cooling the furnace. At the same time, there is a significant saving of electricity for heating. The residual heat is largely determined by the thermal insulation of the lining and the correct distribution of the heat balance of the furnace. The speed of temperature rise affects the thermal balance of the furnace in general, and even the speed of cooling of the furnace, which creates additional energy saving opportunities, which reduces the cost of ceramic products. The article examines the technological processes of sintering ceramic products in high-temperature electric furnaces. A calculation algorithm was selected for performing comparative assessments of energy intensity and possible implementation, which can be used in the analysis of specific situations regarding different types of ceramic parts, the sintering temperature of which exceeds 1400 °C. A factography of the dependences of the power distributed over the floor area on the floor area and the specific power on the internal volume for a range of models of Mobilotherm furnaces designed for firing ceramics with the maximum operating temperature was obtained. It was found that the additional reduction in energy consumption during sintering in electric furnaces for the production of one product and the increase in production productivity are associated with the balancing of the thermal balance of the furnace, the reduction of heat losses and the use of furnace designs in which residual heat can be used. The conducted studies make it possible to assume that the developed methods of calculating the heat balance allow choosing the most optimal furnace heating modes, recommending the most heat-resistant and heat-insulating lining materials.

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Thermodynamic features of the synthesis of high-density ceramic-metal materials “chromium oxide–chromium” from mixtures “chromium oxide–carbon” in the process of hot pressing

Gevorkyan

Nerubatskyi

Вовк

et al. 2023

Low Temperature Physics

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Obtaining ceramic-metal materials Cr2O3–Cr by reduction of chromium with carbon in the process of hot pressing makes it possible to get high-density materials for various functional applications. The thermodynamical study of the interaction of chromium oxide with carbon (soot) is of particular interest, since not only reduced chromium is formed during the synthesis, but also chromium carbides with different stoichiometry, which makes it possible to increase the density and, consequently, the strength of the composite as a whole. Using the partial reduction of chromium oxide with carbon, it is possible to synthesize ceramic-metal materials “chromium oxide–chromium” with different chromium content. The degree of occurrence of this reaction depends on the content of carbon monoxide in its products by lowering the concentration of the obtained pure chromium. This method enables obtaining a ceramic-metal material Cr2O3–22 wt% Cr of eutectic composition, which is characterized by special physical and mechanical properties.

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Determining the influence of ultra-dispersed aluminum nitride impurities on the structure and physical-mechanical properties of tool ceramics

Cited by 10 publications

References 25 publications

Activated Sintering of Cr2O3-Based Composites by Hot Pressing

Activated Sintering of Cr2O3-Based Composites by Hot Pressing

Feature of Increase in Energy Efficiency of High-Temperature Industrial Furnaces With Resistive Heating

Thermodynamic features of the synthesis of high-density ceramic-metal materials “chromium oxide–chromium” from mixtures “chromium oxide–carbon” in the process of hot pressing

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