Slipchenko K. Patterns of structure and properties formation of instrumental purpose composites based on cubic boron nitride with binders of carbides and nitrides of chromium and vanadium.

The thesis for the degree of candidate of technical sciences, specialty 05.02.01 –Materials Science. –V. N. Bakul Institute for Superhard Materials. NAS of Ukraine, Kyiv, 2019. The dissertation is devoted to solving an important scientific and technical problem–establishment of patterns formation of superhard composites based on cubic boron nitride (cBN), using refractory compounds with a wide range of homogeneity and high thermal properties, as a binder, for high-speed machining of iron based alloys. It was found that during HPHT sintering of cBN with Cr3C2 or VC (60 vol.% cBN) and aluminum under pressure of 7.7 GPa and temperatures above 2000 °C, formation of chromium and vanadium borides occurs, which negatively effects on physical and mechanical properties of sintered composites. The material microhardness, alongside with other measured mechanical properties, achieved the highest values between 1850-2300°C which can be considered asan optimum sintering temperature under pressure p= 7.7GPa.Performance testing of sintered composites wasdoneat the Department of Industrial Production of the Lund University (Sweden) and State Enterprise DEMZ NTAK "ALKON" (Kiev). In the conditions of high speed machining of SS-EU1.4404 (AISI 316L, vc= 300 m/min) the most favorable effects on the stability of the tool to mechanical and chemical wear were obtained while using tools from system with vanadium compound binders and aluminum.