STUDY OF SYNERGISTIC EFFECT OF MECHANICAL ACTIVATION AND HIGH PRESSURE AND HIGH TEMPERATURE SINTERING ON THE STRUCTURE OF THE MATERIAL BASED ON BORON NITRIDE

The paper considers the results of the research of the material based on boron nitride after mechanical activation and high pressure and high temperature sintering of hexagonal boron nitride. It is shown, that the structure and phase composition of the resulting material strongly depend on the technological route and the material synthesis conditions. The subsequent chemical purification of the BN powder after mechanical activation leads to a decrease in the content of the hexagonal boron nitride phase. High pressure in the sintering process promotes the formation of material based on cubic boron nitride with a crystallite size of about 50 nm. The additional modifying of boron nitride by aluminum in combination with the second mechanical activation decreases the sintering pressure from 7.7 to 5.5 GPa. At the same time, it leads to the cubic boron nitride grain growth due to the recrystallization process.