Behavior of system of diamond particles with nanometric nickel coating under high pressures and temperatures in sintering process

Using plasma scattering technique, on diamond particles with the size 3-5 micron and nickel (activating additive) concentration 1-2 vol. %, without sp²-carbon formation in a final product, nanometric nickel coating of near 10 nm thickness is deposited. Upon sintering of the diamond composite powder under pressure (8-9 GPa) nickel recrystallization was observed in the whole studied temperature range (700-2400 °C). Almond graphitization in the pores of almond compact begins from non-ordered sp²-carbon formation at temperatures below 800°C, whereas graphite-like structure of non-diamond carbon is formed at temperature above 1400°C. With processing temperature increasing to 2400°C, non-diamond carbon content in diamond compacts was observed as well as relative increasing of the content of graphite-like carbon with 'low' interplanar spacing.