High-pressure, high-temperature sintering of diamond–SiC composites by ball-milled diamond–Si mixtures

Abstract

A new method of sintering diamond-silicon carbide composites is proposed. This method is an alternate to the liquid silicon infiltration technique and is based on simultaneous ball milling of diamond and silicon powder mixtures. Composites with fine-grain diamonds embedded in a diamond–SiC nanocrystalline matrix were sintered from these mixtures. Scanning electron microscopy, x-ray diffraction, and Raman scattering were used to characterize the ball-milled precursors and the sintered composites. It was found that the presence of diamond micron-size particles in the initial powder mixture promotes milling of silicone particles and their transformation into the amorphous state. Mechanical properties of the composites, sintered from mixtures of different ball-milling history at different pressure–temperature conditions, (6 GPa/1400 °C and 8 GPa/2000 °C) were studied.