Effect of deposition temperature and time on microstructure of CVD SiC coating on diamond particles

Diamond-reinforced metallic or ceramic matrix composites are used in a wide array of applications, such as cutting, polishing and thermal management. However, large-scale industrial applications are limited by the interfacial incompatibility due to the surface inertness of diamond. Herein, a homogeneous and dense SiC coating is formed on large-sized (200 μm) diamond particles via static chemical vapor deposition (SCVD) to improve the surface wettability of diamond particles and hinder the oxidation and graphitization of diamond particles at elevated temperatures. The influence of deposition temperature and time on the microstructure of SiC coating is systematically investigated. The results reveal that the low temperature and insufficient time result in incomplete coatings, whereas high temperature and extended time result in the formation of rougher and less uniform coatings. At the deposition temperature of 1100°C for 2 h, the diamond surface is fully covered by a uniform SiC layer, with a thickness of ≈1.2 μm, and the onset oxidation temperature of diamond particles is increased by 120°C, demonstrating a significantly higher oxidation resistance than the raw diamond particles. Moreover, the graphitization of diamond did not occur under given deposition condition.