Microstructure evolution and thermal conductivity of diamond/SiC composites after heat treatment.

In this study, the diamond/SiC composites were fabricated by tape casting combined with Si vapor infiltration process and then heat-treated at 1500 °C in an argon atmosphere for 4, 8, 12 and 16 h, respectively. The effect of heat treatment on the microstructure evolution and thermal conductivity of diamond/SiC composites was investigated. Results showed that the SiC grain size in the matrix grows significantly, and the SiC particles are sintered to form a continuous network after heat treatment. And the growth of SiC grains is controlled by the diffusion and dissolution precipitation mechanism. The thermal conductivity of the composites increased significantly after heat treatment, reaching a maximum value of 423 W/mk after heat treatment at 1500 °C for 8 h, which is 40% higher compared with that without heat treatment. However, longer heat treatment time will lead to volatilization of residual silicon in the composites and reduce its densities and has a negative influence on the thermal conductivity of the composite. The increased thermal conductivity of the composite can be attributed to both the growth of SiC grains and the formation of continuous SiC heat transport channels. Heat treatment provides a new method for improving the thermal conductivity of diamond/SiC composite. [ABSTRACT FROM AUTHOR]