Preparation of Si–diamond–SiC composites by in-situ reactive sintering and their thermal properties

This article described a novel method of preparation of Si–diamond–SiC composites by in-situ reactive spark plasma sintering (SPS) process. The relative packing density of Si–diamond–SiC composite was 98.5% or higher in a volume fraction range of diamond between 20% and 60%. Si–diamond–SiC composites containing 60 vol% diamond particles yielded a thermal conductivity of 392 W/m K, higher than 95% the theoretical thermal conductivity calculated by Maxwell–Eucken's equation. Coefficients of thermal expansion (CTEs) of the composites are lower than the values of theoretical models, indicating strong bonding between the diamond particle and the Si matrix in the composite. The microstructures of these materials were studied by field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD). As a result of reaction between diamond and silicon, SiC phase formed.