Thermal properties of Si(Al)/diamond composites prepared by in situ reactive sintering

This article described a novel method of preparation of diamond–silicon matrix composites via in situ reaction by spark plasma sintering (SPS). Thermal properties of samples sintered under two conditions (vacuum and argon) were evaluated and the effect of Al-addition to Si matrix was demonstrated. The results presented that Si/diamond composite (sintered in argon) yielded a thermal conductivity (TC) of 346.2 W/m K, higher than that of the sample sintered in vacuum, along with a coefficient of thermal expansion (CTE) of 1.455 × 10−6 K. Microstructures of these materials were studied by scanning electron microscopy and X-ray diffraction. As a result of reaction between diamond and silicon, SiC phase formed. The research showed that the addition of Al could not give any benefit to the thermal conductivity of composite, although it contributed to the relative packing density of 99.6% with a volume fraction of 55% of diamond particles. Additionally, the influence of interface on thermal properties of Si(Al)/diamond composites was specifically discussed.