Processing of diamond particle reinforced silicon(Ti) matrix composites by in-situ reactive sintering and their thermal properties

An innovative method of in-situ reactive preparation of diamond/silicon(Ti) matrix composites by spark plasma sintering (SPS) process was applied to produce specimens and the effect of Ti-addition to Si matrix was demonstrated. The relative density of diamond/Si(Ti) matrix composite was >98.1% in a volume fraction of diamond ranging from 40% to 60%. Actually, Si(Ti)/diamond composites containing 60% in volume diamond particles yielded a thermal conductivity (TC) of 525 W m−1 K−1 at room temperature along with a thermal expansion coefficient (TEC) of 1.643×10−6 K−1 at 573 K. TC and TEC of the experimental data were compared with the predictions from several theoretical models. Microstructures of these materials were studied by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Ti addition lowered the melting point and resulted in the formation of TiSi2 phase in Si matrix. The results show that Ti addition is an effective approach for promoting the relative packing density and improving thermal conductivity of sintered samples.