Thermal properties of diamond/Al composites by pressure infiltration: comparison between methods of coating Ti onto diamond surfaces and adding Si into Al matrix

This study was pertained to the effects of Ti coating on diamond surfaces and Si addition into Al matrix on the thermal conductivity (TC) and the coefficient of thermal expansion (CTE) of diamond/Al composites by pressure infiltration. The fracture surfaces, interface microstructures by metal electro-etching and interfacial thermal conductance of the composites prepared by two methods were compared. The results reveal that Ti coating on diamond surfaces and only 12.2 wt% Si addition into Al matrix could both improve the interfacial bonding and increase the TCs of the composites. But the Ti coating layer introduces more interfacial thermal barrier at the diamond/Al interface compared to adding 12.2 wt% Si into Al matrix. The diamond/Al composite with 12.2 wt% Si addition exhibits maximum TC of 534 W·m^?1·K^?1 and a very low CTE of 8.9 × 10^?6 K^?1, while the coating Ti-diamond/Al composite has a TC of 514 W·m^?1·K^?1 and a CTE of 11.0 × 10^?6 K^?1.