Thermal properties of pressureless melt infiltrated AlN-Si-Al composites

Thermal properties of AlN-Si-Al composites produced by pressureless melt infiltration of Al/Al alloys into porous α-Si₃N₄ preforms were investigated in a temperature range of 50-300 C. SEM and TEM investigations revealed that the grain size of AlN particles was less than 1 μm. In spite of sub-micron grain size, composites showed relatively high thermal conductivity (TC), 55-107 W/(m.K). The thermal expansion coefficient (CTE) of the composite produced with commercial Al source, which has the highest TC of 107 W/(m.K), was 6.5×10^-6 K^-1. Despite the high CTE of Al (23.6×10^-6 K^-1), composites revealed significantly low CTE through the formation of Si and AlN phases during the infiltration process.