Thermal properties of pressureless melt infiltrated AlN-Si-Al composites
(1. Department of Metallurgical and Materials Engineering, Mugla Sitki Kocman University, Mugla, Turkey;2. Department of Materials Science and Engineering, Anadolu University, Eskisehir, Turkey;3. Material Science and Engineering Programme, Sabanci University, Istanbul, Turkey)
Abstract: Thermal properties of AlN-Si-Al composites produced by pressureless melt infiltration of Al/Al alloys into porous a-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.
Key words: AlN; ceramic-matrix composites; thermal properties; liquid metal infiltration