Microwave sintering and properties of AlN/TiB2 composites

Abstract

The effect of TiB2 on the densification behavior and properties of microwave-sintered AlN/TiB2 ceramic was investigated. The densification of the composite was significantly retarded in nitrogen atmosphere due to strong nitridation of TiB2 compared to sintering in argon atmosphere. The densities of the AlN/TiB2 composites containing different amounts of TiB2 all reached 99% of the theoretical density during 2 h of sintering at 1850 and 1900 °C. Microstructure analysis revealed that the TiB2 particles were dispersed in the AlN matrix while AlN grains retained its contiguity. This microstructure led to a composite with superior properties; thermal conductivity as high as 149 W/(m K) was achieved. The microwave sintered composites are harder and tougher than pure AlN. Microwave-sintered AlN/TiB2 composite is a promising material for structural applications in which high thermal conductivity and controlled dielectric loss are important.