Synthesis of MgO-CaO-Al 2 O 3 -SiO 2 nanocomposite powder by polymeric complex method as a novel sintering additive of AlN ceramics

A MgO-CaO-Al 2 O 3 -SiO 2 (MCAS) nanocomposite powder with a particle size of 50 nm and a specific surface area of 40.6 m 2 /g was successfully synthesized via heat-treatment of polymeric precursors containing Mg, Ca, Al and Si in air at 700 °C for 5 h. It was characterized as a novel sintering additive for the densification AlN ceramics at a low temperature below 1600 °C. It was found that the nanosized MCAS powder was suitable for the densification of AlN ceramics. In particular, full densification could be achieved when only 1.0 wt% MCAS additive-doped AlN powder compact was sintered for 1 h at 1600 °C, and a thermal conductivity of 84 W/m·K was attained.