Microstructure and properties of AlN-BN composites prepared by sparking plasma sintering method

Spark plasma sintering (SPS) method was applied to prepare aluminum nitride/boron nitride (AlN-BN) composites using Sm2O3-CaF2 as sintering additives. Effects of sintering additive and BN content on microstructure, thermal conductivity and dielectric properties of AlN-BN composites were investigated. The results reveal that dense AlN-BN composites with uniform microstructure can be successfully fabricated by SPS method. Suitable sintering additive not only promotes sintering densification process but also improves thermal and dielectric properties of AlN-BN composites through liquid phase sintering. AlN-BN composites containing 8 wt.% sintering additives exhibit higher thermal conductivity and lower dielectric loss. BN content, sintering additive, impurity elements, secondary phases, dislocation, and pores have influence on dielectric loss of AlN-BN composites. The main polarization mechanism of AlN-BN composites might be the space charge polarization. (C) 2016 Elsevier B.V. All rights reserved.