Effects of microstructure modification on properties of AlN/BN composites

Abstract

It is very difficult to prepare full-densified aluminum nitride-boron nitride (AlN/BN) composite ceramics with homogeneous microstructure and high thermal conductivity. Spark plasma sintering (SPS) was used to fully densify the AlN/BN composites in this work. Microstructure, mechanical properties and thermal conductivity of the SPS sintered AlN/BN composites with 5–30 vol% BN were investigated. The results show that the microstructure of composites is fine and homogenous, and the AlN/BN composites exhibit high mechanical properties. To promote the growth of AlN grains and modify the distribution of grain boundary in AlN/BN composites, a heat treating methodology was introduced through gas pressure sintering (GPS). This processing was significantly beneficial to enhancing the thermal conductivity of the specimen. The thermal conductivity of AlN/BN composites with 5–30 vol% BN reached 60 W/m·K after the samples were treated by GPS.

Keywords

AlN/BN composites / thermal conductivity / microstructure modification

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