Study on microstructure and thermal conductivity of Spark Plasma Sintering AlN ceramics

Dense aluminum nitride (AlN) ceramics were prepared by Spark Plasma Sintering with rare-earth oxide and CaF₂ as sintering additives. The effect of sintering additives on the density, phase composition, microstructure and thermal conductivity of AlN ceramics was investigated. The results showed that those sintering additives not only promoted densification through liquid-phase sintering but also improved thermal conductivity by decreasing oxygen impurities. Thermal conductivities of samples sintered with optimum proportion of rare-earth oxide and CaF₂ were higher than those of other samples. During the Spark Plasma Sintering process, the microstructures, especially the content and distribution of secondary phases, played important roles on the thermal conductivity of AlN ceramics.