Effect of AlN addition on the thermal conductivity of pressureless sintered SiC ceramics

Dense silicon carbide ceramics with 0.5–10   wt% AlN additions were pressureless densified by two steps sintering using B 4 C and C as sintering additives. The effects of AlN content on density, microstructure and thermal conductivity of SiC–AlN composites were investigated. SiC ceramics can be well densified in the presence of AlN. The phonon scattering mechanism and the Klemens–Callaway theory were used to calculate the thermal conductivity evolution of SiC ceramics result from the dissolved Al and N atoms. The main reason for the degradation of thermal conductivities is the point defect scattering dominated by the differences in size and interatomic forces between impurity and host atoms.