Investigation of the effect of the SiC particle size on the properties of the AlN–SiC composite ceramic

In this paper, high density AlN–SiC composite ceramic with Y2O3 as the sintering additive was prepared by pressureless sintering at 2000 °C in an inert gas atmosphere. The effects of original SiC particle size on the properties of the AlN–SiC composite ceramic, such as density, thermal conductivity, electrical resistivity and dielectric properties at X band were characterized and investigated. With the increase of SiC particle size, the density of AlN–SiC composite ceramic decreased, the electrical resistivity increased, and the dielectric constant decreased while the dielectric loss (tgδ) increased. XRD analysis showed no solid solution formed between AlN and SiC. SEM showed a uniform microstructure in the AlN–SiC composite ceramic with micron SiC powder. In this study, AlN–SiC composite ceramic with 2 μm SiC powder showed the best performance, with the highest thermal conductivity of 45.53 W/(m·K) at room temperature, relatively higher tgδ value of 0.37–0.47 and lower dielectric constant of 14–17, reasonably high sintering density and electrical resistivity.