Effect of AlN Content on the Properties of SiC composite ceramics

SiC composites were prepared with MgO-CeO₂ as sintering aids by hot pressing at 1850℃.The densification, thermal conductivity and mechanical properties were investigated with different AlN contents. When AlN is not added, the porosity and bulk density of the sample are the worst 4.71% and 2.43 g/cm³ respectively. When the content of AlN is added to 5wt%, the density of samples increase. The AlN content is further increase to 10wt%-20wt%. The porosity and bulk density of the samples are keep at 0.20% and 3.31 g/cm³ respectively. The highest thermal conductivity of 51.62 W·m^-1·K^-1 is obtained when the AlN content is 10wt%. At the same time,the flexural strength and fracture toughness of the samples reach to the peak of 731.3 MPa and 7.3 MPa · m^1/2 respectively.