Effect of Al2O3-CeO2 molar ratio on mechanical properties of SiC ceramics

In the present work, SiC ceramic samples with Al2O3 and CeO2 sintering additives were prepared by spark plasma sintering (SPS). The effects of Al2O3 to CeO2 molar ratio from 6.25:3.75 to 5:5, 4:6 and 3:7 on sintering behavior, microstructure, Vickers hardness, and fracture toughness of the SiC ceramic samples were investigated and compared. The results showed that, the relative density of SiC ceramic samples increased from 97.8% to 99.2%, and the Vickers hardness increased from 19.72 +/- 0.41 GPa to 21.18 +/- 0.92 GPa as the CeO2 molar ratio increased. The increase in CeO2 molar ratio effectively improved the densification and hardness of SiC ceramics.