Effect of sintering additive composition on microstructure and mechanical properties of silicon nitride

Silicon nitride ceramics doped with four different composition of sintering additives were prepared by hot pressing (HP) sintering. The effect of CeO2 addition and Yb2O3 addition on the formation temperature of liquid phase, the densification, the microstructure and the mechanical properties of Si3N4 ceramics were investigated. The results show that their effects are independent of each other. Furthermore, in comparison to Si3N4 ceramics sintered with sole lanthanide oxides, the samples sintered with both CeO2 and Yb2O3 additions exhibited superior mechanical properties even with a lower sintering temperature.