Pressureless sintering mechanism and microstructure of ZrB2–SiC ceramics doped with boron

A pressureless densification mechanism and microstructure development in ZrB2–20 vol.% SiC ceramics with boron additive were investigated. Results showed that the boron addition removed oxygen impurity and improved the densification process. By adding 1 wt.% boron, fully dense ZrB2–SiC ceramics with a fine-grained microstructure was obtained. However, a higher boron addition would lead to fast grain growth of both SiC and ZrB2 grains and a deteriorated densification behavior by forming a liquid phase. The mechanical properties of the sintered ceramics with 1 wt.% boron addition were also evaluated.