In this paper, ZrB2–SiC composites doped with 0, 3 and 6 wt.% Si3N4 were prepared by a low pressure hot pressing as well as a pressureless sintering techniques at 1900 ℃ for 2 h. The effect of silicon nitride using on the sinterability and microstructure development of such ceramic composites was studied. The results revealed that 6 wt.% Si3N4 can assist the densification process of the hot pressed ceramic composite via the liquid phase sintering mechanism due to the formation of glassy phase. In the pressureless sintering techniqe, adding more Si3N4 can increase the formation of gaseous products which raised the amount of porosities in the final microstructure.
