LAUSR

Abstract Monolithic TiB 2 and TiB 2 –5 wt% Si 3 N 4 ultrahigh temperature ceramics were fabricated by spark plasma sintering (SPS) at 1900 °C for 7 min under 40 MPa. The addition of Si 3 N 4 as a sintering aid had a remarkable impact on the microstructure development of TiB 2 -based ceramic. X-ray diffraction (XRD) analysis and microstructural investigations verified the formation of BN nano-platelets, TiN and SiO 2 in the Si 3 N 4 -doped TiB 2 sample via chemical reactions of Si 3 N 4 with the oxide impurities (TiO 2 and B 2 O 3 ) present on the surface of TiB 2 particles. The removal of surface oxide layers significantly prevented the extreme grain growth of TiB 2 matrix, which resulted in improved sinterability and relatively finer microstructure. Moreover, the formation of SiO 2 promoted the densification through the liquid phase sintering mechanism.