Abstract: The microstructure and mechanical properties of liquid phase sintered SiC followed by post-hot isostatic pressing (HIP) were studied. It is indicated that the effect of post-HIP treatment is changed with the variation of
sintering aids and temperature of liquid phase sintering. After Ar-HIP treatment, the density of SiC is increased and the inside pores are
diminished, but grain growth is depressed. Besides the advantages of the Ar-HIP, N₂-HIP can modify the surface state because of the reaction
between SiC and N₂ so that the mechanical properties are improved. Microstructure analysis has shown that after N₂-HIP treatment,
grain size is decreased and the density is increased. Meanwhile, the results of post-HIP treatment are highly affected by the microstructure
of the liquid phase sintered SiC. When the sintering temperature is relatively lower and the grain size is smaller, after post-HIP treatment, esp.
N₂-HIP treatment, bending strength and fracture toughness of the liquid phase sintered SiC are improved greatly.

Key words: liquid phase sintering, SiC, post-hot isostatic pressing, microstructure, properties