In situ toughening of pressureless liquid phase sintered α-SiC by using TiO2

Abstract

In-situ TiC particles were introduced into the SiC matrix by using TiO2 particles as a Ti source, which was beneficial for the improvement of the fracture toughness of liquid phase sintered SiC ceramics. The in-situ reaction between TiO2 and SiC resulted in the formation of TiC during the sintering process. Compared with the SiC ceramic by adding ready-made TiC particles as reinforced phase, the SiC ceramic had higher density, higher fracture strength and Vickers’ hardness with in situ synthesized TiC. In addition, the fracture toughness of SiC ceramic was also improved by the in-situ introduction of TiC. The fracture toughness of SiC ceramic was enhanced due to the in-situ introduction of small amount of TiC particles, which induced the formation of trace elongated SiC particles. The residual thermal stress field originating from the thermal expansion mismatch between SiC and TiC promoted the crack bridging and deflection, resulting in the improvement of fracture toughness as well.