Oxidation resistance of silicon carbide whisker reinforced sialon composites

Oxidation resistance of silicon carbide whisker (SiCw) reinforced and Y-Yb-Al-O as sintering aid contained sialon composites which were sintered with pressureless sintering and hot isostatic pressing were measured in air at 1473 or 1623K. By oxidation, high temperature strength of composites were slightly increased by oxidation comparing with monolithic whose strength after oxidation were less then before oxidation. From observation of 1623K oxidized specimen, the porous layer whose structure was generated by removing glass phase was under the surface oxidized layer. It is considered that this porous layer may act barrier to diffusion. The thickness of this layer was decreased by SiCw. We suggest that the mechanism of oxidation and effects of SiCw. It is considered that SiCw in the grain boundary of composites act a role of barrier to diffusion, then it leads the enhancement of oxidation resistance of composites like above.