This study examined the strength of SiC composite ceramics according to the effect of surface roughness. If high strength of SiC composite ceramics are obtainable without a mirror polishing, the machining cost can be decreased. In this regard, nonpolished and polished smooth specimens which were polished at several grinding conditions were heat treated at an optimum heating temperature of 1373 K for 1~10 hours, and, the strength was investigated in relation to heat treatment time and surface roughness. The strength of the non-polished smooth specimen increased after heat treatment, but the surface cracks were not healed completely. Besides, the strength reached a saturation point at any heat treatment time. The bending strength depends on the surface roughness. The bending strength using a polishing plate of 125 μm is higher than that of 6 μm at a heat treatment of three hours. This result shows that cracks and defects from machining can be healed by heat treatment within the limits of surface roughness.

Keywords: SiC ceramics, Surface roughness, Crack healing, Bending strength.