Healing properties of SiC ceramics according to surface roughness

This study examines the strength of SiC composite ceramics according to surface roughness. If SiC composite ceramics can obtain high strength without mirror polishing, then machine cost can be decreased. In addition, non-polished and polished smooth specimens which are polished at each grinding condition were heat treated at a healing temperature of 1373 K for 1–10 h. Strength investigates relationships between heat treatment time and surface roughness. The strength of the non-polished smooth specimen increased after heat treatment, but the surface cracks weren’t healing completely. Besides, the strength has reached saturation point at any heat treatment time. Surface roughness affects the bending strengths, and the bending strength depends on surface roughness. The bending strength of specimens with roughness below 4 μm recovered the same as that of smooth specimens with mirror polishing in the heat treatment of 1373 K for 1 h. This result shows that cracks and defects by machining can be healed by heat treatment within limits of surface roughness.