After sintering SiCf/SiC composite ceramics as a material applied to the blanket structure of a fusion reactor, micro-cracks are created by conducting a Vickers test. The presence of a crack was observed using a SEM and the relation between the bending strength and the orientation of the reinforcing fibers were analyzed. There is no relation between the bending strength of SiCf/SiC composite ceramics and the size of a pre-crack until a limited crack size. The crack healing behavior was investigated on SiCf/SiC composite ceramics with a coating of SiO2 nano-colloid on the surface using various methods, such as dipping and a hydrostatic pressure. Although the coating treatment with SiO2 nano-colloid is conducted according to the hydrostatic pressure method, SiO2 oxide is only created at the base of a crack. As a result, the recovery of bending strength cannot be anticipated.

Keywords: Crack healing, SiCf/SiC composite ceramics, SiO2 Nano-colloid.