Crack-Healing Behavior and Mechanical Strength Recovery of 5 vol% Silicon Carbide Particle Dispersed Yttrium Monosilicate Composites

Crack-healing effectiveness was investigated as functions of heat treatment time and temperature on 5 vol% SiC-dispersed Y2SiO5-based composites. Dense specimens of SiC/Y2SiO5 composite were fabricated by the pulsed current sintering technique. Thermal oxidation for crack-healing was conducted at temperatures ranging from 1000 to 1300 degrees C for from 1 to 24 h in air. Bending tests were carried out at room temperature on samples before and after heat treatment in order to clarify the crack-healing performance. The results show that SiC/Y2SiO5 composites possess a considerable crack-healing ability. The surface cracks with approximately 200 mu m in length introduced on the sample surface were disappeared completely after heat treatment at 1300 degrees C for 1 h in air. Mechanism of crack-healing was considered as filling up of cracks by Y2Si2O7 oxidation product which is formed by outward diffusion of cations. Bending strength of samples introduced surface cracks after heat treatment was recovered up to the level as high as that of as-sintered samples.