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

Abstract

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°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 µm in length introduced on the sample surface were disappeared completely after heat treatment at 1300°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.