Enhancement of In situ Self-crack-healing Efficient Temperature Region by SiC Nanosizing

Abstract

Self-crack-healing by oxidation of silicon carbide (SiC) is the most effective method to improve the reliability of ceramics, as this eliminates surface cracks completely. Furthermore, if the service condition corresponds to the state under which self-crack-healing can occur, cracks introduced during service can be completely healed during service. However, the ceramic composites having crack-healing ability exhibit only a small efficient temperature region for crack-healing during service. Therefore, the authors have tried to decrease the temperature at which crack-healing reaction becomes active, as well as to increase the temperature limit for bending strength by size reduction in the contained SiC particles. The present study adapts the following self-propagating high temperature synthesis (SHS) to fabricate alumina composite containing nanosized SiC particles: 3(3Al2O32SiO2) + 8Al + 6C = 13Al2O3 + 6SiC. The formed nanosized SiC particles have a particle size of 10—30 nm and exist in alumina grain. As a result, the temperature at which self-crack-healing becomes active can be decreased 200°C by using SHS. Furthermore, the crack-healed specimen has no large strength decrease up to 1300°C. Therefore, new alumina/ SiC nanocomposite is found to exhibit the in situ self-crack-healing efficient temperature region of 300°C.