Enhancement of the self-healing ability in oxidation induced self-healing ceramic by modifying the healing agent

摘要

The available temperature range of the self-healing induced by high temperature oxidation of SiC can be controlled by the particle size of the contained SiC particles. In this study, three types of alumina-SiC composites were prepared. The SiC particle sizes of the composites were 270, ～30nm, and less than 10 nm. The self-healing abilities were estimated by the strength recovery behavior at several temperatures. The use of nanometer-sized dispersed SiC particles as healing agent decreases the activation energy of the SiC oxidation obtained from the differential thermal analysis with several heating rates. This implies that smaller SiC particles can give rise to the oxidation at lower temperature. Moreover, the lowest temperature at which the cracked strength was completely recovered for 10h was strongly affected by the SiC particle size. As the SiC particle size varied from 270 to ～30nm, the lowest temperature varied from 1300 to 950°C. However, alumina composite containing SiC particles whose particle size is less than 10nm cannot recover completely the cracked strength under every condition, because the space between crack walls cannot be filled with the formed oxide due to the small volume of SiC on the crack walls. Therefore, it was found that there is an optimal SiC particle size for endowing self-healing ability.