ENHANCEMENT OF SELF CRACK HEALING ABILITY IN STRUCTURAL CERAMICS BY SIC NANO-SIZING

摘要

In the present study, the efficient temperature range for in-situ self-crack-healing has been widened by SiC nanosizing. The following self assembly reaction was used to synthesize alumina composites containing nano-size silicon carbide particles: 3(3Al{sub}2O{sub}3 2SiO{sub}2) + 8Al + 6C = 13Al{sub}2O{sub}3 + 6SiC. The SiC particles formed have a particle size from 10 nm to 30 nm and are present both inside matrix alumina grains and on grain boundaries. It was found that the new alumina/SiC nano composites could heal the pre-crack of 0.1 mm at 1223 K for 10 h. The temperature is 250 K lower than that of the previous alumina/SiC composite (SiC particle size = 270 nm). Furthermore, the crack-healed specimens exhibit no large strength decrease up to 1573 K. Therefore, the present new alumina/silicon carbide nano-composites widen the in-situ self-crack-healing efficient temperature range up to 300 K.