Influence of the crack area on the crack-healing performance of silicon carbide whisker reinforced silicon nitride composite

Abstract

The crack healing properties of Si3N4 composite ceramic reinforced by SiC whiskers (Si3N4/SiCw) was studied. Six kinds of pre-cracks were introduced on the center of the tensile side of the specimens, and the relationship between the crack area and crack healing properties was studied. The results show that the healing effect of strength recovery is similar with that of smooth specimens for pre-cracked specimens with crack depth less than 60 μm. As for the propagated crack and the central through crack, the strength recovery rapidly decreases due to the increase of crack depth. It could be concluded that it is difficult to heal pre-cracked specimens with the crack depth over 90 μm. The main reason is considered to be that the melted glass phase blocked in the surface, and prevented the oxidation reaction in the inner of crack.