The crack healing behavior of ZrO2/SiC composite ceramics with TiO2 additive

This paper was carried out to assess the crack-healing behavior of ZrO2 composite ceramics. The ZrO2 composite ceramics were made by adding 10 wt.% SiC and TiO2. The TiO2 additives were changed to 1, 3 and 5 wt.%. The characteristics of crack-healing behavior were studied as a function of annealing temperature and time. Specimens were mirror polished. The cracks of about 100 μm were introduced on the specimen surface by Vickers indenter and specimen were heat-treated. The strength of crack-healing was conducted by a three-point bending, and the each specimens was measured by XRD. The results obtained in this study are as follows: The ZST composite ceramics contained crack-healing properties, and the strength of ZST smooth specimens have been shown to be better than ZS specimens. The optimum crack-healing condition of the ZTS3 specimen was 1073 K, 5 hours in the air. Specimens with heat treatment had micro-cracks and large cracks on the surface, but the micro-cracks on the surface did not affect the bending strength. It was found that specimens display phase transformation from tetragonal crystal to monoclinic crystal after heat treatment.