Crack-healing behavior of hot-pressed TZ3Y20A-SiC ceramics

Crack healing behavior of hot-pressed TZ3Y20A-SiC ceramics has been investigated by high-temperature oxidation. Semi-elliptical surface cracks with a length of 100 μm have been set on the tensile side of each specimen using a Vickers hardness indenter. Based on flexural strength and observations of crack appearance, the effect of crack healing is finally judged. Cracks on ZrO2(Y2O3)–Al2O3 (TZ3Y20A) ceramics cannot be healed by heat treatment. However, for TZ3Y20A-SiC ceramics, complete crack-healing has been realized by heat treatment at 800 °C, 1000 °C and 1100 °C for 30 h, 10 h and 5 h, respectively. The crack-healing mechanism is attributed to the formation of SiO2 caused by high temperature oxidation during heat treatment.