Crack-healing behavior of Al₂O₃-TiB₂-TiSi₂ ceramic material

Al₂O₃-TiB₂-TiSi₂ ceramic material was fabricated by vacuum hot pressing technique and the crack healing behavior was investigated by means of high-temperature oxidation. The Vickers hardness indenter was used to precrack with a standard crack length of 300 µm. According to the recovery of flexural strength and the microstructure of crack appearance, the effects of crack healing temperature, healing time and crack length on crack-healing were studied. At the healing temperature of 800 °C for 90 min, the strength of crack-healing specimen was recovered completely and the recovery percentage of flexural strength reached up to 107.25%, compared with the flexural strength of the smooth specimen. The strength of crack-healing specimens with a crack length of 150 µm and 300 µm were fully recovered, but incomplete recovery appeared at the crack length of 500 µm. The crack-healing mechanism was attributed to the crack-filling with liquid phases of SiO₂ and TiO₂ obtained by X-ray diffraction. The crack surface of Al₂O₃-TiB₂-TiSi₂ ceramic material was observed by Scanning Electron Microscopy and Energy-dispersive Spectrometry.