Mechanical properties and microstructure of Al₂O₃-TiB₂-TiSi₂ ceramic tool material

A new type of Al₂O₃-TiB₂-TiSi₂ ceramic tool material was fabricated by vacuum hot pressing technique. TiSi₂ added into present composite ceramic was for better use of its superior oxidation susceptibility to crack-healing of ceramic. The fracture surface of Al₂O₃-TiB₂-TiSi₂ ceramic tool material was observed by Scanning electron microscopy, energy-dispersive spectrometry and X-ray diffraction. The effects of TiSi₂ content, sintering temperature and sintering duration time on mechanical properties and microstructure of the material were discussed extensively. The average grain size was decreased with an increase in the dosage of TiSi₂. However, an excess of TiSi₂ would cause abnormal growth of grain. Transgranular fracture and intergranular fracture were found on fracture surfaces. It indicated that the optimized content of TiSi₂ was 15 wt%, the optimized sintering parameters of the ceramic tool material were a sintering temperature of 1600 °C, a pressure of 32 MPa and a sintering duration time of 30 min. TiSi and Ti₅Si₃ were identified as the transformed products of vacuum hot pressing. The optimum comprehensive mechanical properties of the Al₂O₃-TiB₂-TiSi₂ ceramic tool material were measured with the flexural strength, Vickers hardness and the fracture toughness of 711.98±41.48 MPa, 16.89±0.27 GPa and 4.82±0.10 MPa m^1/2, respectively.