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

摘要

XA 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 degrees 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.