INSITU REACTED TIB2-REINFORCED ALUMINA

Abstract

In situ formation of TiB2 in Al2O3 matrix through the reaction of TiO2, boron and carbon has been studied. In hot-pressed samples, in addition to TiB2, TiC and Al2TiO5, were also found to be dispersed phases in Al2O3 matrix. However, in the case of pressureless-sintered samples, pure Al2O3/TiB2 composite with > 99% relative density can be obtained through a preheating step held at 1300-degrees-C for longer than 30 min and then sintering at a temperature above 1500-degrees-C. Pressureless-sintered composite containing 20 vol % TiB2 gives a flexural strength of 580 MPa and a fracture toughness of 7.2 MPa m1/2.