Reaction bonded aluminum oxide composites containing cubic boron nitride

The properties of alumina can be improved by incorporating second phases like zirconia or carbides. It has also been reported that reaction bonded aluminum oxide (RBAO) process can be used as a host matrix for large scale second phase reinforcement particles without causing harmful residual stresses normally encountered with shrinking matrix materials. The potential of using cubic boron nitride in reinforcing alumina has not yet been reported. This work reports some improvements in mechanical properties of alumina achieved by incorporating cubic boron nitride particles in a reaction bonded aluminum matrix. Attrition milled aluminum, alumina and cubic boron nitride powders were heat treated to 800 °C in air followed by sintering to 1300 °C in argon. Sintered samples were found to have better density, hardness and fracture toughness compared to conventionally sintered samples of same composition.