Effect of TiN-Al System Binder Ratio on Properties of Polycrystalline Cubic BoronNitride Composite

Taking cubic boron nitride (cBN), TiN, and aluminum as raw materials, polycrystalline cubic boron nitride (PcBN) composites by sintering at 1 500℃ and 5.5 GPa. The effect of the mass ratio (21:4,17:8,13:12,9:16) of TiN to Al in the TiN-Al system binder on the phase composition, microstructure, hardness and wear resistance of PcBN composites was studied. The results show that PcBN composite was mainly composed of BN, TiB₂, TiN, AlN and Al₂O₃ phases. With increasing the aluminum content in the binder, the structure of PcBN composite became denser, and the porosity decreased; the hardness and wear ratio first increased and then decreased. When the mass ratio of TiN to Al was 17:8, the comprehensive property was the best with the largest hardness and wear ratio of 35.8 GPa and 7 500, respectively, and the relatively small porosity of 0.83%.