Effect of tungsten content on microstructure and mechanical properties of PCBN synthesized in cBN-Ti-Al-W system

Polycrystalline cubic boron nitride (PCBN) compacts were prepared using the mixture of cubic BN and Ti-Al-W powders at 5.5 GPa and 1550 °C for 10 min. The influence of different Tungsten (W) content on composition, microstructure, porosity, mechanical property and cutting performance of the PCBN is investigated. The results show that, with the addition of tungsten, the cubic boron nitride (cBN) crystals are connected with each other by the new product phases TiB2, TiN, Al3Ti and W2B under the pressure of 5.5 GPa and the temperature of 1550 °C. The rod-shaped crystals in the PCBN are expanded from the surface portion of the cBN. As the W content increases, the amount of rod-shaped crystals and the length-diameter ratios decrease in the system. When the tungsten content is 6 wt%, PCBN presents the best comprehensive performance and cutting performance, the porosity, the hardness, the flexural strength and the flank wear are 0.55%, 30.71 GPa, 972.3 MPa and 292 μm, respectively.