Effect of sintering temperature on synthesis of PCBN in cBN-Ti-Al-W system

Polycrystalline cubic boron nitride (PCBN) was prepared under high-temperature and ultra high-pressure. The influence of sintering temperature on composition, micro-structure, relative density, porosity, micro-hardness and flexural strength of the PCBN was investigated by means of X-ray diffraction (XRD), field scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that the phase components of PCBN have no significant difference, which are composed of BN, TiN, TiB2, W, AlN, W2B and Al3Ti when the sintering temperature at 1500 °C–1600 °C. The cBN crystals connect with each other by the reaction product. With the increase of sintering temperature, the porosity of PCBN decreased from 1.05% to 0.53%, and the relative density increased from 94.5% to 99%. When the sintering temperature increasing to 1600 °C, the PCBN exhibit optimal comprehensive mechanical properties with a micro-hardness of 34.64GPa and a flexural strength of 1005.23 MPa. [Display omitted] •There are some rod-like crystals and fibrous crystals extend from the cBN boundary.•The fracture of PCBN is the result of the interaction of crystal fracture and transgranular fracture.•When the sintering temperature increasing to 1600°C, the microhardness is 34.64 GPa and the flexural strength is 1005.23 MPa.