Effect of Sintering Temperature on Microstructure and Properties of PcBN Composites

Polycrystalline cubic boron nitride (PcBN) composite was prepared under high temperature and pressure conditions. The phase composition of TiN_0.3/AlN/TaC/WC/VC PcBN composites sintered at different temperatures was analyzed by X-ray diffraction. The microstructure of PcBN composites was analyzed by field scanning electron microscopy. The relative density, abrasive ratio and microhardness of PcBN composites sintered at different temperatures were measured. The experimental results show that the addition of TiN_0.3 accelerates the exchange and transfer of atoms at high temperatures and promotes the formation of internal covalent bonds, resulting in the improvement of the material properties. With the increase of temperature, C and N atoms continuously diffuse into the vacancies in TiN_0.3, resulting in the gradual increase of TiC_0.3N_0.7 content. The TiN_0.3/AlN/TaC/WC/VC PcBN composites had the best overall performance at 1500 °C, with hardness, toughness and abrasive ratio of 26.0 GPa, 8.8 MPa m^1/2, and 271.3, respectively.