High Pressure and High Temperature Sintered PcBN Using Al, B4C and C as Sintering Additive

Polycrystalline cubic boron nitride (PcBN) composites were sintered by high pressure and high temperature sintering (HPHT) at 1450 °C for 3 min under a pressure of 5.0 GPa. Aluminium,boron carbide and carbon in the starting mixture reacts with cubic boron nitride (cBN) to form Al3BC3 and AlN bonding among cBN grains during sintering. X-ray diffraction (XRD) and Scanning electron microscope (SEM) were used to analyze phases and micro-structure of the sintered samples. The dense structure of super hard cBN grains bonded together with Al3BC3 and AlN offers superior hardness and high strength. The Vickers hardness of PcBN composites was 45±5 GPa, and the strength of PcBN composites was 345±15 MPa.