The effect of cBN powder particle size gradation and sintering temperature on the microstructure and properties of PcBN

o obtain high-performance polycrystalline cubic boron nitride (PcBN) composites, cubic boron nitride (cBN) powders with particle sizes of 0.5～1 μm, 1～2 μm, and 4～6 μm were used as raw materials with reasonable particle size gradation, Al-Ti-TiN served as the binder, and PcBN composites were prepared under different sintering temperatures (1350–1550 °C) and ultra-high pressure (5.5 GPa). The effects of sintering temperature on the microstructure and properties of PcBN composites were investigated. The results showed that under high temperature and high pressure, Ti and Al reacted with cBN to form TiB2 and AlN, which combined with TiN to form the novel binder. The PcBN composite composed of cBN particle size gradation exhibited high density. As the sintering temperature increased, thee density, Vickers hardness, fracture toughness, and abrasive ratio of PcBN composites initially increased and then decreased. At 1500 ℃, cBN particles bond well with the binder, and PcBN composite exhibits the best properties. Its density, Vickers hardness, fracture toughness, and abrasive ratio reach their maximum values of 3.57g/cm3, 40.73 GPa, 7.83 MPa·m1/2, and 7663, respectively.