Phase evolution and performance analysis of PcBN carbide insert prepared by integrated sintering with different WC-Co alloy substrate

In this work, polycrystalline cubic boron nitride (PcBN) carbide insert was prepared by a six-anvil high-pressure apparatus at 1500 °C and 5.5 GPa, integrated sintering with different alloy substrates of the Co content. This work studied the effects of different Co content in alloy substrates on phase composition, microstructure, and mechanical properties of the PcBN carbide insert. The result shows that the binder reacted with cBN particles to produce AlN, AlCo, TiB 2 , W 2 B, and Co 2 B. At the same time, transgranular fracture is wide spread in the sintered body. The flexural strength and hardness of the PcBN carbide insert first increase and then fall. When the alloy substrate is WC-11.5 wt% Co, the PcBN carbide insert shows excellent comprehensive performance, with the flexural strength and hardness reaching 1675.67 MPa and 4100.51 Hv, respectively. Through integrated sintering, Co in the alloy substrate diffused and reacted with the binder in the cBN network at the bonding interface, forming a transition area that significantly improves the bonding strength.