Effect of Zr/Al binder ratio on properties of PCBN composites

Polycrystalline cubic boron nitride composites (PCBN) were synthesized by mixing cBN micro-powder, Zr powder and Al powder in different mass ratios under high temperature and ultra-high pressure conditions. The phase composition and microstructure of the composites were analyzed by X-ray diffraction and scanning electron microscopy. The effects of different Zr/Al mass ratios to the sintering behavior and related properties of PCBN composites were studied in order to obtain a binder ratio scheme with excellent performance. The research shows that when the Zr/Al ratio is 16 wt%:8 wt% (2:1), the hardness of the sample is the highest, which is 33.4 GPa, and the fracture toughness is the best 6.6 MPa·m1/2. Crack bifurcation, deflection and particle reinforcement have significant reinforcement and toughening effects on PCBN composites. When the Zr/Al ratio is 12 wt%:12 wt% (1:1), the PCBN composite with the best density is obtained, the porosity is as low as 0.7%, and the strength of the sample is the highest, which is 864.2 MPa.