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 center dot m(1/2). 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.

Automated summary

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, and the effects of different Zr/Al mass ratios on the sintering behavior and related properties of PCBN composites were studied. The research found that the highest hardness of the sample, 33.4 GPa, and the best fracture toughness, 6.6 MPa·m(1/2), were achieved when the Zr/Al ratio was 16 wt%:8 wt% (2:1). Furthermore, a PCBN composite with the best density, porosity as low as 0.7%, and the highest strength of 864.2 MPa was obtained when the Zr/Al ratio was 12 wt%:12 wt% (1:1).