Effect of Y2O3 additive on properties of PCBN composites with TiN-Ti-AlN as binder by high temperature and high pressure sintering

Using TiN-Ti-AlN as the binder, polycrystalline cubic boron nitride (PCBN) composites containing Y ₂O ₃ and not containing Y ₂O ₃ were prepared under high temperature and ultra-high pressure conditions, respectively. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to analyze the phase composition, microstructure and surface crack morphology of the composite material. At the same time, the compactness, microhardness and bending strength of the composite material were tested. The research results show that the phase composition of PCBN sample is mainly composed of BN, TiB ₂ , TiN, AlN and Y ₂O ₃ at an ultra-high pressure of 5.5 GPa and a temperature of 1500 °C. With the increase of Y ₂O ₃ content, the relative density of PCBN first increases and then decreases, and the changes in mechanical properties also tend to be similar. As the content of Y ₂O ₃ increases, it can be seen that the peak intensity of the main peak of TiB ₂ also increases, indicating that the addition of Y ₂O ₃ promotes the reaction between cBN and Ti. When the Y ₂O ₃ content is 3.6%, PCBN has the best comprehensive mechanical properties, with a microhardness of 34.56 GPa and a bending strength of 890 MPa.