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 Y2O3 and not containing Y2O3 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, TiB2, TiN, AlN and Y2O3 at an ultra-high pressure of 5.5 GPa and a temperature of 1500 °C. With the increase of Y2O3 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 Y2O3 increases, it can be seen that the peak intensity of the main peak of TiB2 also increases, indicating that the addition of Y2O3 promotes the reaction between cBN and Ti. When the Y2O3 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.