Effect of binder content on microstructure and mechanical properties of PcBN composites

In this study, polycrystalline cubic boron nitride (PcBN) composites were successfully prepared under ultrahigh pressure (5.5GPa) and high temperature (1500 ?C) by using cBN as precursor and TiC, Ti and Al as binders. The effects of the binders? content on the phase composition, microstructure and mechanical properties were systematically investigated. The results showed that new phases such as TiB2, TiC and AlN were generated during the sintering process, which significantly improved the material properties.With the increase of the binder content, the internal structure of the material tends to be continuous and homogeneous, and the densification is improved. When the binder content is 14wt.%, the composite shows the optimal comprehensive performance. Its microhardness, flexural strength and fracture toughness reach 3490Hv, 970MPa and 7.2MPa?m1/2, respectively, confirming a good balance between hardness and toughness. In addition, the introduction of the binders optimizes the thermal conductivity of the PcBN composites at room temperature as well as at high temperatures. This study provides an important theoretical and experimental basis for the design and preparation of high-performance PcBN composites.