Preparation of Cubic Boron Nitride Polycrystalline Containing Nanodiamond

The polycrystalline cBN was prepared at 5.5 GPa and 1 400 ℃ for 500 s. The cBN was coated with titanium by vacuum slow vaporizing technology, and nanodiamond, aluminum and silicon were also used as additives to binding components. By SEM and XRD inspections, the structure and phases of PcBN were identified. The density, microhardness and heat endurance of PcBN were also tested. The effects of Ti-coating and nanodiamond in PcBN were studied. The results showed that nanodiamond could be used as carbon source to react with silicon, titanium and aluminum to form various compounds with super hardness, high heat resistance and high stability. These compounds improved the structure consistency and eliminated the extra residual stress between different substances. The residual nanodiamond in PcBN was still in diamond structure, and was not graphitized during the sintering. It not only increased the density and hardness of PcBN, but also reduced the bridging effect. As there were so many kinds of compounds distributed in the binder, the compatibility was improved and the heat endurance of PcBN was increased.