Effects of hardness and grain size on wear resistance of polycrystalline cubic boron nitride

The exploration of the factors affecting the wear resistance of superhard materials is an interesting and useful work to practical industrial applications. Compared with the wear resistance measurements, the characterization of hardness and grain size is more convenient and simpler. Therefore, we expect to obtain a quantitative relationship between the hardness and grain size of superhard materials on their wear resistance. In this work, a series of polycrystalline cubic boron nitride (PcBN) compacts with different grain size and hardness were sintered under high temperature and high pressure, and the PcBN samples were made into cutting tools. Then, the edge wear of the cutting tool in the process of turning granite was examined. Based on these measurements, the relationship between hardness and wear resistance is analyzed with the condition of the same grain size (1–2 μm), and the influence of PcBN grain size on wear resistance is also analyzed with the same hardness (45.0 ± 1 GPa). Subsequent results show that the wear resistance of PcBN exhibits a regression parabolic and linearly increasing trend with the increase of hardness and grain size, respectively. Further analyses show that the compactness of PcBN materials, the bonding strength between the crystal grains and the depth of the embedded crystal grains are important factors affecting the wear resistance. These works can play a practical guiding role in the preparation, research and development (R&D) of PcBN, and are expected to be extended to the R&D and application of other superhard materials and hard ceramics. • In this paper, we report the effects of hardness and grain size on wear resistance of polycrystalline cubic boron nitride (PcBN) for the first time under the same turning conditions. • When the grain size is similar, the PcBN wear resistance shows a regression parabolic growth trend with the increase in hardness. • When the hardness is similar, the wear resistance of the measured PcBN samples increases linearly with the increase in grain size. • The three most important factors affecting the wear resistance are the compactness of PcBN materials, the bonding strength between grains, and the embedded depth of grains.