Effect of titanium content on microstructure and mechanical properties of PcBN synthesized in cBN-Si_3N_4-Ti system

摘要

Abstract In this paper, Polycrystalline cubic boron nitride (PcBN) is prepared under a high temperature and an ultra‐high pressure. The influence of different titanium (Ti) content on composition, microstructure, porosity and mechanical property of the PcBN is investigated by means of x‐ray diffraction, field emission scanning electron microscopy and energy dispersive spectroscopy. The results show that, with the addition of titanium, the cubic boron nitride (cBN) particles are connected with each other by the product phases β‐Si3N4, TiN and TiB2 under the pressure of 5.5 GPa and the temperature of 1600 °C. As the increase of titanium content in the system, the amount of rod‐like crystal β‐Si3N4 and TiB2 formed in the system increases, while the porosity remarkably decreases. When the titanium content is 13 wt%, PcBN presents the best comprehensive performance, hardness and flexural strength are 29.2 GPa and 1022.5 MPa, respectively.