Effects of different binder systems on the reaction mechanism, microstructure and mechanical properties of PcBN composites

In this paper, PcBN composites were prepared with cBN, Al and Ti micropowders under high temperature and ultra-high pressure. The phase and microstructure of PcBN were analyzed, and the possible reactions in different systems were deduced. The synthesis process of PcBN under high pressure (5.5 GPa) and different temperature (950-1550 degrees C), and the influence of sintering temperature on the hardness and flexural strength of PcBN were studied. The results show that cBN in cBN-Al and cBN-Ti systems has reacted with Al and Ti respectively at 950 degrees C. In the cBN-Al-Ti system, cBN does not react with Al and Ti alone, but Al and Ti react to form a series of intermetallic compounds. With the increase of temperature, the type and mass of phase change constantly, and tend to be stable at 1350 degrees C. The binder has an obvious chemical reaction at the edge of the cBN particle, and the new phase is generated to firmly bond the internal particles together. The mechanical properties of PcBN sintered by cBN-Al-Ti system are the best.