Effect of Si/Ti additive on the preparation and properties of cBN-diamond composite sintered by high-temperature and high-pressure

CBN-diamond composites with Si/Ti additive were synthesized by high temperature and high-pressure (HPHT) method. The optimum molar ratio of Si/Ti was proposed. Effect of Si/Ti additive on performance of cBN-diamond composites was systematically investigated. The results show that the introduction of Si promoted the densification of specimens and contributed to the formation of Ti (C, N) which reflected the covalent structure of cBN-binder-diamond. The obtained composites presented excellent bending strength of 705 MPa and hardness of 64 GPa. The enhancement in mechanical properties was mainly ascribed to the formation of strong covalent bonds of C-N-Ti, SiC and TiB at grain boundaries.