Effect of Co content on microstructure and properties of TiCN-TiB2 cermets prepared by spark plasma sintering from a TiCN-B4C-Ti-Co system

Series of TiCN-TiB2 cermets were in situ prepared from the TiCN-B4C-Ti-Co system via spark plasma sintering (SPS). The effects of Co content on the densification, microstructure, mechanical properties, and wear resistance of TiCN-TiB2 cermets were investigated. The results showed that the Co addition had little effect on the phase composition of the sintered cermets, but had significant influences on the densification, microstructure and mechanical properties. Appropriate addition of metal Co could enhance densification and promote the grain growth of ceramic phases, but excessive addition resulted in a decrease in hardness and wear resistance. When the Co content was 10 wt%, the cermet obtained the optimal comprehensive performance (a hardness of 1757 HV and a fracture toughness of 7.02 MPa center dot m1/2). Meanwhile, the cermets with 10 wt% Co addition exhibited optimum wear resistance properties due to a good combination of hardness and toughness and moderate grain size. In addition, the formation process and strengthening mechanism in present system were discussed in detail. Results from this work could provide valuable references for the fabrication of TiB2 reinforced TiCN-based cermets.