Effect of C/N ratio and sintering temperature on microstructure and mechanical properties of Ti (C, N)-based cermets

In this paper, the mechanical properties of Ti(C,N)-based cermets were further optimized by varying the C/N ratio and sintering temperature. The results show that all the cermets are consist of Co, TiB2, Ti(C, N), (Ti, W)(C,N) and CoW2B2 phases. A small amount of Co3C phase is present in the sintered specimens at 1600 and 1650°C. The Co3C phase disappears as the sintering temperature increases to 1700 °C. The decrease of C/N ratio and the increase of sintering temperature promote the densification of the cermets. The increase in C/N ratio enhances the mechanical properties of the cermets regardless of the sintering temperature. The hardness, bending strength and fracture toughness of the cermets show linear changes with increasing sintering temperature. The optimized comprehensive properties at a C/N ratio of 0.5 and a sintering temperature of 1650 °C are 1934 HV10, 855 MPa, and 7.07 MPa m1/2.