Effect of Mo2C addition on the formation of core-rim structure and mechanical properties of Ti(C,N)-WC-Mo2C-(Ni, Co) cermet

Ti(C,N)-based cermets with various Mo2C contents (4, 6, 8, 10, 12 and 14 wt%) were fabricated via vacuum hot-pressing sintering. The results showed that the cermets were comprised of coarse hard phase with a core-rim structure and partial fine rimless hard phase, embedded in Ni/Co binder matrix. Mo2C inhibits the rim growth on the coarse hard phase and hinders the dissolution of the fine rimless hard phase, which improves the mechanical properties of cermets. In addition, with the increasing Mo2C content, a bimodal pattern of X-ray diffraction peaks of (Ti,W,Mo) (C,N) solid solution can be observed, which indicates that high content of Mo2C has a different effect on the W and Mo contents in the white core-grey rim and black core-grey rim hard phase. When the Mo2C addition reaches 12 wt%, the cermet exhibits better wear resistance, which is attributed to a film composed of Ti and Mo oxides formed on the sliding interface. This work provides fundamental knowledge about the formation of core-rim structure and mechanical properties of Ti(C,N)-based cermets with various Mo2C contents.