In situ production of ultra-fine Ti(C,N)–TiB2–Co cermets by reactive hot processing from the Co–Ti–C–BN system

• Ti(C,N)–TiB2–Co cermets were produced by RHP method from Co–Ti–C–BN system.
• Co and TiB2 evenly distributed in the ultra-fine Ti(C,N) matrix.
• Dense cermets were achieved by controlling carbon contents in the reactants.
• Compared with YT15, dense Ti(C,N)–TiB2–Co has better wear resistance.
• The formation path of Ti(C,N) from the Co–Ti–C–BN system was explored.

In this paper, ultra-fine Ti(C,N)–TiB2–Co cermets were prepared by reactive hot processing from the Co–Ti–C–BN system. Microstructure observation indicated that Co and TiB2 uniformly distributed in the ultra-fine Ti(C,N) matrix. Carbon contents in the reactants had a great influence on the porosity and properties of synthesized cermets. In the range of 11.76–13.79 at.% carbon, dense samples were obtained. With increasing carbon contents, the relative density and hardness decreased due to the existence of residual carbon. The wear resistance of dense Ti(C,N)–TiB2–Co cermets were better than that of YT15 cemented carbide. In addition, the reaction process in the Co–Ti–C–BN system was explored by differential scanning calorimeter and X-ray diffraction. Results revealed that Ti(C,N) was synthesized through the solid solution of carbon into TiN, and the addition of Co to Ti–C–BN mixtures promoted the production of Ti(C,N) by the formation of Co–Ti liquid.