The tribological performance of Ti(C,N)-based cermet sliding against Si3N4 in water

Ti(C,N)-based cermets have been attracting much attention because of their good high temperature strength, perfect chemical stability, excellent wear resistance, and relatively better machinability. In this paper, the tribological performance of Ti(C,N)/Si3N4 sliding pairs lubricated in water was investigated using a ball-on-disk tribometer at sliding speed of 200 mm/s. The normal loads are controlled at 2 and 5 N, respectively. The experimental results show that, at the normal load of 2 N, ultra-low friction coefficient (μ < 0.005) is obtained at each experiment. At the normal load of 5 N, two kinds of experimental phenomena were observed. One is that an extremely low friction coefficient is achieved within the running-in period of 12 h. The other shows no ultra-low friction after sliding in water even for 24 h. It is proposed that ultra-low friction coefficient mainly owes to hydrodynamic lubrication caused by surface smoothing. The wear mechanism is tribochemical wear while mechanical wear may be the dominating factor in the high friction case at the normal load of 5 N.