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

► When the normal load is 2 N, ultra-low friction coefficient less than 0.005 can be achieved at each experiments. ► At the normal load of 5 N, two kinds of results were obtained: (a) low friction case (μ < 0.005) and (b) high friction case (μ > 0.1). During the whole times of experiments, the appearance probability of the low friction case was about 20%. ► Low friction can only be obtained after a much smoother worn surface achieved both at the load of 2 and 5 N. The smoothing process may be attributed to tribochemical wear. Mechanical wear could be the dominating factors at the high friction case.