Friction and wear properties of N+ ion-implanted silicon nitride

In order to investigate the effect of surface modification by ion implantation on friction and wear properties of sintered silicon nitride, a series of ball on disc type friction and wear tests was carried out on the non-implanted and ion-implanted silicon nitride. Ion implantation changes the friction and wear properties of silicon nitride depending on the dose of ion implantation. The ion-implanted silicon nitride with low dose (1×1017 ions/cm2) shows slightly low friction coefficient accompanying the oscillation of the coefficient, in comparison with the non-implanted silicon nitride. Also the ion-implanted silicon nitride with low dose shows low wear resistance; the wear volume is greater than that of non-implanted silicon nitride. This suggests that the wear progresses in a weak wear resistance layer, i.e., the irradiation damaged layer. On the other hand, the ion-implanted silicon nitride with high dose (2×1017 ions/cm2) shows extremely low friction coefficient during the early stage of rotation cycles, and in this stage the wear scarcely occurs.