EFFECT OF SURFACE ROUGHNESS OF MATING SURFACE AND TRANSFER LAYER ON FRICTION BETWEEN a-CNx AND Si₃N₄ IN NITROGEN

During the sliding between a-CNx and Si₃N₄, applying nitrogen as environmental gas provided very low friction as the level of 0.01 in friction coefficient. In order to know the effect of the running-in process on the reduction of the friction, the effect of surface roughness of mating surface on friction was investigated. It was shown that smooth surface in wear scar of ball provided low friction coefficient. Friction coefficient after running-in was proportional to the Ry value of wear scar of ball. Also smooth thin transferred layer was observed on the wear scar of balls with an AFM after sliding test. Those results showed the smoothing of wear scar, of ball, the generating of the transferred layer from CNx was necessary for low friction.