Friction control between CNx coating and stainless steel ball with electric field

CNx showed ultra low friction that friction coefficient was less than 0.01 sliding against Si/sub 3/N/sub 4/ ball in Nitrogen. However it can not show low friction in air. In order to obtain low friction of CNx coating sliding against stainless steel in air, we applied DC electric voltage to stainless steel. As a result, we showed the possibility of decreasing friction and wear of CNx sliding against stainless steel. Friction coefficient decreased with the increasing negative voltage to apply to the ball and disk in air. On the other hand, positive voltage increased friction coefficient. Friction coefficient of CNx in air decreased from 0.22 to 0.05 by applying electric voltage of DC -200 V. Specific wear rate was decreased with the increasing applied positive and negative voltage. Specific wear rate of CNx in air decreased from 2.86/spl times/10/sup -8/ mm/sup 3//Nm to 1.10/spl times/10/sup -8/ mm/sup 3//Nm by applying electric voltage of DC -200 V.