Abstract
It has been found that carbon nitride (CN_x) coating/silicon nitride (Si_3N_4) provides low and stable friction coefficient of 0.01 or less in nitrogen gas environment, further such low friction is easily obtained by using N_2 gas stream to the contact interface of the frictional pair. In this paper, effect of substrate for the CN_x coating on friction of CN_x/Si_3N_4 under N_2 gas stream is clarified from view points of their surface roughness and surface electrical charge caused by friction. Low friction coefficient of the order of 0.01 is obtained in smooth surface (Ra<21nm) of CN_x/Si_3N_4 under N_2 gas stream by electric discharge with an ionizer or semi-conductive substrate for the CN_x coatings.
