Abstract
About 15% of the available energy in automobile engine is dissipated as mechanical, mainly frictional loss. In automobile engine, friction coefficient of boundary lubrication mode should be expected to be reduced less than 0.05 under reciprocating sliding parts. Recently, in order to overcome this problem, the synergy effect of specific DLC (Diamond-Like-Carbon) coating doped with various elements and friction modifier as MoDTC are expected under boundary oil lubrication. Therefore we prepared carbonaceous hard coatings doped with Ta and N by a combination coating equipment combined with FCVA (Filtered Cathodic Vacuum Arc) deposition and a gas ion implantation source. And a reciprocation sliding friction tests against SUJ2 roller were conducted under PAO base oil and PAO oil including MoDTC. We have prepared 4 different carbonaceous hard coatings as ta-C, ta-CNx, ta-C:Ta and ta-CNx:Ta and reciprocation sliding test was carried out in various sliding conditions. And normal load was decreased by 0.5 N after each 100 sliding cycle up to 0.5 N. For PAO base oil, all of carbonaceous hard coatings showed lower friction coefficient compared with SUJ2 disk. Minimum average friction coefficient was 0.11 for ta-C and ta-C:H. On the other hand, for MoDTC including PAO oil, Nitrogen and Tantalum doping ta-C showed lower friction coefficient.
