Plasma coatings CrAlN and a-C:H for high efficient power train in automobile

The aim of this study is to find out a correlation between the physical interactions, such as adhesion energy and interfacial tension, and the friction behavior of hydrogenated DLC (diamond-like Carbon) (a-C:H) and CrAlN with lubricants for increasing the efficiency of power train. The lubricants investigated are mineral oil, polyalphaolefin, synthetic ester, polyether and polyglycol. The tribological tests for determination of friction behavior of a-C:H and CrAlN with lubricants were performed in a pin-on-disk tribometer in boundary lubrication regime under a contact pressure of 1.2 GPa. The investigations show that for an optimum wettability of the plasma coated surfaces with lubricants, it is important to adapt both the adhesion energy and interfacial tension, such that increasing the adhesion energy of the lubricant on plasma coatings, whilst decreasing interfacial tension leads to a decrease of the friction coefficient.