Mechanism on specific wear of DLC film in engine oil with Mo-DTC

Abstract

In the oscillating wear test under engine oil containing Mo-DTC (Molybdenum Dithio-Carbamate), friction coefficient and wear volume of cylinder-specimen were lower than without Mo-DTC, in contrast, DLC (Diamond-Like Carbon) film was worn deeply. A residue of oil contained amorphous carbon that had higher proportion of sp 2 electron structure and lower density than DLC as coating. Judging by these results of our investigation, DLC film is graphitized in wear test under lubrication. This specific wear of DLC films is based on the wear mechanism that is attributed to graphitization, and the hard molybdenum sulfide and oxide which are decompositions of Mo-DTC are accelerated wear mechanically. © 2012 The Japan Societ ociety of Mechanical En Engineers ineers.