Friction wear characteristics of diamond-like carbon coatings in oils containing molybdenum dialkyldithiocarbamate additive

Diamond-like carbon (DLC) coatings are typically used to reduce the friction of sliding parts in automobiles. However, the utilization of DLC coatings in oils containing molybdenum dithiocarbamate (MoDTC) additive causes severe wear of these parts. In this work, we modified the compositions of DLC coatings by varying the cathodic arc deposition process conditions and investigated the effects of the modified compositions on the coating wear properties. The results showed that the wear loss of the DLC coatings increased with the increasing hydrogen concentration or ratio between the sp2- and sp3-hybridized carbon atoms. In addition, the molybdenum oxide species produced during the MoDTC decomposition interacted with the double bonds of the DLC coatings, leading to their cleavage.