Tribological compatibility analysis of conventional lubricant additives with palm trimethylolpropane ester (TMP) and tetrahedral amorphous diamond-like carbon coating (ta-C)

Abstract

Modern industrial applications involve rigorous operating conditions due to which lubricant either slips out of the contact or its thin layer resides between the interacting surfaces. Deposition of diamond-like carbon coatings and using lubricants capable of physically adsorbing on the interacting surfaces can significantly improve tribological performance. In this study, tribological compatibility of glycerol mono-oleate, molybdenum dithiocarbamate and zinc dialkyldithiophosphate with palm trimethylolpropane ester and tetrahedral amorphous diamond-like carbon coating has been investigated using universal wear testing machine. For comparison, additive-free and formulated versions of polyalphaolefin were used. Moreover, spectroscopic techniques were used to investigate mechanisms responsible for a particular tribological behavior. Among base oils, trimethylolpropane ester proved to be more effective in enhancing friction performance and mitigating wear of contacts when one of the interacting surfaces was ferrous-based. Self-mated tetrahedral amorphous diamond-like carbon coating surfaces resulted in lowest values of friction and wear coefficient of balls.

Tribological Performance of Esters, Friction Modifier and Antiwear Additives for Electric Vehicle Applications

“…For instance, it was found that the lubrication performance of various fatty acids and amines formulated in a polyol ester oil, is highly influenced by structural differences, such as chain length or unsaturations [17] but the influence of the ester performance on the mixture has not been evaluated. Furthermore, the tribological compatibility of a trimethylolpropane (TMP) ester as an additive in a PAO formulation containing glycerol mono-oleate (GMO), molybdenum dithiocarbamate (MoDTC) or zinc dialkyldithiophosphate (ZDDP) was also studied but the main scope was on the influence on DLC coated steel where the ester is more effective by itself [18]. In addition, it was found that under reciprocating conditions, controlled amounts of the ester can improve the lubricant performance, but they can also decrease the activity of the MoDTC additive [19].…”