Effect of Lubricant Additives on the WDLC Coating Structure When Tested in Boundary Lubrication Regime

Abstract

Improvements of coating deposition technology enable the mass production of high

Green Tribology for the Sustainable Engineering of the Future

“…The requirement for greener lubrication was then a clear push to developing even stronger DLC-tailored additives, which may not be the best route for DLC lubrication solutions, and especially green sustainable engineering. Accordingly, many studies have focused on low-sulphated ash, phosphorus and sulfur (SAPS) oils and their interactions with DLC [51] to [54]. These studies showed that even low-SAPS oils can effectively protect the surfaces and reduce the friction.…”

The Effect of a Gear Oil on Abrasion, Scuffing, and Pitting of the DLC-Coated 18CrNiMo7-6 Steel

“…The review of the literature allows one to state that it is the DLC coating that is currently used in the majority of tribological research works.Apart from testing thin coatings, it is also important to select a proper oil to lubricate the coated parts [15]. For decades, a lot of research works have been devoted to investigating the interaction between the lubricating additives in the oil with the steel surface [21][22][23][24][25][26][27][28][29][30][31][32], and the mechanisms of the interaction between steel surfaces and lubricants are well recognized.Concerning the interaction between the oil and the thin coating, the publications are less frequent [15,18,[33][34][35][36][37][38] and have been mostly issued in the last 20 years. Unlike the oil-steel interactions, when testing coatings, one can find different statements and observations in the literature.…”

“…They stated that one of the reasons for the reduction in friction may be the formation of a thin oxygen-containing layer. On the other hand, according to Yang et al [37], performing pin-on-flat experiments of the W-DLC/cast iron tribosystem, lubricated with a PAO oil with AW and FM additives, the lubricant additives reduce the formation of tungsten oxides, which is a more brittle material, that could lead to the failure of the coating, as is seen in base oil lubrication.Yang et al [38] conducted reciprocating pin-on-plate experiments on a W-DLC/cast iron tribosystem lubricated with an oil withAW and FM additives. They stated that the formation of MoS 2 , by chemical decomposition from MoDTC, is dominant in such a system, rather than the possible formation of WS 2 .…”

“…Concerning the interaction between the oil and the thin coating, the publications are less frequent [15,18,[33][34][35][36][37][38] and have been mostly issued in the last 20 years. Unlike the oil-steel interactions, when testing coatings, one can find different statements and observations in the literature.…”

“…They stated that one of the reasons for the reduction in friction may be the formation of a thin oxygen-containing layer. On the other hand, according to Yang et al [37], performing pin-on-flat experiments of the W-DLC/cast iron tribosystem, lubricated with a PAO oil with AW and FM additives, the lubricant additives reduce the formation of tungsten oxides, which is a more brittle material, that could lead to the failure of the coating, as is seen in base oil lubrication.…”