Tribological characteristics of amorphous hydrogenated (a-C:H) and tetrahedral (ta-C) diamond-like carbon coating at different test temperatures in the presence of commercial lubricating oil

Tribological properties of amorphous hydrogenated (a-C:H) and hydrogen-free tetrahedral (ta-C) diamond-like carbon coatings under jatropha biodegradable lubricating oil at different temperatures

“…The results show that a-C:H DLC cannot effectively work at a high temperature of 150 • C. Coating durability decreases with increasing temperature because of the high wear rate, which corresponds to a high degree of graphitization [29]. Contrary to the wear behavior of both coating types, the CoF decreases as the temperature increases.…”

“…However, when tested at 150 • C, a complete delamination of the coating occurs during the test because of the high degree of graphitization of the coating [29]. Although a higher degree of graphitization enhances the transfer film formation, the formation of a graphitic transfer layer cannot be observed in the counter surface (Fig.…”

“…Results of studies on DLC coating interaction with oil are conflicting. Some studies have reported a positive chemical interaction between DLC coatings and oils [26][27][28][29][30], but no or negative interaction was found in other studies [31][32][33][34]. Thus, understanding the behavior of DLC coatings under lubricated conditions is important.…”

Influence of intrinsic and extrinsic conditions on the tribological characteristics of diamond-like carbon coatings: A review

“…In an experimental study, Al Mahmud et al 76 investigated the effect of temperature on the tribological performance of ta-C/steel and a-C:H/steel tribopairs in combination with society of automotive engineers (SAE) 40 fully formulated lubricant. Three sets of tribotests were performed at 50, 100, and 150°C with a constant applied load of 392 N. At higher test temperatures, an increase in I D /I G ratio of both tribopairs was verified by Raman spectroscopy which confirmed that phenomenon of graphitization took place as a result of sliding.…”

“…It is mentioned in the literature that passivation of carbon bonds decreases the surface energy of DLC coatings due to which their ability to react with environmental species such as oxygen and moisture also decreases. 76 As a result, surface deterioration due to oxidation is minimized and service life of the contact increases. GMO also proved to be effective in facilitating the sliding of Cr-DLC coated surfaces and resulted in decreased friction coefficients when used as an additive in A-II base oil.…”