Comparison of an oil-miscible ionic liquid and ZDDP as a lubricant anti-wear additive

• Published in: Tribology international Vol. 71; pp. 88 - 97
• Main Authors: Qu, Jun, Luo, Huimin, Chi, Miaofang, Ma, Cheng, Blau, Peter J., Dai, Sheng, Viola, Michael B.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.03.2014
• Subjects: Additives; Ionic liquids; Lubricant additives; Lubricants; Nanostructure; Oil-soluble ionic liquid; Piston rings; Reciprocating; Thickness; Tribo-film; Wear resistance; ZDDP; Zinc; Oil-soluble ionic liquid; Lubricant additives; Tribo-film; ZDDP
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2013.11.010

This paper reports the anti-scuffing/anti-wear behavior and mechanism of an oil-miscible ionic liquid (IL), trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate, in a base oil at 1.0wt% concentration under both room and elevated temperatures. Results are benchmarked against those for a conventional anti-wear additive, zinc dialkyl-dithiophosphate (ZDDP). Reciprocating sliding, boundary lubrication tests were conducted using a piston ring segment against a cylinder liner piece cut from actual automotive engine components. Although the IL and ZDDP worked equally well to prevent scuffing and reduce wear in the room-temperature tests, the IL significantly outperformed ZDDP in the 100°C tests. The top surfaces and cross sections of the worn surfaces were characterized to reveal the morphology, thickness, nanostructure, and chemical composition of the IL-induced tribo-films. [Display omitted] •Performance and mechanism of an oil-miscible ionic liquid as anti-wear additive.•Direct comparison between the IL and ZDDP at 1.0wt% treat rate in a PAO base oil.•While similar behavior at RT, the IL significantly outperforming ZDDP at 100°C.•Two-layer structured tribo-films revealed on both contact areas of the sliding pair.