Ultralow Boundary Lubrication Friction by Three-Way Synergistic Interactions among Ionic Liquid, Friction Modifier, and Dispersant

• DOI: 10.1021/acsami.0c00980
• Publication Date: 2020-03-19T09:48:13Z
• Authors: Weimin Li; Chanaka Kumara; Huimin Luo; Harry M. Meyer; Xin He; Dien Ngo; Seong H. Kim; Jun Qu
• Keywords: Boundary lubrication; Friction modifier

Interactions among antiwear additives (AWs), friction modifiers (FMs), and dispersant in a lubricating oil are critical for tribological performance. This study investigates compatibilities of three oil-soluble ionic liquids (ILs, candidate AWs) with an FM, molybdenum dithiocarbamate (MoDTC), dispersant, polyisobutene succinimide (PIBSI) under boundary lubrication. Either synergistic or antagonistic effects were observed depending on the IL's chemistry. Adding aprotic phosphonium–alkylphosphate phosphonium–alkylphosphinate IL into containing MoDTC PIBSI had detrimental impact wear behavior. was found to preferably interact/react lose its ability suspending partially consume even deplete IL. In contrast, protic ammonium–alkylphosphate seemed be able coexist work synergistically MoDTC, yielding sustainable, ultralow friction. A three-stage tribochemical process is proposed explain how this + pair interacts contact surface form chemically reacted, wear-protective tribofilm supporting physically adsorbed, friction-reducing film top. provides fundamental insights common lubricant components, antiwear, modifier, which can used guide future development.