Lubrication mechanism of a strong tribofilm by imidazolium ionic liquid

Abstract Friction modifiers (FMs) are surface-active additives added to base fluids reduce friction between rubbing surfaces. Their effectiveness depends on their interactions with surfaces and may be mitigated by the choice of fluid. In this work, performance an imidazolium ionic liquid (ImIL) additive in polyethylene-glycol (PEG) 1,4-butanediol for lubricating steel/steel diamond-like-carbon/diamond-like carbon (DLC—DLC) contacts were investigated. ImIL-containing PEG reduces more effectively steel—steel than DLC—DLC contacts. contrast, adding ImIL results increase Results from Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), focused ion beam-transmission electron microscopy (FIB-TEM) reveal that a surface film is formed steel during PEG. This consists two layers. The top layer composed amorphous easily removed rubbing. bottom layer, which contains iron oxide nitride compound, adheres strongly surface. maintains its contact even after depleted. Such not observed where adsorption hindered, as suggested quartz crystal microbalance (QCM) measurements. No benefit when fluid own sufficiently lubricious, case DLC work provides fundamental insights how compatibilities among fluid, FM, affect IL active additives. It reveals structure (IL) film, effective durable. knowledge useful guiding future development.