Phosphonium phosphate ionic liquids (PP-ILs) have attracted considerable attention in tribology owing to their good miscibility in hydrocarbon fluids and excellent lubrication performance. The majority of the studies in the literature evaluating the lubricating properties of PP-ILs was carried out with high-purity ILs, whose high cost mainly derives from difficult and time-consuming purification required to remove contaminants (<i>e.g.</i>, residual halide ions from the synthesis). Here, we perform macroscale tribological (52100 steel-vs.-52100 steel) experiments in the presence of PP-ILs with systematically-varied concentration of a common halide contaminant, <i>i.e., </i>bromide, to identify its influence on the tribological response of PP-ILs. Based on subsequent analyses of the surface chemistry of steel by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry, a simple phenomenological model will be proposed to account for the observed tribological behavior.

Effects of halide contaminants on the lubricating properties of phosphonium phosphate ionic liquid

ACS Spring Meeting 2021

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