Effect of water on tribocorrosion of imidazolium based ionic liquid

Abstract

Room-temperature ionic liquids (RTILs) have properties such as high thermal stability, low volatility, non-flammability, low melting point, and broad liquid range, whichare applicable to superior lubricants and additives. Previous researches on RTILs as a lubricant have mainly focused on the characterization of various types of RTILs and synthesizing novel functionalized RTILs. Tetrafluoro-borate (BF4) and hexafluoro-phosphate(PF6) are the two of the most commonly used anions and RTILs based on the 1-n-alkyl-3-methylimidazolium cation with either the BF4 or PF 6 anion are known to be effective lubricants. However, both BF 4 and PF6 have been found to undergo complex tribo-chemical reactions and to producecorrosive acid in the presence of water, which is inevitably present in practical use. To understand lubrication mechanism and design RTILs suited for lubricants, it is important to clarify the molecular behavior of water which mixed intoRTILs under lubricatingcondition. © 2013 The Japan Society of Mechanical Engineers.