Formation of Boundary Film from Ionic Liquids Enhanced by Additives

Room temperature ionic liquids (RTILs) have several properties that make them interesting candidates as base fluids for extreme conditions. However, a lack of compatibility with tribo-improving additives combined with an often overly aggressive nature is limiting their use as base fluids. To overcome these drawbacks, hydrocarbon-imitating RTIL base fluids have recently been developed. In this study, the effects of several common additives in the novel RTIL (P-SiSO) were examined by laboratory tribotesting. A reciprocating steel-steel ball-on-flat setup in an air atmosphere was used, where the lubricant performance was evaluated over a range of loads and temperatures. Surface analyses after testing were carried out using optical profilometry, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Neat P-SiSO displayed high performance in the tribotests. At an elevated load and temperature, a shift in lubrication mode was observed with an accompanying increase in friction and wear. Surface analysis revealed a boundary film rich in Si and O in the primary lubrication mode, while P was detected after a shift to the secondary lubrication mode. An amine additive was effective in reducing wear and friction under harsh conditions. The amine was determined to increase formation of the protective Si–O film, presumably by enhancing the anion activity.

[1]  Li Ye Zhu,et al.  Functionalized Ionic Liquids as Lubricants for Steel-Steel Contact , 2011 .

[2]  Maria Forsyth,et al.  A Review of Ionic Liquid Lubricants , 2013 .

[3]  E. S. Forbes Antiwear and extreme pressure additives for lubricants , 1970 .

[4]  M. Fox,et al.  Chemistry and Technology of Lubricants , 1992 .

[5]  Qian Wang,et al.  Hertz Theory: Contact of Ellipsoidal Surface , 2013 .

[6]  María-Dolores Bermúdez,et al.  Ionic Liquids as Advanced Lubricant Fluids , 2009, Molecules.

[7]  Ichiro Minami,et al.  Anti-wear and friction reducing additives composed of ortho-phenylene phosphate-amine salts for polyether type base stocks , 1998 .

[8]  Feng Zhou,et al.  Benzotriazole as the additive for ionic liquid lubricant: one pathway towards actual application of ionic liquids , 2006 .

[9]  Ichiro Minami,et al.  Effect and mechanism of additives for ionic liquids as new lubricants , 2007 .

[10]  Laigui Yu,et al.  Room-temperature ionic liquids: a novel versatile lubricant. , 2001, Chemical communications.

[11]  Miaofang Chi,et al.  Nanostructure and Composition of Tribo-Boundary Films Formed in Ionic Liquid Lubrication , 2011 .

[12]  Feng Zhou,et al.  Tribological performance of phosphonium based ionic liquids for an aluminum-on-steel system and opinions on lubrication mechanism , 2006 .

[13]  Hugh Spikes,et al.  The History and Mechanisms of ZDDP , 2004 .

[14]  Takeru Chiba,et al.  Effects of Carboxylic Acids on Friction and Wear Reducing Properties for Alkylmethylimidazolium Derived Ionic liquids , 2006 .

[15]  Ichiro Minami,et al.  Concept of molecular design towards additive technology for advanced lubricants , 2007 .

[16]  Yi Ze Sun,et al.  Research on Lattice Distortion Modification Processing Technology of Cotton/Linen Fiber and Yarn , 2012 .

[17]  Hugh Spikes,et al.  On the Mechanism of ZDDP Antiwear Film Formation , 2016, Tribology Letters.

[18]  Qunji Xue,et al.  Effect of tetraalkylphosphonium based ionic liquids as lubricants on the tribological performance of a steel-on-steel system , 2007 .

[19]  Jože Vižintin,et al.  Use of equations for wear volume determination in fretting experiments , 2000 .

[20]  R. W. Carpick,et al.  Mechanisms of antiwear tribofilm growth revealed in situ by single-asperity sliding contacts , 2015, Science.

[21]  Tsukasa Torimoto,et al.  New Frontiers in Materials Science Opened by Ionic Liquids , 2010, Advanced materials.

[22]  Erik Nyberg,et al.  Molecular design of advanced lubricant base fluids : hydrocarbon-mimicking ionic liquids , 2017 .

[23]  J. Föhl,et al.  The reaction layer formed on steel by additives based on sulphur and phosphorus compounds under conditions of boundary lubrication , 1982 .

[24]  Ichiro Minami,et al.  Tribo-Chemistry of Phosphonium-Derived Ionic Liquids , 2010 .

[25]  Feng Zhou,et al.  Effect of the functional groups in ionic liquid molecules on the friction and wear behavior of aluminum alloy in lubricated aluminum-on-steel contact , 2005 .

[26]  姜栋,et al.  Crown-Type Ionic Liquids as Lubricants for Steel-on-Steel System , 2011 .

[27]  Stephen M. Hsu,et al.  Boundary lubricating films: formation and lubrication mechanism , 2005 .

[28]  R. Shubkin Synthetic lubricants and high-performance functional fluids , 1992 .

[29]  L. Rudnick Lubricant Additives: Chemistry and Applications , 2007 .

[30]  Ichiro Minami,et al.  Ionic Liquids in Tribology , 2009, Molecules.

[31]  E. S. Forbes The load-carrying action of organo-sulphur compounds—A review☆ , 1970 .

[32]  Feng Zhou,et al.  Tribological evaluation of α, ω-diimidazoliumalkylene hexafluorophosphate ionic liquid and benzotriazole as additive , 2008 .

[33]  Hiroyuki Ohno,et al.  Aspartic Acid-derived Wear-preventing and Friction-reducing Agents for Ionic Liquids , 2008 .

[34]  Maggel Deetlefs,et al.  Ionic liquids: the view from Mount Improbable , 2016 .