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Title: Correlating mechanical properties and anti-wear performance of tribofilms formed by ionic liquids, ZDDP and their combinations

Here we examine the elasticity, hardness, and resistance-to-plastic-deformation (P/S 2) measured via nanoindentation of several tribofilms and correlates these properties to friction and wear behavior. The tribofilms were generated by ball-on-plate reciprocating sliding lubricated by a base oil containing an ionic liquid, phosphonium-organophosphate or ammonium-organophosphate, zinc dialkyldithiophosphate (ZDDP), or combination of IL and ZDDP. Nanoindentation was conducted at room and elevated temperatures. While there seems little correlation between the tribofilm hardness and tribological behavior, a higher modulus generally leads to better friction and wear performance. Interestingly, a lower P/S 2 ratio tends to reduce friction and improve wear protection, which is in an opposite trend as reported for bulk materials. Ultimately, this is likely attributable to the dynamic, self-healing characteristics of tribofilms.
 [1] ;  [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
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Grant/Contract Number:
Accepted Manuscript
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Additional Journal Information:
Journal Volume: 354-355; Journal Issue: C; Journal ID: ISSN 0043-1648
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC), Workforce Development for Teachers and Scientists (WDTS) (SC-27)
Country of Publication:
United States
42 ENGINEERING; nanoindentation; ionic liquid; ZDDP; tribofilm; hardness; resistance-to-plastic-deformation