Title: Ultralow Boundary Lubrication Friction by Three-Way Synergistic Interactions among Ionic Liquid, Friction Modifier, and Dispersant

Abstract

Interactions among antiwear additives (AWs), friction modifiers (FMs), and dispersant in a lubricating oil are critical for tribological performance. This study investigates compatibilities of three oil-soluble ionic liquids (ILs, candidate AWs) with an FM, molybdenum dithiocarbamate (MoDTC), and a dispersant, polyisobutene succinimide (PIBSI) under boundary lubrication. Either synergistic or antagonistic effects were observed depending on the IL’s chemistry. Adding an aprotic phosphonium–alkylphosphate or phosphonium–alkylphosphinate IL into the oil containing MoDTC and PIBSI had detrimental impact on the friction and wear behavior. PIBSI was found to preferably interact/react with the aprotic IL to lose its ability of suspending MoDTC and to partially consume or even deplete the IL. In contrast, a protic ammonium–alkylphosphate IL seemed to be able to coexist with PIBSI and work synergistically with MoDTC, yielding a sustainable, ultralow boundary friction. A three-stage tribochemical process is proposed to explain how this IL + MoDTC pair interacts with the contact surface to form a chemically reacted, wear-protective tribofilm supporting a physically adsorbed, friction-reducing film on top. We report this study provides fundamental insights of the compatibilities among three common lubricant components, antiwear, friction modifier, and dispersant, which can be used to guide future lubricant development.

Authors:

Li, Weimin ^[1]; Kumara, Chanaka  ^[2];

• Search DOE PAGES for author "Kumara, Chanaka"
• Search DOE PAGES for ORCID "0000-0002-1496-8886"

Luo, Huimin  ^[2];

• Search DOE PAGES for author "Luo, Huimin"
• Search DOE PAGES for ORCID "0000-0003-1840-3716"

Meyer III, Harry M.  ^[3];

• Search DOE PAGES for author "Meyer III, Harry M."
• Search DOE PAGES for ORCID "0000-0003-4994-1664"

He, Xin  ^[2];

• Search DOE PAGES for author "He, Xin"
• Search DOE PAGES for ORCID "0000-0002-2504-9084"

Ngo, Dien ^[4]; Kim, Seong H.  ^[4];

• Search DOE PAGES for author "Kim, Seong H."
• Search DOE PAGES for ORCID "0000-0002-8575-7269"

Qu, Jun  ^[2]

• Search DOE PAGES for author "Qu, Jun"
• Search DOE PAGES for ORCID "0000-0001-9466-3179"

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+ Show Author Affiliations

1. Chinese Academy of Sciences (CAS), Lanzhou (China). Lanzhou Inst. of Chemical Physics; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)
4. Pennsylvania State Univ., University Park, PA (United States)

Publication Date:

Thu Mar 19 00:00:00 EDT 2020

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities; Chinese Academy of Sciences (CAS)Division

OSTI Identifier:

1616831

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

ACS Applied Materials and Interfaces

Additional Journal Information:

Journal Volume: 12; Journal Issue: 14; Journal ID: ISSN 1944-8244

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; ionic liquids; MoDTC; ZDDP; friction modifier; dispersant; synergistic effect