TY - JOUR
T1 - Ultralow Boundary Lubrication Friction by Three-Way Synergistic Interactions among Ionic Liquid, Friction Modifier, and Dispersant
AU - Li, Weimin
AU - Kumara, Chanaka
AU - Luo, Huimin
AU - Meyer, Harry M.
AU - He, Xin
AU - Ngo, Dien
AU - Kim, Seong H.
AU - Qu, Jun
N1 - Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/4/8
Y1 - 2020/4/8
N2 - 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. 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.
AB - 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. 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.
UR - http://www.scopus.com/inward/record.url?scp=85083080544&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85083080544&partnerID=8YFLogxK
U2 - 10.1021/acsami.0c00980
DO - 10.1021/acsami.0c00980
M3 - Article
C2 - 32189490
AN - SCOPUS:85083080544
SN - 1944-8244
VL - 12
SP - 17077
EP - 17090
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 14
ER -