Atom Probe Tomography Unveils Formation Mechanisms of Wear-Protective Tribofilms by ZDDP, Ionic Liquid, and Their Combination
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
The development of advanced lubricant additives has been a critical component in paving the way for increasing energy efficiency and durability for numerous industry applications. However, the formation mechanisms of additive-induced protective tribofilms are not yet fully understood because of the complex chemomechanical interactions at the contact interface and the limited spatial resolution of many characterizing techniques currently used. In this paper, the tribofilms on a gray cast iron surface formed by three antiwear additives are systematically studied; a phosphonium-phosphate ionic liquid (IL), a zinc dialkyldithiophosphate (ZDDP), and an IL+ZDDP combination. All three additives provide excellent wear protection, with the IL+ZDDP combination exhibiting a synergetic effect, resulting in further reduced friction and wear. Atom probe tomography (APT) and scanning transmission electron microscopy (STEM) imaging and electron energy loss spectroscopy (EELS) were used to interrogate the subnm chemistry and bonding states for each of the tribofilms of interest. The IL tribofilm appeared amorphous and was Fe, P, and O rich. Wear debris particles having an Fe-rich core and an oxide shell were present in this tribofilm and a transitional oxide (Fe2O3)-containing layer was identified at the interface between the tribofilm and the cast iron substrate. The ZDDP+IL tribofilm shared some of the characteristics found in the IL and ZDDP tribofilms. Finally, tribofilm formation mechanisms are proposed on the basis of the observations made at the atomic level.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1376428
- Journal Information:
- ACS Applied Materials and Interfaces, Vol. 9, Issue 27; ISSN 1944-8244
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Engine Oils in the Field: A Comprehensive Chemical Assessment of Engine Oil Degradation in a Passenger Car
|
journal | May 2019 |
Five-Stage Selection Procedure of Ionic Liquids for Lubrication of Steel–Steel Contacts in Space Mechanisms
|
journal | May 2019 |
Material‐Dependent Antagonistic Effects between Soot and ZDDP
|
journal | February 2020 |
High lubricity and electrical responsiveness of solvent-free ionic SiO 2 nanofluids
|
journal | January 2018 |
Correlation Between Engine Oil Degradation, Tribochemistry, and Tribological Behavior with Focus on ZDDP Deterioration
|
journal | May 2019 |
Similar Records
Correlating mechanical properties and anti-wear performance of tribofilms formed by ionic liquids, ZDDP and their combinations
Tribological bench and engine dynamometer tests of a low viscosity SAE 0W-16 engine oil using a combination of ionic liquid and ZDDP as anti-wear additives