Abstract
We recently reported a new molecular heterocyclic friction modifier (FM) that exhibits excellent friction and wear reduction in the boundary lubrication regime. This paper explores the mechanisms by which friction reduction occurs with heterocyclic alkyl-cyclen FM molecules. We find that these chelating molecules adsorb onto (oxidized) steel surfaces far more tenaciously than conventional FMs such as simple alkylamines. Molecular dynamics simulations argue that the surface coverage of our heterocyclic FM molecules remains close to 100% even at 200 °C. This thermal stability allows the FMs to firmly anchor to the surface, allowing the hydrocarbon chains of the molecules to interact and trap base oil lubricant molecules. This results in thicker boundary film thickness compared with conventional FMs, as shown by optical interferometry measurements.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 40203-40211 |
| Number of pages | 9 |
| Journal | ACS Applied Materials and Interfaces |
| Volume | 10 |
| Issue number | 46 |
| DOIs | |
| State | Published - Nov 21 2018 |
Funding
The authors gratefully acknowledge US Department of Energy for research support under Contract DE-EE0006449 and sincerely thank AkzoNobel and Valvoline Inc for generous sample supplies. Dr. M. Desanker thanks the National Defense Science and Engineering Graduate Fellowship Program of the Department of Defense (DoD) for support. The authors also thank Drs. M. Delferro, A. Erdemir, and A. Greco at Argonne National Laboratory, Dr. Y. He of Sinopec Corp., and Dr. B. Johnson of Northwestern University for helpful discussions.
Keywords
- boundary lubrication film
- elastohydrodynamic lubrication
- friction modifier
- heterocyclic
- surface adsorption
ASJC Scopus subject areas
- General Materials Science