Abstract
While soot in engine oil is known to accelerate the wear of diesel and gasoline direct-injection compression-ignition engines, there is a lack of consensus on the wear mechanism though various hypotheses have been proposed in the literature. Particularly, some recently observed antagonistic effects between soot and a common lubricant antiwear additive, zinc dialkyldithiophosphate (ZDDP), while others did not. The discrepancy is, in part, explained by the strong alloy dependence of such antagonism discovered in this study. Four alloys, 52100 steel and M2, M50, and A2 tool steels, are tested in lubricants containing carbon black (CB, a soot surrogate) with and without ZDDP present. Adding the CB alone to the oil increases the wear rate for all steel alloys as expected. However, distinct wear performance is observed for the four steel alloys when ZDDP is introduced to the CB-containing oil: while the 52100 steel has notable wear reduction, the three tool steels suffer significant wear increase. Comprehensive tribofilm characterization suggests that the Mo content in the steel alloy and the sulfur from ZDDP strongly influence wear behavior. The combination of CB/Mo-catalyzed sulfidation and CB-accelerated abrasion is hypothesized to be responsible for the high wear of the Mo-alloyed tool steels.
| Original language | English |
|---|---|
| Article number | 1901956 |
| Journal | Advanced Materials Interfaces |
| Volume | 7 |
| Issue number | 6 |
| DOIs | |
| State | Published - Mar 1 2020 |
Funding
The authors thank C. Huang from Cummins for providing the carbon black, A.G. Bro, C. Dubin, and O. Farng from ExxonMobil for providing the PAO base oil and PIBSI dispersant, E. Bardasz from Lubrizol for providing the ZDDP, and D. Coffey from ORNL for STEM sample preparation. The authors thank Dr. Y. Zhou from ORNL for his research and technical support at the initial stage of the project. The authors also thank L.F. Allard and D.A. Cullen for technical assistant and discussion with STEM analysis. The research was supported by the Vehicle Technologies Office, Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE). Electron microscopy characterization was performed at ORNL's Center for Nanophase Materials Sciences, sponsored by the Scientific User Facilities Division, Office of DOE‐BES. Note: This manuscript was authored by UT‐Battelle, LLC, under contract DE‐AC05‐00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid‐up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe‐public‐access‐plan ). The authors thank C. Huang from Cummins for providing the carbon black, A.G. Bro, C. Dubin, and O. Farng from ExxonMobil for providing the PAO base oil and PIBSI dispersant, E. Bardasz from Lubrizol for providing the ZDDP, and D. Coffey from ORNL for STEM sample preparation. The authors thank Dr. Y. Zhou from ORNL for his research and technical support at the initial stage of the project. The authors also thank L.F. Allard and D.A. Cullen for technical assistant and discussion with STEM analysis. The research was supported by the Vehicle Technologies Office, Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE). Electron microscopy characterization was performed at ORNL's Center for Nanophase Materials Sciences, sponsored by the Scientific User Facilities Division, Office of DOE-BES. Note: This manuscript was authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).
| Funders | Funder number |
|---|---|
| DOE Public Access Plan | |
| Office of DOE-BES | DE-AC05-00OR22725 |
| Scientific User Facilities Division | |
| U.S. Department of Energy | DE‐AC05‐00OR22725 |
| Office of Energy Efficiency and Renewable Energy | |
| Oak Ridge National Laboratory | |
| ExxonMobil Foundation |
Keywords
- ZDDP
- carbon black
- soot
- steel alloys
- tribocorrosion
- wear