Cooperativity Between Zirconium Dioxide Nanoparticles and Extreme Pressure Additives in Forming Protective Tribofilms: T
- PDF / 4,209,497 Bytes
- 17 Pages / 595.276 x 790.866 pts Page_size
- 113 Downloads / 187 Views
ORIGINAL PAPER
Cooperativity Between Zirconium Dioxide Nanoparticles and Extreme Pressure Additives in Forming Protective Tribofilms: Toward Enabling Low Viscosity Lubricants Meagan B. Elinski1 · Parker LaMascus1 · Lei Zheng2 · Andrew Jackson1 · Robert J. Wiacek2 · Robert W. Carpick1 Received: 9 July 2020 / Accepted: 24 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Realizing the efficiency benefits of low viscosity lubricants requires novel strategies to avoid failures resulting from increased boundary contact. Zirconium dioxide ( ZrO2) nanoparticles (NPs) form protective tribofilms through tribosintering at lubricated contacts in pure hydrocarbon base oils, suggesting they hold promise for reducing boundary contact-induced failures. However, their tribological behavior alongside co-additives found in fully formulated oils has not been examined in depth. Here, the macroscopic tribological performance of dispersed Z rO2 NPs (1 wt% loading; 5 nm diameter nearly spherical ZrO2 tetragonal phase NPs with organic capping ligands for oil solubility) with and without the presence of co-additives found in fully formulated commercial gear oils was studied using a mini-traction machine (MTM). The results show that ZrO2 NPs reproducibly develop surface-bound ~ 100 nm thick tribofilms on both contacting surfaces under a wide range of rolling-sliding contact conditions, from 0 to 100% slide-to-roll ratio. Steady-state traction coefficient values of ZrO2 tribofilms formed alongside co-additives (0.10–0.11) do not substantially differ from ZrO2 tribofilms formed in neat polyalphaolefin base oils (0.10–0.13). However, there is improvement in the tribological performance of the contact, with at least a twofold reduction of wear of the steel. This behavior is proposed to be a result of cooperating mechanisms, where the extreme pressure additives adsorbed on the steel surfaces protect them against early adhesive wear, during the time that a protective Z rO2 tribofilm incorporating the co-additives forms on the steel surfaces, preventing further wear. Graphic Abstract
Keywords Nanoparticles · Tribofilm · Extreme pressure additives · Tribosintering · Low viscosity gear oil · Co-additives
1 Introduction Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11249-020-01346-1) contains supplementary material, which is available to authorized users. * Robert W. Carpick [email protected] 1
Department of Mechanical Engineering & Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104, USA
Pixelligent Technologies LLC, Baltimore, MD 21224, USA
2
In the pursuit of higher vehicle efficiency, lower viscosity lubricants are an important and widely targeted means of reducing viscous losses. For hypoid gears in automotive rear axles alone, power losses heavily depend on lubricant viscosity [1], to the extent that lower viscosity gear oils could provide up to 2.5% fuel savings [2]. Approximately 1.5 × 1012 U.S. g
Data Loading...
