Thornley, A., Wang, Y. orcid.org/0000-0002-0830-4434, Wang, C. orcid.org/0000-0002-4301-3974 et al. (5 more authors) (2022) Optimizing the Mo concentration in low viscosity fully formulated oils. Tribology International, 168. 107437. ISSN 0301-679X
Abstract
Molybdenum dithiocarbamate (MoDTC) is usually added in low viscosity engine oils to improve its ability to reduce friction. However, increasing the amount of MoDTC added results in unwanted sulfated ash increases and other adverse effects. Thus, it is necessary to investigate the optimization of the amount of MoDTC added. The current work investigates this topic in terms of the Mo concentration in the lubricant. Seven different Mo concentrations with the same additive package are tested, whose tribological properties and chemistry of the tribofilm are investigated. For the selected operating conditions in this study, the critical concentration of Mo is determined to be ≈ 350 ppm due to its ability to reduce the friction to ≈ 0.04 under a constant and varying lambda ratio by forming the required threshold thickness of MoS2 within the tribofilm matrix, dominated by zinc dialkyl dithiophosphate (ZDDP) species. In general, increasing the Mo concentration increases the formation rate of MoS2 in the initial stages of the traction, directly forming a thicker MoS2 layer within the tribofilm up to a specific Mo concentration. Induction time also decreases with increasing Mo concentration, and increasing the Mo concentration from 350 to 1000 ppm does not negatively impact the wear generated.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
Keywords: | Molybdenum dithiocarbamate; Film thickness; Low viscosity engine oils; Tribofilm chemistry |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mechanical Engineering (Leeds) > Institute of Functional Surfaces (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 06 Dec 2023 10:36 |
Last Modified: | 06 Dec 2023 10:36 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.triboint.2022.107437 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:201476 |