Khaemba, DN, Neville, A and Morina, A (2016) New insights on the decomposition mechanism of Molybdenum DialkyldiThioCarbamate (MoDTC): a Raman spectroscopic study. RSC Advances, 6 (45). pp. 38637-38646. ISSN 2046-2069
Abstract
Molybdenum DialkyldiThioCarbamate (MoDTC) is a friction modifier that has been used in automotive engines for many years. However, its exact decomposition mechanism within tribocontacts is not fully understood. In this study, an attempt has been made towards understanding the mechanism of MoDTC decomposition in steel/steel contacts by employing Raman spectroscopy. Results show that the main MoDTC decomposition products are MoS2, FeMoO4 and sulphur-rich molybdenum compounds, MoSx (x>2), in contrast to the previously reported MoS2 and MoO3. Formation of these products is dependent on tribological parameters. Raman results from this study indicate that the Mo6+ species previously observed in X-ray Photoelectron Spectroscopy (XPS) analysis are probably from FeMoO4 and not MoO3. This paper presents an alternative reaction pathway for MoDTC decomposition in steel/steel contacts with MoSx as an intermediate product and MoS2 as the final product. FeMoO4 is formed from a side reaction of iron oxides with molybdenum compounds at low temperatures and low MoDTC concentrations. Results also show that friction is dependent on the nature of decomposition products at the tribocontact. Knowledge of MoDTC decomposition reaction pathway will enable the friction performance of MoDTC lubricants to be optimized.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016, The Royal Society of Chemistry. This is an author produced version of a paper published in RSC Advances. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | MoDTC; Raman spectroscopy; MoS2; MoSx; FeMoO4 |
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: | 20 Apr 2016 10:11 |
Last Modified: | 14 Apr 2017 03:28 |
Published Version: | http://dx.doi.org/10.1039/C6RA00652C |
Status: | Published |
Publisher: | Royal Society of Chemistry |
Identification Number: | 10.1039/C6RA00652C |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:98770 |