Influence of NOx and Air on the Ageing Behaviour of MoDTC
File(s)
Published version
Author(s)
Ponjavic, A
Lemaigre, T
Southby, M
Spikes, HA
Type
Journal Article
Abstract
Molybdenum dialkyldithiocarbamates (MoDTCs) are very effective friction modifier additives for use in engine oils and other lubricants. However, as engine oils age during extended drain intervals, MoDTCs can lose some or all of their ability to reduce friction and this is generally believed to result from their oxidative degradation. In this study, MoDTC solutions in base oil have been subjected to oil ageing in a controlled NOx/air flow rate, controlled temperature test apparatus and the effect of ageing on the ability of the MoDTC to reduce friction has been explored. As shown in previous studies, the additive’s friction-reducing properties are completely lost after a quite short period of ageing at 160 °C. However, it was found that at this temperature the presence of NOx has little if any influence on the rate of friction loss, indicating that the latter is controlled primarily by the rate of reaction of oxygen with the base oil and thus the rate of consumption of MoDTC as a peroxide decomposer. By contrast, when ageing tests are carried out at lower temperatures it is found that NOx has a very strong effect on the rate at which MoDTC loses its ability to reduce friction, so that at 100 °C NOx accelerates this rate by two orders of magnitude compared to air alone. This suggests that at low temperatures the rate at which MoDTC is consumed is controlled by its reaction as a radical inhibitor with NOx species.
Date Issued
2017-03-22
Date Acceptance
2017-03-14
Citation
TRIBOLOGY LETTERS, 2017, 65 (2)
ISSN
1023-8883
Publisher
SPRINGER
Journal / Book Title
TRIBOLOGY LETTERS
Volume
65
Issue
2
Copyright Statement
© 2017 The Author(s). Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000401437000022&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Technology
Engineering, Chemical
Engineering, Mechanical
Engineering
Friction modifier
MoDTC
Lubricant degradation
Boundary friction
MoS2
MOLYBDENUM DIALKYLDITHIOCARBAMATE ADDITIVES
FRICTION REDUCING PROPERTIES
0912 Materials Engineering
0913 Mechanical Engineering
Mechanical Engineering & Transports
Publication Status
Published
Article Number
ARTN 52