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@article{Fry:2020:10.1021/acs.langmuir.9b03668,
author = {Fry, B and Moody, G and Spikes, HA and Wong, JSS},
doi = {10.1021/acs.langmuir.9b03668},
journal = {Langmuir},
pages = {1147--1155},
title = {Adsorption of organic friction modifier additives},
url = {http://dx.doi.org/10.1021/acs.langmuir.9b03668},
volume = {36},
year = {2020}
}
TY - JOUR
AB - Organic friction modifier additives (OFMs) are surfactant molecules added to engine oils to reduce friction in the boundary lubrication regime. They are thought to work by forming an absorbed layer which provides low friction. This paper studied the relationship between the adsorption of OFMs and their friction and wear reducing properties in a rubbing contact formed by a stationary glass ball and a rotating silicon disk under the boundary lubrication regime. The effect of molecular structure was investigated by using OFMs of various tail saturation and head group chemistry. OFM tested were oleic acid, octadecylamine, oleylamine and glycerol monooleate. The thickness of an OFM adsorbed layer in hexadecane, examined in-situ by spectroscopic ellipsometry and quartz crystal microbalance (QCM), depends on the molecular structure and the concentration of the OFM. As expected, saturated, linear chain gives the thickest film. A critical OFM layer thickness of about 0.6 nm is necessary to achieve low initial and maximum friction. The thicker OFM layers are accompanied by narrower wear tracks, which are rougher than the wider, smoother wear tracks formed with thinner OFM layers. The interplay between the thickness of the OFM layer and wear track surface roughness results in all OFM layers having similar steady friction. This shows that the apparent effect of OFM depends on the stage of rubbing test: initially on friction; and then subsequently on surface damage. Despite OFMs and the base oil having similar refractive indices, ellipsometry was found to be a suitable technique for examining the adsorption of OFM additives from an oil based solution, and showed reasonable correlation with QCM results.
AU - Fry,B
AU - Moody,G
AU - Spikes,HA
AU - Wong,JSS
DO - 10.1021/acs.langmuir.9b03668
EP - 1155
PY - 2020///
SN - 0743-7463
SP - 1147
TI - Adsorption of organic friction modifier additives
T2 - Langmuir
UR - http://dx.doi.org/10.1021/acs.langmuir.9b03668
UR - https://pubs.acs.org/doi/10.1021/acs.langmuir.9b03668
UR - http://hdl.handle.net/10044/1/76007
VL - 36
ER -