Many Tribology Group publications are Open Access thanks to funding from the EPSRC.


BibTex format

author = {Guegan, J and Southby, M and Spikes, H},
doi = {10.1007/s11249-019-1198-z},
journal = {Tribology Letters},
title = {Friction modifier additives, synergies and antagonisms},
url = {},
volume = {67},
year = {2019}

RIS format (EndNote, RefMan)

AB - There is growing interest in reducing friction in lubricated machine components to thereby increase the energy efficiency of machines. One important way to minimise friction is to employ friction modifier additives to reduce friction in thin film boundary lubrication conditions. There are currently three main types of friction modifier additive, organic friction modifiers, oil soluble organomolybdenum friction modifiers and functionalised polymers. In common practice, a single such additive is generally employed in a formulated lubricant, but it is of interest to explore whether combinations of two friction modifier additives may prove beneficial. In this study, the performance of eight commercial friction modifier additives spanning all three main types was first measured in three quite different friction tests. The aim was to identify the contact conditions under which each additive was most effective. Additive solutions in both a base oil and a formulated engine oil were investigated. In general, functionalised polymers were most beneficial in sliding–rolling contacts, while oil soluble organomolybdenum friction modifiers worked best in severe, reciprocating sliding conditions. However, all friction modifier additive response was strongly affected by the other additives present in formulated engine oils. The friction performance of combinations of friction modifier additives was then explored. When two different friction modifiers additives were combined in solution, several possible outcomes were observed. The most common was for one of the additives to predominate, to give friction that was characteristic of that additive alone, while in some cases friction lay between the values produced by either additive on its own. In a few cases the additives behaved antagonistically so that the combination gave higher friction than either additive by itself. In a few cases true synergy was observed, where a combination of two additives produced lower friction in a g
AU - Guegan,J
AU - Southby,M
AU - Spikes,H
DO - 10.1007/s11249-019-1198-z
PY - 2019///
SN - 1023-8883
TI - Friction modifier additives, synergies and antagonisms
T2 - Tribology Letters
UR -
UR -
VL - 67
ER -