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@article{Dawczyk:2019:10.1007/s11249-019-1148-9,
author = {Dawczyk, J and Morgan, N and Russo, J and Spikes, H},
doi = {10.1007/s11249-019-1148-9},
journal = {Tribology Letters},
title = {Film thickness and friction of ZDDP tribofilms},
url = {http://dx.doi.org/10.1007/s11249-019-1148-9},
volume = {67},
year = {2019}
}
TY - JOUR
AB - Tribofilm formation by several zinc dialkyl- and diaryldithiophosphate (ZDDP) solutions in thin film rolling-sliding conditions has been investigated. A primary, a secondary alkyl and a mixed alkyl ZDDP show similar rates of film formation and generate films typically 150 nm thick. Another secondary ZDDP forms a tribofilm much faster and the film is partially lost after extended rubbing. An aryl ZDDP forms a tribofilm much more slowly. The films all have a pad-like structure, characterised by flat pad regions separated by deep valleys. Three different techniques have been used to analyse the thickness and morphology of the tribofilms: spacer layer imaging (SLIM), scanning white light interferometry (SWLI) of the gold-coated film and contact mode atomic force microscopy (AFM). The SLIM method measures considerably thicker films than the other two techniques, probably because of lack of full conformity of a glass disc loaded against the rough tribofilm. No evidence of a highly viscous layer on top of the solid tribofilm is seen. SWLI and contact mode AFM measure similar film thicknesses. The importance of coating the tribofilm with a reflective layer prior to using SWLI is confirmed. As noted in previous work, the formation of a ZDDP tribofilm is accompanied by a marked shift in the Stribeck friction curve towards higher entrainment speed. For a given ZDDP this shift is found to correlate with the measured tribofilm roughness, proving that it results from the influence of this roughness on fluid entrainment in the inlet.
AU - Dawczyk,J
AU - Morgan,N
AU - Russo,J
AU - Spikes,H
DO - 10.1007/s11249-019-1148-9
PY - 2019///
SN - 1023-8883
TI - Film thickness and friction of ZDDP tribofilms
T2 - Tribology Letters
UR - http://dx.doi.org/10.1007/s11249-019-1148-9
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000459478800004&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR - http://hdl.handle.net/10044/1/68190
VL - 67
ER -