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Effect of lubricant molecular rheology on formation and shear of ultra-thin surface films
journal contribution
posted on 2013-10-14, 08:14 authored by W.W.F. Chong, M. Teodorescu, Homer RahnejatThe physics of molecularly thin fluid films formed between surface features at close range is
investigated. It is found that the interplay between discrete lubricant drainage from such
contacts and localized contact deflection plays an important role both on the load carrying
capacity of these asperity level conjunctions as well as on friction. Small spherical molecules
tend to solvate near assumed smooth surfaces of asperities at nano-scale. Their discrete
drainage at steadily decreasing gaps adds to the viscous friction of any bulk lubricant film.
However, at the same time the generated solvation pressures increase the load carrying
capacity. Conversely, long chain molecules tend to inhibit solvation, thus showing a decrease
in the load carrying capacity, whilst through their wetting action reduce friction.
Consequently, real lubricants should comprise molecular species which promote desired
contact characteristics, as indeed is the case for most base lubricants with surmised properties
of certain additives. The methodology presented underpins the rather empirical implied action
of surface adhered films. This is an initial approach which must be expanded to fluids with a
more complex mix of species. If applicable, this could also be an alternative (potentially time
saving) approach to Monte Carlo simulations for molecular dynamics.
Funding
The authors acknowledge the technical support from partners and sponsorship provided by the EPSRC through the ENCYCLOPAEDIC program grant.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Citation
CHONG, W.W.F., TEODORESCU, M. and RAHNEJAT, H., 2001. Effect of lubricant molecular rheology on formation and shear of ultra-thin surface films. Journal of Physics D - Applied Physics, 44 (165302), 11pp.Publisher
© IOP PublishingVersion
- NA (Not Applicable or Unknown)
Publication date
2011Notes
This article is closed access.ISSN
0022-3727Publisher version
Language
- en