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Effect of lubricant molecular rheology on formation and shear of ultra-thin surface films

Effect of lubricant molecular rheology on formation and shear of ultra-thin surface films
Effect of lubricant molecular rheology on formation and shear of ultra-thin surface films
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 localised 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 show 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 more complex mix of species. If applicable, this could also be an alternative (potentially time saving) approach to Monte-Carlo simulations for molecular dynamics.
0022-3727
165302
Chong, W.W.F.
bd35fdf8-fa6d-4330-8bac-ae20cc8fc58e
Teodorescu, M.
10e22073-39f7-41c3-b2b7-2886c2d976f6
Rahnejat, H.
f5b9b13a-dc42-4fde-a98d-4e0c48bb19ab
Chong, W.W.F.
bd35fdf8-fa6d-4330-8bac-ae20cc8fc58e
Teodorescu, M.
10e22073-39f7-41c3-b2b7-2886c2d976f6
Rahnejat, H.
f5b9b13a-dc42-4fde-a98d-4e0c48bb19ab

Chong, W.W.F., Teodorescu, M. and Rahnejat, H. (2011) Effect of lubricant molecular rheology on formation and shear of ultra-thin surface films. Journal of Physics D: Applied Physics, 44 (16), 165302. (doi:10.1088/0022-3727/44/16/165302).

Record type: Article

Abstract

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 localised 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 show 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 more complex mix of species. If applicable, this could also be an alternative (potentially time saving) approach to Monte-Carlo simulations for molecular dynamics.

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Published date: 2011
Organisations: nCATS Group

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Local EPrints ID: 353117
URI: http://eprints.soton.ac.uk/id/eprint/353117
ISSN: 0022-3727
PURE UUID: 995aea67-2013-4375-ad98-2845de9abb4d

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Date deposited: 30 May 2013 11:45
Last modified: 14 Mar 2024 14:01

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Contributors

Author: W.W.F. Chong
Author: M. Teodorescu
Author: H. Rahnejat

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