Many foodstuffs and personal care products consist of two-phase systems which, during use, are rubbed between compliant biosurfaces to form thin lubricating films. It is important to understand the nature and properties of the films thus formed since these contribute to the user’s sensory perception, and thus appreciation, of the products concerned. In this paper, the lubrication properties of simple oil-in-aqueous phase emulsions are studied in a steel/elastomer “soft-EHL” contact. It is found that overall behavior is strongly dependent on the ratio of the viscosities of the two phases. When the viscosity of the dispersed oil phase is lower or comparable to that of the continuous aqueous phase, the latter enters the contact and controls film formation and friction. However, when the dispersed phase has viscosity at least four times larger than the dispersion medium, the former enters the contact and determines its tribological properties. This effect is believed occur because at high viscosity ratios the droplets are nondeformable and are thus forced into the contact inlet region, where collisions occur that result in shear-induced coalescence. Once a pool of viscous fluid is formed, the lower viscosity bulk fluid is unable to displace it because the viscous shear stress is too small, so the pool acts as a reservoir to supply the contact.
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e-mail: jvicente@ugr.es
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October 2006
Research Papers
Viscosity Ratio Effect in the Emulsion Lubrication of Soft EHL Contact
J. de Vicente,
J. de Vicente
Food Research Centre,
e-mail: jvicente@ugr.es
Unilever R and D Colworth
, Colworth House Sharnbrook, MK44 1LQ, UK; Tribology Section, Department of Mechanical Engineering, Imperial College London
, London, SW7 2BX, UK
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H. A. Spikes,
H. A. Spikes
Tribology Section, Department of Mechanical Engineering,
e-mail: h.spikes@imperial.ac.uk
Imperial College London
, London, SW7 2BX, UK
Search for other works by this author on:
J. R. Stokes
J. R. Stokes
Unilever Corporate Research,
e-mail: Jason.Stokes@unilever.com
Unilever R and D Colworth
, Colworth House Sharnbrook, MK44 1LQ, UK
Search for other works by this author on:
J. de Vicente
Food Research Centre,
Unilever R and D Colworth
, Colworth House Sharnbrook, MK44 1LQ, UK; Tribology Section, Department of Mechanical Engineering, Imperial College London
, London, SW7 2BX, UKe-mail: jvicente@ugr.es
H. A. Spikes
Tribology Section, Department of Mechanical Engineering,
Imperial College London
, London, SW7 2BX, UKe-mail: h.spikes@imperial.ac.uk
J. R. Stokes
Unilever Corporate Research,
Unilever R and D Colworth
, Colworth House Sharnbrook, MK44 1LQ, UKe-mail: Jason.Stokes@unilever.com
J. Tribol. Oct 2006, 128(4): 795-800 (6 pages)
Published Online: June 7, 2006
Article history
Received:
June 20, 2005
Revised:
June 7, 2006
Citation
de Vicente, J., Spikes, H. A., and Stokes, J. R. (June 7, 2006). "Viscosity Ratio Effect in the Emulsion Lubrication of Soft EHL Contact." ASME. J. Tribol. October 2006; 128(4): 795–800. https://doi.org/10.1115/1.2345400
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