Kumar, Deepak and Daniel, Jency and Biswasa, SK (2010) Tribology of steel/steel interaction in oil-in-water mulsion; a rationale for lubricity. In: Journal of Colloid and Interface Science, 345 (2). pp. 307-315.
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Oil droplets are dispersed in water by an anionic urfactant to form an emulsion. The lubricity of this emulsion in steel/steel interaction is explored in a ball on flat nanotribometer. The droplet size and charge are measured using dynamic light scattering, while the substrate charge density is estimated using the pH titration method. These data are combined to calculate the DLVO forces for the droplets generated for a range of surfactant concentration and two oil to water volume ratios. The droplets have a clear bi-modal size distribution. The study shows that the smaller droplets which experience weak repulsion are situated (at the highest DLVO barrier) much closer to the substrate than thebigger droplets, which experience the same DLVO force, are. We suggest that the smaller droplets thus play a more important role in lubricity than what the bigger droplets do. The largest volume of such small droplets occurs in the 0.5 mM-1 mM range of surfactant concentration and 1% oil to water volume ratio, where the coefficient of friction is also observed to be the least. (C) 2010 Elsevier Inc. All rights reserved.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to Elsevier Science.|
|Keywords:||Anionic surfactant; Droplet size; DLVO; Emulsion; Friction; Interaction force|
|Department/Centre:||Division of Mechanical Sciences > Mechanical Engineering|
|Date Deposited:||07 Jun 2010 10:28|
|Last Modified:||19 Sep 2010 06:01|
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