The influence of surface forces on thin film drainage between a fluid drop and a flat solid
The influence of surface forces on thin film drainage between a fluid drop and a flat solid
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DOI：
10.1039/b204500c
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发表时间：
2003-01-01
影响因子：
3.4
通讯作者：
Horn, RG
中科院分区：
文献类型：
--
作者：
Connor, JN;Horn, RG
描述了一个实验，其中云母表面被驱动朝向浸没在水性电解质中的汞滴。在适当的条件下，水膜中的流体动力学压力在汞滴中产生经典的凹坑。使用光学干涉测量法和视频记录来监测液滴的形状和具有亚纳米分辨率的水性膜的厚度，产生高密度的精确数据，其示出了在膜排水时凹坑的形成和演变。施加到汞相的电势的变化允许控制作用在液滴和云母表面之间的表面力，从而突出表面力对膜排水过程的影响。结果表明，表面力对微坑中心处的油膜厚度和微坑的横向范围影响不大。另一方面，在凹坑的边缘处的最小膜厚度即使对弱的表面力也敏感。由于这个最小的膜厚度是一个主要的决定因素的膜排水率，它表明，表面力有一个重要的影响，对整个排水过程。
An experiment is described in which a mica surface is driven towards a mercury drop immersed in aqueous electrolyte. Under appropriate conditions, hydrodynamic pressure in the aqueous film creates a classical dimple in the mercury drop. The use of optical interferometry and video recording to monitor the shape of the drop and the thickness of the aqueous film with sub-nanometre resolution yields a high density of precise data showing the formation and evolution of the dimple as the film drains. Variation of electrical potential applied to the mercury phase allows control of the surface forces acting between the drop and the mica surface, so that the effect of surface forces on the film drainage process is highlighted. It is found that the film thickness at the centre of the dimple and the lateral extent of the dimple are not significantly affected by surface forces. On the other hand, the minimum film thickness at the edge of the dimple is sensitive even to weak surface forces. Since this minimum film thickness is a major determinant of the film drainage rate, it is shown that surface forces have an important effect on the overall drainage process.