The measurement of the surface energy of solids using a laboratory drop tower.
The measurement of the surface energy of solids using a laboratory drop tower.
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DOI：
10.1038/s41526-017-0031-y
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发表时间：
2017
期刊：
影响因子：
5.1
通讯作者：
Calvimontes A
中科院分区：
文献类型：
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作者：
Calvimontes A
本文介绍了一种研究和测量固-液-气体系界面能的方法。该仪器及其测量结果的评价方法可用于分析微重力作用下固着液滴的能量变化。一个数学模型的基础上的热力学润湿的应用程序来评估的界面能作为一个功能的下降形状的变化，由于在实验过程中释放的重力的影响。该模型基于界面的热力学平衡，而不是基于等高线上二维张量的平衡。由于这个原因，该模型不遵循杨氏方程，因为目前的表面润湿表征技术通常这样做。在德国的一位研究人员开发的一个理论模型中，重力被证明会影响表面上一小滴水的形状。BSH Hausgeräte GmbH的Alfredo Calvimontes证明了液滴几何形状在确定界面能方面的重要性。表面张力强烈影响水滴的形状，但人们认为重力对非常小的水滴几乎没有影响。然而，最近的实验工作表明，这可能不是真的。Calvimontes开发了一个理论模型，不同于传统的方法的两百年历史的杨方程，因为它假设界面的热力学平衡，而不是力的平衡，在固体-液体-气体轮廓线。该模型得到了高速摄像机图像的支持，这些图像显示了自由落体中各种表面上的液滴，使用了一个三米的落塔，可以量化从正常重力到微重力的形状变化。
This work presents a technique for the study and measurement of the interfacial energies of solid–liquid–gas systems. The instrument and the evaluation method for the measurements obtained by it, allow the analysis of the energy changes of sessile drops submitted to microgravity. A mathematical model based on the thermodynamic of wetting is applied to evaluate the interfacial energies as a function of the drop shape changes due to the effect of the release of gravitation during the experiment. The presented model bases on the thermodynamic equilibrium of the interfaces and not on the balance of bi-dimensional tensors on the contour line. For this reason, the model does not follow Young’s equation as the current surface wetting characterization techniques usually do. Gravity is shown to influence the shape of a small drop of water on a surface in a theoretical model developed by a researcher in Germany. Alfredo Calvimontes from BSH Hausgeräte GmbH demonstrates the importance of the droplet geometry in determining the interfacial energies. Surface tension strongly influences a water drop’s shape, but it was thought that gravity played little role for very small drops. However, recent experimental work has suggested that this might not be true. Calvimontes develops a theoretical model that differs from the conventional approach of the two hundred- years-old Young’s equation in that it assumes a thermodynamic equilibrium of the interfaces, rather than a balance of forces, on the solid-liquid-gas contour line. The model was supported by high-speed-camera images of droplets on various surfaces in free fall using a three-meter drop tower that allows quantifying the change of shape from normal gravity to microgravity.