Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Beijing Key Laboratory for CO2 Utilization and Reduction Technology, Department of Thermal Engineering, Tsinghua University , Beijing 100084, China.
ACS Appl Mater Interfaces. 2018 Jan 10;10(1):1415-1421. doi: 10.1021/acsami.7b16087. Epub 2017 Dec 19.
Defrosting is essential for removing frost from engineering surfaces, but some fundamental issues are still unclear, especially for defrosting on superhydrophobic surfaces. Here, defrosting experiments on prepared superhydrophobic surfaces were conducted along with the investigation on meltwater evolution characteristics. According to the experiments, the typical meltwater evolution process on superhydrophobic surfaces can be divided into two stages: dewetting by edge curling and dewetting by shrinkage. The edge curling of a meltwater film is a distinct phenomenon and has been first reported in this work. Profiting from the ultralow adhesion of the superhydrophobic surface, edge curling is mainly attributed to two unbalanced forces (one at the interface between the ice slurry layer and pure water layer and the other in the triple phase line area) acting on the layered meltwater film. During the multi-meltwater evolution process, the nonbreaking of chained droplets on superhydrophobic surfaces is also an interesting phenomenon, which is controlled by the interaction between the surface tension and the retentive force because of contact angle hysteresis. An approximate criterion was then developed to explain and determine the status of chained droplets, and experimental data from various surfaces have validated the effectiveness of this criterion. This work may deepen the understanding of defrosting on superhydrophobic surfaces and promote antifrosting/icing applications in engineering.
解冻对于去除工程表面的霜冰至关重要，但一些基本问题仍不清楚，特别是在超疏水表面上的解冻问题。本文通过进行制备的超疏水表面的解冻实验，研究了融冰水的演化特征。根据实验，超疏水表面上典型的融冰水演化过程可分为两个阶段：边缘卷曲的去湿和收缩的去湿。融水膜的边缘卷曲是一种明显的现象，在这项工作中首次被报道。得益于超疏水表面的超低附着力，边缘卷曲主要归因于作用在分层融水膜上的两个不平衡力（一个在冰浆层和纯水层之间的界面处，另一个在三相线区域）。在多次融水演化过程中，超疏水表面上链状液滴不破裂也是一个有趣的现象，这是由接触角滞后引起的表面张力和保持力之间的相互作用控制的。然后提出了一个近似准则来解释和确定链状液滴的状态，来自各种表面的实验数据验证了该准则的有效性。这项工作可能加深对超疏水表面上解冻的理解，并促进工程中的抗霜/防冰应用。
