Advances in Surface Anti-icing of Micro-nano Structures
Icing is a natural phenomenon, and the accumulation of ice on solid surfaces can cause catastrophic events and loss of life and property, and road icing can cause traffic accidents and casualties. Ice accumulation of power lines causes the power system to fail to operate normally; Ice buildup on aircraft body can disturb airflow on wings and other surfaces, reduce lift and increase drag, and bring flight risks. When a large amount of ice accumulates on the surface of the fan blade, the unbalanced load of the unit increases, and the wind energy utilization coefficient of the unit is reduced, resulting in a decrease in power generation. And in serious cases, the wind turbine can not be started normally. The anti-icing and deicing of solid surfaces are essential, and the deicing methods are divided into active deicing and passive deicing. Active deicing methods include electrothermal method, gas thermal method, chemical method, mechanical or manual method. Such methods can not fundamentally solve the problem of ice accumulation, and low efficiency, high energy consumption, high cost, but also bring pollution to the environment. These shortcomings of active deicing methods seriously hinder their wide application and further development. Ice formation is a phase transition process from supercooled liquid water to ice. Hydrophilic materials are easily wet by water, and water droplets are easy to form ice on such solid surfaces. And most engineering materials are hydrophilic, so making the solid surface less attached to droplets is a key technology to prevent ice accumulation. The lotus effect was discovered in the 1970s by observing the natural phenomenon of water rolling freely from the surface of a lotus leaf. Inspired by more natural plants and animals, researchers have begun to create artificial superhydrophobic surfaces, which have micro and nano structures as a more economical, efficient and environmentally friendly passive anti-icing strategy.In order to explore the effective deicing method of solid surfaces, the two formation mechanisms of ice, homogeneous and heterogeneous nuclei, were firstly discussed. In the process of ice formation and melting, liquid was involved. The wetting phenomenon of liquid on solid surface was introduced next. Based on the understanding of the formation of ice and the wetting state of liquid, the latest anti-icing and deicing strategies were reviewed respectively in different periods before, during and after liquid icing on solid surface in recent three years according to the chronological order of icing. Before icing, the solid surface was prevented from icing by dropping off and self-removing droplets; The freezing time could be extended to delay the covering of ice on the solid surface. After icing, the adhesion of ice on the solid surface was reduced, so that it was easier to escape from the solid surface, and the demand for anti-icing and deicing was achieved. However, in practical application scenarios, the super-hydrophobic surface of micro-nano structure would encounter various harsh environments, which would cause damage to the micro-nano structure surface. How to improve the durability of the surface of micro-nano structure is also an urgent problem to be solved. In this paper, the latest research results on these issues are summarized and discussed, and the future research on anti-icing and deicing of micro-nano structure surface is prospected.
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维普
