| The transmission line insulators play a vital role as the insulation against ground for transmission conductor. The icing reduces the dielectric strength of the insulators which may possibly cause icing flashover accidents. Serious icing flashover accidents could lead to line trip, equipment damage or even blackouts of large area, which do serious harm to the national economy and social activities. Therefore, it’s of great engineering value to explore the anti-icing methods for insulators. The research topics about the crystallization process and crystallization inhibition mechanism of water on solid surface is intensely focused and difficult which has important academic value.This paper is inspired by the “lotus effect”. First, the anti-icing property of natural superhydrophobic material-lotus leaf was testified. Then, the nano-particle filling method and magnetron sputtering were adopted to fabricate micro-nano superhydrophobic surface materials based on the morphology and chemical composition of the lotus leaf. Their superhydrophobic performance, anti-icing performance and electrical performance were subsequently investigated. At last, the dynamic and static behaviors of water droplets on superhydrophobic surface at low temperature were studied to explore the mechanism of anti-icing property of the superhydrophobic surface. The main innovative achievements of this paper are given as below.① The anti-icing property of the lotus leaf in glaze icing was testified which found that most of the lotus leaf surface remained free of ice indicating that the superhydrophobic surface can mitigate and prevent the glaze ice under certain conditions. It was found that the true contact area and adhesion strength between solid and water were effectively reduced due to the micro-nano roughness structure and low surface energy of lotus leaf by utilizing the Cassie model to investigate the anti-icing mechanism of the lotus surface. Cooled water droplets could easily roll off the lotus leaf surface reducing the amount of ice.② The micro-nano anti-icing surface material on glass insulators was successfully fabricated with nano-particle filling method. The group structure with low surface energy was obtained which has anti- icing property at certain degree. Optimal surface morphology and hydrophobic performance are gained by adjusting the content, type and grade of the nano particles. The fluorosilicon resin, epoxy resin and nano silica were adopted for material preparation combining the spraying method. The coating with best hydrophobic performance was obtained with 40 wt.% of nanoparticles whose contact angle and sliding angle were 163.1° and 4.1°, respectively. The surface consisted of honeycombed structure with micro nest cell and nanoscale papillae. The surface had low surface energy containing the methyl, methylene and fluorocarbon groups. The as-prepared surface could delay the frost formation process, mitigate the glaze ice on insulator and formation of entire ice layer, reduce the length of icicle, improve the icing flashover voltage and reduce the adhesion strength.③ The nano scale superhydrophobic anti-icing surface material was successfully fabricated with RF magnetron sputtering method. The long-chain alkane structure with low surface energy was obtained which has excellent anti-icing property. The surface was prepared by magnetic sputting, thermal oxidation and low surface energy treatment whose contact angle and sliding angle is 165.6° and less than 1°. The surface consisted of rodlike nano pillars and long-chain alkane with low surface energy. The surface can retard frost remarkablely. 70.4% of the surface area was free of ice after 90 minutes of glaze ice under circumstance of-5℃ which had better anti- icing property than surface created by nanoparticle filling method.④ The dynamic drop impacting and static drop icing processes at low temperature were intensely researched. The mechanism of the anti- icing phenomenon of the superhydrophobic surface was obtained from three aspects based on theoretical analysis. First, when impacting the superhydrophobic surface, the drop can rebound quickly from the surface as low viscous dissipation caused by the roughness and low surface energy. Second, according to the Fourier heat transfer theory, the small real solid-liquid contact area leads to the low heat transfer efficiency and low undercooling level which is beneficial for anti-icing. At last, according to the theory of homogeneous nucleation and heterogeneous nucleation, the energy barrier of heterogeneous nucleation for drop on superhydrophobic surface is high as the low surface energy and small pillar size. The nucleation rate is slow and the the formation of ice is delayed and retarded. |
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