Prepatation And Anti-Icing Performances Of Superhydrophobic Coating For Insulators

Ice accumulation on transmission lines, caused by freezing rain, wet snow or frost, is one of major problems influencing safety of electric power system. Ice accumulation may lead to outage, conductor break, tower collapse, conductor galloping, and insulator flashover of transmission lines, which can lead to great economic losses. Therefore, research on the anti-icing and de-icing of transmission lines has great academic significance and application value. The dissertation presents the preparation, hydrophobicity, and anti-icing performances of a new type of superhydrophobic coating.The work focuses mainly on the following contents:①The microstructure and chemical components, required for superhydrophobic coatings, was studied through analyzing the wetting theory of superhydrophobic coatings. A simple approach, named as the surface self-assemble of nano-particles (SSNP), was proposed to prepare superhydrophobic coatings economically on substrates with large surface area and complicate shapes. A nano-silica superhydrophobic coating was prepared by the approach and its surface microstructure, chemical component, and hydrophobicity were investigated. The research results show that a dual micro- and nano-scale hierarchical structure was fabricated on the nano-silica super-hydrophobic coating by the SSNP. Several drawbacks of the nano-silica super-hydrophobic coating were also presented.②An improved approach to insert a Polydimethylsiloxane (PDMS) transition layer between nano-silica self-assemblies and substrates was proposed to prevent cracks of curing surface of the nano-silica superhydrophobic coating. A PDMS/nano-silica hybrid superhydrophobic coating was prepared by the improved approach. Microstructure, chemical components, and hydrophobicity stability of the PDMS/nano-silica hybrid superhydrophobic coating were investigated.③An experimental method was proposed to measure the super-cooled water droplet capture rate of the superhydrophobic coating. The experimental method was used to measure the super-cooled water droplet capture rate of the PDMS/nano-silica hybrid superhydrophobic coating. The influences of the icing temperature and surface inclined angle to the super-cooled water droplet capture rate were investigated. The change of the super-cooled water droplet capture rate of the PDMS/nano-silica hybrid superhydrophobic coating was also investigated during the ice accumulation. The results show that the PDMS/nano-silica hybrid superhydrophobic coating possesses a very small super-cooled water droplet capture rate.④Ice adhesion strength of the superhydrophobic coating was investigated. Testing devices to measure ice adhesion strength of the superhydrophobic coating were designed. The vertical and shearing forces of ice adhesion to the PDMS/nano-silica hybrid superhydrophobic coating were measured through the approach. Testing results show that the superhydrophobic coating possesses very small ice adhesion strength. The analysis to microstructure of the interface between ice layer and the superhydrophobic coating show the reasons why the very small ice adhesion strength exists on the superhydrophobic coating. Furthermore, the microstructure and hydrophobicity of the PDMS/nano-silica hybrid superhydrophobic coating were measured and analyzed. The results show that shedding influences little on the surface microstructure and hydrophobicity of the superhydrophobic coating⑤Ice accumulation experiments both in laboratory and in filed were carried out to investigate the ice accumulation properties on insulator strings coated with the PDMS/nano-silica hybrid superhydrophobic coating. Morphology and weight of the accumulated ice on the coated insulator strings were both studied. Flashover testes were also carried out on the coated insulator strings. The results show that the ice accumulation on insulators is inhibited and reduced by the superhydrophobic coating.The insulator strings with the superhydrophobic coating possesses very high insulation strength. And the hydrophobicity of the superhydrophobic coating was influenced slightly by impact of the super-cooled rain and shedding of ice.The above results revealed that the PDMS/nano-silica hybrid superhydrophobic coating was prepared through the SSNP method. The PDMS/nano-silica hybrid superhydrophobic coating is capable of anti-icing for transmission lines. The experimental results in both laboratory and filed show the good anti-icing properties of the superhydrophobic coating.