Study On Motion Characteristic Of Water Droplet Driven By Electric Field On A Super Hydrophobic Coating Of Silicone Resin Modified By Nano Silica

Super-hydrophobic coating owns self-cleaning property.The state of water drops on the super-hydrophobic surface is significantly different from that of on the traditional hydrophobic coating when applying an electric field.Discrete water droplets on traditional hydrophobic coating could trigger corona discharge and subsequently cause aging and flashover of the coating.Study on the new type of super-hydrophobic coating and electric field driven motion of discrete water droplets on its surface has the ability to improve the insulation performance and reveal the effect of electric field on self cleaning characteristics of super hydrophobic coating.Aiming at the problem that the surface free energy of currently super-hydrophobic coating is higher and the water droplets are difficult to slide,the author investigated the preparation method of the nano silica modified silicone resin super-hydrophobic coating and surface flashover performance of the prepared super-hydrophobic coating.In addition,the electric driven motion characteristics of water droplets on the prepared super-hydrophobic coating and the water droplet motion dynamics model and simulation were also studied.The main contents are as follows:(1)A novel nano silica modified silicone resin super-hydrophobic coating was fabricated.To reduce the surface free energy,fluoroalkylsilane were selected and serviced as surface modifier of nano silica particles.By mixing with the silicone resin,the super-hydrophobic coating was successfully fabricated.The micro hierarchical structure,chemical composition,hydrophobicity as well as dielectric properties were studied.Results shows the super-hydrophobic fluorinated silicone resin coating owns excellent hydrophobic performance,good anti-corrosion properties,wear resistance and dielectric properties.(2)The surface flashover performance of the prepared silicone resin super-hydrophobic coating was investigated.The local arcs occurred during the surface flashover process of the prepared super-hydrophobic surface was observed and analyzed.The self-cleaning property and anti-pollution performance were verified by assessing the pollution flashover leakage current and flashover voltage.Results show that compared with RTV silicone rubber coating,the prepared super-hydrophobic coating owns lower leakage current and higher flashover voltage.The high insulation performance of the prepared super-hydrophobic surface is mainly attributed to the excellent hydrophobicity and dry bands produced by the moving water droplets driven by electric field.(3)The electric field driven motion characteristics of water droplets on the prepared super-hydrophobic coating was investigated and the effect of electric field on the self-cleaning property of super-hydrophobic coating was revealed.The influence of electric field on the motion behavior of water droplets on the prepared super-hydrophobic coating was studied.The mechanism of charge accumulation in water droplets was analyzed.The self-cleaning process of the prepared super-hydrophobic coating was studied.Results show that the corona discharge occurred in the “droplet-air-coating” contact area is the main reason for the charge accumulation inside the water droplet.Water droplets with volume ranging form 10?L to 100?L on the prepared super-hydrophobic surface could be driven and move along the direction of external electric field.The droplet conductivity ranging from 20 ?S/cm to 1000?S/cm has a weak influence on the motion behavior of water droplets.(4)The dynamics model and simulation method of driven force of water droplets motion on super-hydrophobic coating was investigated.The driving mechanism of electric field on the water droplet motion was revealed.The critical stable electric field strength and mathematic model of electric field distribution were analyzed.The dynamics model of electric driven motion of water droplets was built based on the Navier-Stokes equation.The electric field driving force simulation method was studied.Results show the critical stable electric field strength of water droplets relates to external electric field strength,surface tension and radius of water droplets.The Coulomb driven force applied on the “droplet-air” interface has a decisive effect on the electric driven motion of water droplets on super-hydrophobic coating.(5)The self-cleaning process and its mechanical property of polluted particles on super-hydrophobic coating was investigated.The self-cleaning physical mechanism of polluted super-hydrophobic coating was revealled.Results show that polluted particles on super-hydrophobic coating was attractted strongly by the interface force between water droplet and particles.With the increase of hydrophobicity of the coating,the interfacial attraction force between water droplet and polluted particles increases.The water droplets on the super-hydrophobic coating have the highest interfacial attraction force to the contaminated particles.The above results indicate that the prepared silicone resin super-hydrophobic coating owns excellent insulation properties.The electric field driven motion behavior of water droplets on the prepared super-hydrophobic surface could effectively enhance self-cleaning property.The artificial pollution test results of super-hydrophobic coating show good application potential,which is beneficial to improve the anti-pollution performance of outdoor insulation used in power systems.