Study On Hydrophobic Substance Transfer And Its Characteristics Of Superhydrophobic Anti-pollution Flashover Material

Pollution flashover has always been the research focus of the industry.The accumulation of pollution and the wetting of pollution may lead to the occurrence of pollution flashover.At present,the common coatings and materials used for anti-pollution flashover are RTV（room temperature vulcanized silicone rubber）anti-pollution flashover coatings,HTV（high temperature vulcanized silicone rubber）materials for composite insulator and so on.Silicone rubber material mainly depends on its good hydrophobicity and hydrophobicity transfer to prevent pollution flashover,but it also has the disadvantages,such as surface fouling and weakening or losing hydrophobicity and hydrophobicity transfer,which will lead to the decline of the anti-pollution flashover ability.In recent years,superhydrophobic coating material for external insulation has gradually become one of the research and development hotspots.Bionic superhydrophobic material mainly relies on excellent self-cleaning and super hydrophobicity to prevent a large number of fouling.It is one of the research and development directions of anti-pollution flashover coatings and materials.But in the extreme weather of long-term dry,the surface of superhydrophobic material may still accumulate a certain thickness of pollution.In this case,if superhydrophobic material has hydrophobic substance transfer function similar to hydrophobicity transfer,it can be used as backup guarantee,which plays a positive role in many aspects,preventing pollution from getting wet under the environment of slight rain fog,preventing the pollution mixture droplets from infiltrating the damaged surface and improving the self-cleaning effect of the pollution mixture droplets on the damaged surface.This paper is based on a kind of modified nano-SiO₂superhydrophobic material.According to the the analysis and reference of the common test methods of hydrophobic transfer of silicone rubber material,mainly using diatomite as artificial pollution,the macro test method and indirect test method for hydrophobic substance transfer of superhydrophobic material were put forward.For the hydrophobic substance transfer effect,the verification test,the influence test of different conditions and the improvement test of transfer performance were carried out.Through quantitative and qualitative verification tests,the macroscopic hydrophobic effect of pollution and static contact angle increase of pollution layer all show that the superhydrophobic material can realize the hydrophobic substance transfer.The test results show that the transfer effect has no obvious negative effect on the static contact angle and rolling angle of the material,and has little effect on the rolling angle of the covered pollution material surface.But in the rolling angle test,due to the hydrophobic substance transfer,diatomite particles absorbed by the water drop rolling along the pollution surface were mainly covered on the surface of the water drop and were not easy to enter the interior of the water drop,which eventually led to the rolling stagnation.By changing the test conditions and parameters,it was found that the performance of hydrophobic substance transfer fluctuates in different degrees:it is greatly affected by temperature,increasing the temperature can promote the transfer,and it has transfer effect under medium and high temperature conditions;it is generally affected by the pollution density,increasing the pollution density has a certain degree of impact on the transfer rate and effect,but the influence of pollution density below 2 mg/cm²is limited;the effect of salt isn’t obvious,and appropriate Na Cl salt has no obvious effect on the final effect of hydrophobic substance transfer.In addition,it is found that the superhydrophobic material has a certain degree of hydrophobic material transfer ability to kaolin,but it can not make straw ash show hydrophobic effect.Due to the limited hydrophobic substance transfer performance of the superhydrophobic material,the material was improved by referring to the mechanism of hydrophobicity transfer.The experimental results show that adding a small amount of dimethicone to the primer of superhydrophobic material can improve the transfer rate to diatomite and make the transfer effect more stable.However,there is no transfer effect in the lower temperature environment in winter.In addition,it can not make straw ash show ideal hydrophobic effect.