| Silicone rubber materials are widely used in electrical equipment industry because of its light weight,corrosion resistance,high and low temperature resistance,good insulation performance and so on.At present,the main composition of composite insulator and anti pollution flashover coating in the field of external insulation is silicone rubber,which has excellent hydrophobicity and hydrophobic recovery.Due to the characteristics of energy distribution and climate change in China,long-distance and high voltage transmission lines will inevitably cross some areas with severe ice cover in winter.The ice coating of conductor and insulator not only affects the safety of power grid,but also may cause damage of transmission and transformation equipment and lead to large area power failure.The outer insulation will cause the damage of the insulation material,such as the loss of hydrophobicity of silicone rubber.At present,scholars at home and abroad have made some progress in the research on the recovery characteristics and mechanism of hydrophobicity of silicone rubber,but most of the tests are carried out under corona,plasma treatment,water solution immersion and other damage conditions,while the mechanism of loss and recovery of hydrophobicity of silicone rubber under ice covering environment is still unclear.In view of the above problems,the loss and recovery process of hydrophobicity of the samples under different icing conditions were tested by preparing different formula silicone rubber samples.The influence of different formula and ice coating parameters on the recovery of hydrophobicity of silicone rubber was obtained.The main work and achievements of the paper are as follows:(1)Four groups of 16 formula silicone rubber were designed and samples were prepared.The change process of static contact angle of RTV samples before,after ice coating and after a period of recovery was tested,and the recovery time and rule of hydrophobicity were obtained.The results show that the hydrophobic recovery time is the shortest in the components when the viscosity of silicone rubber is 20000 mpa · s,silica 20%,aluminum hydroxide 26%,coupling agent 1.6%,and the hydrophobic recovery time is the shortest in each component,only 12 hours.The recovery time of hydrophobicity of the material after ice coating increases first and then decreases with the increase of the viscosity of the base adhesive.The less the content of silica,the middle of aluminum hydroxide,the more coupling agent,the shorter the recovery time.All samples can recover to pre icing level within 18 hours.(2)By setting different icing parameters,the influence of the ice type,time,temperature and the number of ice-deicing cycles on the hydrophobicity recovery of materials was obtained.The data show that the ice covering time is 2D,the contact angle of A4 sample only drops from 96 ° to 90.42 °,and the hydrophobicity is still maintained,and the recovery time is only 8h(why is lower than the previous 12 hours).The longer the ice cover time,the slower the hydrophobicity recovery.The environmental temperature has little effect on recovery time.The hydrophobic recovery of silicone rubber will be weakened by cycling "ice-deicing".After the fourth ice coating,the contact angle can only be restored to about 95 °.(3)The surface morphology and chemical composition of the materials under ice were obtained by infrared spectroscopy and SEM.The mechanism of loss and recovery of hydrophobicity was analyzed.The surface microstructure of the ice covered sample has changed obviously,which has the physical defects such as micropores and cracks,which leads to the loss of hydrophobicity;with the increase of temperature,the small molecules inside the silicone rubber move to the surface,and the hydrophobicity gradually recovers. |
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