变压器油对老化硅橡胶憎水迁移特性的影响

Hydrophobicity transfer characteristic of silicone rubber is very important for protecting electrical equipment from pollution flashover accidents, however the presence of oil will aggravate the accumulation of pollution. In this paper, the aged HTV silicone rubber samples were obtained by accelerated thermal aging process, and the effect of the aging on the hydrophobicity transfer characteristic of HTV silicone rubber was investigated via artificial coating. Scanning electron microscopy(SEM)and infrared spectrometer(FTIR)were adopted to analyze the influencing mechanism. The effects of oil absorption and surface oil contamination on the hydrophobicity transfer characteristic of the silicone rubber were analyzed by artificial coating. The results show that: 1) after aging, holes and gullies appeared on the silicone rubber surface, and the interior structure became loose; 2) the Si-O bonds on silicone rubber’s main chains and the methyl groups on side chains were broken, which influenced transfer path of the LMW molecules, and lowered steady-state hydrophobic performance; 3) after oil immersion, the migration speed of the LMW molecules slowed down, the hydrophobicity recovery time of the oil-polluted surface decreased first and then increased with the increase in the oil adsorption, and the steady-state hydrophobic angle of the No.5 sample reduced to 76°after immersion in oil for 50 h; and 4) the oil contamination on the surface hindered the migration of the LMW molecules,which almost made the silicone rubber completely lose its hydrophobicity transfer characteristic, and the steady-state hydrophobic angle of the No.5 sample decreased to 69°. It is concluded that surface oil contamination seriously affects the hydrophobicity transfer characteristic of HTV silicone rubber, so it is extremely necessary to develop oil-resistant HTV silicone rubber.