Evaluation of RTV silicone rubber insulator coatings in a salt-fog chamber

Room-temperature vulcanizing (RTV) silicone rubber insulator coatings were evaluated in a salt-fog chamber. Leakage current was measured to evaluate the coatings. The water path formed on the RTV coated surface probably reorients the hydrophobic groups away from surface. The reorientation of hydrophobic groups increases the wettability of the RTV coated surface. The development of leakage current is strongly dependent on the intensity of water droplets supplied to the surface. Dry band arcing increases due to increased wettability, further accelerating the loss of hydrophobicity of the coatings. After the surface is completely wetted (during 25 h of salt-fog testing), with the nozzles on one side only, the effect of varying the water flow rate on increasing the leakage current is greater than that of varying the air pressure. With the nozzles on both sides, the effect of varying the air pressure is greater than that of varying water flow rate