Effects of addition of silicone fluid on electrical performance of RTV silicone rubber coatings

The room temperature vulcanizing (RTV) silicone rubber was formulated without and with addition of 10% silicone fluid by weight. The addition of silicone fluid to the RTV formulation is made in an attempt to explore the factors and extend the lifetime of the coating. The average leakage current and the leakage current pulse counts were determined as a function of time of exposure to combined electrical stress and salt-fog. Examination of the surface using attenuated total reflection (ATR) Fourier Transform Infrared (FTIR) spectroscopy coupled with the determination of the surface micro-roughness using a Scanning Electron Microscopy (SEM) and a high resolution roughness detector were carried out to characterize the RTV performance under salt-fog condition for different formulations of coatings. The content of the silicone fluid in the RTV coating was determined before and after salt-fog test, at different locations on the surface, and for different RTV formulations, using an extraction technique in an analytical hexane. The contact angle of a droplet of water on the surface, indicating the quality of hydrophobicity, was also determined.