Effects of particles size of ATH fillers on the performance of RTV rubber coatings

The authors present a study of the effects of the particle size of ATH (alumina trihydrate) on the performance of RTV (room-temperature vulcanizing) coatings on fiber glass rod insulators under contamination and wet conditions in a salt-fog chamber. Examination of the surface using attenuated total reflection Fourier transform infrared (FTIR) spectroscopy coupled with determination of the current pulse counts indicates a significant effect of the particle size on the performance of ATH-filled RTV coatings. The best performance leading to the lowest leakage current pulse counts and the longest time to failure was obtained with coatings having 4.5 and 13 /spl mu/m sizes of ATH particles. Measurement of the IR spectra of silicone fluid diffused to the surface shows that the silicone fluid was more pronounced with these two particle sizes.<>