Date of Award


Publication Type

Master Thesis

Degree Name



Electrical and Computer Engineering


Engineering, Electronics and Electrical.


Hackam, R.




The effects of the size of the particles of ATH filler on the life of room temperature vulcanizing (RTV) silicone rubber coating was studied in a salt-fog chamber. The median particle sizes examined were 1.0, 4.5, 13, 17 and 75 $\mu$m. The optimum size giving the lowest leakage current and the longest time to failure of the coating was determined. The particle size affected the roughness of the coating. The roughness was enhanced after a prolonged test in salt-fog. The leakage current affected the amount of silicone fluid on the surface. The amount of silicone fluid present on the surface after exposure to dry-band arcing in salt-fog was a function of the particle size. Measurements of surface roughness, the amount of silicone fluid on the surface, and the leakage current combined with theoretical analysis of the heat of conduction, lead to identification of the mechanisms by which the size of the ATH particle impart resistance to tracking and erosion. The influences of the coating thickness, different substrates, addition of silicone fluid to the coating system and different carrier solvents on the leakage current, pulse current count rates and the life of the RTV coatings were investigated. It was found that all these parameters affected the electrical performance in salt-fog. The content of low molecular weight (LMW) silicone fluid and the diffusion of LMW from the bulk to the surface were determined. ATH filled RTV coatings having thicknesses from 0.17 to 0.99mm, ATH particle sizes from 1.0 to 75 $\mu$m and different carrier solvents were used. (Abstract shortened by UMI.)Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1995 .D46. Source: Masters Abstracts International, Volume: 34-06, page: 2437. Advisers: R. Hackam; E. A. Cherney. Thesis (M.A.Sc.)--University of Windsor (Canada), 1996.