Degradation of Insulating Materials, Including SiO2 DUE to SF6 GAS Dissociation Products

Materials, including silicon dioxide (SiO2), are degraded by SF6 gas dissociation products. Changes in surface resistivity and volume resis tivity due to SF6 dissociation products were investigated in SiO2-containing insulating materials, for instance porcelain. It was found that surface resistance and volume resistance of these materials decrease with exposure of SF6 gas dissociation products and moisture. It was shown that the chemical products that lessen the surface and volume resistivity are some acids and salts of these acids. By chemical analysis, the predominant acid was shown to be H2SiF6.