The dielectric behavior of plasma-treated insulator surfaces

A novel technique of treating insulator surfaces by means of a suitable plasma is presented. It suppresses the presence of hydrophilic ions or groups on the surfaces of glass and porcelain insulators and makes the formation of a hydrophobic surface possible. Experimental results show that the plasma-treated surfaces of the glass and the porcelain insulators exhibit excellent stability during accelerated aging test under thermal stress and exposure to ultraviolet radiation, and also after immersion in solvent, acid, or alkali solutions. The AC flashover voltage is 56% higher for the insulators with plasma treatment than those without such treatment under an artificial fog condition (with salt density of 0.1 mg/cm³). The surface resistance is about three times higher under the same artificial fog condition for the insulators with plasma treatment. On the basis of an analysis of secondary ion mass spectroscopy and infrared spectra results, the mechanisms responsible for the formation of a stable and effective hydrophobic surface by plasma treatment are discussed