Study on Corona Aging Characteristics of Silicone Rubber Material under Different Environmental Conditions

In this article, a silicone rubber-based composite material is selected as the test sample, and a 100-h corona aging test is conducted under different environments using multiple pin-plate electrodes to study the corona discharge characteristics of pin-plate under different humidity, salt fog, and haze environments. The corona aging characteristics of silicone rubber material are analyzed by the static contact angle, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). The results show that, with the increase in the relative humidity (RH), the frequency and energy of corona discharge increase. The discharge frequency under a haze environment is small, but the number and amplitude of the positive half-cycle pulse are larger. With the increase in RH and the deterioration of the environment, the oxidation degree and hydrophobicity loss rate of the material surface are accelerated, and the material surface damage is also aggravated. The aging characteristics of silicone rubber have a positive correlation with the content of water molecules in the air, some hydrophilic -OH, and acidic -COOH appear on the material surface, leading to the insulation performance decrease. As the aging of silicone rubber deepens, its equivalent transverse relaxation time drop increases, the number of H atoms that become low bond energy state inside increases, and the resistance to corona aging decreases. The results of this article can provide some reference for the evaluation, diagnosis, and production of composite insulators in different regions.