Failure Analysis of Silicone Rubber in Corrosive Environment under AC Operation

Composite insulators have been widely used globally due to their outstanding performance. They suffer from acidic or alkaline pollution in coastal or saline-alkali regions, as well as chemical dust released by industrial and mining activities. These substances settle on silicone rubber housings and become corrosive and conductive after dissolving in water, causing damage to the housings. Therefore, this paper investigates the failure characteristics of silicone rubber in energized corrosive environments, including dielectric properties and X-ray Photoelectron Spectroscopy (XPS). The findings demonstrate that as aging duration increases, the real part of complex permittivity (ϵ') and dielectric loss (tan δ) increase. Compared to salt fog, acid fog has a greater effect on the aging of silicone rubber at the same conductivity. The ϵ' and tan δ of complex permittivity increase with applied voltage and acid fog conductivity. After aging experiments, the oxygen content on the surface layer of silicone rubber samples increases significantly, while the carbon content and organic components decrease significantly. After the aging treatment, the content of Si(-O)₂ decreases significantly, whereas the content of Si(O)₃ increases and then decreases, whereas Si(O)₄ exhibits the opposite trend. The research findings can help explore the failure mechanisms of silicone rubber in corrosive environments.