Experimental analysis of surface-chalked silicone rubber materials in naturally aged outdoor insulators

Silicone rubber (SR) composite insulators have become extensively utilized in power systems owing to their outstanding hydrophobic properties and exceptional resistance to pollution-induced flashovers. However, chalking, a prevalent aging phenomenon observed on the surface of SR composite insulators, poses a considerable challenge to their operational efficacy. During routine maintenance in the outdoor insulators of Henan Province, China, a series of chalking silicone rubber materials were encountered, necessitating further investigation into their suitability for future operation. In this study, 6 composite insulators with diverse chalking levels were obtained. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were employed to examine the microscopic composition of the chalked samples. The physical composition was analyzed by thermogravimetric analysis (TGA). Subsequently, microscopic processes occurring during chalking were scrutinized. The findings unveil that chalking stems from SR degradation, as evidenced by PDMS chain breakage, carbon oxidation, and diminished thermostability. This analysis deepens comprehension of chalking mechanisms, thereby playing a pivotal role in ensuring the reliability of power systems.