Surface Erosion–Corona Synergistic Degradation Characteristics and Material Adaptability of High-Temperature Vulcanized Silicone Rubber in Desert Regions

The harsh sandstorm and the strong electric fields generated by operating transmission lines in desert regions can readily lead to performance degradation and shortened service life of high-temperature vulcanized (HTV) silicone rubber (SR) composite insulators. To screen HTV silicone rubber materials suitable for desert applications, this study conducted aging tests under windblown sand erosion, corona aging, and their combined synergistic effect on three HTV silicone rubber materials. By comparing the evolution of surface morphology and chemical structure under single-factor and combined aging conditions, the acceleration mechanism of erosion on corona aging was analyzed. Further comparison of the performance degradation of the three materials after identical aging durations revealed that the higher the hardness of HTV silicone rubber, the stronger its resistance to erosion, and it retains superior corona aging resistance after erosion. Under combined erosion and corona aging, the high-hardness S3 HTV silicone rubber maintained an intact surface micro-morphology and molecular chain structure, with a smaller reduction in elongation at break, sustained high volume and surface resistivity, and no noticeable deterioration in dielectric properties. A comprehensive evaluation demonstrates that the high-hardness S3 silicone rubber exhibits superior environmental adaptability in desert regions.