Analysis of the Effect of Multiple Environmental Factors at High Altitude on the Aging Performance of Silicone Rubber Materials

The highest altitude of China’s ultra-high voltage transmission lines has reached more than 4700 m. Silicone rubber for composite insulators at high altitude has been subjected to the erosion of high temperature, cold, low air pressure, strong ultraviolet radiation and other harsh climatic environments for a long period of time, and the degree of aging has increased significantly, and there are obvious regional differences. In this paper, by building an artificial aging test platform considering temperature, humidity, irradiation and air pressure, and conducting artificial aging tests under the coupling of these four environments, we analyze the degradation of the performance of silicone rubber under multi-environmental factors through insulation resistance value and surface morphology testing of silicone rubber aging specimens with different test cycles, and analyze the failure mechanism of silicone rubber under multi-environmental factors through Fourier infrared spectroscopy and XRD diffraction analysis. The experimental results show that: with the increase of aging degree, the insulation resistance value of SiR decreases, the surface holes and cracks increase, the characteristic peaks of main chain Si-O-Si, side chain Si-(CH
3
)
2
and C-H decrease in general, and there is a period of time to recover, and then decrease; the oxidation and cross-linking reaction of the side chain of SiR are more intense, and the interface between the matrix and the filler is destroyed, and the Aluminum trihydrate filler and silica filler precipitated from the SiR matrix, the organic component is reduced, which affects the high temperature resistance, cold resistance and UV resistance of SiR, thus making the electrical and mechanical properties reduced. The results provide a useful reference for the analysis and study of the aging failure mechanism of in-service composite insulators considering temperature, humidity, irradiation and air pressure environments.