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Silicone rubber (SIR) is widely used in outdoor power equipment due to its excellent electrical insulation and weather resistance. However, during long-term operation, silicone rubber inevitably suffers from the impacts of external natural environments. In this paper, the surface ageing characteristics of SIR under long-term out door environments and its influence mechanism on surface flashover performance were systematically studied by three typical environmental simulation tests of thermal ageing, ultraviolet ageing, and salt spray ageing. Combined with scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and flashover voltage tests, the microscopic morphology evolution, chemical group changes, and flashover performance change laws of silicone rubber under different ageing conditions were comprehensively analyzed. The results show that in the early stage of thermal ageing (0-500 h), the high temperature induces re-crosslinking reaction, which reduces the number of surface defects of silicone rubber. In the later stage of thermal ageing (1 000 h), the molecular chains break, and the surface resistivity of the sample drops to 78% of the initial value, and the flashover voltage decreases by 8%. Ultraviolet ageing destroys the Si-O and Si-C bonds in silicone rubber due to high-energy rays, resulting in the precipitation of particles on the surface and the formation of deep traps. After 1 000 h of ultraviolet ageing, the flashover voltage of the sample decreases by 10.3%. Due to the combined effect of Cl- corrosion and solution penetration in salt spray ageing, significant bulges and corrosion marks appear on the surface of the sample, and the relative dielectric constant of the samples increases by 23%, while the flashover voltage decreases by 31%. Though the quantitative analysis of the entropy weight method, the weights percentages of the effects of salt spray, ultraviolet, and thermal ageing on flashover voltage are 37.1%, 35.7%, and 27.2%, respectively. This suggests that cable accessories in coastal areas with high salt spray and high ultraviolet radiation are more prone to causing insulation failure due to environmental ageing.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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