Bisphenol F epoxy resin (EP) is often used in terminal current lead insulation of superconducting equipment because of its good insulation performance, high mechanical strength, good toughness at cryogenic temperatures, and resistance to cold shock and heat shock. However, due to the wide temperature range of 80–300 K and the strong electric field, the EP-N₂ interface is prone to surface flashover, resulting in terminal insulation failure. To improve the reliability of the current lead insulation, non-linear conductive EP/strontium titanate (SrTiO₃) composites were prepared by modification with nano filling. The changes of dielectric, surface discharge, flashover, and trap distribution characteristics of composite materials were studied, and the mechanism of SrTiO₃ on the surface flashover of composite materials was analysed. The results show that the conductivity of the composite increases with the rise of SrTiO₃ filling content, and the amplitude of improvement is greater under the strong electric field, showing a more significant non-linearity. The composite has a lower trap energy level and a greater number of shallow traps compared to pure EP, which accelerates surface charge de-trapping and reduces charge accumulation, effectively enhancing the discharge and surface flashover voltage of the composite.

中文翻译：

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非线性导电环氧树脂/SrTiO3复合材料在80~300 K温区表面放电研究

双酚F环氧树脂（EP）因其绝缘性能好、机械强度高、低温下韧性好、耐冷冲击和热冲击等优点，常用于超导设备的端子电流引线绝缘。但由于80~300 K的宽温度范围和强电场，EP-N ₂接口容易发生表面闪络，导致端子绝缘失效。为了提高当前引线绝缘的可靠性，通过纳米填充改性制备了非线性导电EP/钛酸锶(SrTiO _{3 )复合材料。}研究了复合材料介电、表面放电、闪络和陷阱分布特性的变化，分析了SrTiO ₃对复合材料表面闪络的作用机理。结果表明，复合材料的电导率随着SrTiO ₃填充量的增加而增加，且在强电场作用下提高幅度更大，表现出更显着的非线性。与纯EP相比，该复合材料具有更低的陷阱能级和更多的浅陷阱数量，加速了表面电荷的脱俘获并减少了电荷积累，有效增强了复合材料的放电和表面闪络电压。