绝缘体表面结构和微观形貌对提高器件真空闪络特性有重要影响。首次提出了表面具有均匀分布纳米级空穴聚合物绝缘子的化学制备方法。通过本体聚合制备纳米级二氧化硅颗粒均匀分布的交联聚苯乙烯复合材料, 机械加工成聚合物绝缘子后, 采用氢氟酸化学腐蚀的方法将绝缘子表面氧化物颗粒去除。采用透射电子显微镜、表面电阻率和短脉冲高压测试平台分别对处理前后绝缘子的表面形貌和绝缘等性能进行了表征, 结果表明: 处理后的交联聚苯乙烯复合材料绝缘子的表面形成了20~50 nm直径的空穴, 空穴的大小和数量分布分别由二氧化硅颗粒的粒径和加入量控制。这种具有特殊表面结构的新型绝缘子的沿面闪络电压较纯交联聚苯乙烯绝缘子提高了15%~20%, 并保持了较好的力学及加工性能。研究方法和实验结果对聚合物绝缘子的表面结构设计及高性能绝缘子的研制提供了一种新的途径。

Surface flashover properties of polymer insulator are very closely related to its surface structure and morphology. To enhance the surface flashover voltage of polymer insulator, nano-SiO2/cross-linked polystyrene (CLPS) composites with modified surface structure of nano-sized cavities were developed by means of both free radical crosslinking copolymerization and surface erosion for the first time. The structures of SiO2/CLPS composites were characterized with Fourier transform infrared spectroscopy(FT-IR) and transmission electron microscopy(TEM). The results showed that nano-SiO2 particles with an average size of 20-50 nm were well dispersed in the cross-linked polystyrene matrix with excellent compatibility between the organic and inorganic components. The cavities with the same size as SiO2 particles could be formed in the surface of the polymer, and SiO2 particles in the inner layer would remain intact. The uniform cavities could be responsible for the improvement of surface flashover property of polymer insulator. The surface flashover voltages of the modified surface insulators were increased by 15%-20% by comparison with that of CLPS. It gives a novel way to develop high dielectric polymer insulator.