绝缘子超疏水表面的制备及其覆冰与闪络行为研究

The accident of insulator flashover caused by ice accumulation (icing flashover) has seriously influenced the safety operation of electric power system. Currently, there is no effective solution at home and abroad. In this study, to mimic the superhydrophobicity and self-cleaning effect of lotus leaf, we propose the use of the low adhesion properties of superhydrophobic surface to prevent water adsorption, thus achieving its anti-icing and anti-flashover function. We will fabricate the superhydrophobic surface of insulator by mixing various of micro and nano particle sized PTFE, SiO2, CaCO3 and Al(OH)3 powders with low surface energy substrate of room temperature vulcanized silicone rubber (RTV-SR), followed by film coating, curing and surface treatment process, and study the influence of preparation technology, formulation and rough structure of the surface on its superhydrophobicity. The testing and evaluation methods of the anti-icing performance of superhydrophobic surface will be preliminarily proposed, the anti-icing mechanism will also be proposed by investigating its anti-icing performance in artificial icing conditions. The flashover behavior of superhydrophobic insulator in artificial icing and ice melting conditions will be investigated and the relationship between the superhydrophobicity of surface with its icing flashover behaviors will be established. This study attempts to provide a scientific basis and a theoretical method for the development of practical insulator anti-icing and anti icing flashover technology.

绝缘子因覆冰造成的闪络（冰闪）事故严重影响电力系统的安全运行，目前国内外尚无有效的解决办法。本研究模仿荷叶的超疏水性和自清洁效应，提出利用超疏水表面粘附力低的性质防止水的吸附，从而实现绝缘子防覆冰和防闪络功能。使用室温硫化硅橡胶作为低表面能物质和成膜物，以各种微纳米粒径的PTFE、SiO2、CaCO3和Al(OH)3作为添加剂，经混合、涂膜、固化和表面处理后在绝缘子上制备超疏水表面。研究制备工艺、配方和表面粗糙结构对表面超疏水性能的影响；初步提出超疏水表面防覆冰性能的测试和评价方法，研究人工覆冰条件下超疏水表面的防覆冰性能，提出相应的防覆冰机理；研究人工覆冰和融冰条件下超疏水绝缘子的闪络行为，建立材料表面超疏水性与其冰闪行为之间的关系。本研究试图为开发实用的绝缘子防覆冰和防冰闪技术提供科学依据和理论方法。

绝缘子覆冰引起的闪络事故对电力系统造成巨大危害。本项目将绝缘子表面加工为绝缘性超疏水涂层表面，以利用其自清洁防污性能阻止绝缘子表面的污秽和水分的集聚，从而达到防覆冰和防闪络的目的。以室温硫化硅橡胶为原料，添加固化剂、促进剂和溶剂，与二氧化硅（聚四氟乙烯、聚偏氟乙烯、氧化锌、钛酸钡等粉体）混合后在基材表面涂覆，固化后得到硅橡胶基超疏水涂层。自行设计并搭建了小型覆冰实验装置对水滴在超疏水表面处于不同温度、倾角和风速下的结冰行为及覆冰后冰层粘附力进行了观测和测试。结果显示当样品处于－10℃以上时过冷水滴能够在表面滚离而不结冰；当风速为5米/秒时，超疏水表面在－10℃时能够延缓水滴结冰时间长达2500秒；人工染污后，仍能在－10℃下阻止过冷水滴结冰且不影响其自清洁效果；粘附力测试实验表明超疏水表面对覆冰的粘附力低于普通疏水表面和亲水表面。使用小型冰风洞设备测试了超疏水样品表面在高风速高水滴含量下的结冰行为。普通样品表面结冰后冰层致密，而在同样结冰条件下，超疏水表面样品的结冰形貌疏松不连续，容易除去。使用闪络电压测试设备测试了超疏水绝缘子和普通绝缘子在覆冰条件下的闪络电压，发现硅橡胶超疏水涂层涂覆绝缘子后其绝缘性几乎没有改变，闪络电压分别为65.1 KV和67.5 KV；人工染污后，普通玻璃绝缘子的闪络电压降为22.4 KV，超疏水绝缘子则较高，为55.8 KV；在融冰过程中，普通玻璃绝缘子和超疏水绝缘子的闪络电压，差别不大，分别为28.7KV和32.4KV。本研究所获得的实验结果表明通过喷涂工艺将硅橡胶涂层涂覆在普通玻璃绝缘子或瓷绝缘子表面可获得优异的绝缘性和超疏水性，提高了绝缘子表面抗污秽积累和水吸附的能力；吸收量的大幅度降低使得绝缘子表面覆冰概率有效降低。同时，由于可溶性电解质污秽因雨水冲刷更易清除，降低了绝缘子表面电导率，导致闪络事故难以发生。因此，绝缘子表面硅橡胶超疏水涂层能降低绝缘子污闪和冰闪概率，有利于电力系统的安全运营。