复合绝缘子粉化伞裙的微观结构与憎水性的关联研究

The Relationship Between Microstructure and Hydrophobicity of Pulverized Composite Insulator Sheds

为研究粉化硅橡胶伞裙的憎水性与其微观结构的关系,针对现场取回的3支粉化的110kV复合绝缘子,通过红外光谱、扫描电镜、能谱分析等方法开展研究。首先,利用静态接触角和喷水分级法测试样本的憎水性,粉化层表面的憎水性相比新样本略有下降,去掉表面的粉化层后,其憎水性明显下降。然后,通过红外光谱测试发现样本的主链和侧链基团(Si-O和Si-CH_3)发生了断裂,侧链甲基含量减少;扫描电镜发现去粉化层后硅橡胶表面存在大量微孔和裂纹,因而导致去粉化层后的硅橡胶伞裙表面憎水性明显降低。最后,通过能谱分析发现,粉化层中的硅含量明显高于去粉化层后硅橡胶表面和材料内部值,同时粉化层表面的粗糙度增加,说明粗糙度和硅氧烷小分子的迁移同时导致粉化层表面的憎水性优于去掉粉化层后的表面。研究结果表明,粉化与硅橡胶伞裙的憎水性关联密切,但仍需深入研究粉化复合绝缘子的运行可靠性和使用寿命。

To analyze the relationship between micro structure and hydrophobicity of the silicone rubber sheds, infra-red spectrum（IR）, scanning electron microscope（SEM） and energy dispersive spectroscopy（EDS） were performed on the three chalking 110 kV composite insulators. Firstly, the hydrophobicity levels were measured using a static contact angle method and a water spray method. Compared to the new sample’s surface, the hydrophobic of the powder layer decreased slightly. After remove the surface layer of powder, its hydrophobic decreased obviously. Then the IR test found that the main chain and side groups（Si-O and Si-CH3） fracture occurred, reducing the side methyl group. The SEM test found a large number of pores and cracks on the surface of the silicone rubber without the powder layer, which led to the reduction in the hydrophobicity of the surface of the silicone rubber sheds after removing the powder layer. Finally, the EDS test found that the silicone content of the powder layer was significantly higher than that on the silicone rubber surface without powder layer and its internal layer which confirm the migration of small silicone molecules, while the powder layer increases the surface roughness. Both the roughness and the small silicone molecules migration result in that the hydrophobicity on the surface layer with the powder is better than the surface after removing the powder. All the results show that the hydrophobicity of the silicone sheds is associated with its chalking state closely, but the operational reliability and service life of the chalking composite insulators need to be understood deeply.