Influence of Non-Soluble Contamination Microscopic Properties on Hydrophobicity Transfer on Silicone Rubber Surface of Composite Insulator

摘要

Contamination withstand performance of power equipment adopting silicon rubber as external insulation is dominated by its hydrophobicity. To reveal hydrophobicity transfer mechanism of various non-soluble pollutant on silicon rubber surface, several inert materials of similar chemical component were selected, including Kaolin, Kieselguhr, and silicon dioxide microspheres. Static contact angle tests at various transfer times are performed to obtain the hydrophobicity transfer characteristics of various pollutants. Scanning electron microscope (SEM) test and mercury intrusion porosimetry (MIP) of these inert materials are also carried out to observe the topographical microstructure. Results show that the variations between static contact angle and hydrophobicity transfer time perform great distinction depending on the microscopic properties of inert material. According to MIP and SEM analysis of Kieselguhr, two kinds of pores are found, which play different part on hydrophobicity transfer process. It is proposed that there are two patterns superimposed in hydrophobicity transfer process. One was the “fast process”, determined by the large pore among inert material particles, controlled hydrophobicity transfer speed in first 10 hours. While the other was the “slow process”, resulted by the small pore in inert material particles, determines the final static contact angle. In conclusion, the hydrophobicity transfer process from silicone rubber surface to pollutant surface is a superposition effect of the two transfer processes, especially for porous inert materials. This paper has researched the concrete hydrophobicity transfer process considering the influence of non-soluble pollutant microcosmic characteristics. The results have great significance for hydrophobicity transfer theory and guidance value for outdoor insulation practice of transmission line.