Superhydrophobic nanostructured coatings for electrical insulators

Controlling surface wettability of ceramic electrical insulators is one of the proposed alternatives to avoid undesired electrical events when these devices are installed in polluted environments. In this sense, the application of super-hydrophobic nanostructured coatings has recently been proposed due to its high water repellency and possibility of surface self-cleaning. In this present study, coatings based on polysiloxane, alumina trihydrate (ATH), and several types of silica (SiO2) were developed using a spray-coating method. Contact angle (CA), sliding angle (SA), thermogravimetric analysis, transmission electron microscopy, scanning electron microscopy (SEM), atomic force microscopy, and inclined plane test (IPT) were applied to characterize fillers and coatings. The results showed that a high quantity of nanoparticles is necessary to achieve superhydrophobicity. The type of silica significantly affected the surface wettability leading to CA from 107 to 160 degrees and SA from 3 to 90 degrees. SEM analysis showed that coatings with hydrophilic silica present a more pronounced topography with microstructured aggregates. The resistance of superhydrophobic coatings to leakage current development was also dependent on type and amount of silica. The superhydrophobic coating with PDMS treated with silica had the best performance during the IPT showing fewer peaks and less accumulated electrical charge.