Superhydrophobic modified-polyurethane coatings for bushing of power transformers: From material to fabrication, mechanical and electrical properties

The presence of dust and coastal salt water found in a high moisture content environment can affect the stability of bushings in power transformers. This problem leads to transformer shut down and in severe conditions it can cause transformer expulsion. To eliminate this problem, a superhydrophobic modified-polyurethane coating was fabricated that contained easy cleaning property. Final coating had contact angles higher than 150° and CAH (Contact Angle Hysteresis) less than 10 degrees. The coating indicated good UV durability and mechanical robustness which was investigated by an abrasion test. It could pass acid rain and dry lightning impulse voltage tests. The best results were attained with the formulation containing 8 wt% nanosilica.