Influence of hydrostatic pressure on wetting state and corrosion of superhydrophobic coatings

The influence of hydrostatic pressure on the wetting and corrosion behavior of a commercially available superhydrophobic coating was studied. Electrochemical impedance spectroscopy (EIS) was used to probe the interface between the substrate and coating, the coating and air layer, and the air layer and electrolyte. It was shown that EIS could effectively be used to study how hydrostatic pressure affects the interface between the coating and electrolyte. Hydrostatic pressure was induced in the system using a modified experimental setup and it was shown that EIS could be used to study the wetting state transition. It was observed that the presence of an air layer at the coating and electrolyte interface is what affects the coating performance and the application of hydrostatic pressure deteriorates the protective properties of the coating. Electrical equivalent circuits were applied to determine the contributions of the air layer to the overall corrosion performance of the system. A phenomenological model has also been presented that represents the mechanism that occurs at the coating and electrolyte interface as the wetting state transition occurs.