Short-term deterioration of polymer-coated 55% Al-Zn: Part 3 - Protective mechanism of inhibitor-modified coatings

Electrochemical impedance spectroscopy (EIS) was used to investigate 55% Al -Zn coated with different thin polymer coatings (approximate to 1 mu m) con taining a passivating inhibitor (Cr[VI]) after exposure to a sodium chlorid e (NaCl) solution for variable times. Impedance data were analyzed using a model developed previously. Investigation of the effects of polymer layer t hickness, chromate concentrations, and polymer particle dimensions revealed the different aspects of the protective principle of this new type of thin -film coating on 55% Al-Zn-coated sheet steel. Evolution of the coating beh avior over time was studied in depth.