SHORT-TERM DETERIORATION OF POLYMER-COATED 55-PERCENT AL-ZN .1. BEHAVIOR OF THIN POLYMER-FILMS

The electrochemical behavior of 55% Al-Zn coated steel sheet, on which a very thin polymeric film (approximate to 1 mu m) was applied, was s tudied using electrochemical impedance spectroscopy (EIS). Use of a st raightforward electric model to analyze the spectra obtained with diff erent polymer films allowed correlation of the coating parameters and the physicochemical processes occurring on a microscale. Exposure to a 0.5% sodium chloride (NaCl) solution for variable time periods gave n ew insight into the mechanisms of protection and short-term degradatio n of the coating.