Effect of passivation treatment and storing on adhesion and protective properties of lacquered tinplate cans

摘要

Tinplate cans internally coated with three commercial lacquer systems were studied. The relationship found between lacquer adhesion, metallic chromium (CrM), chromium oxide (CrOx), and total chromium (CrT) existing in the passivated layer was: adhesion=CrM+10 (CrOx/CrT). The study was completed by conducting electrochemical impedance spectroscopy (EIS) and direct current (DC) polarization experiments up to 410 days. A dilute acetic acid-sodium chloride solution was used as electrolytic and a full opened can was used as the working electrode and an electrolyte cell. Iron dissolution was determined by atomic absorption spectrophotometry (AAS). The EIS, DC, and AAS techniques gave similar results. Passivation treatment did not substantially affect the porosity results.