Ultraschallinduzierte Potentialverschiebungen zur Beurteilung von Korrosionsreaktionen bei Weissblechpackungen

Corrosion reactions in tinplate cans may cause problems during storage by enhanced dissolution of iron. Fundamentals of an electrochemical test method are given to detect the preference of iron corrosion. The method is based on potential changes, which occur during the transition from an unmoved to a vigorous moved state of the electrolyte. For this porpose an ultrasonic source is used. Under those conditions the components of tinplate (tin, iron and the alloy layer FeSn2) show characteristic differences in the potential behaviour. The potential changes depend on the conditions of the cathodic reduction processes of oxygen present in the electrolyte. Corroding iron exhibits a high sensitivity. The results were applied on corrosion processes of unlacquered and lacquered tinplate. Tests were performed to show that there is the possibility to indicate localized corrosion just after the sterilization of cans. The method allows a rapid characterization of the entire food aggressivity resulting from many individual parameters