Elektrochemische Untersuchungen zum Einfluß von Nitrat und Nitrit auf die Ausgangsruhepotentiale und den Kurzschlußstrom des Elementes Eisen/Zinn in Fruchtsäuren und -säften

Electrochemical investigations into the influence of nitrate and nitrite on the starting rest potentials and the short circuit current of the element iron/tin in fruit acids and juices With the aid of electrochemical measurements the influence is studied of nitrate and nitrite additions on the corrosion behaviour of tin and the iron/tin element in various fruit acids (citric, acetic, tartaric, malic and lactic acids) and vegetable and fruit juices; the results are compared with storage tests conducted in parallel. The electrochemical short time test is generally little suitable for showing the influence of nitrates, in particular because of the slow conversion of nitrate into nitrite which is a corrosion accelerator; the nitrite influence, on the other hand, can be shown quite easily since it produces on the one hand a potential shift toward more positive values and, on the other hand, gives rise to an increase in the short circuit current. These results can be applied to coated cans, too, where the nitrite gives rise to strong dissolution of iron with pitting attack.