Observations on the influence of microstructure on electrolytic tinplate corrosion

Corrosion processes on the stratified structure of electrolytic tinplates were characterized by means of alloy-tin couple, pickle-lag, anodic polarization tests, and scanning electron microscopy analyses. To study polarization, citric-citrate and acetic-acetate solutions were employed as artificial media while tomato sauce, canned razor-clams, and mussels were representative of real media. The results made it possible to establish a direct relationship between continuity, homogeneity, and crystallization density of each layer and its resistance to corrosion processes. The continuity and homogeneity conditions also involved organic layers having a protective role.