Technical Note: Cathodic Polarization and Corrosion of Zn and ZnAl in 3% NaCl Solution

In a stimulating note, Leidheiser and Suzuki¹  considered some preliminary results on the cathodic polarization of galvanized coatings in a 3% NaCl solution and followed this with a more detailed article dealing with the effects of metallic cations as corrosion inhibitors for Zn.²  The main idea proposed was that since the corrosion of galvanized coatings under normal conditions is determined by the cathodic reaction, it should be possible to control the corrosion by the catalytic activity of the surface.¹  Briefly, the basis of this claim was that, compared with an as-received (not passivated) coating, a polished specimen was under activation control, had a pronounced peak at −1.30 V (SCE), and was catalytically less active.¹  This behavior was assumed to result from the presence of Al (always present in a commercial coating), which was enriched at the surface and had formed a zinc oxide containing Al. It...