Corrosion of Zinc By Differential Aeration

Abstract Tests were made to study the differential aeration corrosion of zinc in molar NaCl solutions under varying conditions of aeration, pH, and length of test time. Test results led to the conclusion that formation of differential aeration macrocells is due to passivity of zinc on the zones of the specimen where cathodic reduction of oxygen takes place, and that the principal process of corrosion is accompanied by local corrosion processes at the cathodic and anodic areas of the macrocell. With buffered solutions which do not permit the passivation of zinc, distribution of corrosion changes radically, a localized attack taking place at the water level line where the oxygen flux is at a maximum.3.6.2