Zinc electrowinning — a comparison of adherence-reducing pretreatments for aluminium cathode blanks

The use of automatic stripping machines requires a uniform and low adherence of electrowon zinc to aluminium starting sheets. Some impurities in the electrolyte severely affect this adherence. The strong effect of F− ions is first reported. Two pretreatments aimed at lowering the adherence are then compared. Brushing the aluminium blanks gives excellent results whereas anodization, even for long periods of time, is less effective. Influence of these pretreatments on the electrical parameters of zinc deposition has also been examined and economical conclusions are drawn. Differences in the electrocrystallization of zinc on low and high adherence areas are indicated by scanning electron microscopy examination. Mechanisms are proposed to explain the experimental observations. © 1980, All rights reserved.SCOPUS: ar.j