Electrochemical Corrosion Investigations on Binary and Ternary Zinc Alloy Coatings using Gel Electrolytes

Novel agar‐based test electrolytes are used to perform electrochemical corrosion investigations on ZnFe and ZnNi binary as well as ZnFeMo ternary zinc coatings. The objectives of the electrochemical investigations include the characterization of the corrosion behavior, the description of the protective effect of the coatings as well as the investigation of the layer formation and degradation under artificial aging. ZnFe and ZnFeMo coatings are applied with varying iron content as well as an additional passivation layer, respectively, to study the effect on corrosion resistance. The results show that the protective effect of the coatings is not negatively influenced by different iron contents or the addition of molybdenum. Additional passivation of the ZnFe‐containing coatings by means of a passivating agent leads to a significant improvement in the protective effect. Artificial aging leads to a slight degradation of the additional passivation layer whereas coatings without post‐treatment enhance their protective effect by the formation of corrosion product layers.