Application of the electrochemical machining technique for the characterization of zinc coatings

Electrochemical machining is a useful technique for characterizing the inner alloy structure of metallic coatings. In the present study, hot-dip zinc galvanized coatings were fabricated and the microstructures were analyzed after exposing each layer of the coatings by successive anodic machining steps. With this method, the surface after each successive machining step would be free from any mechanical damage or segregation of the dissolution products over the machined surface. The characteristics of the alloy layers and their influence on the behavior of the coatings were investigated under a specific exposure condition. The corrosion performance of the iron-rich inner alloy layers was found to be better than that of the pure zinc top layer as revealed during electrochemical characterization. This paper provides insight into the correlation between the protection strength of the galvanic coating and the quantity of zinc in the coating.