The properties of electrodeposited Zn-Co coatings

The possibility of increasing the corrosion resistance of automotive sheet steel by electrodepositing with Zn-Co alloy coatings was investigated. Proc ess variables during electrodeposition such as current density, electrolyte flow rate, and pH were varied in order to examine their influence on the e lectroplating process, Cobalt contents varying from 0.2 to 7 wt% were easil y obtained. The influence of these process parameters on the characteristic s of the coating could be related to the hydroxide suppression mechanism fo r anomalous codeposition. The structure and the morphology of the coatings were determined using SEM and XRD analysis. Application properties importan t for coating systems used in the automotive industry, such as friction beh avior, adhesion, and corrosion behavior, were investigated on coatings with varying cobalt content, The corrosion resistance of the Zn-Co alloy layers was found to be better than that of pure zinc coatings.