Ecologically green conversion coating for zinc-cobalt alloy

A phytic acid based conversion coating has been designed for Zn-Co alloys. The morphology of this coating was studied by SEM and showed that immersion of coatings for 15 min is smooth and compact. The composition of conversion coatings was analysed by X-ray photoelectron spectroscopy. The analysis data showed that the coating is composed of Zn, C, P, N and O. The presence of Co in the coating was not established. Corrosion protection provided by this coating was evaluated by electrochemical measurements (polarisation curves, electrochemical impedance spectroscopy) in a 0.5M NaCl solution. Electrochemical corrosion measurement showed that the corrosion resistance of the Zn-Co alloy has been improved by the conversion treatment with phytic acid.