Electrochemical coating of zinc carboxylate: A new protection for zinc in atmospheric conditions

To prevent the premature tarnishing of zinc-coated products in moist atmosphere or during wet-dry climatic cycles, new surface treatments of zinc are developed in this study. For that, electrochemical behaviour of pure zinc in this media was studied versus pH and potential by using electrochemical impedance spectroscopy and potentiodynamic techniques. Then, different coatings constituted by zinc heptanoate or zinc hydroxyheptanoate were synthesized by electrochemical oxidation on zinc-coated steel and tested in climatic chamber. The coatings mainly constituted by zinc heptanoate trap the OH- anions and delay the alkalinisation of the zinc surface during the wet-dry cycle. This coating constitutes an environmentally friendly alternative to the usual conversion treatments, to inhibit the formation of hydrozincite (white rust) in atmospheric corrosion.

Automated summary

A new surface treatment for zinc-coated products has been developed to prevent premature tarnishing in moist atmosphere or during wet-dry climatic cycles. The electrochemical behavior of pure zinc was studied under different pH and potential conditions, and coatings constituted by zinc heptanoate or zinc hydroxyheptanoate were synthesized and tested.