Effect of Cerium Ions on the Corrosion of Galvanised Steel in 0.5 M Na 2 SO 3 Solution

Abstract

Chromate conversion coatings have been widely used in industry for a long time to improve the corrosion resistance galvanized steels. Hexavalent chromium, however, has high toxicity and carcinogenesis. Therefore, alternative and more environmentally friendly surface treatments need to be developed. Rare earth metal ions, such as cerium, is recognized as an effective corrosion inhibitor and environmentally friendly. In present study effects of Ce (III) and Ce (IV) ions on the corrosion behaviour of galvanised steel have been studied in 0.5 M Na 2 SO 3 solution. A composite coating of cerium and zinc has been prepared by pulse deposition technique and its effect on the inhibition of corrosion of galvanized steel has been evaluated in terms of E iv

corr , Icorr

and Tafel constants. It was found that the composite coating decreased the corrosion rate by more than 50 times. On the other hand, Ce (IV) ion was found to increase the corrosion rate due to taking part in cathodic reaction.