Effect of Cerium Ions on the Corrosion of Galvanised Steel in 0.5 M Na 2 SO 3 Solution
Date
2012
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Chemistry
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.
Description
Keywords
Potentiodynamic polarisation, Circuit potential, Hexavalent chromium, Galvanized steels