Evaluation of corrosion rate from polarisation curves not exhibiting a Tafel region

Evaluation of corrosion rate by Tafel extrapolation is often impossible, simply because an experimental polarisation curve does not exhibit linear Tafel regions. This paper shows how such curves for the Fe/H 2O/H +/O 2 corrosion system can be accurately deconstructed to furnish both kinetic and ther...

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Bibliographic Details
Published in:Corrosion science 2005-12, Vol.47 (12), p.3034-3052
Main Authors: Flitt, Harvey J., Schweinsberg, D. Paul
Format: Article
Language:English
Subjects:
Applied sciences
Carbon steel
Corrosion
Corrosion environments
Corrosion mechanisms
Corrosion rate
Exact sciences and technology
Metals. Metallurgy
Polarisation curve deconstruction
Tafel behaviour
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Summary:Evaluation of corrosion rate by Tafel extrapolation is often impossible, simply because an experimental polarisation curve does not exhibit linear Tafel regions. This paper shows how such curves for the Fe/H 2O/H +/O 2 corrosion system can be accurately deconstructed to furnish both kinetic and thermodynamic parameters for the anodic and cathodic reactions. The curved anodic branch (due to film formation) is then amenable to correction for IR voltage drop and the resulting Tafel slope and other parameters are then substituted in the Tafel equation to accurately determine i corr. An alternative method to obtain the anodic Tafel slope has been used to validate the above approach. Polarisation curves describing the inhibition of mild steel in industrial cooling water were scanned/digitised from the literature.
ISSN:0010-938X
1879-0496
DOI:10.1016/j.corsci.2005.06.014