Pitting corrosion in presence of inhibitors and oxidants

Abstract

Purpose

The purpose of this paper is to illustrate the usefulness of inhibitors for the prevention of localised corrosion of carbon steel in a low‐aggressive medium. The efficiencies of two inorganic non‐toxic inhibitors are compared, associated with an oxidant.

Design/methodology/approach

Many experiments were conducted. For each experiment, a solution was prepared with different concentrations of pitting agent, inhibitor and oxidant. The performance was then estimated by the pitting potential taken from the voltammograms of carbon steel obtained with each solution.

Findings

The results show that the efficiency of molybdate and tungstate were comparable. The presence of iodate, which plays an oxidizing role, can be synergistic to the inhibitor but harmful if the concentration ratio is not adequate.

Practical implications

The interest in the use of an oxidant is that it makes it possible to reduce the inhibitor concentration, which limits the pH increase and prevents scale deposition.

Originality/value

This work provides useful guidance in the localised corrosion prevention of a semi‐open cooling circuit subject to seasonal sand‐storms. The obtained results from the many experiments carried out were compiled using neural networks for performance prediction.

Citation

Boucherit, M.N., Amzert, S., Arbaoui, F., Hanini, S. and Hammache, A. (2008), "Pitting corrosion in presence of inhibitors and oxidants", Anti-Corrosion Methods and Materials, Vol. 55 No. 3, pp. 115-122. https://doi.org/10.1108/00035590810870419