Electrochemical study on the corrosion of rusted carbon steel in dilute NaCl solutions

Abstract

Purpose

The purpose of this study was to investigate the corrosion of rusted carbon steel in dilute NaCl solution, with the purpose of exploring the effect of the rust layer on metal corrosion and establishing a corrosion model for rusted iron.

Design/methodology/approach

The corrosion behavior of rusted carbon steel in dilute NaCl solution was studied by means of weight-loss determinations, scanning electron microscopy, Raman spectrometry and electrochemical techniques.

Findings

The results indicated that carbon steel had a similar corrosion behavior in all three NaCl solutions. The iron rust, which consisted of a thin γ-FeOOH layer and a thick Fe₃O₄ layer, can facilitate the corrosion process of carbon steel via reduction of γ-FeOOH and the large area cathode of Fe₃O₄. Hence, the corrosion rate of carbon steel was accelerated significantly and finally was determined by the limiting diffusion rate of oxygen.

Originality/value

A corrosion model of rusted carbon steel was established, suggesting that iron rust formed in all slightly acidic waters with low alkalinity probably promotes the corrosion of carbon steel. Anti-corrosion measures for iron in this type of solution, such as desalination water, should be aimed to reduce the promotional effect of the rust layer on metal corrosion.

Citation

Hu, J., Cao, S.-a., Yin, L. and Gao, Y. (2014), "Electrochemical study on the corrosion of rusted carbon steel in dilute NaCl solutions", Anti-Corrosion Methods and Materials, Vol. 61 No. 3, pp. 139-145. https://doi.org/10.1108/ACMM-05-2013-1261