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Characterization of steel surface under cathodic protection in seawater

Mariela Rendón Belmonte (Institute of Engineering, University of Baja California, Mexicali, México)
José Trinidad Pérez Quiroz (Materials Laboratory, Mexican Institute of Transport, Querétaro, México)
Benjamín Valdez Salas (Institute of Engineering, University of Baja California, Mexicali, México)
Miguel Martínez Madrid (Materials Laboratory, Mexican Institute of Transport, Querétaro, México)
Andrés Torres Acosta (Materials Laboratory, Mexican Institute of Transport, Querétaro, México)
Jesús Porcayo Calderón (Electrical Research Institute, Cuernavaca, México)
Miguel Schorr Wiener (Institute of Engineering, University of Baja California, Mexicali, México)

Anti-Corrosion Methods and Materials

ISSN: 0003-5599

Article publication date: 17 May 2013

Abstract

Purpose

The purpose of this paper is to characterize the surface of steel under cathodic protection while submerged in seawater, to understand the mechanism that controls the operation of the protection system.

Design/methodology/approach

Steel rods were immersed in seawater and NaCl solution with applied cathodic protection. The experimental methodology included monitoring of corrosion potential (Ecorr), galvanic current (Igalv) protection potential (Eprotection) and the depolarization potential of steel during the time of exposure. In addition, the chemical composition of the steel surface was assessed using a Scanning Electron Microscope (SEM).

Findings

In this research it was determined that the effectiveness of the CP system was mainly attributable to the formation of an iron oxide film on the steel surface.

Research limitations/implications

It is necessary to carry out analysis of the chemical composition of deposits formed on the steel surface, perhaps using X‐ray diffraction (XRD), to verify the presence of a protective oxide.

Practical implications

Deposits on the steel surface have the beneficial effect of reducing the current required for efficient protection. Deposit formation therefore is of economic interest, as it decreases the cost of protection.

Originality/value

A unique feature of cathodic protection in seawater is the formation of calcareous deposits on metal surfaces. Advantageous aspects of these deposits, such as decrease in cathodic current requirement, have been investigated by various authors from various viewpoints. However, very little attention has been paid to the impact of any iron corrosion product films; the present paper contributes useful understanding and explains the importance of the mechanism that controls the operation of the protection system.

Keywords

Citation

Rendón Belmonte, M., Trinidad Pérez Quiroz, J., Valdez Salas, B., Martínez Madrid, M., Torres Acosta, A., Porcayo Calderón, J. and Schorr Wiener, M. (2013), "Characterization of steel surface under cathodic protection in seawater", Anti-Corrosion Methods and Materials, Vol. 60 No. 3, pp. 160-167. https://doi.org/10.1108/00035591311315418

Publisher

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Emerald Group Publishing Limited

Copyright © 2013, Emerald Group Publishing Limited