Corrosion and passivation of tinplate in Na2CO3 medium:  

Effect of pH, Chloride and carbonate ions

 

M. Belkhaouda1, L. Bazzi1, R. Salghi2, A. Benlhachemi3, B. Hammouti4*, S. El Issami1, M. Hilali1

1 Laboratoire Matériaux & Environnement, Faculté des Sciences, B.P. 8106 Agadir, Maroc.

2Laboratoire d’Ingénierie des Procédés de l’Energie et  de l’Environnement, ENSA B.P. 1136, Agadir, Maroc.

3Laboratoire Matériaux & Environnement, Faculté des Sciences, B.P. 8106, Agadir, Maroc.

4laboratoire de Chimie Appliquée & Environnement. Faculté des Sciences, B.P. 717,  Oujda, Maroc.

* Corresponding author. E-mail: hammoutib@gmail.com

Received: 05 June 2008; revised version accepted: 16 September 2008

 

Abstract

    The corrosion and passivation of tinplate electrode in Na2CO3 solution at different concentrations of NaCl were studied at pH 13 using potentiodynamic polarization and cyclic voltammetry (CV) techniques. In chloride-free Na2CO3 solutions, the I-E response exhibits an active region with two anodic peaks corresponding to the formation of Sn(II) and Sn(IV) species, respectively. The permanent passive layer consists of oxides and /or hydroxides of tin. Addition of NaCl to the alkali solution accelerates the active dissolution of tinplate and leads to breakdown the passive layer at a breakdown potential decreasing with Cl- concentration. The effect of concentration of carbonate ions and pH on the tinplate behaviour was also discussed.

 

Keywords: Corrosion; Passivation; Pitting; Tinplate.

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