A study by electrochemical impedance spectroscopy and surface analysis of corrosion product layers formed during CO2 corrosion of low alloy steel

Rehan de Motte (1) , Edoardo Basilico (1, 2) , Rémy Mingant (1) , Jean Kittel (1) , Francois Ropital (1) , Pierre Combrade (3) , Sophia Necib (4) , Valérie Deydier (4) , Didier Crusset (4) , Sabrina Marcelin (2)

1 IFPEN - IFP Energies nouvelles
2 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
3 ACXCOR
4 ANDRA - Agence Nationale pour la Gestion des Déchets Radioactifs

In the following research, electrochemical and surface analysis techniques are used to define the main contributing factor to the protectiveness offered by a scale formed at high temperature and pH under CO 2 saturated conditions. At 80°C and pH 6.6, trace amounts of a magnetite (Fe 3 O 4) phase was identified at certain locations beneath a more dominant iron carbonate (FeCO 3) film. Furthermore, over time, the evolution of the corrosion product layer towards a very low porosity results in a "diffusion barrier" that is indicated by a positive shift in the open circuit potential and is considered key to corrosion protection.

Keywords: carbon steel; electrochemical impedance spectroscopy analysis; CO2 corrosion; iron carbonate; magnetite; pseudo-passivation

Domains: Material chemistry

Rehan de Motte, Edoardo Basilico, Rémy Mingant, Jean Kittel, Francois Ropital, et al.. A study by electrochemical impedance spectroscopy and surface analysis of corrosion product layers formed during CO2 corrosion of low alloy steel. Corrosion Science, 2020, 172, pp.108666. ⟨10.1016/j.corsci.2020.108666⟩. ⟨hal-02864432⟩