Comparative oxidation behaviour of Fe-9Cr steel in CO 2 and H 2 O at 550 °C: Detailed analysis of the inner oxide layer

L. Martinelli (1) , C. Desgranges (2, 1) , F. Rouillard (1) , K. Ginestar (1) , M. Tabarant (3) , K. Rousseau

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 SCP - Service de Chimie Physique
3 SCP - Société du Canal de Provence et d'Aménagement de la Région Provençale

Fe-9Cr steel was oxidized in pure water vapour and in CO2 at 550C. In both environments the Fe–Cr spinel layer was composed of small equiaxed grains which stoichiometry evolved from Fe2.7Cr0.3O4 to Fe2CrO4 in H2O and from Fe2.6Cr0.4O4 to Fe1.9Cr1.1O4 in CO2. In both cases the mean stoichiometry was Fe2.3Cr0.7O4. Single oxidation mechanism was proposed: the “available space model”. Carbon for oxidation in CO2 and hydrogen for oxidation in H2O were detected at metal/oxide interface within the steel. These atoms could be responsible for nanometric cavities formation by trapping vacancies created by outward cationic diffusion.

Keywords: Steel; TEM; High temperature; corrosion; Oxidation

Domains: Nuclear Theory [nucl-th]; Nuclear Experiment [nucl-ex]

L. Martinelli, C. Desgranges, F. Rouillard, K. Ginestar, M. Tabarant, et al.. Comparative oxidation behaviour of Fe-9Cr steel in CO 2 and H 2 O at 550 °C: Detailed analysis of the inner oxide layer. Corrosion Science, 2015, 100, pp.253-266. ⟨10.1016/j.corsci.2015.07.032⟩. ⟨cea-02384901⟩