Article Dans Une Revue Corrosion Science Année : 2012

Reversible catastrophic oxidation of a 38Fe-34Ni-25Cr alloy induced by sodium sulphate at low oxygen potential atmospheres

Résumé

The chromia-forming nickel-based alloy Haynes (R) HR-120 was oxidised with and without Na2SO4 deposit in a CO/H-2/CO2 (45/45/10%vol.) simulated process atmosphere at 900 degrees C for 96 h. During the first hours of oxidation, samples covered by sodium sulphate exhibit higher oxidation rate than non-covered ones. However, after 24 h both sulphate-covered and uncovered specimens follow the same linear kinetics. In this very low oxygen partial pressure environment (10(-18) atm), the presence of Na2SO4 promotes the growth of localized iron-rich oxide nodules leading to the observed accelerated oxidation. The development of these nodules is discussed to be the result of the chromia dissolution induced by a basic fluxing mechanism. As soon as the salt is evaporated, slower kinetics are observed and the nodules disappear. In these specific conditions, the oxidation could be considered as a self-healing process.

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hal-00674978 , version 1 (20-12-2019)

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L. Couture, Francois Ropital, F. Grosjean, Jean Kittel, V. Parry, et al.. Reversible catastrophic oxidation of a 38Fe-34Ni-25Cr alloy induced by sodium sulphate at low oxygen potential atmospheres. Corrosion Science, 2012, 55, pp.133-139. ⟨10.1016/j.corsci.2011.10.010⟩. ⟨hal-00674978⟩
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