The Role of O2 and H2O Impurities in Dictating the Oxidation Mechanism and Protective Capacity of 9Cr Steels in Hot CO2 - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue High Temperature Corrosion of Materials Année : 2023

The Role of O2 and H2O Impurities in Dictating the Oxidation Mechanism and Protective Capacity of 9Cr Steels in Hot CO2

Fabien Rouillard
Laurence Latu-Romain
  • Fonction : Auteur
Laure Martinelli
Frédéric Miserque
  • Fonction : Auteur
D. J. Young
  • Fonction : Auteur

Résumé

The initial stages of oxidation of 9Cr steel in CO2, O2, CO2–O2 and CO2–O2–H2O is studied by gas phase analysis (GPA) at 550 °C using 13C16,16O2, 18,18O2 and 2H216O isotopic molecules in order to discriminate the reactions of all gas molecules. Protective and non-protective oxide scales are formed on 9Cr steel depending on the exact composition of the gas mixture. In pure CO2, 9Cr steel forms a slow growing chromium-rich oxide scale without any carburization. Adding O2 impurities in CO2 favors the formation of fast growing iron-rich duplex oxide scale coupled to strong carburization. Adding several % of O2 in CO2 favors again the formation of slow growing oxide scale but with different structure and composition than in pure CO2. GPA analyses combined with oxide scale analyses demonstrate that the composition and structure of the transient oxide scale formed on 9Cr surface is determined by the rate at which surface adsorbed oxygen atoms are supplied by the gas phase in the first minutes of exposure. The presence of the very oxidizing O2 molecules in CO2 increases drastically the surface oxidation rate, favoring formation of a non-protective oxide scale which transmits carbon permitting carburization of the steel. Adding water vapor to a CO2 gas environment slows carburization. Preferential adsorption of water vapor molecules over CO2/CO molecules in the inner oxide scale is proposed to explain this result. A unified mechanism for the formation of the transient oxide scale on 9Cr steel in CO2/O2/H2O gas mixtures is described.

Dates et versions

hal-04231480 , version 1 (06-10-2023)

Identifiants

Citer

Fabien Rouillard, François Jomard, Laurence Latu-Romain, Laure Martinelli, Frédéric Miserque, et al.. The Role of O2 and H2O Impurities in Dictating the Oxidation Mechanism and Protective Capacity of 9Cr Steels in Hot CO2. High Temperature Corrosion of Materials, 2023, ⟨10.1007/s11085-023-10186-y⟩. ⟨hal-04231480⟩
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