Corrosion Behavior of AISI 316L Stainless Steel and ODS FeAl Aluminide in Eutectic Li2CO3-K2CO3 Molten Carbonates under Flowing CO2-O2 Gas Mixtures

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Abstract

A kinetics study on AISI 316L stainless steel and ODS (Oxide-Dispersion-Strenghtened) FeAl iron aluminide was conducted concerning its corrosion behavior in molten Li2CO3-K2CO3 eutectic at 650°C in flowing CO2-O2 gas mixtures. The corrosion resistance of FeAl ODS was demonstrated to be significantly superior to that of austenitic AISI 316L steel under all gas conditions tested in this work. At low CO2 partial pressure (PCO2 = 0.3 atm) the corrosion rate of both alloys decreased with time due to the formation of a protective oxide layer. In dry CO2 gas, corrosion of AISI steel proceeded at a near-linear rate, indicative of a surface-controlled reaction. FeAl corroded initially following parabolic behavior, but, on further reaction, exhibited some weight loss. A similar behavior was also observed in a 67CO2-33O2 gas mixture. Corrosion of FeAl in high CO2 gas has been postulated to initiate by acidic fluxing of yttria particles. The attack then develops as pitting and leads to further reaction by general corrosion as a consequence of the formation of active-passive electrochemical cells between the interior of pits and the external surface. The weight loss of AISI 316L in 67CO2-33O2 gas can be ascribed to the high oxidizing power of the gas causing a continuous dissolution of the Cr2O3 layer into a soluble chromate.
Original languageEnglish
Pages (from-to)139 - 156
Number of pages18
JournalOxidation of Metals
Volume53
Issue number1-2
Publication statusPublished - 2000

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All Science Journal Classification (ASJC) codes

  • Metals and Alloys

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