High temperature corrosion of superheater steels by KCl and K2CO3 under dry and wet conditions

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    Abstract

    The influence of both solid KCl and solid K2CO3 on the oxidn. behavior of a ferritic 10CrMo type steel and a nickel-​based Alloy 625 type steel was investigated in the lab.  Samples were exposed for a week at temps. of 500 °C, 550 °C, and 600 °C.  The role of water vapor was also studied by carrying out exposures under two different atmospheres: dry air, and air with a water content of 30​%.  Analyses were performed with SEM​/EDXA to det. the extent of corrosion, the elemental distribution, and the identification of corrosion products.  Both salts were found to be corrosive towards both steels, but the influence of KCl was significantly greater than that of K2CO3.  In terms of durability, Alloy 625 exhibited higher corrosion resistance than 10CrMo.  In the case of 10CrMo, the oxide formed always consisted of iron oxide with a chromium-​rich region near the original steel surface.  In the case of Alloy 625, the oxide consisted mainly of nickel oxide when it formed in the presence of KCl, and chromium oxide when it formed in the presence of K2CO3.
    Original languageUndefined/Unknown
    Pages (from-to)253–264
    Number of pages12
    JournalFuel Processing Technology
    Volume104
    DOIs
    Publication statusPublished - 2012
    MoE publication typeA1 Journal article-refereed

    Keywords

    • Ferritic steel
    • High temperature oxidation
    • Nickel-based alloy
    • Potassium carbonate
    • Potassium chloride
    • Water vapor

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