The effect of oxygen source on the reaction mechanism of potassium chloride-induced high-temperature corrosion

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Abstract

The role of two oxygen sources, air and water vapor, in the initiation of KCl-induced high-temperature corrosion was addressed with three different commercial alloys typically used in power plants. The focus was on the initiation of the corrosion reaction, so an exposure time of 120 minutes at 540°C was used under flowing conditions. The possible selectivity of oxygen in the corrosion reaction was studied by using two different stable oxygen isotopes, 16O in air and 18O in water vapor, and identifying the isotopes after the reaction with ToF-SIMS. In addition, the surface morphologies were imaged with SEM-EDX and the depth profiles mapped with XPS. Despite the chemical composition of the tested alloys, the alloy surface appears to favor a direct reaction with oxygen from water vapor, when available. On the contrary, the oxygen from air is more involved in reaction(s) forming potassium chromate (K2CrO4). The formation of K2CrO4 provides further evidence of the role of potassium in the initiation of KCl-induced high-temperature corrosion.

Original languageUndefined/Unknown
Pages (from-to)1431–1445
JournalCORROSION
Volume74
Issue number12
DOIs
Publication statusPublished - 2018
MoE publication typeA1 Journal article-refereed

Keywords

  • Low alloy steel
  • Stable oxygen isotopes
  • time-of-flight secondary ion mass spectrometry
  • Nickel-based alloy
  • Potassium chloride
  • High-temperature corrosion
  • Biomass combustion
  • Stainless steel

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