Polycrystalline iron and mild steel surfaces in caustic solution

Allan Costine*, Stephen Thurgate, Mike Thornber, Chris Vernon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Combined ultrahigh vacuum-electrochemical (UHV-EC) methods were utilized to expose polycrystalline iron and mild steel surfaces to 0.01 M NaOH and for the subsequent transfer back to the UHV analysis chamber without exposure to air. X-ray photoelectron spectroscopy (XPS) was then employed to elucidate a chemical description of the iron surfaces as a function of the emersion potential. The mild steel electrodes display lower corrosion resistance in the alkali solution, underlining a crucial role played by minor alloying components, such as sulfide and/or carbide. Carbonate, an unavoidable contaminant of caustic solutions, is strongly adsorbed to both iron surfaces, its concentration generally being unaffected by a subsequent water wash. Polycrystalline iron extracted in the soluble ferrate domain shows enhanced corrosion resistance, which is suspected to arise through surface impurity enrichment following the anodic leaching of the FeO422- species. In contrast, mild steel extracted in the ferrate domain exhibits poor corrosion resistance, further highlighting the detrimental effect of certain alloying elements.

Original languageEnglish
Pages (from-to)452-459
Number of pages8
JournalSurface and Interface Analysis
Volume39
Issue number5
DOIs
Publication statusPublished - May 2007

Keywords

  • Bayer process
  • Electrochemistry
  • Fe
  • Iron oxides
  • Scale formation

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