Applied Microscopy

Korean Society of Microscopy (한국현미경학회)
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On-Site Corrosion Behavior of Water-Treated Boiler Tube Steel

  • Seo, Junghwa (School of Nano and Advanced Materials, Changwon National University) ;
  • Choi, Mihwa (Green Growth Technology Laboratory, Korea Electric Power Research Institute) ;
  • He, Yinsheng (School of Nano and Advanced Materials, Changwon National University) ;
  • Yang, Seok-Ran (Green Growth Technology Laboratory, Korea Electric Power Research Institute) ;
  • Lee, Je-Hyun (School of Nano and Advanced Materials, Changwon National University) ;
  • Shin, Keesam (School of Nano and Advanced Materials, Changwon National University)
  • Received : 2015.07.28
  • Accepted : 2015.08.02
  • Published : 2015.09.30
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Abstract

The boiler tubes of X20CrMoV12.1 used in fossil-fired power plants were obtained and analyzed for the effect of water treatment on the steam corrosion-induced oxide scale in an effort to better understand the oxide formation mechanism, as well as pertinent method of maintenance and lifetime extension. The specimens were analyzed using various microscopy and microanalysis techniques, with focuses on the effect of water treatment on the characters of scale. X-ray diffraction analysis showed that the scales of specimens were composed of hematite ($Fe_2O_3$), magnetite ($Fe_3O_4$), and chromite ($FeCr_2O_4$). Electron backscatter diffraction analysis showed that the oxides were present in the following order on the matrix: outer $Fe_2O_3$, intermediate $Fe_3O_4$, and inner $FeCr_2O_4$. After all volatile treatment or oxygenated treatment, a dense protective $Fe_2O_3$ layer was formed on the $Fe_3O_4$ layer of the specimen, retarding further progression of corrosion.

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References

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