Abstract
The scaling of an Fe-20Cr alloy has been studied in H2-H2O-H2S mixtures between 973 and 1223 K. According to a simplified phase diagram, Cr2O3 and FeS should be the thermodynamically stable compounds in the gas mixtures chosen. The reaction followed a mixed rate law between linear and parabolic, indicating that the reaction rate at the scale-gas interface was comparable with the diffusion rate in the scale. At a constant H2/H2S ratio the scaling rate initially decreased slightly with increasing water-vapor pressure. A further increase of the water-vapor pressure resulted in localized sulfide formation, while the other parts of the surface were covered with a Cr2O3 film. Only Cr2O3 formed above a critical water-vapor content. Three zones could be distinguished when a sulfide scale is formed. The outer zone consisted of practically pure FeS; the intermediate zone was a solid solution of (Fe,Cr)S, partially decomposed to FeCr2S4 and metal during cooling; and the inner zone contained small Cr2O3 inclusions in an (Fe,Cr)S matrix.
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References
P. L. Hemmings and R. H. Perkins, “Thermodynamic Phase Stability Diagrams for the Analysis of Corrosion Reactions in Coal Gasification/Combustion Atmospheres,” EPRI FP-539 (December 1977).
S. R. Shatynski,Oxid. Met. 11, 307 (1977).
A. Rahmel,Oxid. Met. 9, 401 (1975).
W. F. Chu and A. Rahmel,Rev. High Temp. Mater. IV, 139 (1979).
P. Singh and N. Birks,Werkst. Korros. 31, 682 (1980).
R. Vogel and R. Reinbach,Arch. Eisenhüttenw. 11, 457 (1938).
R. Vogel and Th. Heumann,Neues Jahrb Mineral. Monatsh. 90, 175 (1950).
K. T. Jacob, D. Bhogeswara Rao, and H. G. NelsonOxid. Met. 13, 25 (1979).
W. Pepperhoff,Arch. Eisenhüttenw. 32, 269 (1961).
H.-E. Bühler and H. P. Hougardy, “Atlas der Interferenzschichten-Metallographie”, Deutsche Gesellschaft für Metallkunde, D-6370 Oberursel (1970).
See e.g., S. Mrowec inHigh-Temperature Metallic Corrosion of Sulfur and Its Compounds, Z. A. Foroulis, ed., (The Electrochemical Society, New York, 1970), p. 55
C. Wagner,Berichte Bunsenges. Phys. Chem. 70, 775 (1966).
W. L. Worrell and H. J. Kaplan, inHeterogeneous Kinetics at Elevated Temperatures G. R. Belton and W. L. Worrell, eds. (Plenum Press, New York, 1970), p. 113.
K. Fischbeck,Z. Elektrochem. Angew. Phys. Chem. 39, 316 (1933).
C. Wagner and K. Grünewald,Z. Phys. Chemie Abt. B40, 455 (1938).
S. Mrowec, T. Walec, and T. Werber,Oxid. Met. 1, 93 (1969).
T. Narita and K. Nishida,Oxid. Met. 6, 157, 181 (1973).
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Chu, W.F., Rahmel, A. The scaling of a Fe-20Cr alloy in H2-H2O-H2S mixtures. Oxid Met 16, 175–191 (1981). https://doi.org/10.1007/BF00603751
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DOI: https://doi.org/10.1007/BF00603751