Corrosion Science and Technology

The Corrosion Science Society of Korea (한국부식방식학회)
권호 표지

Effects of Edta on the Electronic Properties of Passive Film Formed on Fe-20Cr In pH 8.5 Buffer Solution

  • Cho, EunAe (Fuel Cell Research Center, Korea Institute of Science and Technology) ;
  • Kwon, HyukSang (Dept. of Materials Science and Engineering, Korea Advanced Institute of Science and Technology) ;
  • Bernard, Frederic (Dept. of Materials Science and Engineering, Korea Advanced Institute of Science and Technology)
  • Published : 2003.08.01
Download PDF
⟨ Previous Next ⟩

Abstract

The electronic properties of the passive film formed on Fe-20Cr ferritic stainless steel in pH 8.5 buffer solution containing 0.05 M EDTA (ethylene diammine tetraacetic acid) were examined by the photocurrent measurements and Mott-Schottky analysis for the film. XPS depth profile for the film demonstrated that Cr content in the outermost layer of the passive film was higher in the solution with EDTA than that in the solution without EDTA, due to selective dissolution of Fe by EDTA. In the solution with EDTA, the passive film showed characteristics of an amorphous or highly disordered n-type semiconductor. The band gap energies of the passive film are estimated to be ~ 3.0 eV, irrespective of film formation potential from 0 to 700 $mV_SCE$ and of presence of EDTA. However, the donor density of the passive film formed in the solution with EDTA is much higher than that formed in the solution without EDTA, due to an increase in oxygen vacancy resulted from the dissolution of Fe-oxide in the outermost layer of the passive film. These results support the proposed model that the passive film formed on Fe-20Cr in pH 8.5 buffer solution mainly consists of Cr-substituted $\gamma$-$Fe_2O_3$.

Keywords

References

  1. L. J. Oblonsky, M. P. Ryan, and H. S. Isaacs, J. Electrochem. Soc., 145, 1922 (1998)
  2. V. Mitrovic-Scepanovic, B. MacDougall, and M. J. Graham, Corros. Sci., 24, 479 (1984)
  3. R. Kirchheim, H. Heine, H. Fischmeister, S. Hofmann, H. Knote and U. Stolz, Corros. Sci., 29, 899 (1989)
  4. S. Haupt and H. -H. Strehblow, Coros. Sci., 37, 43 (1995)
  5. V. Maurice, W. P. Yang, and P. Marcus, J. Electrochem. Soc., 143, 1182 (1996)
  6. N. E. Hakiki, S. Bound, B. Randot, and M. Da Cunha Belo, Corros. Sci., 37, 1089 (1995)
  7. D. D. Macdonald, J. Electrochem. Soc., 139,3434 (1992)
  8. E. A. Cho, H. S. Kwon, and D. D. Macdonald, Electrochim. Acta., 2001, in preparation
  9. D. A. Frey, Mater. Perform., 20, 49 (1981)
  10. P. C. Searson, R. M. Latanision, and U. Stimming, J. Electrochem. Soc., 135, 1358 (1988)
  11. C. Sunseri, S. Piazza, A. Di Paola, and F. Di Quarto, J. Electrochem. Soc., 134, 2410 (1987)
  12. M. G. S. Ferreira, N. E. Hakiki, G. Goodlet, S. Faty, A. M. P. Simoes, and M. Da Cunha Belo, $7^T^H$ International Symposium on Electrochemical Methods for Corrosion Research, Key Note-08 (2000)
  13. M. Bojinov, G. Fabricius, T. Laitinen, K. Makela, T. Saario, and G. Sundholm, J. Electrochem. Soc., 146, 3238 (1999)
  14. B. Gillot and A. Rousset, J. Solid State Chem., 65, 322 (1986)
  15. J. S. Kim, E. A. Cho, and H. S. Kwon, Corros. Sci., 43, 1403 (2001)
  16. M. H. Dean and U. Stimming, J. Electroanal. Chem., 228, 135 (1987)
  17. M. Da Cunha Belo, in Electrochemical and Optical Techniques for the Study and Monitoring of Metallic Corrosion (M. G. S. Ferreira and C. A. Melendres, Eds.), Kluwer Academic Publishers, Dordrecht, The Netherlands, 1991, p.191
  18. D. D. Macdonald, J. Electrochem. Soc., 139,3434 (1992)
  19. S. Virtanen, P. Schmuki, H Bohni, P. Vuorista, and T. Manytla, J. Electrochem. Soc., 142, 3067 (1995)