Nanocoatings for SOFC Interconnects - Mitigating Chromium Volatilization and Improving Corrosion Properties

Abstract:

Two important degradation mechanisms in Solid Oxide Fuel Cells (SOFC) are directly related to the metallic interconnects. The formation of volatile chromium oxides from metallic interconnects commonly causes fast degradation in cell performance due to poisoning the cathode. Secondly is the ability of the metallic interconnect to form a thin protective oxide one of the most important lifetime limiting factors for SOFC. Chromium volatilization of various uncoated steels is studied as a function of temperature by a recently developed denuder technique which allows time resolved quantification of volatile chromium species. The inhibition of Cr evaporation by Co thin film coatings (800nm) is investigated; it will be shown that these coatings are more effective than much thicker ceramic coatings that are commonly used for this purpose. In order to increase the lifetime of the metallic components in SOFC nano-coatings of reactive elements (RE) have been investigated as well. The application of such coatings can reduce the corrosion rates substantially and thus increase the lifetime of the fuel cell stack. It will be shown that it is possible to combine the positive effects of RE with the beneficial effects of a Co coating and thus to obtain an interconnect material with low Cr evaporation and increased oxidation resistance.

• Periodical: Materials Science Forum (Volume 696)
• Pages: 412-416
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.696.412
• Online since: September 2011
• Authors: J. Froitzheim, J.E. Svensson
• Keywords: Coating, Corrosion, Evaporation, Interconnector, Solid Oxide Fuel Cell (SOFC), Volatilization

References

[1] N. Sakai, et al., Material transport and degradation behavior of SOFC interconnects. Solid State Ionics, 2006. 177(19-25): p.1933-(1939).

DOI: 10.1016/j.ssi.2006.04.044

[2] H. Yokokawa, et al., Thermodynamic considerations on Cr poisoning in SOFC cathodes. Solid State Ionics, 2006. 177(35-36): pp.3193-3198.

DOI: 10.1016/j.ssi.2006.07.055

[3] B.B. Ebbinghaus, Thermodynamics of gas phase chromium species: The chromium oxides, the chromium oxyhydroxides, and volatility calculations in waste incineration processes. Combustion and Flame, 1993. 93(1-2): pp.119-137.

DOI: 10.1016/0010-2180(93)90087-j

[4] E.J. Opila, et al., Theoretical and experimental investigation of the thermochemistry of CrO2(OH)(2)(g). Journal of Physical Chemistry A, 2007. 111(10): p.1971-(1980).

[5] C. -L. Chu, et al., Effects of La0. 67Sr0. 33MnO3 protective coating on SOFC interconnect by plasma-sputtering. International Journal of Hydrogen Energy, 2008. 33(10): pp.2536-2546.

DOI: 10.1016/j.ijhydene.2008.02.061

[6] Z. Yang, et al., Evaluation of Perovskite Overlay Coatings on Ferritic Stainless Steels for SOFC Interconnect Applications. Journal of The Electrochemical Society, 2006. 153(10): p. A1852-A1858.

DOI: 10.1149/1.2239371

[7] X. Montero, et al., MnCo1. 9Fe0. 1O4 spinel protection layer on commercial ferritic steels for interconnect applications in solid oxide fuel cells. Journal of Power Sources, 2008. 184(1): pp.172-179.

DOI: 10.1016/j.jpowsour.2008.05.081

[8] W. Qu, et al., Electrical and microstructural characterization of spinel phases as potential coatings for SOFC metallic interconnects. Journal of Power Sources, 2006. 153(1): pp.114-124.

DOI: 10.1016/j.jpowsour.2005.03.137

[9] Z. Yang, et al., (Mn, Co)3O4 spinel coatings on ferritic stainless steels for SOFC interconnect applications. International Journal of Hydrogen Energy, 2007. 32(16): pp.3648-3654.

DOI: 10.1016/j.ijhydene.2006.08.048

[10] M. Stanislowski, et al., Reduction of chromium vaporization from SOFC interconnectors by highly effective coatings. Journal of Power Sources, 2007. 164(2): pp.578-589.

DOI: 10.1016/j.jpowsour.2006.08.013

[11] J. Wu, et al., The performance of solid oxide fuel cells with Mn-Co electroplated interconnect as cathode current collector. Journal of Power Sources, 2009. 189(2): pp.1106-1113.

DOI: 10.1016/j.jpowsour.2008.12.079

[12] C. Macauley, et al., The influence of pre-treatment on the oxidation behavior of Co coated SOFC interconnects. International Journal of Hydrogen Energy. In Press, Corrected Proof.

[13] R. Trebbels, et al., Investigation of Chromium Vaporization From Interconnector Steels With Spinel Coatings. Journal of Fuel Cell Science and Technology. 7(1).

DOI: 10.1115/1.3117607

[14] H. Kurokawa, et al., Chromium vaporization of bare and of coated iron-chromium alloys at 1073 K. Solid State Ionics, 2007. 178(3-4): pp.287-296.

DOI: 10.1016/j.ssi.2006.12.010

[15] J. Froitzheim, et al., Investigation of Chromium Volatilization from FeCr Interconnects by a Novel Denuder Technique. Journal of The Electrochemical Society, 2010. 157: p. B1295.

DOI: 10.1149/1.3462987