Influence of Alloying Elements on the Behavior of Different Ferritic Steels as Candidate Materials for SOFC Interconnect
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The efficiency of a solid oxide fuel cell (SOFC) can be improved by using a Ni-mesh between the ferritic steel interconnect and the Ni/YSZ anode. However, interdiffusion processes can lead to internal oxidation within the Ni-mesh and some microstructural changes, i.e., formation of an austenite zone and accelerated formation of σ-phase at the ferrite/austenite interface. These changes may adversely affect the performance of the cell during long-term operation. The present work focused on the influence of certain alloying elements on the overall behavior of the ferritic steel under simulated SOFC operating conditions to define conditions to minimize σ-phase formation without degrading the oxidation resistance and mechanical properties of the steel. The experimental results indicate that decreasing the amount of Cr and adjusting the amount of Nb, Si and W of the steel is a possible way to achieve that goal.
KeywordsFerritic steels Chromium content Alloying elements Oxidation behavior Interdiffusion processes σ-phase
L. G.-F. and G. H. M. gratefully acknowledge the Office of Naval Research for support of their participation in this collaboration under Contract N00014-12-1-0612, Dr. Airan Perez, Scientific Monitor. The authors are grateful to M. Hua and Q. Wang for carrying out the EBSD analyses and to Mr. W. Nowak for carrying out the GDOES analyses. Part of the investigations was carried out in the frame of the ZEUS III project funded by the German Ministry of Economics (BMWi) under Contract nr. FKZ0327766A-D. VDM Metals GmbH is acknowledged for supplying the studied materials.
Compliance with Ethical Standards
Conflict of interest
The authors declare they have no conflict of interest.
Human and Animal Rights Statement and Informed Consent
There were no human participants or animals in this study.
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