Modelling Microstructural and Chemical Degradation of Ferritic Stainless Steels for SOFC Interconnects

Tuesday, 25 July 2017: 09:00
Atlantic Ballroom 3 (The Diplomat Beach Resort)
M. Oum (University of Birmimgham), J. Andrews, and R. Steinberger-Wilckens (University of Birmingham)
Ferritic Fe-based (FeCrX) alloys forming a protective chromium oxide film are used for providing electrical interconnection in high temperature Solid Oxide Fuel Cells (SOFC) are susceptible to degradation mechanisms in the presence of high temperatures (>600oC), and humid air. These translate by the increase in interconnect electrical contact resistance and the formation of volatile chromium species causing poisoning of the adjacent cathode.


Modelling tools and techniques are increasingly becoming popular to gain better understanding of the degradation mechanisms that lead to the formation of volatile chromium species. This research work examines the oxidation behaviour of uncoated ferritic stainless steels system operated at temperature of 700oC in both wet (3% humidity) and dry conditions.


A model is presented based on the physical processes involved. The model is able to predict the weight gain of the samples upon oxidation, the oxide film thickness, the volatilization of chromium and the useable lifetime of interconnects based on chromium depletion. Parameter determination from standard experiments is discussed along with the physical and design insights from the model. Perhaps most importantly the model provides recommendations regarding accelerated testing of FeCrX interconnects and control of the Chromia film thickness.


Acknowledgements: This work was supported by the European FCH JU in project SCORED 2:0 under contract no. 325331 and the EPSRC.