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Influence of temperature and steam content on degradation of metallic interconnects in reducing atmosphere

: Folgner, Christoph; Sauchuk, Viktar; Kusnezoff, Mihails; Michaelis, Alexander


Kriven, W.M.:
41st International Conference on Advanced Ceramics and Composites 2017. Proceedings : A collection of papers presented at the 41st International Conference on Advanced Ceramics and Composites, January 22-27, 2017, Daytona Beach, Florida
Chichester: Wiley, 2017 (Ceramic engineering and science proceedings 38.2017, Nr.3)
ISBN: 978-1-119-47470-8
ISBN: 1-119-47470-1
ISBN: 978-1-119-47474-6
ISBN: 1-119-47474-4
Art. 20180110
International Conference on Advanced Ceramics and Composites (ICACC) <41, 2017, Daytona Beach/Fla.>
Bundesministerium für Bildung und Forschung BMBF
6. EFP; 121215; SOFC degradation
Fraunhofer IKTS ()
metallic interconnector; anode gas; degradation; chromium oxide; dualgas atmosphere; resistance

Three ferritic steels (Crofer 22 APU,Crofer 22 H,AISI441) were tested in SOFC anode gas environment in a temperature range between 725–875°C. The experiments were carried out under variation of water vapor content in the gas mixture for different exposure times in order to create accelerated degradation testing conditions for metallic interconnectors (MICs) and to investigate the behavior of these materials caused by the formation of growing chromium oxide based scales. Both gravimetric measurements and FESEM/EDX data was analyzed to characterize the oxidation kinetics and the microstructure of the oxide scales. A clear correlation between increasing temperatures and increasing oxide growth rate constants kw can be demonstrated in all materials. This interrelation results in thicker surface oxide scales. The structures of the oxide layers are specific for each material and consist of Cr2O3 and (Cr,Mn)3O4 with different element distribution and thickness ratio. Beside this, the zone of an inner oxidation with Al-, Si- and Ti-rich oxide inclusions can be seen in ferritic samples, whose microstructures differ depending on analyzed materials and temperatures. Electrical measurements in dual gas atmosphere reveal also an increase of resistance within 1000 h material exposure. The results of oxide growth in tested samples are compared with data derived from real stacks.