Ex-situ experimental benchmarking of solid oxide fuel cell metal interconnects

• Published in: Journal of power sources Vol. 437; p. 226900
• Main Authors: Bianco, Manuel, Tallgren, Johan, Hong, Jong-Eun, Yang, Shicai, Himanen, Olli, Mikkola, Jyrki, Van herle, Jan, Steinberger-Wilckens, Robert
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2019
• Subjects: Chromium poisoning; Corrosion evolution; Ferritic stainless; Interconnects; Protective coatings; Solid oxide fuel cell; Steels; Chromium poisoning; Interconnects; Ferritic stainless; Steels; Corrosion evolution; Protective coatings; Solid oxide fuel cell
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2019.226900

Solid oxide fuel cells (SOFCs) can convert hydrocarbon fuels, such as methane, into heat and electricity with a high conversion efficiency. The fuel flexibility of the SOFC derives from the high operating temperature (600-900 °C). Such a high temperature stresses the materials used in the SOFC stacks, notably the metals constituting the interconnect (IC). Research centres developed in last twenty years specific alloys and coatings compositions. This led to a vast literature production of solutions to mitigate the degradation of the metals used in SOFC stacks. Unfortunately, the testing method and conditions change from one laboratory to another making the comparison of the results often impossible. This article compares systematically more than sixty different solutions to limit the degradation in the IC. The samples differed for the steel composition, the coating deposition technique, and the coating composition. A modified 4-probe technique and SEM/EDS post-test characterization measure the area specific resistance and chromium retention of the samples. Testing results indicate that i) deposition technique is the most relevant parameter, ii) in presence of coatings, the performances are independent of the type of ferritic stainless steel substrate iii) nitriding helps to limit the outward chromium diffusion in case of porous coatings. •More than 60 combinations of material solutions for SOFC interconnects are tested.•Chromium retention and area specific resistance of these solutions are measured.•Coating deposition technique is the key for an interconnect of good performance.•Cheaper commercial stainless steel (K41) can compete with SOFC-specific steels.•Steel nitriding improves chromium retention when coatings are porous.