Metallic Thin-Film Co- and Ce/Co-Coated Steels as Interconnect Material in IT-SOFC

Abstract

Cr vaporization, oxide scale growth, and the electrical scale resistance (ASR) were studied at 650 °C on coated interconnects intended for IT-SOFC applications. The custom-made SOFC interconnect steel Sanergy HT was coated with thin-film Co- and Ce/Co-coatings and compared to the less expensive substrate steel AISI 441 which was coated with Ce/Co and a 15-20 µm thick commercial MCO-coating. All coated materials mitigated Cr vaporization, and due to the very thin chromia scales formed at the low exposure temperature, ASR values below 10 mΩcm2 were measured for all materials after 500 h at 650 °C. The results in this study show that thin-film metallic Co- and Ce/Co-coated steels show excellent properties as interconnect materials for IT-SOFCs. Thick MCO-coatings can also be used at low temperatures, however, the coating method might be a critical issue for low-temperature applications.