Investigation of coated FeCr steels for application as solid oxide fuel cell interconnects under dual-atmosphere conditions

Dual-atmosphere conditions are detrimental for the ferritic stainless steel interconnects used in solid oxide fuel cells, resulting in non-protective oxide scale growth on the air side. In this paper, low-cost steels AISI 441 and AISI 444 and the tailor-made Crofer 22 APU, were investigated at 800 degrees C and 600 degrees C under dual-atmosphere conditions: air-3%H2O on one side and Ar-5%H-2-3%H2O on the other side. At 800 degrees C, the uncoated and Ce/Co-coated steels formed protective layers of (Cr,Mn)(3)O-4/Cr2O3 and (Co,Mn)(3)O-4/Cr2O3 respectively on the air side after 336 h. However, at 600 degrees C, the Ce/Co-coated AISI 441 and AISI 444 showed similar to 20 -25 mu m thick Fe2O3/(Fe,Cr)(3)O-4 oxide scale on the air side after 336 h. Ce/Co coated Crofer 22 APU remained protective after 772 h at 600 degrees C, indicating better resistance to the dual atmosphere. The effect of Ce/Co coatings on the air side and the need for coatings on the fuel side are discussed and compared with experimental data. (c) 2022 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.