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

Journal article, 2023

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 °C and 600 °C under dual-atmosphere conditions: air-3%H2O on one side and Ar-5%H2-3%H2O on the other side. At 800 °C, the uncoated and Ce/Co-coated steels formed protective layers of (Cr,Mn)3O4/Cr2O3 and (Co,Mn)3O4/Cr2O3 respectively on the air side after 336 h. However, at 600 °C, the Ce/Co-coated AISI 441 and AISI 444 showed ∼20–25 μm thick Fe2O3/(Fe,Cr)3O4 oxide scale on the air side after 336 h. Ce/Co coated Crofer 22 APU remained protective after 772 h at 600 °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.