Effect of coatings on long term behaviour of a commercial stainless steel for solid oxide electrolyser cell interconnect application in H2/H2O atmosphere

Abstract

K41X (AISI 441) stainless steel evidenced a high electrical conductivity after 3000 h ageing in H2/H2O side when used as interconnect for solid oxide electrolyser cells (SOEC) working at 800 °C. Perovskite (La1 − xSrxMnO3 − δ) and spinel (Co3O4) oxides coatings were applied on the surface of the ferritic steel for ageing at 800 °C for 3000 h. Both coatings improved the behaviour of the steel and give interesting opportunities to use the K41X steel as interconnect for hydrogen production via high temperature steam electrolysis. Co3O4 reduced into Co leading to a very good Area Specific Resistance (ASR) parameter, 0.038 Ω cm2. Despite a good ASR (0.06 Ω cm2), La1 − xSrxMnO3 − δ was less promising because it partially decomposed into MnO and La2O3 during ageing in H2/H2O atmosphere.