Oxidation Behaviour of SUS430 Ferritic Stainless Steel and Effects of Gaseous Cr Species Volatilization on LSCF Cathode Surface in Solid Oxide Fuel Cell Operating Temperature

Oxidation offerritic stainless steel SUS430-based interconnects in intermediate temperature solid oxide fuel cell (IT-soFc) contributes to the formation of oxide scales containing volatile chromium (Cr) species around the component. In a longterm operation, Cr volatilization causes Cr poisoning on the cathode component, which is in contact with the SUS430 interconnect. La0.6Sr0.4Co0.2Fe0.8O3-delta (iscF) cathode is currently the best candidate for IT-SOFC cathode. This study aims to determine the effects of the long-term oxidation of SUS430 steel on volatile Cr species formation and to investigate the influence of Cr volatilization on the LSCF cathode performance. The results show that the oxidation of SUS430 steel for 200 h parabolically increased its weight due to oxide scale formation. The scale consists of two layers, namely, the spinel on top and the chromia layer, which does not affect the SUS430 conductivity. However, Cr deposition on the LSCF cathode surface causes the formation of SrCrO4 and Cr2O3 crystallites. This phenomenon reduces the catalytic activity and increases the electrical resistance and the activation energy due to the high amount of oxygen vacancies. Therefore, the mitigation of volatile Cr species is important in maintaining the long-term stability of IT-SOFCs.