Characterization of La0.8Sr0.2Co0.5Mn0.5O3-δ Coating on Alloy Interconnect in SOFC

Abstract

Chromia-forming ferritic stainless steels are being considered for interconnector applications in planar solid oxide fuel cell (SOFC) stacks because of their low cost and excellent physical properties. Nevertheless, some problems still need to be solved as the performance degradation due to the oxide scale growth at the cathode contact surface and the evaporation of volatile Cr-containing species, which poisons the cathode materials. An alternative and probably simple way is to coat one thin protective layer to limit Cr evaporation and to develop a conductive scale. In this study, La0.8Sr0.2Co0.5Mn0.5O3-δ (LSCM8255) has been considered to obtain a conductive layer. Steel SUS430 surface had been coated with LSCM8255 layer using screen printing combined with dry press method. The microstructure evolution of the interface between the metallic substrate and oxide layers had been investigated by scanning electron microscopy and energy dispersive X-ray spectroscopy line scan analysis. There was few Cr evaporated into the LSCM8255 coating, and small peaks of Cr2O3 and 3Cr2O3•Fe2O3 after isothermal oxidation at 850oC for 500hrs. The variation with time of the area specific resistance (ASR) at 850{degree sign}C had been recorded up to 500h, and low ASR 0.03 Ω•cm2 was observed by a four probe dc technique.