Improvements in oxidation resistance and conductivity of Fe-Cr metallic interconnector by (La0.8Ca0.2)(Cr0.9Co0.1)O3 coating

In this study, the effect of perovskite (Ca,Co)-doped LaCrO3 (LCCC) coating on a commercial ferritic stainless steel (SS430) as metallic interconnector in intermediate-temperature solid oxide fuel cell has been investigated in terms of oxidation kinetics and area specific resistance (ASR) at 800 °C in air environment. The LCCC coating was deposited on SS430 by atmospheric plasma spraying from a spray-dried (La0.8Ca0.2)(Cr0.9Co0.1)O3 powder of 10–30 um. The plasma-sprayed LCCC coating had a low porosity of ∼1.0 area% and a good electrical conductivity of 33 S/cm at 800 °C. The protective LCCC coating significantly lowered the growth rate of thermally grown oxide scale of SS430 by inhibiting oxygen inward diffusion. The oxidation of the LCCC coated SS430 for 1200 h led to the formation of duplex Cr2O3-LaCrO3 scale layer of ∼1 um in thickness. A high conductive LaCrO3 phase in the oxide scale was formed by the chemical interactions between the Cr2O3 scale and the LCCC coating. The ASR for the LCCC coated sample was limited to 9.2 mΩ·cm2 after oxidation for 1200 h at 800 °C, which was much lower than ASR for the uncoated sample.