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 (La_0.8Ca_0.2)(Cr_0.9Co_0.1)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.