La0.7Sr0.3MnO3 (- delta) barrier for Cr2O3-forming SOFC interconnect alloy coated by electrostatic spray deposition

Abstract: In this work, electrostatic spray deposition (ESD) technology was used to deposit dense, free-cracks and thin La_0.7Sr_0.3MnO_3 − δ (LSM) layers on SS446 alloy interconnect to be used in solid oxide fuel cell (SOFC) after subsequent annealing at 800 °C in air for 2 h. The corrosion resistance of uncoated and LSM-coated steels has been studied by electrical and thermogravimetric measurements. The oxidation rate was strongly reduced for LSM-coated steel in ambient air and pure oxygen at 800 °C for 250 h. It was found for the first time that a dense LSM coating as thin as 300 nm efficiently reduces the oxidation rate by limiting outward Cr^3 + diffusion. A protective chromia scale was detected by SEM and EDS at the interfacial layer. The area specific resistance (ASR) of LSM-coated SS446 was found very low (30 mΩ·cm²) and stable in comparison with the uncoated one (80 mΩ·cm²) after 200 h oxidation in air at 800 °C. The results of this work demonstrate the possibility of automated production of dense conductive interconnect LSM-coated materials and give a standard thickness to obtain stable long-term operation.