Effect of High-Temperature Exposure on Degradation of La0.6Sr0.4CoO3 Coated Metallic Interconnects for ITSOFC and SOEC

Abstract

Previous studies showed the formation of new phases affecting the electrical properties of LSC thin films deposited on stainless steel substrates, which are commonly tested for ITSOFC and SOEC interconnects. A 4.3 μm thick La 0.6 Sr 0.4 CoO 3 coating was deposited on AISI430 steel by spray pyrolysis, followed by heat treatment (800°C/2h) and an oxidation in air (800°C/96h). The La 0.6 Sr 0.4 CoO 3 phase interacted with the metallic substrate and formed SrCrO 4 , causing degradation of the perovskite into La 0.9 Sr 0.1 CoO 3 . An EDS mapping showed Sr and Cr enrichment in the coating/substrate interface. TG analysis indicated a lower mass gain for the coated substrate. The total ASR at 800°C of the interconnect before and after oxidation was 3.23 Ω.cm 2 and 3.98 Ω.cm 2 , respectively. The Ea underwent very small variation, remaining around 0.24 eV (T≤300°C) and 0.65 eV (T≥400°C). The reaction of Cr from the substrate and Sr from LSC seems to have impaired the performance of the interconnect.