Mitigation of Chromium Poisoning of Ferritic Interconnect from Annealed Spinel of CuFe2O4

Abstract

Low-temperature solid oxide fuel cells permit the possibility of metallic interconnects over conventional ceramic interconnects. Among various metallic interconnects, the ferritic interconnects are the most promising. However, chromium poisoning in them adversely affects their performance. To resolve this issue, various coatings and pretreatment methods have been studied. Herein, this article encloses the coating of CuFe2O4 spinel over two prominent ferritic interconnects (Crofer 22 APU and SUS 430). The CuFe2O4 spinel layer coating has been developed by the dip-coating of both samples in CuFe2O4 slurry, followed by heat treatment at 800 °C in a reducing environment (5% hydrogen and 95% nitrogen). Additionally, both samples were annealed to further enhance their spinel coating structure. The morphological and crystallinity analysis confirmed that the spinel coating formed multiple layers of protection while annealing further reduced the thickness and improved the densities. Moreover, the area-specific resistance (ASR) and weight gain rate (WGR) of both samples before and after annealing was calculated using mathematical modeling, which matches with the experimental data. It has been noted that CuFe2O4 spinel coating improved the ASR and WGR of both samples which were further improved after annealing. This research reveals that the CuFe2O4 spinel is the promising protective layer for ferritic interconnects and annealing is the better processing technique for achieving the preferred properties.