Microstructure and area specific resistance of cathodic half cells for solid oxide fuel cells composed of perovskite-type cathodes and Co-alloy-coated ferritic stainless steel interconnects

In order to prevent oxidation and Cr poisoning, a Co-W coating has been applied on ferritic stainless steel (FSS), which is used as the interconnect parts of solid oxide fuel cells (SOFCs). However, the electrical properties of the Co–W-coated stainless steels have not yet been evaluated. In this st...

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Bibliographic Details
Published in:Surface & coatings technology 2021-01, Vol.406, p.126659, Article 126659
Main Authors: Gan, Lu, Montero, Xabier, Sheikh, Saad Ahmed, Saeki, Isao, Murakami, Hideyuki
Format: Article
Language:English
Subjects:
Cathodes
Cathodic half-cell
Chromium
Cobalt base alloys
Co–W coating
Electrical conductivity
Electrical properties
Electrical resistivity
Electrode materials
Ferritic stainless steel
Ferritic stainless steels
Interconnections
Microstructural analysis
Microstructure
Oxidation
Oxidation resistance
Oxide coatings
Perovskites
Poisoning
Solid oxide fuel cell
Solid oxide fuel cells
Tungsten
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Summary:In order to prevent oxidation and Cr poisoning, a Co-W coating has been applied on ferritic stainless steel (FSS), which is used as the interconnect parts of solid oxide fuel cells (SOFCs). However, the electrical properties of the Co–W-coated stainless steels have not yet been evaluated. In this study, cathodic half-cells were experimentally manufactured with La0.8Sr0.2MnO3 (LSM) and La0.8Sr0.2Co0.8Fe0.2O3 (LSCF) as cathodes, and uncoated, Co-coated, and Co–W-coated FSSs as interconnects, respectively. Then their oxidation property and area-specific resistance (ASR) were evaluated at 800 °C. Based on phase identification and microstructural analysis, the Co–W-coating was confirmed to effectively suppress the Cr poisoning of the cathode. The ASR values of the Co–W-coated steel with LSM and LSCF as cathodes were 102 and 97 mΩ cm2, respectively, which are adequate for SOFC application. Furthermore, when the LSM was applied as a cathode material, the formation of Mn spinels enhanced the adherence between the cathode and interconnected parts. Thus, the combination of Co–W-coated FSS steel with LSM as the cathode material exhibited the optimal combination of electrical conductivity and microstructural stability. Graphic abstract. [Display omitted] •Cathodic half-cells were fabricated to investigate the electrical properties of Co-W coating in SOFC.•Performance of protective coatings for interconnects in SOFC was evaluated.•The formation mechanism and benefits of Co-Mn spinels in the protective coating were elucidated.
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2020.126659