Composite Cu-LaFeO3 Conversion Coatings on a 18Cr Ferritic Stainless Steel for IT-SOFC Interconnects: An Investigation on Structure and Formation Mechanism. Issue 7 (9th June 2017)

• Record Type: Journal Article
• Authors: Masi, A.; Frangini, S.; Seta, L. Della; McPhail, S. J.; Carlini, M.
• Is Part Of: Journal of the Electrochemical Society. Volume 164:Issue 7(2017)
• Page Start: F850
• Page End: F857
• Publication Date: 2017-06-09
• Subjects: Conversion coating -- Interconnect -- Molten carbonate -- Perovskite -- Solid Oxide Fuel Cells -- Interconnect; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.1601707jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : In this work, a novel iron chemical conversion coating process has been applied to deposit a composite Cu-LaFeO3 perovskite coating layer on a commercial 18Cr ferritic stainless steel for application as Intermediate-Temperature Solid Oxide Fuel Cell (IT-SOFC) interconnect. The conversion process is carried out at 600°C under a CO2 gas atmosphere in a binary eutectic lithium-sodium molten carbonate bath containing lanthanum, magnesium and copper additions in form of their respective oxides. Multi-layer coatings are obtained, with a surface composite layer formed by a dense perovskite polycrystalline thick film with metallic copper particles encased in the perovskite grains grown on a Fe-rich spinel sublayer. Copper oxide additions significantly promote the formation of the LaFeO3 perovskite layer, and the experimental results suggest that galvanic coupling phenomena between the alloy elements and copper take place during the coating formation process. Chemical stability and Cr diffusion barrier properties of the composite coating have been evaluated in air exposure experiments at 700°C for 200 h. The perovskite phase shows high stability after the high temperature exposure, with no detectable sign of Cr diffusion in the layer. Details on functional properties of these composite conversion coatings for IT-SOFC applications will be reported in a subsequent study.