Chemical stability of ferritic alloy interconnect for SOFCs

Kei Ogasawara, Harukuni Kameda, Yoshio Matsuzaki, Teruhiro Sakurai, Toshihiro Uehara, Akihiro Toji, Natsuko Sakai, Katsuhiko Yamaji, Teruhisa Horita, Harumi Yokokawa

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)

Abstract

A ferritic alloy interconnect was studied through solid oxide fuel cell (SOFC) stack operation at intermediate temperatures. Certain pretreatment of the alloy surface proved to be effective for controlling initial degradation of the stack performance, presumably by the formation of stable and conductive oxide scale. Evidences were found that glass sealant containing alkali metals affected the oxidation behavior of the alloy surface not in contact with the cathode material. A thick scale rich in iron tended to be formed at the air side in the vicinity of the glass sealant, while a thinner scale rich in chromium was preferably found in the other. Alkali metal components were found in that thick oxide layer. At the interface between the alloy and the cathode current collector, a strontium chromate, which might cause chromium poisoning at the cathode/electrolyte interface, was formed, and that was found to be distributed over the current collector away from the interface. A thermodynamic equilibrium calculation using a thermodynamic database revealed that the chromium component is highly reactive with alkali or alkali earth metals and forms stable chromates. Some of those chromates are very stable and may hinder the formation of stable oxide scale such as Mn-Cr-O spinels or Cr2 O3, and may cause the severe oxidation of the alloy.

Original languageEnglish
Pages (from-to)B657-B663
JournalJournal of the Electrochemical Society
Volume154
Issue number7
DOIs
Publication statusPublished - 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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