Chemical Potential Diagrams for Fe-Cr-Li-K-C-O System: Thermodynamic Analysis on Reaction Profiles Between Alloys and Alkali Carbonates

Harumi Yokokawa, Natsuko Sakai, Tatsuya Kawada, Masayuki Dokiya, Ken Ichiro Ota

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)

Abstract

A chemical thermodynamic analysis has been made on reactions between Fe-Cr alloys and mixed alkali carbonates with a local equilibrium approximation using various kinds of chemical potential diagrams for the Fe-Cr-Li-K-C-0 system. The compounds stable in the presence of carbonates have been shown in a log P(02) vs. log P(CO2) plot; their stabilities depend on the valence stability of the transition metal ions and the stabilization energy of double oxides. A log (a(Li)/a(M)) vs. log (a(K)/a(M)) diagram for the M-Li-K-C-O (M = Fe, Cr) systems visualizes which double oxides can be formed sequentially between the alkali carbonates and the transition metal oxides. A log (a(Cr)/a(Fe)) vs. log P(02) plot for the Fe-Cr-Li-K-C-O system under conditions of a(Li2C03) = 0.34, a(K2C03) = 0.14, and P(02) = 1 bar can be compared with experimental results on multilayered oxide scale on 310 and 316 stainless steels which were tested as separators in molten carbonate fuel cells. Reaction paths connecting the reaction products in the respective oxide scales formed on 310 and 316 can be represented on chemical potential diagrams. The activities of Cr and Fe in the alloys are the main factor of determining the oxide scales.

Original languageEnglish
Pages (from-to)3565-3577
Number of pages13
JournalJournal of the Electrochemical Society
Volume140
Issue number12
DOIs
Publication statusPublished - 1993 Dec
Externally publishedYes

ASJC Scopus subject areas

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

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