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Thermodynamic modeling of chemical interactions between CaO–TiO2 ceramics and molten salts

Published online by Cambridge University Press:  03 March 2011

I. Johnson  and
P.S. Maiya
I. Johnson
Affiliation:
Chemical Technology Division, Argonne National Laboratory, Argonne, Illinois 60439
P.S. Maiya
Affiliation:
Energy Technology Division, Argonne National Laboratory, Argonne, Illinois 60439
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Abstract

The mixed-oxide compounds of CaO with TiO2 are of interest in the development of container vessels for actinide recycling processes in which Ca (dissolved in molten salt) is used to reduce the actinide oxide to actinide metal. The chemical interactions between the mixed-oxide compounds and molten salt saturated with Ca have been analyzed by applying thermodynamic principles. Although the solubility of CaO in molten salt is suppressed by the formation of mixed oxide with TiO2, thermodynamic calculations show that corrosion of CaO-TiO2 ceramics by molten CaCl2 or CaCl2-20 mole % CaF2 that contains metallic Ca in solution occurs by dissolution of the CaO component of the mixed-oxide compounds in the molten salt and reduction of the TiO2 component by the metallic Ca. The thermodynamic predictions are consistent with the experimental observations. The corrosion products produced and the sequence of the various phases depend upon the activity of the CaO produced in the molten salt by reduction reactions. The results of this study show that ceramic materials in the CaO-TiO2 system are not suitable container materials for actinide recycling.

Type
Articles
Information
Journal of Materials Research , Volume 9 , Issue 3 , March 1994 , pp. 739 - 745
Copyright
Copyright © Materials Research Society 1994

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References

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