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Experimental Determination of Dissolution Kinetics of Zr-Substituted Gd-Ti Pyrochlore Ceramics: Influence of Chemistry on Corrosion Resistance

Published online by Cambridge University Press:  11 February 2011

Icenhower J.P. ,
Weber W.J. ,
Hess N.J. ,
Thevuthasen S. ,
Begg B.D. ,
McGrail B.P. ,
Rodriguez E.A. ,
Steele J.L.  and
Geiszler K.N.
Icenhower J.P.
Affiliation:
Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, U.S.A.
Weber W.J.
Affiliation:
Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, U.S.A.
Hess N.J.
Affiliation:
Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, U.S.A.
Thevuthasen S.
Affiliation:
Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, U.S.A.
Begg B.D.
Affiliation:
ANSTO, PMB1, Menai, New South Wales 2234, Australia
McGrail B.P.
Affiliation:
Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, U.S.A.
Rodriguez E.A.
Affiliation:
Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, U.S.A.
Steele J.L.
Affiliation:
Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, U.S.A.
Geiszler K.N.
Affiliation:
Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, U.S.A.
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Abstract

The corrosion resistance of a series of zirconium-substituted gadolinium pyrochlore, Gd2(Ti1-x Zrx)2O7, where x = 0.0, 0.25, 0.50, 0.75, and 1.00, were evaluated using single-pass flow-through (SPFT) apparatus at 90°C and pH = 2. The zirconate end-member, Gd2Zr2O7, has a defect fluorite structure, which distinguishes it from the face-centered cubic structure of the true pyrochlore specimens. In addition to the chemical variation, the samples include annealed, un-annealed, and ion-bombarded monoliths. In the case of the titanate end-member, Gd2Ti2O7, the annealed specimen exhibited the least reactivity, followed by the un-annealed and ion-bombarded samples (2.39×10-3, 1.57×10-2, and 1.12×10-1 g m-2 d-1, respectively). With increasing zirconium content, the samples displayed less sensitivity to processing or surface modification with the zirconate end-member exhibiting no difference in reactivity between annealed, un-annealed, and ion-bombarded specimens (rate = 4.0×10-3 g m-2 d-1). In all cases, the dissolution rate decreased with increasing zirconium content to the Gd2(Ti0.25Zr0.75)2O7 composition (1.33x10-4 g m-2 d-1), but the zirconate end-member yielded rates nearly equal to that of the titanate end-member. These results demonstrate that to achieve the greatest radiation and corrosion resistance in this series, the Gd2(Ti0.25Zr0.75)2O7 composition should be considered.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 757: Symposium II – Scientific Basis for Nuclear Waste Management XXVI , 2002 , II6.1
Copyright
Copyright © Materials Research Society 2003

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References

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