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ESCA Investigation of the Reaction Products Formed on Titanium Exposed to Water Saturated Bentonite Clay

Published online by Cambridge University Press:  28 February 2011

Håkan Mattsson
Affiliation:
Department of Engineering Metals, Chalmers University of Technology, S-412 96 Göteborg SWEDEN
Ingemar Olefjord
Affiliation:
Department of Engineering Metals, Chalmers University of Technology, S-412 96 Göteborg SWEDEN
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Abstract

Titanium is one of the materials proposed in the Swedish programme for the final containment of spent nuclear fuel. In the present investigation, the final repository environment was simulated on the laboratory scale by embedding titanium and a Ti-Pd alloy in dense, water-saturated bentonite clay. The temperature was 95°C and the exposures lasted between 4 months and 2 years. Analysis was performed using ESCA combined with ion etching.

The reaction products formed on the surface consists of TiO2 Montmorillonite - the main constituent of bentonite - is incorporated in the oxide. Suboxides exist near the oxide/metal interface.

The oxide thickness is in the range 70–100 Å. The oxide growth between 4 months and 2 years is small. No significant influence of Pd could be noted. If it is assumed, that the oxide growth follows a logarithmic law, the expression giving the thickest oxide is y = 5.5 In t (where y is the oxide thickness (Å) and t is the exposure time (s)).

Type
Research Article
Copyright
Copyright © Materials Research Society 1985

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