Oxidation of Zircaloy-4 in steam at 1300 to 2400/sup 0/C
The oxidation kinetics of Zircaloy-4 in steam have been extended to 2400/sup 0/C. Growth of the ZrO/sub 2/ and ..cap alpha..-Zr layers display parabolic behavior over the entire temperature range studied; however, a discontinuity in the oxidation kinetics above 1510/sup 0/C causes rates to increase above those previously established by the Baker-Just relationship. This increase coincides with the tetragonal-to-cubic phase transformation in ZrO/sub 2-x/. No additional discontinuity in the oxide growth rate is observed upon melting of Zr(O). The effects of temperature gradients have also been taken into account and corrected values representative of near-isothermal conditions have been computed. Experiments have been performed in steam-hydrogen mixtures at 1565 and 1815/sup 0/C. Concentrations of hydrogen up to 90 mole % have no effect on the oxidation kinetics. The rate controlling factor appears to be the available flux of oxygen atoms incident to the reaction surface, and is not dependent upon hydrogen content.
- Research Organization:
- Pacific Northwest Labs., Richland, WA (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 5315760
- Report Number(s):
- PNL-SA-13122; CONF-850601-2; ON: DE85016281
- Country of Publication:
- United States
- Language:
- English
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220900 -- Nuclear Reactor Technology-- Reactor Safety
36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
KINETICS
METALLOGRAPHY
OXIDATION
REACTION KINETICS
STEAM
TIN ALLOYS
VERY HIGH TEMPERATURE
ZIRCALOY
ZIRCALOY 4
ZIRCONIUM ALLOYS
ZIRCONIUM BASE ALLOYS