Oxidation kinetics of Zircaloy-4 alloy at 673 K determined by GDOES technique - Publication - Bridge of Knowledge

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Oxidation kinetics of Zircaloy-4 alloy at 673 K determined by GDOES technique

Abstract

Oxidation of zirconium alloys is a process that takes place during the operation of nuclear reactors and is essential for assessing the durability of fuel claddings. The present study was aimed to determine the oxidation kinetics of the Zircaloy-4 alloy using GDOES (glow discharge optical emission spectroscopy) at temperature 673 K corresponding to the conditions of use of fuel pellets. The tests were performed on non-oxidized samples as well as after their oxidation for 0.5, 2, 15 and 48 h. Oxygen layer growth was also investigated by thermogravimetric analysis after oxidation for 0.5 h. The naturally generated oxide at room temperature, designated as non-oxidized, has a thickness of 23±2 nm. After 2 h oxidation, an oxide possessing a thickness of 42±4 nm with about 155 nm of oxygen traces was observed. Oxidation for 15 h resulted in formation of an oxide with a thickness of 130±10 nm with a transition distance to the pure alloy of 240 nm. Finally, a layer with a thickness of 235±10 nm appeared after oxidation for 48 h, while the distance after which the measurement includes only a pure alloy without the oxygen traces is about 310 nm. The results show that oxidation can be described by the exponential kinetic equation, what has the parabolic form after 15 or 48 h of oxidation, which well fit the previous results. However, at shorter oxidation times the kinetic equation has the quasi-parabolic form (n < 2). The reason for changing the form of the equation can be attributed to the effect of defective crystalline structure on oxygen diffusion in the oxide layer as the porosity, crevices and cracks.

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Category:
Articles
Type:
artykuły w czasopismach recenzowanych i innych wydawnictwach ciągłych
Published in:
Inżynieria Materiałowa no. 228, pages 34 - 38,
ISSN: 0208-6247
Language:
English
Publication year:
2019
Bibliographic description:
Trybuś B., Olive J., Zieliński A.: Oxidation kinetics of Zircaloy-4 alloy at 673 K determined by GDOES technique// Inżynieria Materiałowa. -Vol. 228., iss. 2 (2019), s.34-38
DOI:
Digital Object Identifier (open in new tab) 10.15199/28.2019.2.1
Verified by:
Gdańsk University of Technology

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