High temperature steam oxidation of chromium-coated zirconium-based alloys: Kinetics and process

By J. Brachet, E. Rouesne, J. Ribis, T. Guilbert, S. Urvoy, G. Nony, C. Toffolon-Masclet, M. L. Saux, N. Chaâbane, H. Palancher and 4 more. 2020

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The oxidation of chromium-coated zirconium-based alloys is studied under steam at temperatures ranging from 800 °C up to 1500 °C and for oxidation times ranging from a few minutes up to a few hours. For oxidation temperatures up to 1300 °C, the overall oxidation kinetics is nearly parabolic at the beginning of oxidation, when the Cr outer layer is protective. Finally, it significantly accelerates and hydrogen is absorbed during a short period. These steps correspond to different oxidation and diffusion mechanisms, involving: growth of outer chromia scale; Zr-Cr interdiffusion, inducing Zr(Cr,Fe)2 intermetallic layer thickening then disappearance due to transformation into metallic chromium and zirconia; transport of oxygen through residual chromium (in particular along grain boundaries) and into the zirconium substrate, and finally growth of a sub-coating zirconia. The additional effect of the Zr-Cr eutectic reaction occurring when the oxidation temperature is increased beyond 1300 °C is also studied and briefly discussed. © 2020 Elsevier Ltd

Subfields: Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/4e94cddf9bdd940eb1ff421b1c85536f4d87dc6d