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

• DOI: 10.1016/j.corsci.2020.108537
• Publication Date: 2020-02-14T16:20:38Z
• Authors: Jean-Christophe B...; Elodie Rouesne; Joël Ribis; Thomas Guilbert; Stéphane Urvoy; Guillaume Nony; Caroline Toffolon...; Matthieu Le Saux; Nihed Chaabane; Hervé Palancher; Amandine David; Jérémy Bischoff; Julien Augereau; Edouard Pouillier
• Keywords: Zirconium alloys; [SPI]Engineering Sciences [physics]; 670; High temperature steam oxidation; Chromium coating; Chromium coating Zirconium alloys High temperature steam oxidation Enhanced accident tolerant nuclear fuel claddings; [CHIM.MATE]Chemical Sciences/Material chemistry; Enhanced accident tolerant nuclear fuel claddings; 02 engineering and technology; 0210 nano-technology; 620

Abstract 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.