Microstructural characterization of accident tolerant fuel cladding with Cr-Al alloy coating layer after oxidation at 1200 ℃ in a steam environment

• Published in: Nuclear engineering and technology Vol. 52; no. 10; pp. 2299 - 2305
• Main Authors: Park, Dong Jun, Jung, Yang Il, Park, Jung Hwan, Lee, Young Ho, Choi, Byoung Kwon, Kim, Hyun Gil
• Format: Journal Article
• Language: Korean
• Published: 2020
• Subjects: Accident tolerant fuel; Zr alloy; High temperature oxidation; Coating; Cr-Al alloy; Microstructure
• ISSN: 1738-5733; 2234-358X

Zr alloy specimens were coated with Cr-Al alloy to enhance their resistance to oxidation. The coated samples were oxidized at 1200 ℃ in a steam environment for 300 s and showed extremely low oxidation when compared to uncoated Zr alloy specimens. The microstructure and elemental distribution of the oxides formed on the surface of Cr-Al alloys have been investigated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). A very thin protective layer of Cr2O3 formed on the outer surface of the Cr-Al alloy, and a thin Al2O3 layer was also observed in the Cr-Al alloy matrix, near the surface. Our results suggest that these two oxide layers near the surface confers excellent oxidation resistance to the Cr-Al alloy. Even after exposure to a high temperature of 1200 ℃, inter-diffusion between the Cr-Al alloy and the Zr alloy occurred in very few regions near the interface. Analysis of the inter-diffusion layer by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) measurement confirmed its identity as Cr2Zr.