Role of preferential orientation on the oxidation resistance of Cr coatings: A first-principles study

Abstract

Chromium (Cr) coatings are regarded one of the most effective strategies for mitigating oxidation in zirconium-based nuclear fuel cladding, particularly under high-temperature accident conditions. Experimental studies frequently report pronounced preferential orientations in Cr coatings on zirconium substrates, yet their specific influence on oxidation performance remains poorly characterized. Here, Cr coatings with (100), (110), and (211) orientations are systematically investigated to elucidate their role in oxidation resistance, with a particular focus on their oxygen adsorption and diffusion mechanisms, using density functional theory (DFT) calculations. The results reveal that oxygen atoms adsorb almost uniformly on Cr surfaces, favoring hollow sites across all three preferential orientations. The (110) surface exhibits the lowest adsorption energy for interstitial oxygen and the highest energy barrier for oxygen diffusion, indicating that oxygen penetration is most challenging on this surface, thereby enhancing the oxidation resistance of Cr coatings. In contrast, on the (100) and (211) surfaces, oxygen atoms readily interact with subsurface Cr atoms, facilitating inward diffusion and reducing oxidation resistance. This study elucidates the impact of preferential orientations on the oxidation resistance of Cr coatings and provides a theoretical foundation for developing coatings with enhanced resistance to oxidation.