First-principles calculation of oxygen absorption, solution and diffusion in Zr and its coatings (Cr, Cr/α-Al2O3)

This work used first-principles calculations to investigate the O behavior near the Zr(0001), Cr(100), and α-Al₂O₃(0001) surfaces, as well as in the Zr(0001)/Cr(100) and Cr(100)/α-Al₂O₃(0001) interfaces. The calculation of absorption, solution, and migration energies, and the analysis of interlayer distances, electronic properties, and jump rates, demonstrated that the α-Al₂O₃(0001) surface possesses the highest resistance to O ingression among these three surfaces. Moreover, the evaluation of interfacial bonding strength revealed that Cr layers are competent to tightly adhere to both Zr substrate and α-Al₂O₃ coating. Consequently, this work proposed a promising coating, Cr/α-Al₂O₃ composite coating with high adhesion work for resisting the delamination of the composite coating. The composite coating exhibits better oxidation resistance than both Zr substrate and Cr coating, which primarily owes to the outer α-Al₂O₃ coating as a shielding layer since O atoms can easily cross the interfaces according to the calculation of migration energies. This work provided theoretical guidance for the development of zircaloy cladding coating materials.