Synergistic regulation of hydrogen trapping-diffusion at grain boundaries and interfacial hydrogen resistance in La₂O₃/Y-doped Cr₂O₃-based coatings

Abstract

To mitigate hydrogen embrittlement in hydrogen-transport pipeline steels under prolonged hydrogen exposure, this study optimizes the hydrogen barrier performance of Cr₂O₃-based coatings via plasma spraying and investigates the mechanistic role of La₂O₃/Y doping using first-principles calculations. The Cr₂O₃/La₂O₃ coating delayed hydrogen breakthrough time by 21-fold and reduced steady-state current density by 95.9 %, while the Cr₂O₃/Y coating demonstrated superior performance with a 27-fold delay in breakthrough time and a 97.8 % current density reduction. Mechanistic analysis revealed that La enhances H diffusion barriers at interstitial sites and forms efficient hydrogen traps via oxygen vacancies with ultralow insertion energy, whereas Y achieves dual regulation: interstitial trapping through low-energy sites and vacancy blocking via lattice strain induced by Cr-O/Y-O bond length mismatch. Atomic-scale insights further elucidated how rare-earth oxides (La₂O₃, Y₂O₃) regulate grain boundaries, vacancy defects, and hydrogen diffusion pathways, establishing a synergistic framework for designing high-performance hydrogen barrier coatings. These findings bridge atomic-scale mechanisms to macroscopic performance, offering a theoretical foundation for optimizing anti‑hydrogen coating systems.