Corrosion Resistance and Deuterium Aging Performance of α-Al2O3 Composite Hydrogen Permeation Barrier Coatings

Hydrogen permeation barriers (HPBs) are essential to the development of both hydrogen and nuclear fusion energy. However, their structural stability and barrier efficiency under extreme conditions are scarcely reported, despite their significant importance to practical applications. Here, we experimentally investigated the effect of Li4SiO4 corrosion and deuterium aging on the structure and performance of an α-Al2O3 composite hydrogen permeation barrier coating under simulated fusion conditions. The results demonstrate that this coating could retain its dense and defect-free structure after corrosion with Li4SiO4 powders at 550 °C for 2 days, exhibiting good tritium breeder compatibility. Moreover, after the deuterium aging test for 6 months, its phase composition and microstructure show no significant changes, maintaining a compact and crack-free matrix strongly bonded to the substrate. After 6-month aging, the hydrogen permeation resistance of the α-Al2O3 composite coating at 500 °C is still 1450 times higher than that of the steel substrate without any aging. This work provides critical insights into designing highly reliable hydrogen permeation barrier coatings and understanding their performance evolution under harsh fusion environments.