Improving hydrogen isotope permeation resistance on T91 steel: The role of Plasma-Induced-Oxide-Interlayer

• Effect of wettability on tritium permeation coating was studied for the first time. • A plasma (Fe, Cr)O oxidation interlayer was introduced on the surface of T91 steel. • Both tritium permeation resistance and thermal shock behavior were improved. The high permeability of hydrogen isotopes in structural materials poses significant challenges to fusion reactors. This study innovatively enhances the comprehensive performance of hydrogen isotopes permeation barrier coatings by introducing an intermediate layer to modify the wettability of the substrate for the first time. A plasma oxidation treatment was conducted on the surface of T91 steel to form an (Fe, Cr)O oxide intermediate layer, followed by the application of an α-Al 2 O 3 coating. Experimental results demonstrate that the sample with the intermediate layer exhibits superior hydrogen permeation resistance, enhanced corrosion resistance after plasma oxidation, and improved thermal shock performance. This research offers a promising method for developing high-performance hydrogen isotope permeation barrier coatings on T91 steel.