Nanostructured thin films for hydrogen-permeation barrier

The authors confirmed that applying a coating of Al2O3, TiC, or TiN on a substrate reduced the hydrogen permeation by a factor of at least one order of magnitude compared with uncoated substrates. Al2O3 films consisting of fine crystal grains, with diameters of about 40 nm or less, provided superior hydrogen-permeation barriers on the test specimens. The test specimens coated with TiN or TiC films, with columnar crystals grown vertically on the substrate, tended to exhibit higher hydrogen permeability. The microcrystalline structures with many grain boundaries are expected to provide effective hydrogen-barrier performance. (C) 2015 American Vacuum Society.