TiN films consisting of fine crystal grains, with diameters of about 100 nm or less, provided superior hydrogen-permeation barriers. Applying a coating of TiN on a stainless steel substrate reduced the hydrogen permeation by a factor of about 100 to 5,000 compared with uncoated substrates. Effect of microstructure of films on hydrogen-permeation behavior is studied. The test specimens coated with films, with columnar crystals grown vertically on the substrate, tended to exhibit higher hydrogen

more »

... ermeability. The grain boundaries of the films became trap sites for hydrogen and microcrystalline structures with many grain boundaries are expected to provide effective hydrogen-barrier performance.