Hydrogen Permeation Characteristics of TiN-Coated Stainless Steels

Abstract

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 permeability. 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.