Hydrogen permeation through steels and alloys with different protective coatings

Hydrogen permeation through EP-750 and EI-914 stainless steels and EK-63 nickel alloy with a diffusion-type Al+Cr+Si coating and a TiN ion-plasma deposited coating was measured. It is shown that the Al+Cr+Si coating reduces by several times hydrogen permeation into the steels and builds a very effective hydrogen protective barrier for the nickel alloy. Deposition of the TiN coating results in a reduction of permeability by 2–4 times depending on the material. The annealing of coated samples in a hydrogen atmosphere at elevated temperatures results in the degradation of the protective coating.