Hydrogen permeation barrier development and characterisation

The control of hydrogen losses in a hydrogen production industrial plant is of crucial importance especially for its safety implications. The high temperatures and pressures required in hydrogen production processes as well as the corrosive process fluids can enhance drastically the intrinsic permeation characteristics of metals and alloys. To reduce hydrogen permeation and a subsequent mechanical degradation of structural materials, hydrogen permeation barriers can be applied. As shown by previous works performed in the frame of the European Fusion Technology Programme, satisfactory hydrogen permeation reductions were achieved using alumina-rich coatings. Several deposition techniques were investigated and coatings were obtained by chemical vapour deposition (CVD) and hot dipping, and these processes seem to have exhibited a better TPB efficiency with respect to the coatings obtained by spray techniques. This work contains a review of the deposition techniques and the efficiency of the different hydrogen permeation barriers developed in the frame of the EU Fusion Programme.