Effect of surface on hydrogen permeation through pure aluminum

The permeation behavior of hydrogen through pure aluminum has been investigated in the temperature range of 625 K to 773 K by a gas permeation technique. The permeation rate of hydrogen was strongly affected by the conditions on the surface where the hydrogen was introduced into the sample. The presence of the oxide layer on the surface made the hydrogen be hard to permeate through the sample. The oxide layer was reduced by hydrogen during the permeation run at a higher temperature above 700K, which resulted in the larger permeation rate of hydrogen in the subsequent permeation runs. On the other hand, the permeation rate of hydrogen was decreased by the temporary poisoning of the surface. The poisoned surface was cleaned by keeping the sample under high vacuum at a higher temperature above 700K.