Hydrogen permeation characteristics of aluminum-coated and aluminum-modified steels

• Published in: Journal of nuclear materials 1980, Vol.88 (1), p.168-173
• Main Authors: Van Deventer, E.H., MacLaren, V.A., Maroni, V.A.
• Format: Article
• Language: English
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/0022-3115(80)90397-9

The emergence of controlled nuclear fusion based on the D-T reaction has spurred research on tritium permeation. Nearly all structural materials for > 300 deg C (an exception may be Al-base alloys) require a 100- to 1000-fold permeation-reducing barrier. Stainless steel 321-SS samples having approx 4 mu m partially oxidized Al coatings were prepared in an Ar atmosphere by sputter etching, and subsequently sputter depositing Al. Permeation declined steadily, presumably due to in situ oxidation by background oxygen in the permeation apparatus. The over-all reduction was a factor of 20-30. For Al/Al2O3/Al (respectively, 1, 1, 2 mu m)-coated 321-SS, the Al2O3 was provided by sputtering 10% O in Ar. Here the permeation reduction factor compared to uncoated was at best 10X. Electron microprobe tests on Al-coated 321-SS showed the migrating well into the surface with evidence of a Ni--Al phase approx 10 mu m inward from the Al/321-SS interface. The O layer may be present in a very narrow zone (1 mu m) near the surface of the coating.13 refs.--EPAA/AF.