Preparation of Alumina Coatings as Tritium Permeation Barrier by a Composite Treatment of Low Temperature Plasma

The alumina coatings as a tritium permeation barrier were prepared on stainless steel bulk by a composite low temperature plasma method of magnetron sputtering, heat treatment and O ion implantation. The phases, surface morphologies, chemical composition and O element distribution of the coatings were characterized by XRD, SEM, EDS and AES individually, and scratch adhesion test, thermal shock resistance and tritium permeability test were also performed. The results show that the Al coatings deposited by magnetron sputtering are well, and Fe-Al alloys interlayer is formed after heat treatment. In O ion implantation process, the oxygen depth is deepened and the oxygen density gradient decreases with higher accelerating voltage at definite doses; meanwhile it can be seen that 8×1017 ions/cm2 is the crucial dose, above which the oxygen density is more homogeneous. After a series of tests, the obtained coatings have the good performance of film-substrate cohesion, thermal shock resistance and the tritium permeation resistance, and the coatings, which were treated by superposition at 8×1017 ions/cm2 doses, have the best tritium permeability resistance, and the trillium permeability decreases 3 orders of magnitude compared with that of the stainless steel bulk at 600 °C.