Tritium permeation barrier-aluminized coating prepared by Al-plating and subsequent oxidation process

Abstract Aluminum rich coatings forming Al 2 O 3 on surface are widely applied as tritium permeation barrier (TPB) on structural materials in fusion reactor. In this work, we proposed a new three-step method for preparing such aluminum rich coating on HR-2 steel: ambient temperature melts salt electroplating followed by heat treating and artificial oxidation at 700 °C. Al deposition from AlCl 3 /EMIC was performed with a deposition rate of 15 μm/h. After heat treated for 2 h, the aluminized coating appeared homogeneous, with thickness of 11–13 μm and free of visible porosity, and exhibited a three-layer structure. After oxidized in 10 −2 Pa O 2 for 80 h, the finally fabricated coating showed a double-layered structure consisting of an outer γ-A1 2 O 3 layer with thickness of 0.1 μm and inner (Fe,Cr,Mn,Ni)Al/(Fe,Cr,Mn,Ni) 3 Al layer of 32 μm thickness, without any visible defects. The deuterium permeation rate through the coated HR-2 steel was reduced by 2–3 orders of magnitude at 600–727 °C.