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

Aluminum rich coatings forming Al2O3 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 AlCl3/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 O2 for 80 h, the finally fabricated coating showed a double-layered structure consisting of an outer γ-A12O3 layer with thickness of 0.1 μm and inner (Fe,Cr,Mn,Ni)Al/(Fe,Cr,Mn,Ni)3Al 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.