HOT DIPPING ALUMINIZED COATING AS HYDROGEN PERMEATION BARRIER

The hydrogen permeation experiment of MA NET II with hot dipping aluminized coating was performed in temperature range of 573 to 623K, in gas phase and in liquid Pb-17Li phase. The hydrogen permeation reduction factor (PRP) evaluated in gas phase is 620 at 573K and 260 at 623K, and in liquid Pb-17Li phase is 24-45 at 573K and P2-30 at 623K. The self-healing of coating is obvious and effective above 673K. The pressure dependence of permeation flux indicates strong surface contribution. The way of filling hydrogen by continuous flow and/or bubble can increase permeation flux. The result of SEM-EDS shows that the microcrack is on the surface of the wetted part, but not on the not wetted part. The crack is superficial and affects only thin outside layer not penetrate aluminized layer. The surface elemental analysis shows that Al/O atomic ratio changes from 2/3 of not wetted part to about 1 of wetted part. The damage of coating surface seems to be related to the interaction of outside layer with liquid Pb-17Li and thermal stress during heating sample.