Fusion Reactor Package Layers Of Different Materials Coated Anti-tritium Permeability Studies

The single films of SiO2, TiN and multiple films of TiN+TiC+TiN, TiN+TiC+SiO2 with the thickness of um were deposited on the surface of 316L stainless steel by physical vapor deposition technology. After annealing at various temperatures, the results of SEM show that the films are compact, thermal shock-resistant, oxidation-resistant and have good compatibility with bulk. The tritium permeability in 316L with films was measured at various temperatures, the results show that the tritium permeability in 316L with TiN and natural oxide film are 2 orders of magnitude lower, that in 316L with SiO2 is 3-4 orders of magnitude lower, that in 316L with TiN+TiC+TiN is 4-5 orders of magnitude lower, and that in 316L with TiN+TiC+Si02 is 4-6 orders of magnitude lower than that in 316L with Pd film, at 200-600 癈. The SIMS, IR and Raman analysis results show that the tritium permeation barrier(TPB) is formed when TiC and SiO2 films are annealed in hydrogen at about 350癈.SiC film was coated on the surface of 316L stainless steel by substrate bias-assisted radio frequency (RF) sputtering as tritium permeation barrier (TPB) of first wall and blanket in fusion reactor. SEM, XRD and FTIR examined the microstructure of films. The results show that the film is compact, uniform and has good adherence with bulk. The crystalline structure of film is as microcrystalline cubic phase P-SiC and shows (111) preferred direction, the adsorption peak corresponds to the stretch frequency peak of Si-C bond of P-SiC. A multiple transition layer (Ti and TiN) was deposited on stainless steel before depositing SiC film, and result in significant improving adhesion of SiC film to stainless steel. The tritium permeation reduction factor (PRF) of 316L with film evaluated at 500癈 is above a factor of 104, compared with 316L with Pd film. It's was found that the bias voltage and RF power influence the quality of film and PRF. The appropriate technology was chosen and identified from some various preparation technologies.The hydrogen permeation experiment of MANET II with hot dipping aluminizedcoating was performed in temperature range of 300 to 450, in gas phase and in liquid Pb-17Li phase. The hydrogen permeation reduction factor (PRF) evaluated in gas phase is 620 ~ 263 and in liquid Pb-17Li phase is 45 ~ 30. But, The PRFs obtained are still not satisfied for the goal of tritium permeation barrier. The self-healing of coating is obvious and effective above 400癈. 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 change from about 2/3 of not wetted part to about 1/1 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.