Preparation and Characterization of Al2O3/Y2O3 Multilayer Coatings As Tritium Permeation Barrier

Tritium permeation barrier (TPB) is a promising solution to reduce fuel loss and environmental contamination caused by tritium permeation in fusion reactor. A multilayered Al2O3/Y2O3 TPB coating containing a total of 10 nanolayers was prepared by magnetron sputtering technology. The Auger electron spectroscopy, field emission scanning electron microscopy, and X-ray diffraction demonstrated the formation of the multilayer structure with crystalline Y2O3 and amorphous Al2O3 sublayers. Further, the effect of Ar/O-2 flow ratio (Gamma) during Al2O3 sublayer deposition on the phase structure, surface morphology, nano-hardness, corrosion resistance, He ion irradiation resistance and deuterium permeation behavior of the multilayered coating was explored systematically. The results show that the Al2O3 sublayer with lower Gamma benefits the (222) preferred orientation of Y2O3 sublayer. The nano-hardness of Al2O3/Y2O3 coating gradually increases with the decrease of F. The coating with Gamma = 1:1 performs the best corrosion resistance and He ion irradiation tolerance. The deuterium permeation test shows a lower deuterium ion current of the Al2O3/Y2O3 coating compared to their single-layer counterparts, where the deuterium gas-driven permeation process is controlled by a combination regime of recombination and diffusion. Our study could provide a potential coating material for the TPB design of fusion reactor.