Preparation and characterization of Al2O3/Y2O3 multilayer coatings as tritium permeation barrier

Abstract

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/O2 flow ratio (Γ) 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 Γ benefits the (222) preferred orientation of Y2O3 sublayer. The nano-hardness of Al2O3/Y2O3 coating gradually increases with the decrease of Γ. The coating with Γ = 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.