Abstract:In this study, by combining micro-arc oxidation (MAO) and sol-gel technology, the composite MAO/ZrO?-Y?O? hydrogen barrier coatings were successfully prepared on the surface of ZrH1.8 zirconium hydride matrix. The effects of the content of Y?O? concentration (0-16 mol%) and heat treatment temperature (300-600°C) on the microstructure, phase composition, and hydrogen-blocking properties of the coatings were systematically investigated. The results showed that the composite coatings exhibited optimal performance when the Y?O? content was 12 mol%, the porosity was as low as 2.9%, the tetragonal phase of zirconia (t-ZrO?) content reached 18.32%, the hydrogen permeation reduction factor (PRF) was elevated to 19.3, and the hydrogen-loss temperature was increased to 682°C. The heat treatment at 600°C further optimized the surface integrity and crystallization of the coatings, and led to the increase of the hydrogen loss temperature to 686°C. The hydrogen barrier mechanism of the coatings was attributed to the synergistic effect of physical barrier, chemical trapping of oxygen vacancies and phase stabilization.