Chemical compatibility between the α-Al2O3 tritium permeation barrier and Li4SiO4 tritium breeder

alpha-Al2O3 tritium permeation barriers were exposed in a 1-MPa He+0.5-MPa H-2 atmosphere to Li4SiO4 ceramic tritium breeder at 623 K for 120-1000 h, to evaluate its chemical compatibility in a simulated breeder blanket environment. The as-deposited coating is composed of the alpha-Al2O3 phase with a uniform and dense surface morphology. The short-term (below 360 h) effects of corrosion are almost negligible. However, the morphology and structure of the coating change significantly when the corrosion time reaches 1000 h, and grain boundary corrosion, delamination, holes and corrosion products of LiAlO2 are observed. A microscopic model is proposed to understand the corrosion mechanism of the alpha-Al2O3 coating in contact with the Li4SiO4 ceramic.