Corrosion characteristic of AlN, Y2O3, Er2O3 and Al2O3 in Flinak for molten salt blanket system

For liquid breeder blanket system using molten salts, tritium barrier, anti-corrosion barrier, tritium recovery system and heat exchanger make important roles. Especially in the heat exchanger, the tritium permeation from primary coolant loop to secondary coolant loop must be inhibited by the tritium barrier for safety. To develop it, it is essential to optimize chemical stability of the barrier material against molten salts. In the present study, the corrosion on bulk specimens of AlN, Y2O3 Er2O3 and Al2O3 in Flinak was investigated. The static corrosion tests were performed for 230 and 1010 hours using these specimens with high purity Flinak at 600C in Ar atmosphere. Weight measurement and surface analysis of the specimens were carried out before and after the corrosion test. Chemical analysis of the Flinak also did before and after the corrosion test. AlN showed corrosion resistance, even though the surface was slightly oxidized and corroded. Er2O3, Y2O3 and Al2O3 dissolved into Flinak. In Er2O3 corrosion, Zr in the matrix as an impurity might affect on the corrosion. The Y2O3 corrosion was small. The weight loss due to the corrosion was affected by the breaking of the specimens with porous structure. And the Al2O3 corrosion was large. The surface structure changed to rough surface. These corrosion behaviors agreed with prediction based on thermodynamic evaluation.