Preparation of Li4SiO4 Ceramics Tritium Breeder and Its Interface Corrosion Behavior with 14Cr-ODS Steel

The chemical compatibility between Li4SiO4 pebbles and ODS steel is important for the safe operation of the fusion reactor. In the present paper, the transformation of microstructure and component for contact interface between ODS steel and pebbles after 300 h heat preservation in an argon atmosphere at 500, 600, and 700 degrees C was investigated. The results show that serious element interdiffusion and reaction can be observed at the interface between Li4SiO4 pebbles and ODS steel at temperatures of 600 similar to 700 degrees C. For the surface of Li4SiO4 pebbles, a thin reaction layer appears due to the diffusion of Fe and Cr from ODS steel, which also causes the increase of density and decrease of crush load from 51 N (500 degrees C) to 32 N (700 degrees C). XRD patterns show that the new phase of LiCrO2 and LiFeO2 appears on the surface of ODS steel, which suggests that the Li and O atoms in Li4SiO4 pebbles can diffuse into ODS, and react with Fe and Cr elements to form corrosion layers at high temperature. The corrosion layers can be divided into two oxide sub-layers at 700 degrees C. The outermost layer is a mixture of LiFeO2 and LiCrO2, and the next layer is mainly LiFeO2. For the surface of ODS steel, the oxygen diffusion coefficient is 2.2x10(-4) cm(2)/s at 700 degrees C for 300 h. It suggests that the ODS steel as a blanket structure material steel needs a resisted corrosion coating in the design of a blanket in the future.