Progress in the development of insulator coating for liquid lithium blankets

This paper overviews the recent progress in the development of insulator coating for liquid Li blanket. Insulator coating for mitigating the MHD pressure drop is the key issue for self-cooled liquid lithium blankets with V-alloy structures. Recent efforts are focused on developing Er₂O₃ and Y₂O₃ coatings with various physical and chemical coating technologies. Because of low allowance of the crack areal fraction for the single-layer coating, the in situ healing and the two-layer coating with metallic overlayer have also been investigated. Recent mono-metallic loop experiments with high impurity control showed high stability of V and V-alloy overlayer covering the ceramic coating on V-4Cr-4Ti substrate in flowing Li at 700°C. The development of fabrication technology for the two-layer coating on large and complex shaped surfaces will be the next necessary step. The studies on the effects of radiation on the coating (resistivity, microstructure, mechanical properties and compatibility) need to be enhanced.