In situ formation of CaO insulator coatings on vanadium alloys

A key issue for the self-cooled lithium blanket concept with a vanadium alloy structure is the development of an electrically insulating coating on the coolant channel walls to mitigate the magneto-hydrodynamic pressure drop in a high magnetic field. A systematic investigation of the thermodynamics and kinetics of oxygen and calcium interactions in the vanadium alloy/lithium system is being conducted to define the system parameters required for in situ formation of a CaO coating on vanadium alloys. This paper presents results of theory and modeling as well as experimental results on the formation of CaO coatings on vanadium alloys after exposure at temperatures of 600–700 °C to lithium with a small fraction of Ca added. Coatings of 10–30 μm with high electrical resistivity (>108 Ω cm) have been formed on V-alloys.