Compatibility of multi-layer, electrically insulating coatings for vanadium-lithium blankets

The objective of this work is to demonstrate that a multi-layer, electrically insulating coating will acceptably reduce the magneto hydrodynamic (MHD) pressure losses in a lithium-cooled blanket. Coatings of Er₂O₃ or Y₂O₃ with an overlying coating of vanadium have been fabricated by physical vapor deposition. Coatings have demonstrated acceptable as-received resistivity at 800 °C in vacuum and at 600 °C in contact with Li. When the Y₂O₃ coating was completely covered with a 10 μm vanadium layer, it survived exposure to Li for 100 h at 800 °C without degradation. The interaction between V alloys and Li at ≤800 °C is now the critical compatibility issue and a loop test is being constructed. New ceramic materials based on the Y-Ti-O system also are being explored.