Abstract
Characterization was performed on two-layer V/Y2O3 coatings deposited on V-4Cr-4Ti and exposed to Li in a thermal convection loop at 400°-700°C for 2,350h. The coatings exposed at lower temperatures (≤504°C) showed adequate electrical resistivity at 500°C in vacuum after exposure and the morphology of the Y2O3 layer was unchanged. XPS and EELS analysis showed no indication of Li penetration to the oxide layer after exposure at 437°C. However, coatings exposed at higher temperatures (≥565°C) showed higher conductivity after exposure and a change in the Y2O3 grain morphology was apparent using TEM. At the highest temperature, a continuous layer of recrystallized oxide grains was observed adjacent to the substrate suggesting that a reaction occurred between Y2O3 and V-4Cr-4Ti rather than Li infiltration. However, no layer formed during a 2,350h anneal at 700°C of an unexposed coating.
