Chemical formation of erbium oxide layer on V–4Cr–4Ti during exposure to liquid lithium doped with erbium

The promising way to mitigate magneto-hydrodynamic (MHD) pressure drop in self-cooled Li/V-alloy blanket is to use electrical insulating coating. The chemical formation of Er2O3 layer on V–4Cr–4Ti during exposure in liquid Li doped with Er was explored. V–4Cr–4Ti specimens were oxidized at 973 K for 0.5–8 h, annealed at 973 K for 16 h, and finally exposed for 20–300 h at 873 K. The Er2O3 layer formed on V–4Cr–4Ti specimens that were oxidized plus annealed, but did not form on either as-received or oxidized only specimens. The resistivity of V–4Cr–4Ti coated with Er2O3 is ∼1013 Ω cm at room temperature which is much larger than the minimum requirement. The Er2O3 layer is stable in liquid Li after 300 h at 873 K. The results indicate that the oxygen source to form Er2O3 layer is the pre-charged oxygen in V–4Cr–4Ti, and that annealing after oxidation to homogenize the oxygen distribution in specimen is necessary.