Fusion Science and Technology / Volume 64 / Number 2 / August 2013 / Pages 211-215
Materials Development / Proceedings of the Twentieth Topical Meeting on the Technology of Fusion Energy (TOFE-2012) (Part 1), Nashville, Tennessee, August 27-31, 2012
Previous studies by the authors showed that hydrogen permeation reduction factor (PRF) of Er2O3 coating on ferritic steels by Metal Organic Decomposition (MOD) depends on the Cr level of the substrate steels and the annealing conditions. The reason of the dependence was attributed to the composition of the oxide layer formed beneath the coating. The PRF was shown to be larger when Cr2O3 layer was formed than when Fe2O3 layer was formed. This paper reports further investigation of the effect of temperature and oxygen partial pressure of the annealing on the composition of the oxide layer. A diffusion modeling of Cr and O was performed to account for the experimental data. The results showed that the data can be well explained assuming that Cr2O3 layer is formed when supply of Cr exceeds that of O at the substrate surface.