Compatibility of erbium oxide coating with liquid lithium–lead alloy and corrosion protection effect of iron layer

• Li–Pb compatibility of Er2O3 and Er2O3-Fe two-layer coatings was examined with static immersion tests.
• Li–Pb corrosion occurred at the Er2O3 coating surface with loss of Er, and the coating–substrate interface.
• Deuterium permeation reduction of Er2O3 coatings after Li-Pb compatibility tests at 500 °C severely degraded after 1505-h immersion.
• Fe outer layer decreased corrosion rate of Er2O3 coatings, but was corroded at 500 °C.

Li–Pb compatibility of Er2O3 and Er2O3-Fe two-layer coatings has been explored for an understanding of corrosion behaviors and effects of the protection layer. The coatings were peeled off after static Li–Pb immersion test at 600 °C due to the degradation of adhesion between the coating–substrate interface. A loss of Er and then subsequent corrosion of Er2O3 were shown after immersion at 500 °C for 500 and 1505 h. However, the outer Fe layer played a role to decrease corrosion rate of the coatings by comparing with the results of Er2O3 single layer coatings. Deuterium permeation measurements after corrosion tests at 500 °C showed that the Er2O3 coatings kept permeation reduction factors of 102–103 after 500 h immersion, but seriously degraded after 1505 h immersion. Corrosion mechanisms suggest that corrosion protection properties will be modified by an optimization of the outer Fe layer and a control of oxygen concentration in Li–Pb.