Corrosion behavior and failure mechanism of amorphous Al2O3 coating at high-temperature LBE

Aluminide coating is a promising candidate material to prevent the LBE corrosion on structural materials in Generation IV lead-based reactor. However, the corrosion resistance and its failure mechanism remain a long-standing challenge. Here, we synthesis an amorphous Al2O3 coating via radio frequency magnetron sputtering (RFMS). Corrosion pits are observed at the macro scale on the coated substrate after LBE corrosion at 550 °C for 2000 h, because of the consumption of ferritic/-martensitic (F/M) steel caused by oxidation. In particular, the volume expansion of corrosion nodules while covered by the Al2O3 coating is investigated. Furthermore, calculation results demonstrate that the concentration of Pri-stress in corrosion products induced coating failure. A model based on corrosion morphology and related properties is proposed to illustrate the stress distribution of corrosion nodules and the further failure mechanism of coatings. This work not only provides a deep understanding on the failure mechanism of brittle ceramic coating, but also paves the way for designing high-performance coatings in reactor.