Corrosion behavior of AlCrFeTiNb and AlCrFeTiNb/(AlCrFeTiNb)N coatings in flowing lead–bismuth eutectic alloy with saturated oxygen concentration at 550 ℃

Abstract

The AlCrFeTiNb monolayer coatings and the AlCrFeTiNb/(AlCrFeTiNb)N multilayer coatings are specially designed and prepared on ferritic/martensitic (F/M) steel cladding tube by magnetron sputtering technology, and their corrosion behavior in flowing (∼2 m/s) lead–bismuth eutectic (LBE) alloy with saturated oxygen concentration at 550 ℃ are systematically investigated. For the AlCrFeTiNb coatings, as the coating thickness increases, the LBE oxidation corrosion rate and the stress corrosion-induced crack density increase. The generation of penetrating cracks leads to the LBE infiltration and internal oxidation of the coatings. For the AlCrFeTiNb/(AlCrFeTiNb)N coatings, increasing the modulation period can reduce LBE oxidation corrosion rate, and the appropriate modulation period can also avoid the formation of penetrating cracks. The multilayer structure design has been proved to be effective in improving the LBE erosion resistance and inhibiting the stress corrosion-induced cracking by tailoring the appropriate modulation period and implanting more protective interlayers.