Effects of Y2O3 Addition on the Microstructure and Static Lead-Bismuth Eutectic Thermal Corrosion Behaviors of FeCrAlTiC-xY2O3 Laser Clade Coatings

Abstract

In order to prevent the lead-bismuth eutectic (LBE) corrosion of stainless-steel components used in nuclear reactors, the FeCrAlTiC-xY2O3 coatings were prepared on 304 stainless steel (304SS) by laser cladding. After adding Y2O3, Y2TiO5 and Y2Ti2O7 formed, which have a combined strengthening effect on improving hardness. The 0.2 wt.% Y2O3 coating showed the highest hardness as ~489 HV. In the 400 °C wear test, the weight loss of coating samples was less than ~5.2 mg, while the weight loss of 304SS samples was ~35.5 mg. The 0 wt.% Y2O3 coating showed the highest wear resistance, indicating that adding Y2O3 could result in the decrease of wear resistance. The LBE corrosion behaviors of coatings at 500 °C were investigated. The results showed that a uniform and dense oxide scale with a low growth rate was obtained on the coating surface, and no penetration of LBE into the coating was observed. After 1000 h of corrosion, the oxide scale of coatings grew to merely a ~0.3 μm thickness. The corrosion resistance mechanism of the coating in oxygen-saturated LBE at 500 °C was proposed based on experimental results along with a thermodynamic and kinetic analysis.