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.

Study on Microstructure and Mechanical Properties of A100-Y2O3 Coatings on Low-Carbon Steel by Laser Cladding

“…This shows that when the addition of Y2O3 is less than 1.5%, the increase in the microhardness of the A100-Y2O3 cladding coatings is not enough. The increase in the microhardness of the coating with Y2O3 is mainly due to fine grain strengthening caused by grain refinement and the precipitation strengthening of Y2O3 [23]. An in-depth examination of the data in Table 4 reveals interesting patterns.…”