Formation and oxidation behavior of Ce-modified MoSi2-NbSi2 coating on niobium alloy

Abstract MoSi2-NbSi2 coating and Ce-modified MoSi2-NbSi2 coating were prepared on Nb-alloy through a new two-step process, including molybdenum slurry spraying and halide-activated pack cementation. The bare alloy was pulverized after oxidation at 1600 °C for 15 min. The both two coated samples have the effective protection for 24.7 h and 28.5 h with the weight gain rate of 3.578 and 2.947 mg2‧cm-4‧h-1, respectively. Ce-modified samples show better performance due to Ce has the ability of grain refinement. The reasons for the excellent performance are the good matching between MoSi2 outer layer and NbSi2 inner layer and the continuous SiO2 oxide scale.