Development of silicide coatings over Nb-NbCr₂ alloy and their oxidation behavior at 1250°C

The aims of this study were to develop silicide coatings for Nb-NbCr₂ alloy and to evaluate their oxidation behavior. Both of the coatings prepared by single deposition of Si and co-deposition of Si-Y were composed of (Nb,Cr)Si₂ and (Cr,Nb)Si₂, showing a similar structure. After oxidation at 1250°C for 50h, the weight gains of the bare alloy and the un-modified silicide coating were 246.9 and 90.3mg/cm² respectively, while the weight gain of Y-modified silicide coating was only 13.1mg/cm². The introduction of Y³⁺ in the scale showed a suppressing effect on the outward diffusion of chromium cations and the inward migration of oxygen anions, thereby retarding the oxide scale growth rate of the silicide coating at 1250°C in static air.