High temperature sulfidation and oxidation of sputter-deposited Nb−Al−Si coatings

Abstract

The sulfidation and oxidation behavior of amorphous 58Nb-38Al-4Si(at.%) coating sputter-deposited with d.c. magnetron sputtering was studied between 700 and 900 o C under 0.1 atm of pure S 2 (g) and 1 atm of air, respectively. The coating approximately followed the parabolic sulfidation and oxidation rate law, and displayed superior resistance to sulfidation and oxidation. The coating sulfidized to Al 2 S 3 and NbS 2 which protected the substrate. The coating oxidized to TiO 2 , AlNbO 4 and κ-Al 2 O 3 which acted as an oxidation barrier. The mechanisms of sulfidation and oxidation of the prepared coating are discussed.