Hot corrosion studies of a salt‐coated Ni‐based superalloy under flowing wet air and sulfur vapor ambient

Corrosion of a salt‐coated Ni‐superalloy has been studied at 900°C under a wet air and sulfur vapor ambient. The corrosion thickness, after an incubation of ~60 hr, linearly increases with the corrosion time t and the onset of surface spallation occurred at t  ≈ 60 hr. The corroded layer consists of a corrosion front dominated by Cr 3 S 4 scales and linear precipitate structures, an inner corrosion layer dominated by Ni 3 S 2 and NiO, and an outer corrosion layer dominated by Al 2 O 3 networks surrounding the Ni 3 S 2 and/or NiO scale structures. The corrosion mechanism is discussed based on the coexistence of H 2 O, sulfur, and oxygen.