High Temperature SO-2-gas Corrosion of Ni-Cr-Co Base Superalloy between 800 and 1000℃

摘要

The Ni-base superalloy, INCONEL740, whose major alloying elements are 24.31 wt.%Cr-20 wt.%Co, was corroded in an Ar-0.2%SO-2-gas atmosphere between 800 and 1000℃ for 50, and 100 hr in an electric furnace. The scales formed after SO-2-gas corrosion tests were generally adherent at 800 and 900℃. At 1000℃, massive scale spallation however occurred over the entire surface. The scales consisted of Cr-2O-3, (Ni,Co)Cr-2O-4, and TiO-2, indicating that not sulfidation but an oxidation reaction prevailed owing to the thermodynamic stability of concerning oxides.