Hot corrosion behavior of Co modified NiAl coating on nickel base superalloys

The microstructure and corrosion behavior was studied for a Co modified NiAl coating formed on the superalloy DZ125 by pack cementation process. The hot corrosion kinetics showed that the mass gain of the coated specimen was three orders of magnitude lower than that of the uncoated specimen at 1173 K up to 100 h. The corrosion product formed on the surface of the coating mainly consisted of a protective α-Al2O3 film. The presence of Co in the coating could promote the establishment of a protective Al2O3 scale on the coating and restrain the internal diffusion of sulphur in the coating.

The corrosion product formed on the surface of Co modified NiAl coating mainly consisted of a continuous and compact α-Al2O3 film after hot corrosion at 1173 K for 100 h.Figure optionsDownload as PowerPoint slideHighlights
► A Co modified NiAl coating shows good resistance to hot corrosion.
► The oxide formed on the coating consisted of continuous and compact α-Al2O3.
► Co promoted the establishment of Al2O3 scale and restrained internal diffusion of sulphur.