Hot corrosion and cyclic oxidation performance of a PtAl2-dispersed (Ni,Pt)Al coating prepared by low-activity high-temperature aluminizing

Abstract

The dual phase PtAl 2 -dispersed (Ni,Pt)Al coating (DP coating) and single phase (Ni,Pt)Al coating (SP coating) have been prepared simultaneously with an intermediate Pt content at the surface before low-activity high-temperature aluminizing process. Hot corrosion and cyclic oxidation performance of these two Pt-modified coatings are investigated in comparison with unmodified NiAl coating (UM coating). The results show that DP coating displays better hot corrosion resistance than SP and UM coating due to its higher Al content and faster Al diffusion rate in PtAl 2 phase. The cyclic oxidation resistance of DP coating is comparable to SP coating, while lighter rumpling is achieved at the surface of DP coating. This is because the volume change accompanied by phase transformation from ζ-PtAl 2 to β-(Ni,Pt)Al in DP coating is less than that from β-(Ni,Pt)Al to γ’-Ni 3 Al in SP coating. Moreover, ζ-PtAl 2 is superior to β-(Ni,Pt)Al in creep resistance, which also qualifies DP coating with less rumpling than SP coating with the same residual stress. • PtAl 2 -dispersed (Ni,Pt)Al coating was prepared with an intermediate Pt content at the surface before LAHT aluminizing. • PtAl 2 -dispersed (Ni,Pt)Al coating is superior to (Ni,Pt)Al coating in hot corrosion resistance at 900 °C. • PtAl 2 -dispersed (Ni,Pt)Al coating showed lighter rumpling than (Ni,Pt)Al coating during cyclic oxidation at 1100 °C. • PtAl 2 -dispersed (Ni,Pt)Al coating makes up the disadvantages of both the pure (Ni,Pt)Al and PtAl 2 coating.