Abstract
A Zr-doped single-phase (Ni,Pt) Al coating was prepared on a Ni-based single crystal superalloy through electroplating Pt-Zr composite layer and subsequent gaseous aluminisation treatments. Hot corrosion and isothermal oxidation tests of NiAl, (Ni,Pt) Al and Zr-doped (Ni,Pt) Al coatings were conducted in static air. The results indicated that Zr-doped coatings showed superior hot corrosion resistance to both conventional aluminide and (Ni,Pt) Al coatings, the enhanced performance was mainly attributed to the advantageous effects of Zr that interacted with S and Cl. The mechanism and role of Zr played in the corrosion test are discussed. Meanwhile, Zr-doped (Ni,Pt) Al coating demonstrated lower oxidation rate constant, which was mainly attributed to the favoring effects of Zr preferring to segregate at grain boundaries of oxide scale. Besides, the addition of zirconium effectively delayed the oxide phase transformation from θ-Al2O3 to α-Al2O3 in early oxidation stage and the coating degradation from β-NiAl to γ'-Ni3Al in stable oxidation stage.
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