High-throughput composition screening of Pt-modified aluminide coating for corrosion resistance in molten Na2SO4-NaCl salts at 900 °C

Abstract

A high-throughput magnetron sputtering technique was developed to fabricate multi-component Pt-modified aluminide ((Ni, Pt)Al) coatings to enhance corrosion resistance through compositional optimization. (Ni, Pt)Al, Dy-doped (Ni, Pt)Al, and Zr-doped (Ni, Pt)Al coatings were successfully prepared, all exhibiting dense and uniform microstructures with the thickness of approximately 30 μm. The (Ni, Pt)Al coatings featured compositional gradients of Pt (3–20 at.%) and Al (40–55 at.%). Increasing Pt content induced a phase transition from single-phase β-(Ni, Pt)Al to two-phase consisting of β-(Ni, Pt)Al and ζ-PtAl₂. The hot corrosion behavior of representative coatings was investigated in the Na₂SO₄/NaCl (75:25, wt%) environment at 900 °C for 100 h. The coating with the composition 45.1Ni-8.3Pt-46.6Al (at.%) exhibited superior performance, forming the thinnest and compact α-Al₂O₃ oxide scale (~5 μm) while exhibiting the smallest internal oxidation depth (~10 μm). Furthermore, Dy and Zr doping improved the hot corrosion resistance by delaying the θ-Al₂O₃ to α-Al₂O₃ phase transition and reducing stress-induced cracking. Zr was more effective between the two dopants, as Dy extended the presence of the less protective θ phase. The experimental results provide some theoretical guidance for the subsequent design of (Ni, Pt)Al coatings and can lead to the development of thermal barrier coatings in corrosive environments.