Comparative analysis of electrodeposited Pt, Ru and Pt-Ru overlays for high-temperature oxidation protection

Abstract

Platinum (Pt) and ruthenium (Ru), both members of the platinum-group metals (PGMs), are renowned for their exceptional resistance to corrosion, oxidation, and high temperatures, making them promising candidates for advanced high-temperature applications. This study investigates the direct current (DC) electrodeposition of Pt, Ru, and a binary Pt-Ru alloy onto NiCoCrAlYTa-coated single-crystal superalloy CMSX-4, along with their vacuum annealing and respective effects on the isothermal oxidation behavior of the system at 1100 °C. All the electrodeposited overlays demonstrated substantial enhancement in oxidation resistance. However, Pt exhibited the highest protection efficiency, Ru the least, and the Pt-Ru alloy provided an intermediate level of performance. Microscopic and X-ray diffraction analyses revealed that the competitive formation of protective α-Al2O3 and spinel NiAl2O4 phases on the coated surfaces played a crucial role in determining the oxidation resistance, driven by atomic interactions between the elements in the NiCoCrAlYTa bond coat and the overlay metals. Despite Ru's relatively lower oxidation resistance compared to Pt, its significantly lower cost offers potential advantages in cost-sensitive, high-temperature applications. These findings provide valuable insights into optimizing Pt-group metal coatings for durability in high-performance systems.

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