Hf Modified NiAl Bond Coat for Thermal Barrier Coating Application
The Hf doped NiAl coatings were co-evaporated and co-deposited onto the superalloy substrate by electron beam physical vapor deposition (EB-PVD). During heat-treatment, HfO2 was formed on the NiAl coatings. And, Hf enriched at the interface between the coating and the interdiffusion zone, which could prevent outward diffusion of elements in the substrate. The NiAl coating doped with 0.5% Hf effectively improved the high temperature oxidation resistance compared to the Hf free NiAl coating and the high Hf content coating. Also, the addition of Hf to the coating contributed to enhancing the adherence of TGO layer to coating.
Yafang Han et al.
L. D. Sun et al., "Hf Modified NiAl Bond Coat for Thermal Barrier Coating Application", Materials Science Forum, Vols. 546-549, pp. 1777-1780, 2007