ABSTRACT: An effective diffusion barrier between a superalloy and aluminide coating would reduce coating degradation by lowering the rate of Al loss to the substrate by interdiffusion, and by inhibiting diffusion of substrate elements (such as Cr, Re, Ta, W) into the coating, both of which reduce corrosion and oxidation resistance. In this preliminary study, Hf-Ni and Hf-Pt were evaluated as potential high-temperature diffusion barrier layers. These materials were sputter deposited onto single-crystal superalloys, followed by various heat treatments. Coatings were subsequently aluminized to form NiAl or NiPtAl coatings for characterization and testing in cyclic oxidation at 1150°C.

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SOURCE: J. A. Haynes, Y. Zhang, K. M. Cooley, L. Walker, K. S. Reeves, and B. A. Pint. “High-Temperature Diffusion Barriers for Protective Coatings.” Poster presented at the International Conference on Metallurgical Coatings and Thin Films. San Diego, CA. April, 2004.