The Role of Bond Coat in Advanced Thermal Barrier Coating
A novel diffusion barrier bond coat with a duplex layer structure, a sigma phase Re-Cr-Ni barrier and Ni aluminides as an aluminum reservoir was formed on a Ni based superalloy (TMS 82+) and Hastelloy X. The oxidation behavior of both alloys with and without the sigma- Re-Cr-Ni -phase as a diffusion barrier was investigated at temperatures of 1373K (Hastelloy X) and 1423K (TMS-82+) for up to 360ks. It was found that the Re-Cr-Ni acts as a diffusion barrier for both inward diffusion of Al and outward diffusion of alloying elements in the alloy substrate.
Masaaki Naka and Toshimi Yamane
T. Narita et al., "The Role of Bond Coat in Advanced Thermal Barrier Coating ", Materials Science Forum, Vol. 502, pp. 99-104, 2005