70 巻 (2006) 8 号 p. 690-693
A new and stable bond coat system, EQ coating, which is in equilibrium thermodynamically with γ/γ′ substrate, suppresses the diffusion of alloying elements between the substrate and coating, and the formation of secondary reaction zone(SRZ). In this study, β phase is proposed as the candidate for oxidation-resistant EQ coating material based on its high Al content. γ/γ′ superalloy for the substrate material and γ, γ′ and β phase alloys for the coating materials which are in equilibrium were designed by using thermodynamic calculation and EDX technique in Ni-Co-Cr-Al-Hf-Mo-Ta-W system. Cyclic oxidation examination and diffusion experiment for the alloys developed were performed and the suitability of the β phase coating for EQ bond coat is discussed. Creep strength property was examined for the developed γ/γ′ single-crystal superalloy.