Effects of a nano carbide coating fabricated by EB-PVD on the interfacial stability of aluminide coated superalloy

Thermal barrier coatings (TBCs) are widely adopted in hot structures of modern gas turbine engines in aerospace as well as other applications. However, due to the significant interdiffusion between superalloys substrate and coating during high-temperature service, the phase transition would occur in the substrate, leading to degradation in the mechanical properties of the hot structures. It is crucial to introduce a diffusion barrier and systematically evaluate the properties of the barrier with depth understanding of the mechanism underpin preventing the diffusion. In this study, a novel nano carbide coating was fabricated by electron beam-physical vapor deposition (EB-PVD) as a diffusion barrier to inhibit the interdiffusion at high temperatures. The effects of the nano carbide coating on the evolution of interfacial microstructure between the superalloy substrate and a typical β-(Ni,Pt)Al coating were investigated at 1100 °C. The results indicate that the nano carbide coating results in a decrease in the thickness of substrate diffusion zone (SDZ) from ∼53 μm to ∼45 μm for 100 h and the outward diffusion rate of Mo, showing a good performance in inhibiting the interdiffusion between the superalloy substrate and the bond coat.