Effect of Ultrasonic Shot Peening on Morphology and Structure of NiCrAlYSi Coatings on Superalloys for Blade Applications

The study evaluated and compared the surface morphology, roughness, and coating structure of ultrasonic shot peening (USP)-treated samples of the NiCrAlYSi-coated GH4169 alloy used for turbine blades and discussed the influence of blade-surface roughness and coating thickness on aerodynamic performance. The NiCrAlYSi coating was deposited on the surface of the alloy using electron beam-physical vapor deposition (EB-PVD), and the NiCrAlYSi bond coat was subsequently surface treated at Almen intensities of 0.1 A, 0.15 A, and 0.2 A by USP. The results following USP treatment indicated that the bond coat becomes denser with a smoother surface and a porosity reduction ranging from 12.5% to 50%, accompanied by localized enrichment of Cr elements near the substrate. Additionally, the study examined the influence of coating thickness and roughness on turbine blade aerodynamic performance, validating the effectiveness of USP in reducing these factors, thereby potentially enhancing the aerodynamic efficiency of coated turbine blades.