The Influence of Surface Shot Peening on the Isothermal Oxidation Behavior of NiCrAlYSi Coating

Thermal barrier coatings (TBCs), which mainly comprise top and bond coats, have been applied to the hot components of gas turbine engines owing to their low thermal conductivity, high-temperature oxidation resistance, gas corrosion resistance, and so on. However, a thermally grown oxide (TGO) layer, which germinates between top and bond coats, has a considerable effect on the service life of TBCs. Moreover, the microstructure optimization and growth inhibition of a TGO layer are crucial. The surface modification of bond coat in TBCs has been introduced to reduce and optimize the growth rate of a TGO layer. Among these methods, the surface shot peening of bond coat has yet to be extensively elucidated at high service temperatures. Furthermore, the influence of surface shot peening on isothermal oxidation behavior has rarely been reported in literature. In the present research, NiCrAlYSi coating was prepared using vacuum arc ion plating. The influence of the surface shot peening process on the isothermal oxidation behavior of NiCrAlYSi coating was investigated in detail, which indicated that the surface roughness of NiCrAlYSi coating reduced after the shot peeing. In this process, the compactness and smoothness of NiCrAlYSi coating improved, which could avoid the formation of an abnormal oxidation area in the coating due to the penetration and diffusion of oxygen atoms inside the coating. A uniform and low thickness deviation TGO layer could be generated at the surface. The TGO layer growth rate of NiCrAlYSi coating with 0.4 MPa and 5 min shot peening reduced by 60% compared to no shot peening, and the oxidation resistance of NiCrAlYSi coating improved.