Comparison of thermal cycling behavior of plasma-sprayed nanostructured and traditional thermal barrier coatings

Nanostructured and traditional thermal barrier coatings have been prepared by atmospherical plasma spraying (APS) on NiCrAlY-coated superalloy substrates. Nanostructured thermal barrier coating has relatively longer lifetime than the common coating after cyclic testing at 1050, 1100 and 1150 °C. A transient thermal structural finite element solution was employed to analyze the stress distribution in the coatings. The reasons why the two kinds of the coatings have different lifetimes have been explored. The results indicate that the stresses (Sx) within the nanostructured yttria stabilized zirconia (YSZ) ceramic layer in the axial (x) direction is about 67% that of the traditional YSZ. The stress (Sy) in the radial (y) direction at the vicinity of the interface between the thermally grown oxide scale (TGO) and the YSZ topcoat at the edge of the sample is only about 73% that of the traditional YSZ. So it could be concluded that the decrease of the stress in the nanostructured ceramic layers is a fundamental reason, resulting in longer thermal cycling lifetime of the nanostructured thermal barrier coating.