Abstract:
A thermal barrier coating (TBC) with depth-varying material properties is formed on a turbine component. Exemplary depth-varying material properties include physical ductility, strength and thermal resistivity that vary from the TBC layer inner to outer surface. Exemplary ways to modify physical properties include application of plural separate overlying layers of different material composition or by varying the applied material composition during the application of the TBC layer. Various embodiment described herein also apply a calcium-magnesium-aluminum-silicon (CMAS)-retardant material over the TBC layer to retard reaction with or adhesion of CMAS containing combustion particulates to the TBC layer. In other embodiments the CMAS retardant material is also applied within engineered groove features (EGFs) that are formed in the TBC surface.
Abstract:
Engineered groove features (EGFs) are formed within thermal barrier coatings (TBCs) of turbine engine components. The EGFs are advantageously aligned with likely stress zones within the TBC or randomly aligned in a convenient two-dimensional or polygonal planform pattern on the TBC surface and into the TBC layer. The EGFs localize thermal stress- or foreign object damage (FOD)-induced crack propagation within the TBC that might otherwise allow excessive TBC spallation and subsequent thermal exposure damage to the turbine component underlying substrate. Propagation of a crack is arrested when it reaches an EGF, so that it does not cross over the groove to otherwise undamaged zones of the TBC layer. In some embodiments, the EGFs are combined with engineered surface features (ESFs) that are formed in the component substrate or within intermediate layers applied between the substrate and the TBC.