Turbine component cooling hole within a microsurface feature that protects adjoining thermal barrier coating

Abstract

Cooling holes in a turbine component, such as a blade, vane or combustor transition, are formed in and surrounded by a micro surface feature (MSF) that protects the adjoining thermal barrier coating (TBC) from delamination or crack propagation during the hole formation or during engine operation. The MSF effectively functions as a circumferential sleeve around the cooling hole margin so that relatively more friable TBC material that would otherwise define the cooling hole margin is not directly exposed to coolant fluid exhausting the hole, foreign object damage (FOD) or contact with cooling hole formation tooling when fabricating the hole through the TBC layer. The MSF is formed as a projection from the component substrate or during subsequent application of a metallic bond coat (BC) layer.

What is claimed is: 
     
         1 . A turbine component that is adapted for incorporation within a turbine engine, having an outer surface for exposure to heated working fluid that drives the engine, comprising:
 a metallic substrate having a substrate surface;   a micro surface feature (MSF) projecting from the substrate surface, having an MSF sidewall and an MSF upper surface forming part of the turbine component outer surface, capping the MSF sidewall;   a cooling hole formed within and circumscribed by the MSF upper surface, the hole extending within the substrate; and   a thermally sprayed or vapor deposited or solution/suspension plasma sprayed thermal barrier coat (TBC) applied over the substrate and abutting the MSF sidewall, forming part of the component outer surface, for exposure to heated working fluid.   
     
     
         2 . The component of  claim 1 , further comprising the cooling hole having a central axis that is skewed relative to the substrate surface. 
     
     
         3 . The component of  claim 2 , further comprising the MSF sidewall having a central axis that is skewed relative to the substrate surface. 
     
     
         4 . The component of  claim 1  the MSF sidewall having an undercut outer surface profile for mechanically anchoring the TBC thereto. 
     
     
         5 . The component of  claim 1 , the MSF top surface and the TBC forming a flush outer surface profile, exposing the MSF top surface. 
     
     
         6 . The component of  claim 1 , the MSF formed in the metallic substrate. 
     
     
         7 . The component of  claim 6 , further comprising a bond coat BC interposed between the substrate, including the MSF, and the TBC. 
     
     
         8 . The component of  claim 1 , the MSF formed in a bond coat interposed between the substrate and the TBC. 
     
     
         9 . The component of  claim 1 , further comprising a plurality of MSFs and cooling holes arrayed about the metallic substrate. 
     
     
         10 . A turbine engine, comprising:
 a turbine housing;   a rotor having blades rotatively mounted in the turbine housing;   turbine vanes mounted in the turbine housing at least upstream of the blades; and   at least one turbine component having an outer surface for exposure to heated working fluid that drives the blades, the component including:   a metallic substrate having a substrate surface;   a micro surface feature (MSF) projecting from the substrate surface, having an MSF sidewall and an MSF upper surface forming part of the turbine component outer surface, capping the MSF sidewall;   a cooling hole formed within and circumscribed by the MSF upper surface, the hole extending within the substrate; and   a thermally sprayed or vapor deposited or solution/suspension plasma sprayed thermal barrier coat (TBC) applied over the substrate and abutting the MSF sidewall, forming part of the component outer surface, for exposure to heated working fluid.   
     
     
         11 . The turbine engine of  claim 10  the component MSF sidewall having an undercut outer surface profile for mechanically anchoring the TBC thereto. 
     
     
         12 . The turbine engine of  claim 10 , the component MSF formed in the metallic substrate. 
     
     
         13 . The turbine engine of  claim 12 , the component further comprising a bond coat BC interposed between the substrate, including the MSF, and the TBC. 
     
     
         14 . The turbine engine of  claim 10 , the component MSF formed in a bond coat interposed between the substrate and the TBC. 
     
     
         15 . The turbine engine of  claim 10 , the component further comprising a plurality of MSFs and cooling holes arrayed about the metallic substrate. 
     
     
         16 . A method for making a turbine component that is adapted for incorporation within a turbine engine, having an outer surface for exposure to heated working fluid that drives the engine and cooling holes formed through the outer surface, comprising:
 providing a metallic substrate having a substrate surface;   forming a micro surface feature (MSF) projecting from the substrate surface, having an MSF sidewall and an MSF upper surface forming part of the turbine component outer surface, capping the MSF sidewall;   applying a thermally sprayed or vapor deposited or solution/suspension plasma deposited thermal barrier coat (TBC) layer over the substrate surface and abutting the MSF sidewall, forming part of the component outer surface, for exposure to engine heated working fluid; and   forming a cooling hole within and circumscribed by the MSF upper surface.   
     
     
         17 . The method of  claim 16 , comprising forming the MSF in the substrate upper surface by directly casting it therein. 
     
     
         18 . The method of  claim 17 , further comprising:
 forming a thermally sprayed bond coat (BC) layer on the substrate surface and the MSF prior to applying the TBC layer; and   applying the TBC layer over the BC layer.   
     
     
         19 . The method of  claim 16 , further comprising:
 forming a thermally sprayed bond coat (BC) layer on the substrate surface, including the MSF formed therein prior to application of the TBC layer;   applying the TBC layer over the BC layer, including the MSF; and   shaping the TBC layer outer surface so that it is flush with and exposes the MSF top surface.   
     
     
         20 . The method of  claim 16 , further comprising forming the MSF sidewall with an undercut outer surface profile for mechanically anchoring the TBC thereto.