Method for creating a textured bond coat surface

Abstract

A method for forming a textured bond coat surface ( 48 ) for a thermal barrier coating system ( 44 ) of a gas turbine component ( 34 ). The method includes selectively melting portions of a layer of alloy particles ( 16 ) with a patterned energy beam ( 20 ) to form successive layers of alloy material ( 16′, 16 ″) until a desired surface geometric feature ( 26 ) is achieved. The energy beam pattern may be indexed between layers to form a protruding undercut ( 28 ) in the geometric feature. The patterned energy beam may be formed by directing laser energy from a diode laser ( 30 ) through a cartridge filter ( 32 ). Particles of a flux material ( 18 ) may be melted along with the alloy particles to form a protective layer of slag ( 22 ) over the melted and cooling alloy material.

The invention claimed is: 
     
         1 . A method for forming a textured bond coat surface for a thermal barrier coating system, the method comprising:
 depositing a layer of powder comprising particles of a metal alloy and particles of a flux material onto a surface;   selectively melting portions of the layer of powder with an energy beam to form a pattern of the metal alloy covered by a layer of slag on the surface;   removing the layer of slag; and   repeating the depositing and selectively melting steps if required to achieve a desired textured surface.   
     
     
         2 . The method of  claim 1 , where the depositing step comprises depositing the layer of powder to comprise particles of a bond coat material and particles of a flux material to form the desired textured surface on a bond coat layer. 
     
     
         3 . The method of  claim 1 , further comprising:
 depositing the layer of powder to comprise particles of a superalloy material and particles of a flux material onto the surface of a superalloy substrate to create the desired textured surface on the superalloy substrate; and   depositing a layer of bond coat material over the textured superalloy substrate surface.   
     
     
         4 . The method of  claim 1 , wherein the step of selectively melting comprises directing a laser energy beam toward the layer of powder through beam shaping optics. 
     
     
         5 . The method of  claim 1 , wherein the step of depositing comprises pre-placing a layer of mixed metal alloy and flux material particles onto the surface. 
     
     
         6 . The method of  claim 1 , wherein the step of depositing comprises simultaneously directing a spray of metal alloy particles and a spray of flux material particles onto the surface. 
     
     
         7 . The method of  claim 1 , wherein the step of depositing comprises depositing a layer of particles of the metal alloy onto the surface and then depositing a layer of particles of the flux material onto the layer of particles of the metal alloy. 
     
     
         8 . The method of  claim 1 , further comprising selecting the particles of metal alloy and the particles of flux material to have overlapping mesh size ranges. 
     
     
         9 . The method of  claim 1 , further comprising forming the desired textured surface to include a geometric feature comprising a protruding undercut by:
 selectively melting portions of a first layer of powder with the energy beam having a first pattern to form a first layer of the geometric feature; and   selectively melting portions of a second layer of powder with the energy beam having a second pattern indexed from the first pattern to form a second layer of the geometric feature cantilevered beyond the first layer to at least partially define the protruding undercut.   
     
     
         10 . A gas turbine engine component comprising a thermal barrier coating system comprising the geometric feature formed by the method of  claim 9 . 
     
     
         11 . A method for forming a textured surface for a thermal barrier coating system, the method comprising:
 depositing particles of a bond coat material onto a surface;   selectively melting portions of the bond coat material particles with an energy beam pattern to form a first layer of a desired textured surface of the bond coat material on the surface; and   repeating the depositing and selectively melting steps to form subsequent layers of the textured surface until the desired textured surface of the bond coat material is achieved.   
     
     
         12 . The method of  claim 11 , further comprising indexing the energy beam pattern between layers such that not all layers have the same geometry. 
     
     
         13 . The method of  claim 11 , further comprising indexing the energy beam pattern between layers to form a geometric feature comprising a protruding undercut. 
     
     
         14 . A gas turbine engine component comprising a thermal barrier coating system comprising the geometric feature formed by the method of  claim 13 . 
     
     
         15 . The method of  claim 11 , further comprising:
 depositing particles of the bond coat material and particles of a flux material onto the surface;   selectively melting portions of the bond coat and flux material particles to form a first layer of the bond coat material covered by a layer of slag on the surface; and   removing the slag prior to any subsequent depositing and selectively melting step.   
     
     
         16 . The method of  claim 11 , further comprising selectively melting the portions of the bond coat material particles with a laser beam patterned by beam shaping optics comprising a filter cartridge. 
     
     
         17 . The method of  claim 16 , wherein a first filter cartridge is used to form a first laser beam pattern for a first layer, and a second filter cartridge is used to form a second laser beam pattern different than the first laser beam pattern for a subsequent layer.