Roughened coatings for gas turbine engine components

Abstract

A gas turbine engine component with an aluminide coating on at least a portion of an airflow surface that includes a roughening agent effective to provide a desired surface roughness and a deposition process for forming such aluminide coatings. A layer including a binder and the roughening agent may be applied to the superalloy substrate of the component and the aluminide coating formed on the airflow surface portion by exposing the component and layer to an appropriate deposition environment. Suitable roughening agents include metal and ceramic particles that are dispersed on the airflow surface portion before exposure to the deposition environment. The particles, which are substantially intact after the aluminide coating is formed, are dispersed in an effective number to supply the desired surface roughness.

1 . A deposition process for a superalloy gas turbine engine component having an airflow surface, comprising:
 dispersing a plurality of particles on at least a portion of the airflow surface; and   forming an aluminide coating on the airflow surface portion that includes the dispersed particles in a substantially intact condition and in an effective number such that the aluminide coating has a desired surface roughness.   
     
     
         2 . The deposition process of  claim 1  wherein forming the aluminide coating further comprises:
 exposing the gas turbine engine component to a deposition environment effective to form the aluminide coating. 
 
     
     
         3 . The deposition process of  claim 2  wherein dispersing the particles further comprises:
 applying a layer comprising the particles on the airflow surface portion and a binder effective to adhere the particles to the airflow surface while the aluminide coating is formed. 
 
     
     
         4 . The deposition process of  claim 3  wherein exposing the gas turbine engine component to the deposition environment further comprises:
 forming the aluminide coating from a metal originating from a vaporized donor material, silicon from the layer, and the particles from the layer. 
 
     
     
         5 . The deposition process of  claim 1  wherein dispersing the particles further comprises:
 applying a layer comprising the particles on the airflow surface portion and a binder effective to adhere the particles to the airflow surface while the aluminide coating is formed. 
 
     
     
         6 . The deposition process of  claim 5  wherein applying the layer further comprises:
 applying the layer across an entire surface area of the airflow surface. 
 
     
     
         7 . The deposition process of  claim 5  wherein applying the layer further comprises:
 applying the layer in a discrete areas on the airflow surface. 
 
     
     
         8 . The deposition process of  claim 5  wherein the substrate includes first and second edges bounding the airflow surface, and applying the layer further comprises:
 applying stripes of the layer that are inclined to intersect at least one of the first and second edges. 
 
     
     
         9 . The deposition process of  claim 5  wherein the substrate includes first and second edges bounding the airflow surface, and applying the layer further comprises:
 applying stripes of the layer that are substantially parallel to the first and second edges. 
 
     
     
         10 . The deposition process of  claim 5  wherein applying the layer further comprises:
 mixing the particles with a binder comprising a silane solution; and 
 placing the binder on the airflow surface portion so as to bind the particles to the airflow surface portion. 
 
     
     
         11 . The deposition process of  claim 1  wherein the desired surface roughness of the aluminide coating is greater than about 0.68 microinches. 
     
     
         12 . The deposition process of  claim 1  wherein the desired surface roughness of the aluminide coating is greater than about 0.75 microinches. 
     
     
         13 . The deposition process of  claim 1  wherein the desired surface roughness of the aluminide coating is greater than about 100 microinches. 
     
     
         14 . The deposition process of  claim 1  wherein the desired surface roughness of the aluminide coating ranges from about 120 microinches to about 130 microinches. 
     
     
         15 . The deposition process of  claim 1  wherein the airflow surface has a convex curvature. 
     
     
         16 . The deposition process of  claim 1  wherein the particles are distributed in separated discrete areas across the airflow surface.