Coating system for improved leading edge erosion protection

Abstract

A gas turbine engine includes airfoils. At least a portion of the airfoils are coated with a coating that provides for erosion and corrosion protection for the portion of the airfoils.

What is claimed is: 
     
         1 . A method for coating a portion of a gas turbine engine blade, the method comprising the steps of
 providing a gas turbine blade, the blade further comprising an airfoil section having an exterior surface and   applying a coating layer to a preselected exterior surface selected from the group consisting of the leading edge surface, the concave side surface, the convex side, and combinations thereof, the coating layer selected from the group consisting of tungsten-tungsten carbide, tungsten carbide cobalt, cobalt-chrome-tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, and diamond like carbon,   wherein the coating layer at the leading edge surface has a thickness from about 10 μm to about 100 μm.   
     
     
         2 . The method of  claim 1 , wherein the coating layer at the leading edge surface has a thickness from about 35 μm to about 75 μm. 
     
     
         3 . The method of  claim 2 , wherein the coating layer at the concave and convex surfaces is from about 5 μm to about 50 μm. 
     
     
         4 . The method of  claim 1 , further including the step of applying a metallic bond coat layer to the exterior surface of the airfoil before the coating layer. 
     
     
         5 . The method of  claim 4 , wherein the metallic bond coat layer has a thickness from about 2.5 μm to about 10 μm. 
     
     
         6 . The method of  claim 5 , wherein the metallic bond coat layer is selected from the group consisting of Ni, Ti, and Cr. 
     
     
         7 . The method of  claim 1 , further including the step of nitriding the surface of the airfoil. 
     
     
         8 . The method of  claim 7 , wherein the nitrided depth is from about 10 μm to about 50 μm. 
     
     
         9 . The method of  claim 1 , further including the step of carburizing the surface of the airfoil. 
     
     
         10 . The method of  claim 9 , wherein the carburized depth is from about 10 μm to about 50 μm. 
     
     
         11 . The method of  claim 1 , wherein the coating is applied using coating spray methods from the group consisting of HVOF, HVAF, solution plasma spray, electo spark deposition, and cold spray. 
     
     
         12 . The method of  claim 11 , wherein the coating powder size is less than 50 μm. 
     
     
         13 . The method of  claim 12 , wherein the powder size is less than 20 μm.