Upgrading aluminide coating on used turbine engine component

Abstract

A method of upgrading an aluminide coating on a used turbine engine component to a platinum aluminide coating. The method involves cleaning at least one surface of the component to remove hot corrosion products from the surface without damaging the aluminide coating. In one embodiment, the cleaning step involves immersing the component in a heated solution comprising acetic acid while agitating the solution using ultrasonic energy. A layer of platinum is then deposited onto the cleaned surface of the component. A second aluminide coating is then formed on the surface of the component to upgrade the component. The invention also relates to a turbine engine component, e.g., a turbine blade, having a metal-based substrate and a platinum aluminide coating on at least one surface thereof, which coating has been upgraded from an aluminide coating originally on the component using the above method.

1 . A method for upgrading an aluminide coating on a used turbine engine component to a platinum aluminide coating, said method comprising: 
 a) cleaning at least one surface of the component to remove hot corrosion products from the surface without damaging the aluminide coating;    b) depositing a layer of platinum onto the cleaned surface of the component; and then    c) forming a second aluminide coating on the surface of the component.    
     
     
         2 . A method as recited in  claim 1 , wherein step a) comprises immersing the component in a solution comprising acetic acid.  
     
     
         3 . A method as recited in  claim 2 , wherein the solution comprises from about 4% to about 8% acetic acid.  
     
     
         4 . A method as recited in  claim 2 , wherein the component is immersed in the solution for at least about two hours, and the solution is agitated using ultrasonic energy.  
     
     
         5 . A method as recited in  claim 4 , wherein the solution has a temperature of from about 150° F. (about 66° C.) to about 175° F. (about 77° C.).  
     
     
         6 . A method as recited in  claim 1 , wherein the platinum layer is heated to a temperature of from about 1700° F. to about 1950° F. (about 927° C. to about 1066° C.) for from about 0.5 to about 2 hours prior to forming the second aluminide coating.  
     
     
         7 . A method as recited in  claim 1 , wherein the platinum layer deposited on the surface of the component has a thickness of from about 5 to about 10 microns.  
     
     
         8 . A method as recited in  claim 7 , wherein the platinum layer is heated to a temperature of from about 1700° F. to about 1950° F. (about 927° C. to about 1066° C.) for from about 0.5 to about 2 hours prior to forming the second aluminide coating.  
     
     
         9 . A method as recited in  claim 8 , wherein step a) comprises immersing the component in a solution comprising acetic acid that has a temperature of from about 150° F. (about 66° C.) to about 175° F. (about 77° C.), and the solution is agitated using ultrasonic energy.  
     
     
         10 . A method as recited in  claim 1 , wherein the second aluminide coating has a thickness of from about 25 to about 75 microns.  
     
     
         11 . A method as recited in  claim 10 , wherein the component is a turbine blade.  
     
     
         12 . A method for upgrading an aluminide coating on a used turbine engine component to a platinum aluminide coating, said method comprising: 
 a) cleaning at least one surface of the component to remove hot corrosion products from the surface without damaging the aluminide coating by immersing the component in a solution comprising acetic acid;    b) depositing a layer of platinum having a thickness of from about 2 to about 20 microns onto the cleaned surface of the component; and then    c) forming a second aluminide coating having a thickness of from about 10 to about 100 microns on the surface of the component.    
     
     
         13 . A method as recited in  claim 12 , wherein in step a) the solution comprises from about 4% to about 8% acetic acid.  
     
     
         14 . A method as recited in  claim 12 , wherein in step a) the component is immersed in the solution for at least about two hours.  
     
     
         15 . A method as recited in  claim 14 , wherein the solution has a temperature of from about 150° F. (about 66° C.) to about 175° F. (about 77° C.).  
     
     
         16 . A method as recited in  claim 15 , wherein the solution is agitated using ultrasonic energy.  
     
     
         17 . A method as recited in  claim 12 , wherein the platinum layer deposited on the surface of the component has a thickness of from about 5 to about 10 microns.  
     
     
         18 . A method as recited in  claim 17 , wherein the platinum layer is heated to a temperature of from about 1700° F. to about 1950° F. (about 927° C. to about 1066° C.) for from about 0.5 to about 2 hours prior to forming the second aluminide coating.  
     
     
         19 . A method as recited in  claim 18 , wherein the second aluminide coating has a thickness of from about 25 to about 75 microns.  
     
     
         20 . A method as recited in  claim 19 , wherein in step a) the solution comprises from about 4% to about 8% acetic acid, and has a temperature of from about 150° F. (about 66° C.) to about 175° F. (about 77° C.).  
     
     
         21 . A method as recited in  claim 20 , wherein in step a) the component is immersed in the solution for at least about two hours, and the solution is agitated using ultrasonic energy.  
     
     
         22 . A method as recited in  claim 21 , wherein the component is a turbine blade.  
     
     
         23 . A turbine engine component having a metal-based substrate and a platinum aluminide coating on at least one surface thereof, said coating having been upgraded from an aluminide coating originally on the component by a method comprising: 
 a) cleaning at least one surface of the component to remove hot corrosion products from the surface without damaging the aluminide coating;    b) depositing a layer of platinum onto the cleaned surface of the component; and then    c) forming a second aluminide coating on the surface of the component.    
     
     
         24 . A turbine engine component as recited in  claim 23 , wherein step a) comprises immersing the component in a solution comprising acetic acid.  
     
     
         25 . A turbine engine component as recited in  claim 24 , wherein the component is immersed in a solution comprising from about 4% to about 8% acetic acid for at least about two hours.  
     
     
         26 . A turbine engine component as recited in  claim 23 , wherein the platinum layer deposited on the surface of the component has a thickness of from about 5 to about 10 microns.  
     
     
         27 . A turbine engine component as recited in  claim 26 , wherein the platinum layer is heated to a temperature of from about 1700° F. to about 1950° F. (about 927° C. to about 1066° C.) for from about 0.5 to about 2 hours prior to forming the second aluminide coating.  
     
     
         28 . A turbine engine component as recited in  claim 27 , wherein the second aluminide coating has a thickness of from about 25 to about 75 microns.  
     
     
         29 . A turbine engine component as recited in  claim 28 , wherein in step a) the component is immersed in a solution comprising acetic acid for at least about 2 hours, and the solution has a temperature of from about 150° F. (about 66° C.) to about 175° F. (about 77° C.).  
     
     
         30 . A turbine engine component as recited in  claim 29 , wherein the component is a turbine blade.