Coated components and methods of fabricating coated components and coated turbine disks

Abstract

Coated components and methods of fabricating coated components and coated turbine disks are provided. In an embodiment, by way of example only, a coated component includes a substrate comprising a superalloy in an unmodified form and a coating disposed over the substrate, where the coating comprises the superalloy in a modified form. The modified form of the superalloy includes, by weight, at least 10% more chromium and at least 10% more of one or more noble metals than the unmodified form of the superalloy, and the modified form of the superalloy is substantially free of aluminum

1 . A method of fabricating a coated component, the method comprising the steps of:
 chromizing a substrate comprising a superalloy to form a chromium-enriched exterior portion of the substrate; and   diffusing a noble metal into the chromium-enriched exterior portion of the substrate to form the coated component.   
     
     
         2 . The method of  claim 1 , wherein the step of chromizing includes a vacuum process comprising the steps of:
 surrounding at least a portion of the substrate with pure chromium; and   subjecting the substrate to a vacuum environment and a heat treatment after the step of surrounding.   
     
     
         3 . The method of  claim 1 , wherein the step of chromizing includes a pack cementation process comprising the steps of:
 packing a powder comprising chromium around at least a portion of the substrate; and   subjecting the substrate to a heat treatment after the step of packing.   
     
     
         4 . The method of  claim 3 , wherein the powder further comprises aluminum oxide. 
     
     
         5 . The method of  claim 4 , wherein the powder further comprises an activator selected from the group consisting of ammonium chloride, chromium (II) chloride, chromium (III) chloride, and a halide. 
     
     
         6 . The method of  claim 1 , wherein the step of diffusing comprises:
 electroplating the noble metal to the substrate; and   heat treating the electroplated substrate to diffuse the noble metal therein.   
     
     
         7 . The method of  claim 6 , wherein:
 the step of electroplating comprises electroplating about 10 microns of the noble metal to the substrate; and   the step of heat treating comprises exposing the electroplated substrate to a vacuum or argon atmosphere at a temperature in a range of about 1050° C. to about 1150° C. for a duration in a range of two hours to five hours.   
     
     
         8 . The method of  claim 1 , further comprising the steps of:
 cleaning a surface of the chromium-enriched exterior portion of the substrate, before the step of diffusing.   
     
     
         9 . A method of fabricating a coated turbine disk, the method comprising the steps of:
 chromizing a substrate comprising a superalloy to form a chromium-enriched exterior portion of the substrate;   cleaning a surface of the chromium-enriched exterior portion of the substrate;   electroplating a noble metal to the surface of the chromium-enriched exterior portion of the substrate to form an electroplated substrate; and   heat treating the electroplated substrate to diffuse the noble metal therein to form the coated turbine disk.   
     
     
         10 . The method of  claim 9 , wherein the step of chromizing includes a vacuum process comprising the steps of:
 surrounding at least a portion of the substrate with pure chromium; and   subjecting the substrate to a vacuum environment and a heat treatment after the step of surrounding.   
     
     
         11 . The method of  claim 10 , wherein the step of chromizing includes a pack cementation process comprising the steps of:
 packing a powder comprising chromium around at least a portion of the substrate; and   subjecting the substrate to a heat treatment after the step of packing.   
     
     
         12 . The method of  claim 9 , wherein:
 the step of electroplating comprises electroplating about 10 microns of the noble metal to the substrate; and   the step of heat treating comprises exposing the electroplated substrate to a vacuum or argon atmosphere at a temperature in a range of about 1050° C. to about 1100° C. for a duration in a range of two hours to three hours.   
     
     
         13 . A method for fabricating a coated component, the method comprising the steps of:
 providing a superalloy substrate; and   modifying the superalloy substrate to produce a corrosion-resistant coating containing enriched with chromium and at least one noble metal and substantially free of aluminum.   
     
     
         14 . The method of  claim 13 , wherein the step of modifying comprises:
 chromizing the superalloy substrate to form a chromium-enriched exterior portion;   depositing a first noble metal onto the chromium-enriched exterior portion; and   diffusing the first noble metal into the chromium-enriched exterior portion to produce the corrosion-resistant coating.   
     
     
         15 . The method of  claim 14 , wherein the step of diffusing comprises heating the superalloy substrate within a furnace while exposing the superalloy substrate to one of a vacuum and an inert gas to diffuse the first noble metal into the chromium-enriched exterior portion and produce the corrosion-resistant coating. 
     
     
         16 . The method of  claim 14 , wherein the step of chromizing comprises utilizing one of a vacuum chromizing process and a pack cementation chromizing process to form a chromium-enriched exterior portion of the superalloy substrate. 
     
     
         17 . The method of  claim 14 , wherein the step of depositing comprises depositing platinum onto the chromium-enriched exterior portion utilizing one of an electroplating process and a chemical vapor deposition process. 
     
     
         18 . The method of  claim 14 , wherein the step of depositing comprises depositing a mixture of noble metals onto the chromium-enriched exterior portion. 
     
     
         19 . The method of  claim 18 , wherein the mixture of noble metals comprises platinum and palladium in a ratio of about 2:1 to about 1:2, by weight. 
     
     
         20 . The method of  claim 14 , wherein the step of modifying comprises initially diffusing chromium and subsequently diffusing at least one noble metal into the superalloy substrate to produce a corrosion-resistant coating containing, by weight, between about 20% and about 40% chromium, between about 10% and about 30% of the at least one noble metal, and less than about 3% aluminum.