Components and methods for forming a layer of chromia thereon

Abstract

Components and methods for forming a layer of chromia on a substrate thereof are provided. The methods include forming a mixture that includes at least one chromia promoter, applying the mixture to a surface of a substrate formed of a nickel-based alloy having between 1 wt. % and 30 wt. % chromium, and forming a layer of chromia (Cr2O3) on the surface of the substrate by performing a heat treatment on the surface with the mixture thereon, wherein during the heat treatment oxygen diffuses from the at least one chromia promotor and reacts with the chromium in the substrate to form the layer of chromia on the surface.

What is claimed is: 
     
         1 . A method, comprising:
 forming a mixture that includes at least one chromia promoter;   applying the mixture to a surface of a substrate formed of a nickel-based alloy having between 1 wt. % and 30 wt. % chromium; and   forming a layer of chromia (Cr 2 O 3 ) on the surface of the substrate by performing a heat treatment on the surface with the mixture thereon, wherein during the heat treatment oxygen diffuses from the at least one chromia promotor and reacts with the chromium in the substrate to form the layer of chromia on the surface.   
     
     
         2 . The method of  claim 1 , wherein the at least one chromia promoter includes cobalt (II) oxide (CoO), nickel (II) oxide (NiO), iron (II) oxide (FeO), iron (III) oxide (Fe 2 O 3 ), zinc oxide (ZnO), aluminum oxide (Al 2 O 3 ), or a combination thereof. 
     
     
         3 . The method of  claim 1 , wherein the mixture includes at least a first powder comprising a glass material, a glass-ceramic material, or a combination thereof, wherein the method includes forming an additional layer that includes the glass material, the glass-ceramic material, or the combination thereof on the layer of chromia during the heat treatment. 
     
     
         4 . The method of  claim 3 , wherein the first powder includes at least a first metal oxide chosen from the group consisting of zirconium dioxide (ZrO 2 ), aluminum oxide (Al 2 O 3 ), barium oxide (BaO), strontium peroxide (SrO 2 ), cobalt oxide (CoO), silicon dioxide (SiO 2 ), boron trioxide (B 2 O 3 ), titanium oxide (TiO 2 ), any combination thereof, or a glass powder composition configured to form one or more of zirconium dioxide (ZrO 2 ), aluminum oxide (Al 2 O 3 ), barium oxide (BaO), strontium peroxide (SrO 2 ), cobalt oxide (CoO), silicon dioxide (SiO 2 ), boron trioxide (B 2 O 3 ), titanium oxide (TiO 2 ). 
     
     
         5 . The method of  claim 4 , wherein the first powder includes a second metal oxide chosen from the group consisting of cobalt (III) oxide (Co 2 O 3 ), zinc oxide (ZnO), nickel (II) oxide (NiO), iron (II) oxide (FeO), iron (III) oxide (Fe 2 O 3 ), chromium (III) oxide (Cr 2 O 3 ), or any combination thereof. 
     
     
         6 . The method of  claim 3 , wherein the at least one chromia promoter includes particles having a metallic core encased in a ceramic shell, wherein the additional layer is a cermet material. 
     
     
         7 . The method of  claim 3 , wherein during the heat treatment the first powder provides a layer of protection over the surface of the substrate that promotes the formation of the layer of chromia by maintaining a specific partial pressure of the oxygen diffused from the at least one chromia promotor on the surface of the substrate. 
     
     
         8 . The method of  claim 1 , wherein the heat treatment is performed at a temperature that is less than an age-hardening temperature of the nickel-based alloy. 
     
     
         9 . The method of  claim 1 , wherein the heat treatment is performed at a temperature of equal to or less than 850° C. 
     
     
         10 . The method of  claim 1 , wherein the nickel-based alloy includes an amount of chromium equal to or less than 15 wt. %. 
     
     
         11 . The method of  claim 1 , wherein the nickel-based alloy includes an amount of chromium equal to or less than 10 wt. %. 
     
     
         12 . The method of  claim 1 , wherein the layer of chromia has a density of 4.69 to 5.22 g/cm 3 . 
     
     
         13 . The method of  claim 1 , wherein the layer of chromia has a thickness of 100 nm to 5 μm. 
     
     
         14 . The method of  claim 1 , wherein the substrate is a component of a gas turbine engine. 
     
     
         15 . A component, comprising:
 a substrate formed of a nickel-based alloy having between 1 wt. % and 30 wt. % chromium; and   a layer of chromia disposed on and in contact with the substrate having a density of 4.69 to 5.22 g/cm 3 .   
     
     
         16 . The component of  claim 15 , wherein the nickel-based alloy includes an amount of chromium equal to or less than 15 wt. %. 
     
     
         17 . The component of  claim 15 , wherein the nickel-based alloy includes an amount of chromium equal to or less than 10 wt. %. 
     
     
         18 . The component of  claim 15 , wherein the layer of chromia has a thickness of 100 nm to 5 μm. 
     
     
         19 . The component of  claim 15 , further comprising an additional layer disposed on and in contact with the layer of chromia, wherein the additional layer includes a glass material, a glass-ceramic material, or a combination thereof. 
     
     
         20 . The component of  claim 15 , wherein the component is configured to be installed in a gas turbine engine.