Surface treatment for aqueous slurry-based environmental barrier coating

Abstract

A method for coating a ceramic matrix composite substrate with an environmental barrier coating includes the steps of: treating a surface of a ceramic matrix composite substrate to adjust wettability of the surface; and applying an aqueous slurry-based environmental barrier coating to the surface. The treating step can be a plasma treatment to remove organic contaminants, and can also be a treatment to modify oxidative state of the surface. The treatment can produce a surface for treatment that is hydrophilic and has a contact angle with aqueous-slurry coating materials of less than 40 degrees.

1 . A method for coating a ceramic matrix composite substrate with an environmental barrier coating, comprising the steps of:
 treating a surface of a ceramic matrix composite substrate to adjust wettability of the surface, wherein the treating step is a plasma treating step; and   applying an aqueous slurry-based environmental barrier coating to the surface.   
     
     
         2 . The method of  claim 1 , wherein the substrate is at least one of a turbine vane or a turbine blade. 
     
     
         3 . The method of  claim 1 , wherein the surface has organic contaminants, and wherein the treating step removes the organic contaminants. 
     
     
         4 . The method of  claim 3 , wherein the organic contaminants comprise absorbed hydrocarbons, surface contaminants from handling, machining and packaging, and residual contaminants from the manufacturing process. 
     
     
         5 . The method of  claim 1 , wherein the treating step comprises changing the oxidative state of the surface to adjust wettability of the surface. 
     
     
         6 . (canceled) 
     
     
         7 . The method of  claim 1 , wherein the plasma treating step comprises placing the substrate in a chamber, evacuating the chamber, introducing process gas to the chamber, and generating plasma within the chamber. 
     
     
         8 . The method of  claim 7 , wherein the process gas is selected from the group consisting of fluorine gas, Sulphur hexafluoride, water vapor, hydrogen, chlorine gas, hydrochloric acid, argon, IBr, ICl and combinations thereof. 
     
     
         9 . The method of  claim 1 , wherein the aqueous slurry-based coating comprises a mixture of water, binder, and oxidation protection phase. 
     
     
         10 . The method of  claim 1 , wherein the treating step produces a surface that is hydrophilic. 
     
     
         11 . The method of  claim 1 , wherein the treating step produces a surface having a contact angle of less than 40 degrees with the aqueous slurry-based environmental barrier coating. 
     
     
         12 . The method of  claim 1 , wherein the applying step is selected from the group consisting of spraying, dipping, electrophoretic application, painting and combinations thereof. 
     
     
         13 . The method of  claim 1 , further comprising the step of applying environmental barrier coating materials to the surface as an aqueous-slurry, and curing the aqueous-slurry on the surface to produce the environmental barrier coating. 
     
     
         14 . The method of  claim 1 , further comprising applying a protective layer over the environmental barrier coating.