SURFACE TREATMENT FOR AQUEOUS SLURRY-BASED ENVIRONMENTAL BARRIER COATING
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.