Article comprising environmental barrier coating

Abstract

An article includes a substrate, a substantially hermetic sealing layer disposed on the substrate, and a porous transition layer disposed on the substrate between the sealing layer and the substrate. The article also includes one or more openings extending through the substrate to the porous transition layer.

1 . An article comprising:
 a substrate;   a substantially hermetic sealing layer disposed on the substrate; and   a porous transition layer disposed on the substrate between the sealing layer and the substrate,   
       wherein the article comprises one or more openings extending through the substrate to the porous transition layer. 
     
     
         2 . The article according to  claim 1 , further comprising a bond coat disposed on the substrate, wherein the porous transition layer is disposed between the sealing layer and the bondcoat. 
     
     
         3 . The article according to  claim 2 , wherein the substrate comprises a ceramic matrix composite material. 
     
     
         4 . The article according to  claim 3 , wherein the substrate comprises silicon carbide (SiC). 
     
     
         5 . The article according to  claim 3 , wherein the composite comprises a matrix phase and a reinforcement phase, and wherein the matrix phase and the reinforcement phase comprise silicon carbide. 
     
     
         6 . The article according to  claim 1 , wherein the bondcoat comprises silicon carbide and/or silicon nitride. 
     
     
         7 . The article according to  claim 2 , wherein the sealing layer comprises a rare earth silicate and/or an alkaline earth aluminosilicate. 
     
     
         8 . The article according to  claim 2 , wherein the porous transition layer comprises a rare earth silicate and/or silicon carbide. 
     
     
         9 . The article according to  claim 2 , wherein the porous transition layer has a porosity of 10 to 90%. 
     
     
         10 . The article according to  claim 2 , wherein the porous transition layer has an average pore diameter of 0.1 to 100 μm. 
     
     
         11 . The article according to  claim 2 , wherein the one or more openings have an average diameter of 1 to 1000 μm. 
     
     
         12 . The article according to  claim 2 , said article comprising a substrate cavity, and wherein said one or more openings open into the cavity. 
     
     
         13 . The article according to  claim 2 , further comprising a topcoat disposed over the sealing layer. 
     
     
         14 . The article according to  claim 13 , wherein the topcoat comprises a ceramic material selected from the group consisting of silicates, aluminates, and yttria-stabilized zirconia. 
     
     
         15 . The article according to  claim 13 , wherein the topcoat comprises a rare earth monosilicate, a rare earth disilicate, or combinations thereof. 
     
     
         16 . The article according to  claim 2 , further comprising an intermediate layer disposed between the sealing layer and the porous transition layer, wherein the intermediate layer comprises a barrier material that is substantially inert with respect to silica. 
     
     
         17 . The article according to  claim 16 , wherein the barrier material comprises a rare-earth disilicate. 
     
     
         18 . The article according to  claim 17 , wherein the barrier material comprises yttrium disilicate. 
     
     
         19 . The article according to  claim 1 , wherein the article comprises a component of a gas turbine assembly. 
     
     
         20 . A method for making an article, said method comprising:
 disposing a bondcoat over a substrate;   disposing a porous transition layer over the bondcoat;   disposing a sealing layer over the porous transition layer, wherein the sealing layer comprises a rare earth silicate or an alkaline-earth aluminosilicate; and   forming one or more openings, said openings extending through the substrate and bondcoat to the porous transition layer.   
     
     
         21 . The method according to  claim 20 , wherein the substrate and the bondcoat comprise silicon carbide, said method further comprising:
 disposing an intermediate layer over the porous transition layer, said intermediate layer comprising a barrier material that is substantially inert with respect to silica; and   disposing a topcoat over the sealing layer.