Water based environmental barrier coatings for high temperature ceramic components

Abstract

Environmental barrier coatings for high temperature ceramic components including: a bond coat layer; an optional silica layer; and at least one transition layer including: from about 85% to about 100% by volume of the transition layer of a primary transition material selected from a rare earth disilicate, or a doped rare earth disilicate; and from 0% to about 15% by volume of the transition layer of a secondary material selected from Fe 2 O 3 , iron silicates, rare earth iron oxides, Al 2 O 3 , mullite, rare earth aluminates, rare earth aluminosilicates, TiO 2 , rare earth titanates, Ga 2 O 3 , rare earth gallates, NiO, nickel silicates, rare earth nickel oxides, Lnb metals, Lnb 2 O 3 , Lnb 2 Si 2 O 7 , Lnb 2 SiO 5 , borosilicate glass, alkaline earth silicates, alkaline earth rare earth oxides, alkaline earth rare earth silicates, and mixtures thereof; where the transition layer is applied to the component as a slurry including at least water, the primary transition material and at least one slurry sintering aid, and where a reaction between the slurry sintering aid and the primary transition material results in the transition layer having a porosity of from 0% to about 15% by volume of the transition layer.

1 . An environmental barrier coating for high temperature ceramic components, the barrier coating comprising:
 a bond coat layer;   an optional silica layer; and   at least one transition layer including:
 from about 85% to about 100% by volume of the transition layer of a primary transition material comprising a rare earth disilicate, or a doped rare earth disilicate; and 
 from 0% to about 15% by volume of the transition layer of a secondary material selected from the group consisting of Fe 2 O 3 , iron silicates, rare earth iron oxides, Al 2 O 3 , mullite, rare earth aluminates, rare earth aluminosilicates, TiO 2 , rare earth titanates, Ga 2 O 3 , rare earth gallates, NiO, nickel silicates, rare earth nickel oxides, Lnb metals, Lnb 2 O 3 , Lnb 2 Si 2 O 7 , Lnb 2 SiO 5 , borosilicate glass, alkaline earth silicates, alkaline earth rare earth oxides, alkaline earth rare earth silicates, and mixtures thereof; 
   
       wherein the transition layer is applied to the component as a slurry comprising at least water, the primary transition material and at least one slurry sintering aid, and wherein a reaction between the slurry sintering aid and the primary transition material results in the transition layer comprising a porosity of from 0% to about 15% by volume of the transition layer. 
     
     
         2 . The coating of  claim 1  wherein the transition layer includes from about 85% to about 99% by volume of the transition layer of the primary transition material, and from about 1% to about 15% by volume of the transition layer of the secondary material. 
     
     
         3 . The coating of  claim 2  comprising more than one transition layer. 
     
     
         4 . The coating of  claim 3  wherein each transition layer comprises a different combination of primary transition materials and secondary transition materials. 
     
     
         5 . The coating of  claim 2  optionally comprising any one or more of:
 an outer layer including:
 from about 85% to about 100% by volume of the outer layer of a primary outer material comprising a rare earth monosilicate or a doped rare earth monosilicate, and 
 from 0% to about 15% by volume of the outer layer of the secondary material; and 
 
 a compliant layer including:
 from about 85% to about 99% by volume of the compliant layer of a primary compliant material selected from BSAS, and a rare earth doped BSAS; and 
 from about 1% to about 15% of a secondary compliant material selected from the group consisting of Ln 2 O 3 , Ln 2 Si 2 O 7 , Ln 2 SiO 5 , Ln 3 Al 5 O 12 , Al 2 O 3 , mullite, and combinations thereof 
 
 
       wherein the outer layer comprises a porosity of from about 0% to about 30% by volume of the outer layer, and the compliant layer comprises a porosity of from about 0% to about 15% by volume of the compliant layer. 
     
     
         6 . The coating of  claim 5  wherein the doped rare earth disilicate of the transition layer and the doped rare earth monosilicate of the outer layer comprise a doping composition selected from the group consisting of iron, aluminum, titanium, gallium, nickel, boron, an alkali, and alkali earth, and an Lnb rare earth metal. 
     
     
         7 . The coating of  claim 6  wherein the transition layer comprises a thickness of from about 0.1 mils to about 40 mils, the outer layer comprises a thickness of from about 0.1 mils to about 3 mils, and the compliant layer comprises a thickness of from about 0.1 mils to about 40 mils. 
     
     
         8 . The coating of  claim 7  comprising an intermediate layer including the primary outer material. 
     
     
         9 . The coating of  claim 7  wherein the outer layer includes from about 85% to about 99% by volume of the outer layer of the primary outer material, from about 1% to about 15% by volume of the outer layer of the secondary material. 
     
     
         10 . The coating of  claim 7  wherein the high temperature ceramic component comprises a ceramic matrix composite or a monolithic ceramic turbine engine component selected from the group consisting of combustor components, turbine blades, shrouds, nozzles, heat shields, and vanes. 
     
     
         11 . The coating of  claim 10  wherein the sintering aid is selected from the group consisting of iron oxide, gallium oxide, aluminum oxide, nickel oxide, titanium oxide, boron oxide, alkaline earth oxides, carbonyl iron, iron metal, aluminum metal, boron, nickel metal, iron hydroxide, gallium hydroxide, aluminum hydroxide, nickel hydroxide, titanium hydroxide, alkaline earth hydroxides, iron carbonate, gallium carbonate, aluminum carbonate, nickel carbonate, boron carbonate, alkaline earth carbonates, iron oxalate, gallium oxalate, aluminum oxalate, nickel oxalate, titanium oxalate, water soluble iron salts, water soluble gallium salts, water soluble aluminum salts, water soluble nickel salts, water titanium salts, water soluble boron salts, and water soluble alkaline earth salts. 
     
     
         12 . The coating of  claim 10  wherein the sintering aid comprises an Lnb metal and SiO 2 . 
     
     
         13 . An environmental barrier coating for high temperature ceramic components, the barrier coating comprising:
 a bond coat layer comprising silicon;   an optional silica layer;   at least one transition layer including:
 from about 85% to about 100% by volume of the transition layer of a primary transition material comprising a rare earth disilicate, or a doped rare earth disilicate; and 
 from 0% to about 15% by volume of the transition layer of a secondary material; and 
   
       any one or more of:
 an outer layer including:
 from about 85% to about 100% by volume of the outer layer of a primary outer material comprising a rare earth monosilicate or a doped rare earth monosilicate, and 
 from 0% to about 15% by volume of the outer layer of the secondary material; 
 
 an intermediate layer comprising the primary outer material; and 
 a compliant layer including:
 from about 85% to about 100% by volume of the compliant layer of a primary compliant material selected from BSAS, and a rare earth doped BSAS; and 
 from about 0% to about 15% of a secondary compliant material selected from the group consisting of Ln 2 O 3 , Ln 2 Si 2 O 7 , Ln 2 SiO 5 , Ln 3 Al 5 O 12 , Al 2 O 3 , mullite, and combinations thereof wherein the transition layer, the outer layer, and the compliant layer are applied to the component as a slurry, at least one slurry of the transition layer, outer layer, or compliant layer comprises water, the primary material and at least one slurry sintering aid, and wherein a reaction between the slurry sintering aid and the primary material results in the transition layer comprising a porosity of from 0% to about 15% by volume of the transition layer, the outer layer comprising a porosity of from about 0% to about 30% by volume of the outer layer, and the compliant layer comprising a porosity of from about 0% to about 15% by volume of the compliant layer. 
 
 
     
     
         14 . The coating of  claim 13  wherein the doped rare earth disilicate of the transition layer and the doped rare earth monosilicate of the outer layer comprise a doping composition selected from the group consisting of iron, aluminum, titanium, gallium, nickel, boron, an alkali, and alkali earth, and an Lnb rare earth metal. 
     
     
         15 . The coating of  claim 14  wherein the transition layer comprises a thickness of from about 0.1 mils to about 40 mils, the outer layer comprises a thickness of from about 0.1 mils to about 3 mils, and the compliant layer comprises a thickness of from about 0.1 mils to about 40 mils. 
     
     
         16 . The coating of  claim 15  comprising an intermediate layer including the primary outer material. 
     
     
         17 . The coating of  claim 15  wherein the high temperature ceramic component comprises a ceramic matrix composite or a monolithic ceramic turbine engine component selected from the group consisting of combustor components, turbine blades, shrouds, nozzles, heat shields, and vanes. 
     
     
         18 . The coating of  claim 15  wherein the sintering aid used with the transition layer slurry and outer layer slurry is selected from the group consisting of iron oxide, gallium oxide, aluminum oxide, nickel oxide, titanium oxide, boron oxide, alkaline earth oxides, carbonyl iron, iron metal, aluminum metal, boron, nickel metal, iron hydroxide, gallium hydroxide, aluminum hydroxide, nickel hydroxide, titanium hydroxide, alkaline earth hydroxides, iron carbonate, gallium carbonate, aluminum carbonate, nickel carbonate, boron carbonate, alkaline earth carbonates, iron oxalate, gallium oxalate, aluminum oxalate, nickel oxalate, titanium oxalate, water soluble iron salts, water soluble gallium salts, water soluble aluminum salts, water soluble nickel salts, water titanium salts, water soluble boron salts, and water soluble alkaline earth salts; and, the slurry sintering aid used with the compliant layer slurry is selected from the group consisting of rare earth nitrate, rare earth acetate, rare earth chloride, rare earth oxide, ammonium phosphate, phosphoric acid, polyvinyl phosphoric acid, and combination thereof 
     
     
         19 . The coating of  claim 15  wherein the sintering aid used with the transition layer slurry and outer layer slurry comprises an Lnb metal and SiO 2 . 
     
     
         20 . An environmental barrier coating for high temperature ceramic components, the barrier coating comprising:
 a bond coat layer comprising silicon;   an optional silica layer;   at least one transition layer including:
 from about 85% to about 99% by volume of the transition layer of a primary transition material comprising a rare earth disilicate, or a doped rare earth disilicate; and 
 from 1% to about 15% by volume of the transition layer of a secondary material; and 
   
       any one or more of:
 an outer layer including:
 from about 85% to about 99% by volume of the outer layer of a primary outer material comprising a rare earth monosilicate or a doped rare earth monosilicate, and 
 from 1% to about 15% by volume of the outer layer of the secondary material; 
 
 an intermediate layer comprising the primary outer material; and 
 a compliant layer including:
 from about 85% to about 99% by volume of the compliant layer of a primary compliant material selected from BSAS, and a rare earth doped BSAS; and 
 from about 1% to about 15% of a secondary compliant material selected from the group consisting of Ln 2 O 3 , Ln 2 Si 2 O 7 , Ln 2 SiO 5 , Ln 3 Al 5 O 12 , Al 2 O 3 , mullite, and combinations thereof 
 
 
       wherein the transition layer, the outer layer, and the compliant layer are applied to the component as a slurry, at least one slurry of the transition layer, outer layer, or compliant layer comprises water, the primary material and at least one slurry sintering aid, and wherein a reaction between the slurry sintering aid and the primary material results in the transition layer comprising a porosity of from 0.01% to about 15% by volume of the transition layer, the outer layer comprising a porosity of from about 0.01% to about 30% by volume of the outer layer, and the compliant layer comprising a porosity of from about 0.01% to about 15% by volume of the compliant layer. 
     
     
         21 . The coating of  claim 20  wherein the doped rare earth disilicate of the transition layer and the doped rare earth monosilicate of the outer layer comprise a doping composition selected from the group consisting of iron, aluminum, titanium, gallium, nickel, boron, an alkali, and alkali earth, and an Lnb rare earth metal. 
     
     
         22 . The coating of  claim 21  wherein the transition layer comprises a thickness of from about 0.1 mils to about 40 mils, the outer layer comprises a thickness of from about 0.1 mils to about 3 mils, and the compliant layer comprises a thickness of from about 0.1 mils to about 40 mils. 
     
     
         23 . The coating of  claim 22  comprising an intermediate layer including the primary outer material. 
     
     
         24 . The coating of  claim 22  wherein the high temperature ceramic component comprises a ceramic matrix composite or a monolithic ceramic turbine engine component selected from the group consisting of combustor components, turbine blades, shrouds, nozzles, heat shields, and vanes. 
     
     
         25 . The coating of  claim 24  wherein the slurry sintering aid used with the transition layer slurry and outer layer slurry is selected from the group consisting of iron oxide, gallium oxide, aluminum oxide, nickel oxide, titanium oxide, boron oxide, alkaline earth oxides, carbonyl iron, iron metal, aluminum metal, boron, nickel metal, iron hydroxide, gallium hydroxide, aluminum hydroxide, nickel hydroxide, titanium hydroxide, alkaline earth hydroxides, iron carbonate, gallium carbonate, aluminum carbonate, nickel carbonate, boron carbonate, alkaline earth carbonates, iron oxalate, gallium oxalate, aluminum oxalate, nickel oxalate, titanium oxalate, water soluble iron salts, water soluble gallium salts, water soluble aluminum salts, water soluble nickel salts, water titanium salts, water soluble boron salts, and water soluble alkaline earth salts; and, the slurry sintering aid used with the compliant layer slurry is selected from the group consisting of rare earth nitrate, rare earth acetate, rare earth chloride, rare earth oxide, ammonium phosphate, phosphoric acid, polyvinyl phosphoric acid, and combination thereof. 
     
     
         26 . The coating of  claim 24  wherein the slurry sintering aid used with the transition layer slurry and outer layer slurry comprises an Lnb metal and SiO 2 .