Abstract: Environmental barrier coatings including a bondcoat layer including silicon and a rare earth silicate-based hermetic layer and rare earth silicate-based non-hermetic layer are provided. The rare earth silicate-based hermetic layer is deposited on the bondcoat via a thermal spray process and has an elastic modulus ranging from 100 GPa to 180 GPa. The at least one rare earth silicate-based non-hermetic layer is deposited on the rare earth silicate-based hermetic layer and has an elastic modulus ranging from 50 GPa to 100 GPa. Coated gas turbine engine components and methods for coating gas turbine engine components are also provided.

Abstract: In one aspect, a method for performing in situ repairs of internal components of a gas turbine engine may generally include inserting a repair tool within an interior of the gas turbine engine such that a tip end of the repair tool is positioned within the gas turbine engine and an exterior end is positioned outside the gas turbine engine. The method may also include positioning the tip end of the repair tool adjacent to a defect of an internal component, wherein the defect defines a fillable volume along a portion of the internal component. In addition, the method may include intermixing two or more constituents of a repair agent within the repair tool at a mixing location defined within the gas turbine engine, and expelling the repair agent from the tip end such that the fillable volume is at least partially filled with the repair agent.

Abstract: Methods for forming a sintered patch on a silicon-based substrate are disclosed. The methods include applying a patch slurry on the silicon-based substrate, drying the patch slurry on the silicon-based substrate to form a dried patch material, and sintering the dried patch material in an oxidizing atmosphere to form a sintered patch on the silicon-based substrate. The patch slurry includes a patch material containing silicates in a fluid carrier.

Abstract: In one aspect, a method for performing in situ repairs of internal components of a gas turbine engine may generally include inserting a repair tool within an interior of the gas turbine engine such that a tip end of the repair tool is positioned within the gas turbine engine and an exterior end is positioned outside the gas turbine engine. The method may also include positioning the tip end of the repair tool adjacent to a defect of an internal component, wherein the defect defines a fillable volume along a portion of the internal component. In addition, the method may include intermixing two or more constituents of a repair agent within the repair tool at a mixing location defined within the gas turbine engine, and expelling the repair agent from the tip end such that the fillable volume is at least partially filled with the repair agent.

Abstract: In one aspect, a method for performing in situ repairs of internal components of a gas turbine engine may generally include inserting a repair tool within an interior of the gas turbine engine such that a tip end of the repair tool is positioned within the gas turbine engine and an exterior end is positioned outside the gas turbine engine. The method may also include positioning the tip end of the repair tool adjacent to a defect of an internal component, wherein the defect defines a fillable volume along a portion of the internal component. In addition, the method may include intermixing two or more constituents of a repair agent within the repair tool at a mixing location defined within the gas turbine engine, and expelling the repair agent from the tip end such that the fillable volume is at least partially filled with the repair agent.

Abstract: Methods of forming an environmental barrier coating are disclosed. A method includes disposing a powder-based coating on a substrate, heat-treating the powder-based coating at a temperature greater than 800° C. and less than 1200° C. to form a porous coating that includes surface-connected pores, infiltrating at least some of the surface-connected pores of the porous coating with an infiltrant material to form an infiltrated coating, and sintering the infiltrated coating at a temperature greater than 1200° C. and less than 1500° C. to form the environmental barrier coating on the substrate.

Abstract: Methods for forming a sintered bond coat (64) on a silicon-based substrate (14) and articles (50) formed by the methods are disclosed. The methods include applying a bond coat slurry on the silicon-based substrate (14), drying the bond coat slurry on the silicon-based substrate to form a dried bond coat (44), and sintering the dried bond coat (44) in an oxidizing atmosphere to form a sintered bond coat (64) on the silicon-based substrate (14). The bond coat slurry includes a bond coat patching material in a bond coat fluid carrier. The articles (50) include a silicon-based substrate (14), a sintered bond coat (64) formed on the silicon-based substrate (14), and a sintered environmental barrier coating (EBC) (66) formed on the sintered bond coat (64). The sintered bond coat (64) includes a silicon-based phase and an oxide of the silicon-based phase.

Abstract: A coating system on a CMC substrate is provided, along with methods of its tape deposition onto a substrate. The coating system can include a bond coat on a surface of the CMC substrate; a first rare earth silicate coating on the bond coat; a first sacrificial coating of a first reinforced rare earth silicate matrix on the at least one rare earth silicate layer; a second rare earth silicate coating on the sacrificial coating; a second sacrificial coating of a second reinforced rare earth silicate matrix on the second rare earth silicate coating; a third rare earth silicate coating on the second sacrificial coating; and an outer layer on the third rare earth silicate coating. The first sacrificial coating and the second sacrificial coating have, independently, a thickness of about 4 mils to about 40 mils.

Abstract: A method for forming a patch repair on a silicon-based component is disclosed. The method includes applying a patch on a damaged area of a silicon-based component, drying the patch to form a dried patch, and sintering in situ the dried patch to form a patch repaired portion of the silicon-based component. The patch includes a patching material and the patching material includes a plurality of nanoparticles having a median particle size less than 100 nanometers. The plurality of nanoparticles includes at least one of silicon, silicon alloy, silica, or a metal silicate.

Abstract: A coated seal slot system for turbomachinery includes a first turbine component comprising a first groove having at least one first coating attached to at least a portion of the first groove of the first turbine component, a second turbine component comprising a second groove having at least one second coating attached to at least a portion of the second groove of the second turbine component. The first and the second turbine components are disposable adjacent to each other with the first groove having the first coating and the second groove having the second coating together forming a coated seal slot extending across a gap between the first turbine component and the second turbine component. A seal is disposable in the coated seal slot and extendable across the gap between the first and the second turbine components and engageable with the first coating and the second coating to inhibit leakage of gas through the gap.

Abstract: A rare earth silicate-based hermetic layer includes a thermal sprayed coating including a rare earth silicate having a hermetic microstructure. An environmental barrier coating includes a bond coat layer including silicon; and at least one rare earth silicate-based hermetic layer deposited on the bond coat layer by thermal spraying. The rare earth silicate-based hermetic layer includes a thermal sprayed coating including a rare earth silicate having a hermetic microstructure. An article for service in extreme environments may be provided with such an environmental barrier coating. A thermal spray feedstock for producing a rare earth silicate-based hermetic layer.

Abstract: In one aspect, a method for performing in situ repairs of internal components of a gas turbine engine may generally include inserting a repair tool within an interior of the gas turbine engine such that a tip end of the repair tool is positioned within the gas turbine engine and an exterior end is positioned outside the gas turbine engine. The method may also include positioning the tip end of the repair tool adjacent to a defect of an internal component, wherein the defect defines a fillable volume along a portion of the internal component. In addition, the method may include intermixing two or more constituents of a repair agent within the repair tool at a mixing location defined within the gas turbine engine, and expelling the repair agent from the tip end such that the fillable volume is at least partially filled with the repair agent.

Abstract: A stacked up structure can include a first environmental barrier coating (EBC) layer and a second EBC layer. A first process can be used to form the first layer and a second process can be used to form the second layer. In one embodiment interfacial material can be formed for improved bonding of the second layer to the first layer. The interfacial material can define a continuous or discontinuous layer of nonuniform thickness.

Abstract: Methods of forming an environmental barrier coating are disclosed. A method includes disposing a powder-based coating on a substrate, heat-treating the powder-based coating at a temperature greater than 800° C. and less than 1200° C. to form a porous coating that includes surface-connected pores, infiltrating at least some of the surface-connected pores of the porous coating with an infiltrant material to form an infiltrated coating, and sintering the infiltrated coating at a temperature greater than 1200° C. and less than 1500° C. to form the environmental barrier coating on the substrate.

Abstract: A coated seal slot system for turbomachinery includes a first turbine component comprising a first groove having at least one first coating attached to at least a portion of the first groove of the first turbine component, a second turbine component comprising a second groove having at least one second coating attached to at least a portion of the second groove of the second turbine component. The first and the second turbine components are disposable adjacent to each other with the first groove having the first coating and the second groove having the second coating together forming a coated seal slot extending across a gap between the first turbine component and the second turbine component. A seal is disposable in the coated seal slot and extendable across the gap between the first and the second turbine components and engageable with the first coating and the second coating to inhibit leakage of gas through the gap.

Abstract: A coating system on a CMC substrate is provided, along with methods of its tape deposition onto a substrate. The coating system can include a bond coat on a surface of the CMC substrate; a first rare earth silicate coating on the bond coat; a first sacrificial coating of a first reinforced rare earth silicate matrix on the at least one rare earth silicate layer; a second rare earth silicate coating on the sacrificial coating; a second sacrificial coating of a second reinforced rare earth silicate matrix on the second rare earth silicate coating; a third rare earth silicate coating on the second sacrificial coating; and an outer layer on the third rare earth silicate coating. The first sacrificial coating and the second sacrificial coating have, independently, a thickness of about 4 mils to about 40 mils.

Abstract: There is set forth herein a silicon-based patch formulation comprising about 25 to 66 percent by volume of a solvent; about 4 to 10 percent by volume of a silicon-comprising binding material; and about 30 to 65 percent by volume of a patching material, the patching material comprising particles having one or more non-actinide Group IIIA elements, wherein a molar ratio of the one or more non-actinide Group IIIA elements to silicon within the patch formulation is about 0.95 to 1.25.

Abstract: Processes for fabricating ceramic membranes include providing a porous substrate having at least one inner channel extending therethrough and having surfaces defined by porous walls, depositing a coating slurry on surfaces of the inner channel(s), and sintering. Sintering temperatures for the processes range from about 400° C. to 800° C. Coating slurries for use in the processes include a boehmite sol and a colloidal suspension of porous alumina particles.

Abstract: A bond layer may be applied to the substrate of an article and a first layer may be applied to the bond layer by thermal spray. A second layer may be applied above the first layer by slurry coating.

Abstract: There is set forth herein a silicon-based patch formulation comprising about 25 to 66 percent by volume of a solvent; about 4 to 10 percent by volume of a silicon-comprising binding material; and about 30 to 65 percent by volume of a patching material, the patching material comprising particles having one or more non-actinide Group IIIA elements, wherein a molar ratio of the one or more non-actinide Group IIIA elements to silicon within the patch formulation is about 0.95 to 1.25.