Abstract:
In some examples, a coating may include at least one feature that facilitates visual determination of a thickness of the coating. For example, the coating may include a plurality of microspheres disposed at a predetermined depth of the coating. The plurality of microspheres may define a distinct visual characteristic. By inspecting the coating and viewing at least one of the microspheres, the thickness of the coating may be estimated. In some examples, the plurality of microspheres may be embedded in a matrix material, and the distinct visual characteristic of the microspheres may be different than the visual characteristic of the matrix material. In other examples, the at least one feature may include at least one distinct layer in the coating system that includes a distinct visual characteristic, such as a color of the distinct layer.
Abstract:
A method including applying layers of multiple constituents where the constituents are capable of producing a non-equilibrium condition on the contacting surfaces of a ceramic matrix composite component and a gas turbine engine component where one outer coating includes a first constituent and the other outer coating includes a second constituent; forming a component assembly with the ceramic matrix composite component coupled to the gas turbine engine component with contact between the outer coatings; adding an energy to facilitate an equilibrium reaction between the first constituent of the first outer coating and the second constituent of the second outer coating; and as a result of adding the energy, forming a bond structure in the component assembly with a product of the equilibrium reaction where the bond structure affixes the ceramic matrix composite component to the gas turbine engine component between the first constituent and the second constituent.
Abstract:
A method includes providing a ceramic fiber preform with a range of 20 to 40 volume percent fiber which can include silicon carbide fibers; coating the ceramic fiber preform with a boron nitride interface coating; infiltrating the ceramic fiber preform with a ceramic matrix with a range of 20 to 40 volume percent silicon carbide; infiltrating the ceramic fiber preform with a constituent material such as boron carbide, boron, and carbon; and infiltrating the ceramic fiber preform with a eutectic melt material where the metallic eutectic melt can include at least one material from a group consisting of: a transition metal-silicon eutectic melt such as zirconium silicide, a transition metal-boride eutectic melt such as zirconium boride, and a transition metal-carbide eutectic melt such as zirconium carbide.
Abstract:
A method for modifying a ceramic matrix component is disclosed including identifying a non-conforming region of a composite component capable of operating in a gas turbine engine; removing at least a portion of the non-conforming region to create an exposed surface of the composite component; preparing a preform in response to the removing at least a portion of the non-conforming region; applying a reactive constituent surface region to at least one of the exposed surface of the composite component and the preform, the reactive constituent surface region being capable of producing a non-equilibrium condition; positioning the preform to provide a contact region between the exposed surface of the composite component and the preform proximate the reactive constituent surface region; and reacting the reactive constituent surface region in an equilibrium reaction at the contact region to form a bond structure between the exposed surface of the composite component and the preform.
Abstract:
A method for making a gas turbine engine matrix composite structure. The method includes providing at least one metal core element, fabricating a matrix composite component about the metal core element, and removing at least part of the metal core element from the matrix composite component by introduction of a halogen gas.
Abstract:
An article may include a substrate and a coating system on the substrate. The coating system may include an environmental barrier coating (EBC) layer and a CMAS resistant layer on the EBC layer (e.g., as the top coat of the system). The CMAS layer includes a rare-earth (RE) monosilicate composition including a plurality of RE metal cations, wherein RE monosilicate composition is configured to react with CMAS to form a reaction product including a RE apatite phase with a RE2O3·SiO2 composition, wherein the RE of the RE2O3·SiO2 composition includes at least one of the plurality of RE metal cations of the RE monosilicate.
Abstract:
An article may include a substrate including a ceramic or a ceramic matrix composite. The substrate defines a hot side surface configured to face a heated gas environment and a cool side surface opposite the hot side surface. The article also includes a cool side coating on the cool side surface. The cool side coating comprises at least one material having a flow temperature equal to or slightly less than a temperature of the heated gas environment.
Abstract:
The disclosure describes articles having coating systems configured to inhibit or prevent crystallization of TGO at the operating temperature of the article. An article includes a substrate defining a surface; a bond coat on the surface of the substrate; a coating layer that includes a boron dopant configured to inhibit crystallization of amorphous silicon dioxide thermally grown oxide on the bond coat at an operating temperature of the article. By inhibiting or preventing TGO crystallization, the described coating systems may increase a useable life of the component.
Abstract:
In some examples, an article may include a substrate and a coating on the substrate. In accordance with some of these examples, the coating may include a bond layer and an overlying layer comprising at least one oxide. In some examples, the bond layer comprises silicon metal and at least one of a transition metal carbide, a transition metal boride, or a transition metal nitride.
Abstract:
A method may include oxidizing a surface of a silicon-containing substrate to form a layer including silica on the surface of the silicon-containing substrate. The method also may include depositing, from a slurry including at least one rare earth oxide, a layer including the at least one rare earth oxide on the layer including silicon. The method additionally may include heating at least the layer including silica and the layer including the at least one rare earth oxide to cause the silica and the at least one rare earth oxide to react and form a layer including at least one rare earth silicate.