Abstract: A method includes forming an abrasion-resistant coating on a substrate including graphite, and grinding the coating to a predetermined flatness index and a predetermined roughness index. An assembly includes the substrate including graphite, and the abrasion-resistant coating formed on the substrate. The assembly may be configured to operate at elevated temperatures.

Abstract: Components of gas turbine engines, aircraft comprising the components, and methods of producing the components are provided. The component includes a surface, and a set of tiles secured to the surface at interfaces between the set of tiles and the surface and between each of the set of tiles. The set of tiles conform to the surface and in combination define a coating system on the surface that includes an environmental barrier coating and/or a thermal barrier coating.

Abstract: In some examples, a method for making a refractory component includes depositing carbon on a surface of a refractory substrate. The carbon fills surface voids on the surface of the refractory substrate. A melting point of the refractory substrate is greater than or equal to about 1500 degrees Celsius (° C.). The method includes applying a metal slurry to a surface of the refractory substrate following the deposition of the carbon and reacting a metal of the metal slurry with the carbon to form a metal carbide phase within the surface voids of the refractory substrate.

Abstract: Components and methods for forming a layer of chromia on a substrate thereof are provided. The methods include forming a mixture that includes at least one chromia promoter, applying the mixture to a surface of a substrate formed of a nickel-based alloy having between 1 wt. % and 30 wt. % chromium, and forming a layer of chromia (Cr2O3) on the surface of the substrate by performing a heat treatment on the surface with the mixture thereon, wherein during the heat treatment oxygen diffuses from the at least one chromia promotor and reacts with the chromium in the substrate to form the layer of chromia on the surface.

Abstract: A corrosion and wear-resistant brake disc is disclosed. The brake disc comprises a brake body having at least one braking surface, and a corrosion and wear-resistant coating electrodeposited on the braking surface. The corrosion and wear-resistant coating comprises a precipitation-hardened cobalt-phosphorus (CoP) alloy and exhibits a Vickers hardness of from about 900 to about 1050 HV. A method of preparing the brake disc is also disclosed, and comprises electrodepositing a cobalt-phosphorus (CoP) alloy onto at least one braking surface of a disc body to a thickness of at least about 150 ?m to give a coated disc body. The method also comprises heat treating the coated disc body to precipitation harden the CoP alloy and give the corrosion and wear-resistant coating on the braking surface.

Abstract: A method includes forming an article from a silicon-rich refractory mixture. The silicon-rich refractory mixture includes a silicon-rich silicon carbide preceramic polymer and a silicon carbide powder. The method includes heating the preform to pyrolyze the silicon-rich silicon carbide preceramic polymer and form a silicon-rich refractory material. The silicon-rich refractory material includes the silicon carbide powder and excess silicon in a silicon carbide matrix. The method further includes heating the silicon-rich refractory material to oxidize at least a portion of the excess silicon and form a reinforced refractory material. The reinforced refractory material includes a silicon dioxide phase at grain boundaries of the silicon carbide powder.

Abstract: Components for a gas turbine engine and method for producing the components are provided. The components may include a substrate and a thermal barrier coating (TBC) having at least a first layer secured to a surface of the substrate. The first layer is formed of a ceramic material with a first microstructure that includes a plurality of interconnected unit cells having struts that have a relative density of greater than 98 percent and a closed cell porosity of 10 percent or greater. The TBC is secured to the substrate subsequent to formation of the TBC.

Abstract: Components having coating systems that include mud cracks, methods for forming the coating systems, and vehicles including the components are provided. The components include a substrate having silicon nitride and a coating system on a surface of the substrate. The coating system includes a first layer of a first coating material on the substrate, wherein the first coating material includes a rare earth silicate and has a first thickness measured in a direction perpendicular to the surface of the substrate, and a second layer of a second coating material on the first layer, wherein the second coating material includes a rare earth silicate and has a second thickness that is greater than the first thickness. The second layer includes mud cracks that extend from an exterior surface thereof toward the substrate, and the mud cracks have widths in a range of about 50 to 200 micrometers.

Abstract: A pyrolysis system for generating hydrogen gas by hydrocarbon pyrolysis may include a pyrolysis furnace and a heating system. The pyrolysis furnace may include a chamber defining a furnace interior. The chamber may include a thermal barrier. The heating system may include a heating element coupled to an electrical lead at a lead junction. The lead junction may be within the furnace interior. The electrical lead may include a refractory material. A maximum cross-sectional area of the electrical lead may be less than a minimum cross-sectional Joule area of the heating element. A technique for assembling a system configured to generate hydrogen gas by hydrocarbon pyrolysis may include positioning the heating element within the furnace interior of the pyrolysis furnace, and coupling the electrical lead to the heating element at the lead junction within the furnace interior.

Abstract: Components having coating systems that include mud cracks, methods for forming the coating systems, and vehicles including the components are provided. The components include a substrate having silicon nitride and a coating system on a surface of the substrate. The coating system includes a first layer of a first coating material on the substrate, wherein the first coating material includes a rare earth silicate and has a first thickness measured in a direction perpendicular to the surface of the substrate, and a second layer of a second coating material on the first layer, wherein the second coating material includes a rare earth silicate and has a second thickness that is greater than the first thickness. The second layer includes mud cracks that extend from an exterior surface thereof toward the substrate, and the mud cracks have widths in a range of about 50 to 200 micrometers.

Abstract: A method for forming a high temperature coating includes applying carbon powder to a surface of a carbon/carbon (C/C) composite substrate to force the carbon powder into one or more surface voids of the surface of the C/C composite substrate. The carbon powder has a substantially same composition and morphology as a surface portion of the C/C composite substrate. The method includes applying a metal slurry to the surface of the C/C composite substrate following the application of the carbon powder and reacting a metal of the metal slurry with carbon of the carbon powder and carbon of the surface portion of the C/C composite substrate to form a metal-rich antioxidant layer of a metal carbide on the C/C composite substrate.

Abstract: An article includes a substrate. The substrate includes at least two phases. The first phase includes a carbon-carbon (C/C) composite. The second phase includes a metal carbide. The second phase is disposed within a plurality of interconnected pores of the first phase, wherein the second phase extends from a surface of the substrate to a depth of at least 300 micrometers below the surface of the substrate.

Abstract: An assembly includes a first tube defining a first smooth, planar surface at an end of the first tube. The assembly includes a second tube defining a second smooth, planar surface at an end of the second tube. The assembly includes a force mechanism configured to apply a force to at least one of the first tube or the second tube to maintain contact between the first surface and the second surface. The first surface and the second surface are configured to interface to form a substantially hermetic seal when the assembly is cycled through a temperature cycle. The force is substantially normal to the first and second surfaces.

Abstract: Components of gas turbine engines, aircraft comprising the components, and methods of producing the components are provided. The component includes a surface, and a set of tiles secured to the surface at interfaces between the set of tiles and the surface and between each of the set of tiles. The set of tiles conform to the surface and in combination define a coating system on the surface that includes an environmental barrier coating and/or a thermal barrier coating.

Abstract: A method for forming a refractory component of foundry system includes forming a preform from a refractory mixture. The refractory mixture includes a silicon carbide preceramic polymer and at least one of a refractory powder or refractory aggregate. The method further includes heating the preform to pyrolyze the silicon carbide preceramic polymer and form a refractory material defining the refractory component. The resulting refractory material includes at least one of the refractory powder or the refractory aggregate in a silicon carbide matrix. The refractory component defines an oxidation-resistant surface configured to contact molten metal.

Abstract: Methods and systems are provided for filling cracks in an environmental barrier coating and/or a thermal barrier coating (EBC/TBC). The method comprises locating a component within an enclosure of an apparatus, the component including a substrate having the EBC/TBC thereon, wherein the EBC/TBC includes cracks extending from an exterior surface of the EBC/TBC toward the substrate, reducing pressure within the enclosure to a first pressure that is less than atmospheric pressure, applying a filler slurry to the exterior surface to cover the cracks while the EBC/TBC is exposed to the first pressure, increasing the enclosure to a second pressure that is greater than the first pressure, wherein the second pressure is sufficient to cause the filler slurry on the EBC/TBC to infiltrate into and fill the cracks, and sintering the filler slurry sufficient to cure the filler slurry within the cracks.

Abstract: A method for forming a high temperature coating includes forming a pre-sintered ceramic coating on a ceramic composite substrate. The pre-sintered ceramic coating includes a plurality of ceramic particles. The method further includes sintering at least a portion of the pre-sintered ceramic coating by heating the portion of the pre-sintered ceramic coating to a sintering temperature of the plurality of ceramic particles using joule heating. The sintering temperature is greater than about 1000 degrees Celsius (° C.).

Abstract: An example method for forming a high temperature coating includes depositing a carbon layer on to a surface of a composite article using chemical vapor deposition. The composite substrate includes a composite substrate including a carbon matrix. The surface of the composite article includes one or more surface voids. The method further includes applying a metal slurry to the surface of the composite article following the deposition of the carbon layer and reacting a metal of the metal slurry with carbon of the carbon layer to form an antioxidant layer of a metal carbide on the composite article.

Abstract: A method is provided. The method includes: forming a stator for a high-power density electric machine, the stator having a plurality of slots for receiving stator coils and having a back-iron; inserting the stator coils in the plurality of slots; and inserting a potting material in the plurality of slots of the stator, the potting material in thermal contact with adjacent stator coils and in thermal contact with the back-iron; wherein the potting material is formed by: mixing silicon carbide particles with a silicon carbide preceramic polymer to form a mixture; diluting the mixture with solvents to form a slurry; drying the slurry to form a paste; forming the paste into a shape; and firing the paste to form a ceramic material.

Abstract: The disclosure describes continuous vacuum processing of a fiber tow. Continuous vacuum processing includes passing a fiber tow through a plurality of vacuum chambers and operating at least two vacuum chambers of the plurality of vacuum chambers at a different level of vacuum pressure than each other.