Abstract: The present disclosure relates generally to blades used in gas turbine engines. More specifically designs in accordance with the present disclosure include turbine blades comprising ceramic matrix composite materials with abrasive tips coupled thereto.

Abstract: A ceramic matrix composite (CMC) seal segment for use in a segmented turbine shroud for radially encasing a turbine in a gas turbine engine. The CMC seal segment comprises an arcuate flange having a surface facing the turbine and a portion defining a bore for receiving an elongated pin, with the bore having a length that is at least 70% of the length of the elongated pin received therein. The CMC seal segment is carried by the carrier by at least one of the elongated pins being received within the bore. The CMC seal segment portion defining a pin-receiving bore is radially spaced from the arcuate flange by a spacing flange extending radially outward from the arcuate flange.

Abstract: A method is provided in which a first tape is applied to an outer surface of a ceramic matrix composite (CMC). A second tape is applied to the first tape. The second tape is heated to at least a melting temperature of the second tape.

Abstract: A gas turbine engine may comprise a blade track and a method of making the same. The blade track may be constructed of ceramic matrix composite components including main body members and joints.

Abstract: A system of infiltration for producing a ceramic matrix composite (CMC) is provided in which a slurry is applied to an outer surface of a porous preform. The porous preform includes a framework of ceramic fibers. The slurry may include a solvent and a particulate. The porous preform may be infiltrated with the slurry. The particulate in the slurry may include a plurality of coarse particles and a plurality of fine particles. The coarse particles may have a d50 factor of 10-20 microns. The fine particles may have a d50 factor of 0.5-3 microns. A ratio of coarse particles to fine particles in the slurry may be between 1.5:1 and 4:1, inclusively.

Abstract: A method is provided in which a resin coating is applied to a surface of a preform. The resin coating includes a carbonaceous resin and a particulate. The preform is added to a tooling. The preform, which is positioned in the tooling, is cured. The tooling is removed. The resin coating on the surface of the preform is pyrolyzed to form a resin carbon-char layer on the surface of the preform. The preform and the resin carbon-char layer are infiltrated with silicon to form a ceramic matrix composite (CMC) component including a layer of silicon carbide. During the infiltration, the silicon reacts with carbon in the resin carbon-char layer to form the layer of silicon carbide on the preform.

Abstract: Methods of reducing dry crack formation in ceramic matrix composite green bodies are provided. Some of the methods expose the green body to a gaseous atmosphere at a relatively high humidity for a first period, and then slowly lower the humidity over a second period, where the gaseous atmosphere is at room temperature for both periods. Other methods start the gaseous atmosphere at room temperature and then raise the temperature to a higher temperature while the humidity is relatively high, and hold that temperature even as the humidity is lowered in the second period.

Abstract: In some examples, a method may include depositing, from a slurry comprising particles including silicon metal, a bond coat precursor layer including the particles comprising silicon metal directly on a ceramic matrix composite substrate. The method also may include locally heating the bond coat precursor layer to form a bond coat comprising silicon metal. Additionally, the method may include forming a protective coating on the bond coat. In some examples, an article may include a ceramic matrix composite substrate, a bond coat directly on the substrate, and a protective coating on the bond coat. The bond coat may include silicon metal and a metal comprising at least one of Zr, Y, Yb, Hf, Ti, Al, Cr, Mo, Nb, Ta, or a rare earth metal.

Abstract: A combustor of a gas turbine engine and a turbine shroud for a turbine of a gas turbine engine are disclosed. The combustor is configured to ignite a mixture of compressed air and fuel in a combustion chamber included therein. The turbine shroud is configured to direct products of the combustion reaction toward a plurality of rotatable turbine blades of the turbine to cause the plurality of turbine blades to rotate.

Abstract: A segmented turbine shroud for radially encasing a rotatable turbine in a gas turbine engine comprising a carrier, a ceramic matrix composite (CMC) seal segment, and an elongated pin. The carrier defines a pin-receiving carrier bore and the CMC seal segment defines a pin-receiving seal segment bore. The elongated pin extends through the carrier bore and the seal segment bore. The pin-receiving carrier bore includes a cantilevered member such that the carrier bore has a length sufficient to effect radial flexion between the carrier bore and the pin received within the carrier bore during operation of the turbine.

Abstract: A method of processing a CMC component includes preparing a fiber preform having a predetermined shape, and positioning the fiber preform with tooling having holes facing one or more surfaces of the fiber preform. After the positioning, a clamping pressure is applied to the tooling to force portions of the one or more surfaces of the fiber preform into the holes, thereby forming protruded regions of the fiber preform. During the application of the clamping pressure, the fiber preform is exposed to gaseous reagents at an elevated temperature, and a matrix material is deposited on the fiber preform to form a rigidized preform including surface protrusions. After removing the tooling, the rigidized preform is infiltrated with a melt for densification, and a CMC component having surface bumps is formed. When the CMC component is assembled with a metal component, the surface bumps may reduce diffusion at high temperatures.

Abstract: A method of forming a barrier layer on a ceramic matrix composite (CMC) is described. The method includes forming a particulate surface layer comprising silicon particles on an outer surface of a fiber preform. The particulate surface layer is nitrided to convert the silicon particles to silicon nitride particles. After the nitriding, the fiber preform and the particulate surface layer are infiltrated with a molten material comprising silicon. Following infiltration, the molten material is cooled, thereby forming a ceramic matrix composite with a barrier layer thereon, where the barrier layer comprises silicon nitride and less than 5 vol. % free silicon. The barrier layer may also include silicon carbide and/or one or more refractory metal silicides.

Abstract: A method for infiltrating a porous preform for a gas turbine engine is provided, which comprises providing a chamber for infiltrating a porous preform. The porous preform is positioned within a slurry confinement fixture within the chamber. A vacuum is created in the chamber. A solvent is added to the slurry confinement fixture until a pressure in the chamber is substantially equal to an equilibrium partial pressure of the solvent. A slurry is added to the slurry confinement fixture. The slurry includes the solvent and a particulate. The pressure in the chamber is increased, and the slurry is urged into the porous preform.

Abstract: A method of altering a surface of a ceramic matrix composite to aid in nodule removal is described. A fiber preform comprising a framework of ceramic fibers is heated to a temperature at or above a melting temperature of silicon. During the heating, the fiber preform is infiltrated with a molten material comprising silicon. After the infiltration, the fiber preform is cooled, and the infiltrated fiber preform is exposed to a gas comprising nitrogen during cooling. Silicon nitride may be formed by a reaction of free (unreacted) silicon at or near the surface of the infiltrated fiber preform with the nitrogen. Thus, a ceramic matrix composite having a surface configured for easy nodule removal is formed. Any silicon nodules formed on the surface during cooling may be removed without machining or heat treatment.

Abstract: A bladed disk preform system is provided. Multiple sheets are formed or provided. Each of the sheets may include multiple ceramic fibers. Slots may be cut in each of the sheets before or after forming. The slots extend from an outer edge of the sheets inward toward a center of the sheets. The sheets are stacked on top of each other to form a bladed disk preform. The bladed disk preform is porous. The bladed disk preform may include a plurality of blade portions extending outward from a root portion. Each of the slots is positioned between adjacent blade portions.

Abstract: A method of forming an impurity barrier layer on a CMC substrate may include introducing, to a heated plume of a thermal spray gun, a composite feedstock that includes a first coating material including a plurality of first particles; and a second coating material that may be different from the first coating material, where the second coating material at least partially encapsulates at least a portion of respective surfaces of the plurality of first particles; and directing, using the heated plume, at least the first coating material to a surface of a CMC substrate to deposit an impurity barrier layer including at least the first coating material.

Abstract: A method of melt infiltrating a green ceramic matrix composite (CMC) article, wherein the green CMC article includes a ceramic reinforcing structure. The method includes heating a localized region of the green CMC article; melting a metal alloy infiltrant to form a molten metal alloy; and introducing the molten metal alloy into the localized region to infiltrate the reinforcing structure of the green CMC article with the metal alloy infiltrant and form the CMC article.

Abstract: In some examples, a technique for infiltrating a porous preform with a slurry to form an infiltrated-preform, where the slurry includes a plurality of solid particles, where the plurality of solid particles include a plurality of fine ceramic particles defining an average fine particle diameter, a plurality of coarse ceramic particles defining an average coarse particle diameter, and a plurality of diamond particles, where the average fine particle diameter is less than the average coarse particle diameter, and infiltrating the infiltrated-preform with a molten metal infiltrant to form a ceramic matrix composite (CMC) article.

Abstract: A method of making a fiber preform for ceramic matrix composite (CMC) fabrication comprises laminating an arrangement of fibers between polymer sheets comprising an organic polymer, which may function as a fugitive binder during fabrication, to form a flexible prepreg sheet. A plurality of the flexible prepreg sheets are laid up in a predetermined geometry to form a stack, and the stack is heated to soften the organic polymer and bond together the flexible prepreg sheets into a bonded prepreg structure. Upon cooling of the bonded prepreg structure, a rigid preform is formed. The rigid preform is heated at a sufficient temperature to pyrolyze the organic polymer. Thus, a porous preform that may undergo further processing into a CMC is formed.

Abstract: A multi-piece disk for use in a turbine of a gas turbine engine. The multi-piece disk includes a fore disk segment and an aft disk segment coupled with the fore disk segment for movement with the fore disk segment. The fore disk segment and the aft disk segment are formed to define slots that extend through the disk segments and are configured to receive turbine blades therein.