Abstract: A ceramic matrix composite includes a plurality of ceramic fibers and an interface coating disposed on the plurality of ceramic fibers. The interface coating includes a carbon-based layer disposed on each ceramic fiber of the plurality of ceramic fibers and a boron-nitride based layer disposed on the first carbon-based layer. The ceramic matrix composite also includes a ceramic matrix surrounding the plurality of ceramic fibers. A ceramic matrix composite and a method of forming a ceramic matrix composite component are also disclosed.

Abstract: A method for forming ceramic matrix composite (CMC) component includes forming a fiber preform, positioning the fiber preform into a chemical vapor infiltration reactor chamber, and densifying the fiber preform. Densification includes infiltrating the fiber preform with a first gas comprising precursors of silicon carbide and infiltrating the fiber preform with a second gas comprising a first rare earth element, wherein the steps of infiltrating the fiber preform with the first gas and infiltrating the fiber preform with the second gas are conducted simultaneously to produce a first rare earth-doped silicon carbide matrix in a first region of the component.

Abstract: Disclosed herein is a chemical vapor infiltration method including flowing ceramic precursors through a preform and depositing a matrix material on the preform at a first gas infiltration pressure, increasing the gas filtration pressure to a second gas infiltration pressure, and lowering the gas infiltration pressure to a third gas infiltration pressure which is intermediate to the first and second gas infiltration pressures.

Abstract: A method of improving surface roughness of ceramic matrix composites (CMCs) is provided. The method includes completing a formation of the CMCs and a chemical vapor infiltration (CVI) process to initially coat the CMCs, inspecting a CMC surface, identifying, from a result of the inspecting, a defect in the CMC surface that negatively impacts a surface roughness characteristic thereof, locally targeting and ablating the defect and re-inspecting the CMC surface to ensure that the defect is correct.

Abstract: Disclosed herein is a chemical vapor infiltration method including flowing ceramic precursors through a preform and depositing a matrix material on the preform at a first gas infiltration pressure, increasing the gas filtration pressure to a second gas infiltration pressure, and lowering the gas infiltration pressure to a third gas infiltration pressure which is intermediate to the first and second gas infiltration pressures.

Abstract: Disclosed herein is a composite ply comprising fill and warp tows; or optional axial and bias tows; wherein one or more of the fill tows and/or the warp tows or wherein one or more of the optional axial and/or bias tows comprise a polymer yarn while the remaining portion of the fill tows and/or the warp tows or the remaining portion of the bias and/or optional axial tows comprise the polymer yarn; and wherein the polymer yarn is melted to bond to the fill or warp tows to prevent removal from the ply.

Abstract: A method of preparing a ceramic fabric for use in a ceramic matrix composite includes transforming a ceramic tow from a first tow geometry to a second tow geometry, thereby reducing a first dimension of the ceramic tow and increasing a second dimension of the ceramic tow orthogonal to the first dimension to produce a flattened tow. The method includes weaving or braiding the flattened ceramic tow to form a ceramic fabric.

Abstract: A method of machining cooling holes includes providing a workpiece in which a cooling hole is to be formed. The cooling hole, once formed, defines distinct first and second sections. The workpiece is secured in a fixture that is mounted in a first machine. In the first machine, a laser is used to drill a through-hole in a wall of the workpiece. The through-hole is spatially common to the first and second sections of the cooling hole. After drilling the through-hole, the fixture with the workpiece secured therein is removed from the first machine and mounted in a second machine. In the second machine, ultrasonic machining is used to expand a portion of the through-hole to form the second section. An abrasive slurry used in the process is drained through the through-hole during the ultrasonic machining.

Abstract: A method of forming a ceramic matrix composite includes applying a binder comprising water and 5% to 15% polyvinyl alcohol to a ceramic material and decomposing the binder to leave behind a discontinuous carbon layer within the ceramic material. The step of applying the binder includes one of a spraying, pipetting, painting, immersing, and pre-pregging technique.

Abstract: A fiber-reinforced component for use in a gas turbine engine includes a first braided fiber sleeve forming a cooling channel and a plurality of fiber plies enclosing the first braided fiber sleeve, with the plurality of fiber plies forming first and second walls separated by the first braided fiber sleeve. The fiber-reinforced component further includes a matrix material between fibers of the braided fiber sleeve and the plurality of fiber plies.

Abstract: A method for forming a ceramic matrix composite (CMC) component with an internal cooling channel includes partially densifying a first fiber preform to form a portion of a final ceramic matrix volume, machining a first channel into a surface of the partially densified first fiber preform, covering the first channel with a fibrous member to form a near net shape fiber preform with an internal passage formed by the first channel and the fibrous member, and densifying the near net shape fiber preform.

Abstract: A method for forming ceramic matrix composite (CMC) component includes forming a fiber preform, positioning the fiber preform into a chemical vapor infiltration reactor chamber, and densifying the fiber preform. Densification includes infiltrating the fiber preform with a first gas comprising precursors of silicon carbide and infiltrating the fiber preform with a second gas comprising a first rare earth element, wherein the steps of infiltrating the fiber preform with the first gas and infiltrating the fiber preform with the second gas are conducted simultaneously to produce a first rare earth-doped silicon carbide matrix in a first region of the component.

Abstract: A fiber-reinforced component for use in a gas turbine engine includes a first braided fiber sleeve forming a cooling channel and a plurality of fiber plies enclosing the first braided fiber sleeve, with the plurality of fiber plies forming first and second walls separated by the first braided fiber sleeve. The fiber-reinforced component further includes a matrix material between fibers of the braided fiber sleeve and the plurality of fiber plies.

Abstract: A method of forming a ceramic matrix composite component with cooling channels includes embedding a plurality of wires into a preform structure, densifying the preform structure with embedded wires, and removing the plurality of wires to create a plurality of corresponding channels within the densified structure.

Abstract: A method of forming a ceramic matrix composite component includes forming a fiber preform, the fiber preform including a plurality of ceramic fiber plies, a non-reduced fiber region having an areal weight, and a reduced fiber region characterized by a reduced areal weight less than the areal weight of the non-reduced fiber region by at least 5 percent. The method further includes selectively applying ceramic particles to the reduced fiber region in such manner as to avoid applying the ceramic particles to the non-reduced fiber region, and subsequently densifying the preform.

Abstract: A method for forming a ceramic matrix composite (CMC) component with an internal cooling channel includes forming a first fiber member, forming a first depression in a surface of the first fiber member, covering the first depression with a second fiber member to form a near-net shape fiber preform of a component with an internal channel defined in part by the first depression, and densifying the fiber preform.

Abstract: A fiber-reinforced component for use in a gas turbine engine includes a fiber sleeve forming a cooling channel and a plurality of fiber plies enclosing the fiber sleeve, with the plurality of fiber plies forming first and second walls separated by the fiber sleeve. The fiber-reinforced component further includes a matrix material between fibers of the fiber sleeve and the plurality of fiber plies.

Abstract: A component for a gas turbine engine includes a body that has a first circumferential side and a second circumferential side. A circumferentially extending passage extends from the first circumferential side to the second circumferential side. The first circumferential side has an outer height that is less than an inner height of the second circumferential side.

Abstract: A ceramic matrix composite includes a plurality of ceramic fibers and an interface coating disposed on the plurality of ceramic fibers. The interface coating includes a carbon-based layer disposed on each ceramic fiber of the plurality of ceramic fibers and a boron-nitride based layer disposed on the first carbon-based layer. The ceramic matrix composite also includes a ceramic matrix surrounding the plurality of ceramic fibers. A ceramic matrix composite and a method of forming a ceramic matrix composite component are also disclosed.

Abstract: A ceramic matrix composite includes at least one ply of ceramic fibers and a a ceramic matrix material deposited on the ceramic fibers. A fiber volume fraction is between about 35-45% and an areal weight fibers is between about 150-450 g/m2. A method of fabricating a ceramic matrix composite component is also disclosed.