# US 11,905,851 B2 · CMC trailing edge 3D weaved cross brace

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- Number: US 11,905,851 B2
- Document ID: US11905851B2
- Status: Granted
- Kind: B2
- Application number: 18/126,556
- Filed: 2023-03-27
- Published: 2023-10-05
- Granted: 2024-02-20
- Earliest claimed: 2022-04-01
- Assignees: Rtx Corporation
- Applicants: Raytheon Technologies Corporation
- Inventors: Russell Kim; James T. Roach; Jonas Banhos
- Web page: https://patentgrep.com/patent/US11905851B2

## CPC

- F01D 5/282: {Selecting composite materials, e.g. blades with reinforcing filaments}
- F01D 5/147: {Construction, i.e. structural features, e.g. of weight-saving hollow blades (F01D5/148, F01D5/16 and F01D5/20 take precedence; blade shape F01D5/141; blades with cooling or heating channels or cavities F01D5/18; heating, heat-insulating or cooling means on blades F01D5/18)}
- F01D 5/284: {Selection of ceramic materials}
- C04B 35/565: based on silicon carbide
- F01D 9/041: {using blades (F01D5/148 takes precedence)}
- F05D 2230/31: Layer deposition
- F05D 2240/122: related to the trailing edge of a stator vane
- F05D 2250/75: given by its similarity to a letter, e.g. T-shaped
- F05D 2300/2261: of silicon
- F05D 2300/6012: Woven fabrics
- F05D 2300/6033: Ceramic matrix composites [CMC]
- F05D 2300/6034: Orientation of fibres, weaving, ply angle
- Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A method of forming a ceramic matrix composite airfoil includes forming a fibrous ceramic preform by laying up a plurality of plies to form a hollow core cavity, overwrapping the plurality of plies of the core cavity with a first overwrap layer, weaving together a tows of first free portion and tows of a second free portion of the first overwrap layer to form a cross brace, overwrapping the plurality of plies of the core cavity and the first overwrap layer with a second overwrap layer, and consolidating the first free portion and the second free portion of the first overwrap layer and a third free portion and a fourth free portion of the second overwrap layer to form a trailing edge.

## Claims

### Claim 1

A method of forming a ceramic matrix composite airfoil, the method comprising: forming a fibrous ceramic preform by: laying up a plurality of plies to form a hollow core cavity; overwrapping the plurality of plies of the core cavity with a first overwrap layer; weaving together a tows of first free portion and tows of a second free portion of the first overwrap layer to form a cross brace, the cross brace having an “X” shaped cross-sectional geometry; overwrapping the plurality of plies of the core cavity and the first overwrap layer with a second overwrap layer; and consolidating the first free portion and the second free portion of the first overwrap layer and a third free portion and a fourth free portion of the second overwrap layer to form a trailing edge, wherein the cross brace is disposed in a trailing edge void of the fibrous preform, partially defining a plurality of sub-cavities of the trailing edge void; and wherein the hollow core cavity and a first of the plurality of sub-cavities are separated from each other by a common wall comprised of a subset of the plurality of plies.

### Claim 2 (depends on 1)

The method of claim 1, wherein overwrapping the plurality of plies of the core cavity with the first overwrap layer comprises: weaving a fabric layer around the plurality of plies.

### Claim 3 (depends on 2)

The method of claim 2, wherein forming the cross brace comprises: interweaving tows of the first free portion and tows of the second free portion.

### Claim 4 (depends on 1)

The method of claim 1, wherein overwrapping the plurality of plies of the core cavity with the first overwrap layer comprises: laying up a sheet over the plurality of plies of the core cavity.

### Claim 5 (depends on 4)

The method of claim 4, wherein forming the cross brace comprises: stitching together a first free portion and a second free portion of the cloth.

### Claim 6 (depends on 1)

The method of claim 1, wherein forming the fibrous ceramic preform further comprises: stitching a reinforcing fiber through the first overwrap layer and the second overwrap layer in the trailing edge void.

### Claim 7 (depends on 1)

The method of claim 1, wherein forming the fibrous ceramic preform further comprises: inserting a fibrous insert into one of the plurality of sub-cavities.

### Claim 8 (depends on 1)

The method of claim 1 and further comprising: densifying the fibrous preform using at least one of chemical vapor infiltration, chemical vapor deposition, polymer infiltration and pyrolysis, and melt infiltration.

### Claim 9

A ceramic matrix composite airfoil comprising: a leading edge; a trailing edge opposite the leading edge; a pressure side extending from the leading edge to the trailing edge; a suction side opposite the pressure side and extending from the leading edge to the trailing edge; a hollow core cavity adjacent the leading edge and between the pressure side and the suction side; a trailing edge void between the leading edge and the trailing edge, and between the pressure side and the suction side; and a cross brace formed in the trailing edge void, the cross brace having an “X” shaped cross-sectional geometry, wherein the cross brace partially defines a plurality of sub-cavities; and wherein a shared wall separates a first of the plurality of sub-cavities from the hollow core cavity.

### Claim 10 (depends on 9)

The airfoil of claim 9, wherein a first free portion and an opposing second free portion of a ceramic overlap layer forms the cross brace and partially forms the trailing edge.

### Claim 11 (depends on 10)

The airfoil of claim 10, wherein the cross brace comprises a central intersecting point.

### Claim 12 (depends on 11)

The airfoil of claim 11, where the first free portion is disposed on the pressure side, and aft of the intersecting point, is disposed on the suction side.

### Claim 13 (depends on 9)

The airfoil of claim 9 and further comprising: a fibrous insert disposed within one of the plurality of sub-cavities.

### Claim 14 (depends on 9)

The airfoil of claim 9, wherein the cross brace is coextensive with the trailing edge void and a span of the airfoil.

### Claim 15 (depends on 9)

The airfoil of claim 9, wherein the airfoil is formed from tows of silicon carbide and a matrix of silicon carbide.

### Claim 16 (depends on 9)

The airfoil of claim 9, wherein the airfoil is part of a stationary vane of a gas turbine engine.

### Claim 17 (depends on 9)

The airfoil of claim 9, wherein the cross brace is formed from a first woven ceramic overlap layer, and wherein the first ceramic overlap layer is disposed between ceramic plies defining the core cavity, and a second, outer ceramic overlap layer.