WO2019108203A1

WO2019108203A1 - Hybrid ceramic matrix composite components with intermediate cushion structure

Info

Publication number: WO2019108203A1
Application number: PCT/US2017/063946
Authority: WO
Inventors: Ke Huang; Ramesh Subramanian
Original assignee: Siemens Aktiengesellschaft
Priority date: 2017-11-30
Filing date: 2017-11-30
Publication date: 2019-06-06

Abstract

There is provided a component that includes a core (14) that includes a first material (16) of a metal material (24) or a ceramic matrix composite material (22). A shell (18) surrounds the core (14). The shell (18) is of a second material (20) that is the other of the metal material (24) or the ceramic matrix composite material (22) of the first material (16). A circumferential gap (26) is disposed between the core (14) and the shell (18). An intermediate cushion (28) is disposed within the circumferential gap (26). The intermediate cushion (28) is of a deformable material and is effective to transfer a thermal and mechanical load between the core (14) and the shell (18).

Description

HYBRID CERAMIC MATRIX COMPOSITE COMPONENTS WITH INTERMEDIATE

CUSHION STRUCTURE

FIELD OF THE INVENTION

The present invention relates to hybrid high temperature components for use in high temperature environments, such as in gas turbines. The components comprise a core of a first material (ceramic matrix composite or a metal) and an outer shell formed from a second material (the other of the CMC or metal material of the first material). Between the core and the outer shell, there is provided an intermediate cushion for allowing heat transfer and load transfer between the core and shell during their operation in a high temperature environment.

BACKGROUND OF THE INVENTION

Gas turbines comprise a casing or cylinder for housing a compressor section, a combustion section, and a turbine section. A supply of air is compressed in the compressor section and directed into the combustion section. The compressed air enters the combustion inlet and is mixed with fuel. The air/fuel mixture is then combusted to produce a high temperature and high pressure (working) gas. This working gas is then ejected past the combustor transition and injected into the turbine section of the turbine.

The turbine section comprises rows of vanes which direct the working gas to the airfoil portions of the turbine blades. The working gas travels through the turbine section, causing the turbine blades to rotate, thereby turning the rotor. The rotor is also attached to the compressor section, thereby turning the compressor and also an electrical generator for producing electricity. A high efficiency of a combustion turbine is achieved by heating the gas flowing through the combustion section to as high a temperature as is practical. The hot gas, however, may degrade the various metal turbine components, such as the combustor, transition ducts, vanes, ring segments and turbine blades that it passes when flowing through the turbine.

For this reason, strategies have been developed to protect such components from extreme temperatures including the development and selection of high temperature materials adapted to withstand these extreme temperatures, and cooling strategies to keep the components adequately cooled during operation. For one, ceramic matrix composite (CMC) materials have been developed with high temperature resistance. CMC materials include a ceramic or ceramic matrix reinforced with ceramic fibers. While CMC materials provide excellent thermal protection properties, the mechanical strength of CMC materials is still notably less than that of corresponding high temperature superalloy materials.

For this reason, proposed solutions have also added strengthening materials to the CMC material or supported the CMC material with a material having a greater mechanical strength. For example, some manufactured components include a CMC body having a metallic core (rod) extending radially therethrough for added mechanical strength for the CMC body. In some embodiments, the CMC body is in the form of a plurality of stacked laminates, each laminate formed from the CMC material. The CMC laminates are slid over a metal core and retained/compressed via a retaining structure or other structure that compresses the stack of laminates. In other embodiments, CMC laminates may be slid over a metal column (rod) that is additively manufactured as the laminates are stacked.

In the hybrid components described above, directly interfacing the metal and the CMC body portions allows for desirable heat and load transfer between the CMC body and the metal core. Flowever, due to the differing thermal expansion differences between the two materials, these direct interfaces render the CMC portion prone to cracking and failure as the metal portion expands to a greater degree during high temperature operation. Accordingly, in such embodiments, a circumferential gap is typically provided between the metal core and the CMC shell in order to accommodate thermal expansion of the metal core toward the CMC shell. Flowever, the gap reduces the thermal/mechanical load transfer between the shell and the core which may ultimately results in hot spots, high stress zones, and failure of the CMC material.

Accordingly, improved solutions for thermal and mechanical load transfer between CMC and metal in such hybrid components are desired. BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in the following description in view of the drawings that show:

FIG. 1 illustrates a component having a metal core, a CMC shell, and an intermediate cushion therebetween in accordance with an aspect of the present invention.

FIG. 2 illustrates a component having a CMC core, a metal shell, and an intermediate cushion therebetween in accordance with an aspect of the present invention.

FIG. 3 illustrates a component comprising a plurality of stacked CMC laminates, a metal core, and an intermediate cushion in accordance with an aspect of the present invention.

FIG. 4 illustrates an embodiment of a unit cell of negative Poisson ration (NPR) structure in accordance with an aspect of the present invention.

FIG. 5 illustrates an embodiment of an intermediate cushion (NPR structure) comprising a plurality of the unit cells of FIG. 4 in accordance with an aspect of the present invention.

FIG. 6 illustrates another embodiment of an intermediate cushion in accordance with an aspect of the present invention.

FIGS. 7-10 illustrate steps in making a component in accordance with an aspect of the present invention.

FIGS. 11 -15 illustrate steps in making a component in accordance with another aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with one aspect, the present invention is directed to hybrid components which comprise a core of a first material (CMC or metal) and a shell about the core of a second material (the other of the CMC or metal material of the first component). In between the core and the shell, there is an intermediate cushion which allows thermal and mechanical load transfer from the core to the shell and/or vice- versa. The intermediate cushion is formed from a material that has a degree of deformability, e.g., changes shape in response to thermal expansion of the core and/shell. In a particular embodiment, the intermediate cushion comprises an auxetic material or a material having a negative Poisson ratio (NPR) as will be described in detail below. In some embodiments, the intermediate cushion may be formed by additively manufacturing a suitable material within a gap provided between the core and the shell. In this way, the interface and thermal/load transfer between the CMC material and the metal material may be optimized on a layer by layer basis within the

component. Moreover, the intermediate cushion may transfer both thermal and mechanical loads of the CMC to the core.

In accordance with one aspect, there is thus provided a component comprising: a core formed from a first material comprising a metal material or a ceramic matrix composite material; a shell surrounding the core, the shell comprising a second material comprising the other of the metal material or the ceramic matrix composite material of the first material; a circumferential gap disposed between the core and the shell; and an intermediate cushion disposed within the circumferential gap, the intermediate cushion comprising a deformable material and effective to transfer a thermal and mechanical load between the core and the shell.

In another aspect, there is thus provided a process for forming a component comprising: positioning an intermediate cushion within a gap between a core and a shell which surrounds the core, the intermediate cushion comprising a deformable material and effective to transfer a thermal and mechanical load between the core and the shell, the core comprising a metal material or a ceramic matrix composite material and the shell comprising the other of the metal material or the ceramic matrix composite material of the core.

Referring now to the figures, FIG. 1 shows a cross section 10 of a component 12 in accordance with an aspect of the present invention. As shown, the component 12 comprises a core 14 formed from a first material 16 and a shell 18 surrounding the core 14 formed from a second material 20 (different from the first material 16). The first and second material 16, 20 are each of a metal or a ceramic matrix composite (CMC) material. In an embodiment, the shell 18 comprises a CMC material 22 while the core 14 comprises a metal material 24 as shown in FIG. 1. In still other embodiments, as shown in FIG. 2, the core 14 may comprise a CMC material 22 while the shell 18 comprises a metal material 24. In any case, between the core 14 and the shell 18, there is provided a circumferential gap 26.

Within the circumferential gap 26, there is provided an intermediate cushion 28 which is configured to change shape upon thermal expansion of the core 14 and/or shell 18. For example, as shown in FIG. 1 , when the core 14 comprises a metal material 24 and the shell 18 comprises a CMC material 22, the core 14 may expand to a greater degree at the high operating temperatures of a gas turbine engine. In this way, the core 14 may grow into a body of the intermediate cushion 28. In addition, the intermediate cushion 28 not only accommodates the greater thermal growth of the metal portion (relative to the CMC portion) in the component 12, but also importantly maintains direct physical contact with both the core 14 and the shell 18 to thereby transfer thermal and mechanical loads from the shell 18 to the core 14, and/or vice- versa. For example, when the shell 18 is in direct contact with the hot gas path of the gas turbine, thermal and mechanical loads may be transferred from the shell 18 to the core 14.

The component 12 may be shaped and dimensioned into any suitable form suitable for its desired application. In certain embodiments, the combination of CMC with metal (e.g., a superalloy) may increase a maximum operating temperature of the component by 200-300° C or more relative to the metal component alone. In an embodiment, the component 12 comprises a component for use in a turbine engine, such as one having an operating temperature of 800° C or more, and in certain embodiments of 1200° C or more. In an embodiment, the component 12 comprises a stationary component of a gas turbine, such as a stationary vane or a transition cone.

In another embodiment, the component 12 comprises a rotating component for a gas turbine, such as a blade. Flowever, the present invention is not so limited and any desired component may be formed with the structures and processes described herein.

In an embodiment and as was shown in FIG. 1 , the component 12 comprises a core 14 of a metal material 24 and a shell 18 of a CMC material 22 about the core 14.

In an embodiment, the shell 18 comprises a uniform or continuous body of the CMC material 22. In other embodiments, the shell 18 comprises a plurality of laminates, each formed from the CMC material, which are stacked on one another to form the shell 18 of the components. An embodiment of component 12 wherein a plurality of CMC laminates 30 are stacked one another to define the shell 18 is illustrated in FIG. 3. In this embodiment, the laminates 30 are stacked over two spaced apart metal cores 14 and the intermediate cushion 28. In still another embodiment, when the shell 18 comprises a CMC material 22, the shell 18 may be manufactured by a process as disclosed in PCT/US2016/059029, wherein a ceramic material is injected into a fiber material to form a ceramic fiber composite which is then 3D printed in a desired pattern to form the CMC piece (e.g., shell 18). The entirety of PCT/US2016/059029 is incorporated by reference herein.

Similarly, when provided, the core 14 comprising the metal material 24 may be cast as a uniformly solid piece. Alternatively, the core 14 may be produced by an additive manufacturing process as is known in the art, e.g., a selective laser

manufacturing (SLM) technique (SLM). In certain embodiments, the core 14 comprising the metal material 24 and/or the intermediate cushion 28 are formed in situ as CMC laminates 30 are stacked on one another. Processes for building a metal core as CMC laminates are stacked on one another are disclosed in PCT/US2015/023017, the entirety of which is incorporated by reference herein. In yet another embodiment and referring to FIG. 2, there is shown a component 12B having a core that instead comprises a CMC material 22 while the shell 18 instead comprises a metal material 24.

The CMC material 22 of the core 14 or the shell 18 (as the case may be) may comprise any suitable ceramic or a ceramic matrix material which hosts a plurality of reinforcing fibers as is known in the art. The CMC material 22 may comprise a fiber reinforced matrix material or metal reinforced matrix material as may be known or later developed in the art, such as one commercially available from the COI Ceramics Co. under the name AS-N720. If a fiber reinforced material is used, the fibers may comprise oxide ceramics, non-oxide ceramics, or a combination thereof. For example, the oxide ceramic fiber composition can include those commercially available from the Minnesota Mining and Manufacturing Company under the trademark Nextel, including Nextel 720 (alumino-silicate), Nextel 610 (alumina), and Nextel 650 (alumina and zirconia). For another example, the non-oxide ceramic fiber composition can include those commercially available from the COI Ceramics Company under the trademark Sylramic (silicon carbide), and from the Nippon Carbon Corporation, Limited under the trademark Nicalon (silicon carbide).

The matrix material composition that surrounds the fibers may be made of an oxide or non-oxide material, such as alumina, mull ite, aluminosilicate, ytrria alumina garnet, silicon carbide, silicon nitride, silicon carbonitride, and the like. A CMC material 22 may combine a matrix composition with a reinforcing phase of a different

composition (such as mullite/silica), or may be of the same composition

(alumina/alumina or silicon carbide/silicon carbide). The fibers may be continuous or long discontinuous fibers, and may be oriented in a direction generally parallel, perpendicular, or otherwise disposed relative to the major length of the CMC material 22. The matrix composition may further contain whiskers, platelets, particulates, or fugitives, or the like. The reinforcing fibers may be disposed in the matrix material in layers, with the plies of adjacent layers being directionally oriented to achieve a desired mechanical strength.

The fibers may be provided in various forms, such as a woven fabric, blankets, unidirectional tapes, and mats. In an embodiment, the CMC material 22 is formed from a plurality of plies of the fiber material, which is infused with a ceramic material and subjected to a suitable heat treatment process, e.g., sintering. A variety of techniques are known in the art for making a CMC material and such techniques can be used in forming the CMC material 14 for use herein. In addition, exemplary CMC materials 14 are described in U.S. Patent Nos. 8,058,191 , 7,745,022, 7,153,096; 7,093,359; and 6,733,907, the entirety of each of which is hereby incorporated by reference.

It is appreciated that the selection of materials may not be the only factor which governs the properties of the CMC material 22 as the fiber direction may also influence the mechanical strength of the material, for example. As such, the fibers for the CMC material 22 may have any suitable orientation, such as those described in U.S. Patent No. 7,153,096. In still another embodiment, the CMC material 22 portion may be manufactured by a process as disclosed in PCT/US2016/059029, the entirety of which is incorporated by reference herein, wherein a ceramic material is injected into a fiber material to form a ceramic fiber composite which is then 3D printed in a desired pattern to form the CMC portion.

The metal material 24 of the core 14 or shell 18 as the case may be may comprise any suitable metal (e.g., alloy) material which will provide an added

mechanical strength or support to the CMC material 22 and/or the component 12. In an embodiment, the metal material 24 comprises a superalloy material, such as a nickel- based or a cobalt-based superalloy material, as is well known in the art. The term "superalloy" may be understood to refer to a highly corrosion-resistant and oxidation- resistant alloy that exhibits excellent mechanical strength and resistance to creep - even at high temperatures. Exemplary superalloy materials are commercially available and are sold under the trademarks and brand names Hastelloy, Inconel alloys (e.g., IN 738, IN 792, IN 939), Rene alloys (e.g. Rene N5, Rene 41 , Rene 80, Rene 108, Rene 142, Rene 220), Haynes alloys, Mar M, CM 247, CM 247 LC, C263, 718, X-750, ECY 768, 262, X45, PWA 1483 and CMSX (e.g. CMSX-4) single crystal alloys, GTD 111 , GTD 222, MGA 1400, MGA 2400, PSM 116, CMSX-8, CMSX-10, PWA 1484, IN 713C, Mar- M-200, PWA 1480, IN 100, IN 700, Udimet 600, Udimet 500 and titanium aluminide, for example. The metallic portion may be formed by any suitable process known in the art, such as by casting or an additive manufacturing process.

In any case, in any of the embodiments described herein, there is a

circumferential gap 26 between the core 14 and the shell 18. The gap 26 may be of any suitable to accommodate the differential thermal growth between the core 14 and the shell 18. In an embodiment, the gap 26 has a thickness of 20-1000 micron. Within the gap 26, there is provided the intermediate cushion 28, which provides a physical interface between the core 14 and the shell 18 to facilitate thermal and mechanical load transfer between the core 14 and the shell 18. In addition, during sufficient high temperature operation, the shape of the intermediate cushion 28 may adapt to the dimension change of the core 14 and/or the shell 18 due to thermal expansion differences therebetween and/or mechanical loads placed on the cushion 28. To fill the gap 26, the intermediate cushion 28 may also have a thickness which fills the

dimensions of the gap. Thus, in an embodiment, the intermediate cushion 28 may also have a thickness of 20-1000 micron. The intermediate cushion 28 comprises a material which is deformable upon growth/movement of the core 14 and/or shell 18 into the intermediate cushion 28. This deformability may be accomplished by a range of different materials - so long as the materials are capable of changing shape or deforming in response to mechanical or thermal loads, including thermal growth of the core 14 and/or shell 18. In an

embodiment, the intermediate cushion 28 is one that comprises a material having a porosity of 50% or more. The high porosity at least contributes to the deformability of the intermediate cushion 28. In an embodiment, the material of the intermediate cushion 28 may comprise a metallic material, such as a superalloy material as described. In other embodiments, the intermediate cushion 28 may comprise a polymeric material. In addition, the intermediate cushion 28 may be in any suitable physical form. In certain embodiments, the intermediate cushion 28 comprises a foam, a mesh, a honeycomb, or any other physical form having a porosity of > 50%.

Exemplary high porosity (> 50%) materials for use with the intermediate cushion 28 are disclosed in C. Beyer, D. Figueroa, Design and Analysis of Lattice Structures for Additive Manufacturing, J. of Manufacturing Sci. and Eng., December 2016, vol. 138, 121014-1 , for example (the entirety of which is incorporated by reference herein). The reference illustrates a number of exemplary unit structures having an internal structure that provides a high degree of porosity (> 50%) and a reduced macro yield strength (relative to a solid structure). In an embodiment, the intermediate cushion 28 comprises a material having a relative yield strength of .25 or less compared to a solid form. It is appreciated that the internal structure is without limitation so long as it provides the desired porosity and macro yield strength.

In a particular embodiment, the intermediate cushion 28 comprises a foam, such as a metallic foam. Exemplary processes for manufacturing a metallic foam is described in JOM, 52 (12) (2000), pp. 22-27, the entirety of which is incorporated by reference herein. For example, a metallic foam for use herein may be manufactured by preparing a molten metals with a desired viscosity and thereafter injecting gas(es) or adding gas-releasing blowing agents which cause the formation of bubbles in situ, thereby producing the foam. In another embodiment, a metallic foam may be

manufactured by preparing a supersaturated metal-gas system under high pressure and initiating bubble formation by pressure and temperature control. In yet another embodiment, a metallic foam may be manufactured by mixing one or more metal powders with a blowing agent, compacting the mixture, and then foaming the compact by melting.

In accordance with another aspect, the intermediate cushion 28 may be formed from an additive manufacturing process, such as a selective laser manufacturing (SLM), laser metal deposition (LMD), or other manufacturing process. In certain embodiments, the intermediate cushion is formed within the gap 26 as the core 14 and shell 18 are formed or assembled. When additive manufacturing is utilized, a desired porosity may be provided in the resulting deposited material by any suitable method, including introducing a gas into the deposited molten material as the material is deposited and melted or by avoiding melting of material in selected layers and thereafter removing the material.

In accordance with another aspect, the intermediate cushion 28 may comprise a material having a negative Poisson’s ratio (also known in the art as an auxetic or auxetic material) in order to achieve the desired propert(ies) for the intermediate cushion 28. A material’s Poisson’s ratio refers to a ratio of transverse contraction strain to longitudinal extension strain for the material. Most common materials become thinner in cross section when stretched and therefore have a positive Poisson's ratio. However, some materials known as auxetics have a negative Poisson’s ratio - meaning that when they are stretched they become larger/thicker in a direction perpendicular to the applied force. For example, if a tensile force is applied, the hinge-like structures may extend, thereby causing lateral expansion. If a compressive force is applied, the hinge-like structures fold, thereby causing lateral contraction. In certain embodiments, auxetics may be formed by modifying the macrostructure of a material such that the material includes hinge-like features which change shape when a force is applied.

By way of example and referring again to FIG. 1 , if the core 14 expands into the intermediate cushion 28 due to high gas turbine operating temperatures, for example, the intermediate cushion 28 can expand in size in a direction perpendicular to the applied force (e.g., out of the page in FIG. 1 ). In addition, with an NPR material, a length of the intermediate cushion 28 will not expand in the circumferential direction (C) as its width (W) decreases (as a result of the core 14 growing into the intermediate cushion 28). This maintains a tight fit of the intermediate cushion 28 about the core 14 and enables the cushion 28 to adequately deform to the shape of the core 14, and thereby transfer mechanical and thermal loads between the core 14 and the shell 18.

In particular embodiments, the intermediate cushion 28 comprises a suitable foam material having a negative Poisson ratio, such as a modified polymeric foam. In an embodiment, the NPR material comprises a modified polyurethane foam. An exemplary polymeric foam structure is disclosed in US Patent No. 4,668,557, the entirety of which is incorporated by reference herein. To form the polymeric foam structure, a conventional open-cell foam material is triaxially compressed and heated beyond its softening point to produce a permanent deformation therein. In yet another embodiment, the intermediate cushion comprises a suitable polymeric material, such as an expanded polytetrafluoroethylene (ePTFE) material sold under the commercial trademark GORE-TEX®. In still further embodiments, the intermediate cushion comprises a dilational material. As used herein, a dilational material refers to a stable, three-dimensional isotropic auxetics with an ultimate Poisson’s ratio of -1.

In still another embodiment, the NPR structure comprises an engineered three- dimensional (3D) auxetic structure as described in, for example, US 2010/0119792, the entirety of which is incorporated by reference herein. In an embodiment, as described in US 2010/0119792 and as shown in FIGS. 4-5, the 3D auxetic structure 35 comprises a plurality of pyramid-shaped unit cells 29, each having four base points A, B, C, and D defining the corners of a square lying in a horizontal plane. Four stuffers 30 of equal length extend from a respective one of the base points A-D to a point E spaced apart from the plane. Four tendons 32 of equal length, but less than that of the stuffers 30, extend from a respective one of the base points A-D to a point F between point E and the plane. The stuffers 30 and tendons 32 may have any suitable cross-sectional shape, such as rectangular or round shape. The stuffers 30 may be formed from the group consisting of a metal, ceramic, polymeric, or other material. The tendons 32 may be formed from a metal, a polymer, fibers, fiber ropes, or any other suitable tensile material. This configuration may be formed multiple times so as to form a unit cell 29. As shown in FIG. 5, a plurality of unit cells 29 are arranged together to form the 3D auxetic structure 35. In certain embodiments, a plurality of the unit cells 29 are arranged together in the same horizontal plane with the base points of each cell 29 connected to one another.

In still another embodiment, the intermediate cushion 28 comprises a material additively manufactured so as to have a desired NPR value. In an embodiment, for example, the desired material characteristics may be provided by forming slots in the subject material as the intermediate cushion 28 is being formed by an additive manufacturing process, for example. The slots may comprise any suitable shape, such as S-shaped slots, T-shaped slots, or the like. FIG. 6 illustrates a cross-section of a through thickness 36 of the cushion 28 portion of the component 10 having a plurality of spaced apart T-shaped slots 34 formed in the cushion 28 to give a desired NPR value.

In one aspect, an intermediate cushion 28 formed with through thickness slots is capable of withstanding a significant amount of strain as the cushion 28 reduces thermal expansion mismatch between the CMC material 22 and the metal material 24.

In accordance with another aspect, cooling air may be flowed through the intermediate cushion 28 in order to cool the shell and/or core of the component and thus further reduce thermal mismatch between the core and the shell. In certain embodiments, the core and/or the shell may further include cooling holes formed therein for flow of a cooling gas (e.g., air) there through in an axial and/or radial direction through the component 12.

In accordance with another aspect, there are disclosed methods for forming a component 12 having an intermediate cushion 28 between the shell 18 and core 14 as described herein. In particular, there is disclose a process for forming a component 12 comprising arranging an intermediate cushion 28 within a gap 26 between a core 14 and a shell 18 which surrounds the core 14. The intermediate cushion 28 is effective to transfer a thermal or mechanical load between the shell 18 and the core 14. The core 14 is formed from a metal material 24 or a ceramic matrix composite material 22, and the shell 18 is formed from the other of the metal or ceramic matrix composite material. The process further includes assembling the core 14, shell 18, and the intermediate cushion 28 together to form the component 12. In an embodiment, the core 14, shell 18, and cushion 28 are fabricated individually and then assembled together by joining the intermediate cushion 28 to the core 14 and thereafter positioning the shell 18 over the core 14 and the intermediate cushion 28. The joining may be done by welding, brazing, soldering, or a like process. In another embodiment, the intermediate cushion 28 is additively manufactured on the core 14 and the shell 18 is positioned over the core 14 and the intermediate cushion 28.

Referring to the figures, FIG. 7-11 illustrate an embodiment of a process, wherein a core 14 is provided as shown in FIG. 7. The core 14 itself may be formed from any suitable process. For example, when the core 14 comprises a metal material, the core 14 may be formed by any a casting process, an additive manufacturing process, or any other process known in the art. When an additive manufacturing process is utilized for the core 14, shell 28, or cushion 28, the additive manufacturing process may comprises any of a selective laser manufacturing or melting (SLM), a selective laser sintering (SLS), or a laser metal deposition technique. SLM and SLS are manufacturing techniques that build components layer by layer from powder beds. In these processes, a powder bed of a component final material, or a precursor material, is deposited onto a working surface. Thereafter, laser energy is directed onto the powder bed following a cross-sectional area shape of the component to create a layer or slice of the

component. The deposited layer or slice then becomes a new working surface for the next layer.

When the core 14 comprises a ceramic matrix composite material, the CMC material may also be formed by any suitable process, such as a typical lay up process, the stacking of CMC laminates as described herein, or via 3D printing a ceramic loaded fiber into the desired form. Alternatively, the core 14 of a CMC material or metal material may be provided from a commercially available source.

Next, the intermediate cushion 28 may be fabricated on the core 14 by any suitable process as shown in FIG. 8, such as an additive manufacturing process. In certain embodiments, the cushion 28 integrates, e.g., is metallurgically bonded, with the core 14; however, it is understood that the present invention is not so limited. In some embodiments, this is done by welding the formed intermediate cushion 28 to the core As mentioned, in an embodiment, the cushion 28 is formed by an additive manufacturing process, wherein the cushion 28 is built up layer by layer by the deposition of a material for the cushion 28. The cushion material may be in any suitable form, such as a powder, feed wire, or the like. To form each layer of the cushion 28, the cushion material is melted via a suitable energy source, e.g., laser, and is allowed to resolidify. During resolidification of a given layer of the cushion 28, in certain

embodiments, the cushion material may integrate with the material of the core 14. In an embodiment, a desired porosity and/or NPR value for the intermediate cushion 28 is also provided during the additive manufacturing process. In a particular embodiment, for example, a desired NPR value for the cushion 28 is provided by forming slots of a desired shape (S-slots, T-slots, or the like) in a through thickness of the cushion as the cushion 28 being formed. See again FIG. 6. In certain embodiments, slots are formed in a through thickness of the cushion 28 by depositing powder of the cushion material and not melting (by laser or otherwise) the powder in the area defining the slots for a given layer. Thereafter, once the material is melted and solidified (at least partially), the unmelted powder may be removed by blowing, vacuum, or otherwise to define the slots therein. Thereafter, as shown in FIG. 9, a shell 18 (which is the other of the CMC or metal material that comprises the core 14) is provided by a suitable process described herein. The shell 18 is sized so as to form a tight fit about a circumference of the cushion 28 and core 14 once arranged there over (FIG. 10) to complete fabrication of the component 12.

In accordance with another aspect and as shown in FIGS. 11-15, the

components (core 14, shell 18, and intermediate cushion 28) are each separately fabricated (FIG. 11 , 12, and 14) and then assembled together. As shown in FIG. 13, the cushion 28 may be attached to the core 14 by a suitable joining process, such as a welding technique. Thereafter, the shell 18 may be arranged over the core 14 and the cushion 28 to complete fabrication of the component 12.

While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.

Claims

CLAIMS What we claim is:

1. A component (12) comprising:

a core (14) formed from a first material (16) comprising a metal material (24) or a ceramic matrix composite material (22);

a shell (18) surrounding the core (14), the shell (18) comprising a second material (20) comprising the other of the metal material (24) or the ceramic matrix composite material (22) of the first material (16);

a circumferential gap (26) disposed between the core (14) and the shell (18); and an intermediate cushion (28) disposed within the circumferential gap (26), the intermediate cushion (28) comprising a deformable material and effective to transfer a thermal and mechanical load between the core (14) and the shell (18).

2. The component (12) of claim 1 , wherein the core (14) comprises the metal material (24), and wherein the shell (18) comprises the ceramic matrix composite material (22).

3. The component (12) of claim 1 , wherein the core (14) comprises a ceramic matrix composite material (22), and wherein the shell (18) comprises a metal material (24).

4. The component (12) of claim 1 , wherein the intermediate cushion (28) comprises an auxetic material having a negative Poisson ratio.

5. The component of claim 1 , wherein the intermediate cushion (28) comprises an auxetic material having a negative Poisson ratio and a plurality of slots (34) formed in a through thickness (36) of the intermediate cushion (28).

6. The component of claim 1 , wherein the intermediate cushion (28) comprises a material having a porosity of at least 50%.

7. The component of claim 1 , wherein the intermediate cushion (28) comprises a material having a yield strength of .25 or less relative to a solid material.

8. The component of claim 1 , wherein the intermediate cushion (28) is in a form of a member from the group consisting of a foam, a mesh, and a honeycomb.

9. The component of claim 1 , wherein the intermediate cushion (28) comprises a thickness of from 20 micron to 1000 micron.

10. A process for forming a component (12) comprising:

positioning an intermediate cushion (28) within a gap (26) between a core (14) and a shell (18) which surrounds the core (14), the intermediate cushion (28)

comprising a deformable material and effective to transfer a thermal and mechanical load between the core (14) and the shell (18), the core (14) comprising a metal material (24) or a ceramic matrix composite material (22) and the shell (18) comprising the other of the metal material (24) or the ceramic matrix composite material (22) of the core (14).

11. The process of claim 10, wherein the core (14), shell (18), and

intermediate cushion (28) are fabricated individually and then assembled together by joining the intermediate cushion (28) with the core (14) and thereafter positioning the shell (18) over the core (14) and the intermediate cushion (28).

12. The process of claim 10, wherein the intermediate cushion (28) is additively manufactured on the core (14), and wherein the shell (18) is positioned over the core (14) and intermediate cushion (28).

13. The process of claim 10, wherein the core (14) comprises the metal material (24), and wherein the shell (18) comprises the ceramic matrix composite material (22).

14. The process of claim 10, wherein the intermediate cushion (28) comprises an auxetic material having a negative Poisson ratio.

15. The process of claim 10, wherein the intermediate cushion (28) comprises an auxetic material having a negative Poisson ratio and a plurality of slots (34) formed in a through thickness (36) of the intermediate cushion (28).