HYBRID COMPONENT COMPRISING A METAL-REINFORCED CERAMIC MATRIX COMPOSITE MATERIAL

Abstract

A hybrid metal-reinforced ceramic matrix composite (CMC) material component is provided having a body including a ceramic matrix composite material and a metal skeleton structure encompassing at least a portion of the body. A retaining structure carried by the metal skeleton structure is further included to induce a compressive force on the body to limit movement of the body and the metal skeleton structure relative to one another and enable the metal skeleton structure to carry a greater amount of an external load than the body.

Description

STATEMENT REGARDING FEDERALLY SPONSORED DEVELOPMENT

Development for this invention was supported in part by Contract No. DE-FE0023955, awarded by the United States Department of Energy. Accordingly, the United States Government may have certain rights in this invention.

FIELD

The present invention relates to high temperature components for use in high temperature environments such as gas turbines. More specifically, aspects of the present invention relate to hybrid components comprising a metal-reinforced ceramic matrix composite (CMC) material and methods for manufacturing the same.

BACKGROUND

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 a combustion inlet and is mixed with fuel. The air/fuel mixture is then combusted to produce high temperature and high pressure gas. This working gas is then ejected past a combustor transition and travels 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. As working gas travels through the turbine section, the gas causes 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. Hot gas is then exhausted from the system. High efficiency may be achieved by heating the gas flowing through the combustion section to as high a temperature as is practical. The hot gas, however, may degrade various turbine components such as combustor components, transition ducts, vanes, ring segments, exhaust components, and turbine blades that the hot gas passes when flowing through the turbine.

For this reason, strategies have been developed to protect such components from extreme temperatures, such as 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 that comprise a ceramic matrix material hosting a plurality of reinforcing fibers therein. While these 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. Thus, though excellent for resisting thermal protection in high temperature applications, CMC materials are not suitable for carrying structural loads. One existing challenge in the art is thus how to apply CMC materials in regions of the gas turbine that are structurally loaded in a safe and cost-effective manner.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 1 is a perspective view of a component in accordance with an aspect of the present invention.

FIG. 2 is a perspective view of a component comprising a CMC body formed from stacked laminates in accordance with an aspect of the present invention.

FIG. 3 illustrates another embodiment of a metal skeleton structure in accordance with an aspect of the present invention.

FIG. 4 illustrates a CMC body being inserted within a metal skeleton structure in accordance with an aspect of the present invention.

FIG. 5 illustrates a CMC body comprising threaded ends structured to mate with fasteners in accordance with an aspect of the present invention.

FIG. 6 illustrates a CMC body having a thermal barrier coating about an exterior of the CMC body in accordance with an aspect of the present invention.

DETAILED DESCRIPTION

The present inventors have developed hybrid components, which satisfy a need for high temperature components having increased thermal and corrosion resistance while also having a desired strength in order to carry structural loads. In one aspect, the component comprises a CMC material reinforced with a metal skeleton structure. When employed in a gas turbine, the CMC material of the component acts as a heat shield between the hot inner gas flowing through the turbine while the metal skeleton structure both supports the CMC material and carries structural loads to a greater extent than the CMC material. In certain embodiments, the metal skeleton structure may further comprise any attachment(s) or interface(s) necessary for use of the device in a gas turbine. In this way, the attachment(s) or interface(s) for the metal-reinforced CMC components described herein may remain metal and nearly identical to current configurations where the component is formed solely from a superalloy, for example.

In accordance with one aspect, there is provided a hybrid component including a body comprising a ceramic matrix composite material and a metal skeleton structure encompassing at least a portion of the body. The component further comprises a retaining structure carried by the metal skeleton structure effective to induce a compressive force on the body to limit movement of the body and the metal skeleton structure relative to one another and allow the metal skeleton structure to carry a greater amount of an external load than the body.

In accordance with another aspect, there is provided a method for forming a hybrid component. The method comprises mating a body comprising a ceramic matrix composite material with a metal skeleton structure such that the metal skeleton structure encompasses at least a portion of the body. In addition, the method comprises supplying a compressive force on the body via a retaining structure carried by the metal skeleton structure which limits movement of the body and the metal skeleton structure relative to one another and allows the metal skeleton structure to carry a greater amount of an external load than the body.

Now referring to the figures, there is shown an exemplary component 10 in accordance with an aspect of the present invention comprising a body 12 formed at least in part from a ceramic matrix composite (CMC) material 14. In certain embodiments, the body 12 may define a cavity 15 therein. The body portion 12 (hereinafter “CMC body 12”) is at least partially encompassed about its exterior 16 by a metal skeleton structure 18. In certain embodiments, a retaining structure 20 is provided which limits or prevents movement of the CMC body 12 relative to the metal skeleton structure 18, and vice-versa. In a particular embodiment, the retaining structure 20 is configured or structured such that it applies a compressive force to the CMC body 12 in order to maintain the CMC body 12 in a fixed position while also allowing the metal skeleton structure 18 to bear further structural loads for the component 10.

The CMC body 12 may be of any suitable size and dimension for its intended application. In addition, the CMC body 12 is at least partially formed from the CMC material 14. The CMC material 14 may include a ceramic matrix material that hosts a plurality of reinforcing fibers as is known in the art. In certain embodiments, the CMC material 14 may be anisotropic, at least in the sense that it can have different strength characteristics in different directions. It is appreciated that various factors, including material selection and fiber orientation, can affect the strength characteristics of a CMC material. The CMC material 14 may comprise oxide, as well as non-oxide CMC materials. In an embodiment, the CMC material 14 may comprise alumina, and the fibers may comprise an aluminosilicate composition consisting of approximately 70% alumina; 28% silica; and 2% boron (sold under the name NEXTEL™ 312). The fibers may be provided in various forms, such as a woven fabric, blankets, unidirectional tapes, and mats. 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 to be used herein for the body 12. Exemplary CMC materials 14 for use herein are described in U.S. Pat. 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. As mentioned, the selection of materials is not the only factor which governs the properties of the CMC material 14 as the fiber direction may also influence the mechanical strength of the material, for example. As such, the fibers for the CMC material 14 may have any suitable orientation such as those described in U.S. Pat. No. 7,153,096.

In one embodiment, the CMC body 12 comprises a continuous solid body having as shown in FIG. 1. In another embodiment, as shown in FIG. 2, the body 12 may comprise a plurality of stacked laminate plates 22 formed from the CMC material 14. In this embodiment, each of the stacked laminate plates 22 may be cut to a desired shape via a laser cutting process and stacked to provide the desired body 12. In certain embodiments, the stacked laminate plates 22 may be provided with a support structure, such as a tie rod, extending through the stacked laminates. The plates may further include suitable structures, such as retainers, for radial compression of the plates. Exemplary processes for forming a body of stacked laminates from a CMC material and associated structures are set forth in U.S. Pat. Nos. 8,528,339; 7,255,535; 7,402,347; 7,247,002; 7,247,003; 7,198,458; and 7,153,096, for example, the entirety of each of which is hereby incorporated by reference. Some advantages a stacked laminate structure include enabling CMC material to itself bear some structural loading via the individual plates, as well as increasing a number of possible dimensions and configurations for an associated component by controlling the structure of the component on a level-by-level basis.

The metal skeleton structure 18 may comprise any metal material which may provide an added strength to the body 12 and may carry an extent of loading on the component 10. In certain embodiments, the metal material may comprise an alloy material such as a Fe-based alloy, a Ni-based alloy, a Co-based alloy as are well known in the art. In certain embodiments, the alloy may comprise a superalloy. 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. In an embodiment, the metal skeleton structure 18 may be formed from a metal material having a melting temperature of from 450-600° C. due to the thermal protection provided by the CMC material 14.

The metal skeleton structure 18 may comprise any suitable dimensions, shape, or configuration that extends about at least a portion of the exterior 16 of the CMC body 12. Referring again to FIG. 1, in certain embodiments, the metal skeleton structure 18 may be configured to extend from a base portion 24 of the CMC body 12 to a top portion 26 of the CMC body 12. In the exemplary embodiment shown in FIG. 1, the metal skeleton structure 18 comprises a plurality of spaced apart ribs 28 that encompass and provide structural support to the body 12. The ribs 28 may be of any suitable number, size, and shape to provide a desired degree of structural reinforcement to the body 12 and carry a structural load thereon.

It is appreciated that the present invention, however, is not limited to the embodiment of FIG. 1 and that the metal skeleton structure 18 may alternatively comprise any other suitable structure which encompasses at least a portion, if not all, of an exterior 16 of the CMC body 12 and which defines at least a plurality of openings 25 that allows at least a portion of the exterior 16 of the body 12 to remain exposed to the surrounding environment. Without limitation, for example, the metal skeleton structure 18 may alternatively comprise another structure such as a grid-like structure 30 as shown in FIG. 3 having a plurality of intersecting metal members 32 defining openings 34.

The exposure of the exterior 16 of the CMC body 12 may offer significant advantages, such as in an environment where the body 12 is exposed to a cooling air flow, such as circulating shell air. In this way, the CMC body 12 can be passively cooled and the amount of cooling air utilized for active cooling, which typically travels through or within the CMC body 12, may be reduced. This not only allows for material and cost savings, but allows for higher inlet temperatures which in turn may translate to greater performance and efficiency. Moreover, in certain embodiments, cooling air reduction in a combustion system can be either used to: 1) reduce primary zone temperature (PZT) for a constant rotor inlet temperature (RIT) operation case, thereby leading to reductions in NOx emissions; or 2) increase RIT (for a constant NOx case), thereby leading to increase in power output and combined cycle (CC) efficiency.

In certain embodiments, the metal skeleton structure 18 and the CMC body 12 comprise an interface which helps prevent rotation of the body 12 relative to the metal skeleton structure 18, or vice-versa. For example, in the embodiment shown in FIG. 4, the body 12 may comprise a plurality of channels 36, each channel 36 having a depth such that at least a portion of a respective rib 28 of a metal skeleton 18 may be received and disposed therein. In a particular embodiment, the ribs 28 of the metal skeleton 18 may be slidably inserted within the channels 36 to provide the desired interface between the CMC body 12 and the metal skeleton 18 for the component 10. These channels 36 may also be provided in the stacked laminate structure of FIG. 2. In an alternative embodiment, the ribs 28 of the metal support structure 18 may instead comprise channels 36 therein which are configured to receive corresponding portions of the CMC body 12 therein.

The retaining structure 20 may be any suitable structure for at least maintaining contact between the CMC body 12 and the metal skeleton 18. In certain embodiments, the retaining structure 20 is further configured to induce a compressive force on the CMC body 12. In this way, the metal skeleton structure 18 may be configured to receive an external load thereon instead of the structurally weaker CMC body 12. Referring again to FIG. 1, by way of example only, the retaining structure 20 may comprise a retaining ring 38 which is configured to engage and fit over an exterior portion 39 the ribs 28 of the metal skeleton 18. The retaining ring 20 may further include channels or clasps 40 as shown within which the ribs 28 may be engaged within or otherwise inserted. Although the retaining ring 38 is shown as fitting over a topmost portion of the metal skeleton structure 18, it is understood that the present invention is not so limited. Further, the retaining ring 38 may comprise one or more additional retaining rings, or alternatively may comprise any other suitable structure.

The component 10 and/or retaining structure 20 may include any further structure(s) effective to at least assist in providing a compressive force on the CMC material 12. In an embodiment, for example, as shown in FIG. 5, a plurality of fasteners 42 may be provided which are configured to mate with threaded ends 44 on the ribs 28. The retaining ring 38 is omitted from FIG. 5, but referring again to FIG. 1, it can be appreciated that as fasteners 42 (such as nuts or bolts) are tightened, the fasteners 42 may increasingly cause the retaining ring 38 and/or metal skeleton structure 18 to place a greater compressive load or force on the CMC body 12. This load or force not only maintains the CMC body 12 in a fixed position relative to the metal skeleton structure 18, but also forces the metal skeleton structure 18 to carry at least an amount of an external load upon a further application of an external load to the component 10. In this way, the CMC body 12 may primarily carry thermal loads while the metal skeleton structure 18 may primarily carry structural loads upon use of the component in an environment exposing the component 10 to such loads, such as in a gas turbine environment.

In accordance with another aspect of the present invention, the metal skeleton structure 18 may be fabricated so as to be formed with or otherwise may include any mating parts necessary for the component 10 to mate with another component. When not integral components, the mating parts may be joined to the metal support structure 18 via any suitable method such as welding or soldering. Referring again to FIG. 1, for example, the component 10 may include a flange 44 on a base portion 24 thereof for attaching the component 10 to another component which is configured to mate with or receive the flange 44. Further, the component 10 may comprise a plurality of tabs 45 on a top portion 26 thereof for attachment of the component 10 to a combustor, for example. In an embodiment, the flange 44, tabs 45, or any other suitable mating structures are formed from metal. In this way, the mating parts for the component 10 may remain metal and nearly identical to current configurations. As such, the components described herein can be easily incorporated into existing turbine systems.

In accordance with another aspect, to afford greater thermal protection to the component 10, a thermal barrier coating (TBC) 48 may be applied to an internal surface 50 of the CMC body 12 to prevent oxidation of or thermal damage to the CMC material since the internal surface 50 is exposed to high temperatures as shown in FIG. 6. FIG. 6 is a cross-section taken at line A-A of FIG. 4. In one embodiment, the thermal barrier coating 48 may comprise a friable graded insulation (FGI) as is known in the art. See, for example, U.S. Pat. Nos. 7,563,504; 7,198,462; 6,641,907; 6,676,783; and 6,235,370, each of which are incorporated by reference herein. In further embodiments, such thermal barrier coatings may instead or also be applied to an outer periphery of the CMC body 12.

In accordance with another aspect of the present invention, there are provided methods for manufacturing a metal-reinforced CMC component. In one embodiment, as was shown in FIG. 4, a metal skeleton structure 18 as described herein may be first fabricated according to desired specifications, or otherwise provided from a commercial or suitable source. The metal skeleton structure 18 may be cast or otherwise formed as a single piece, or may alternatively require joining of one of more of its components to remaining portions of the metal skeleton structure 18. Thereafter, the CMC body 12 as described herein may be provided which may be configured for slidable insertion into the metal skeleton structure 18 via aligning the ribs 28 with channels 36 in the CMC body 12 and sliding the CMC body 12 therein in the direction of arrow B as shown.

Thereafter, referring again to FIG. 1, the retaining structure 20 may be placed on an exterior of the metal skeleton structure 18 and the retaining structure 20 secured or otherwise tightened to prevent movement of the CMC body 12 relative to the metal skeleton structure 18. For example, clasps 40 carried by the retaining structure 20 may engage ribs 28 therein. Thereafter, as described previously, fasteners 42 may be tightened on threaded ends 44 of the ribs 28 such that the retaining structure 20 and/or metal skeleton structure 18 exerts a compressive load on the CMC body 12. This compressive load not only keeps the CMC body 12 in place, but also allows the metal skeleton structure 18 to bear further external loads.

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

1. A hybrid component comprising:

a body comprising a ceramic matrix composite material;

a metal skeleton structure encompassing at least a portion of the body and extending between a base and a top of the body; and

a retaining structure carried by the metal skeleton structure effective to induce a compressive force on the body to limit movement of the body and the metal skeleton structure relative to one another and allow the metal skeleton structure to carry a greater amount of an external load than the body.

2. The component of claim 1, wherein the metal skeleton structure comprises an alloy material.

3. The component of claim 2, wherein the alloy material has a melting point of from 450-600° C.

4. The component of claim 1, wherein the metal skeleton structure comprises a mating structure such that the component can be connected to another structure.

5. The component of claim 4, wherein the mating structure comprises a circumferential flange or tabs for attachment of the component to another structure.

6. The component of claim 1, wherein the metal skeleton structure comprises a plurality of ribs extending radially from a base portion thereof.

7. The component of claim 6, wherein one of the body and the ribs comprises a plurality of channels configured to receive a portion of the other of the body and the ribs therein.

8. The component of claim 7, wherein the body comprises a plurality of channels, and wherein the ribs are configured for slidable insertion into the plurality of channels.

9. The component of claim 1, wherein the retaining structure comprises a retaining ring disposed about the metal skeleton structure and a plurality of fasteners configured to cause the retaining ring to induce a compressive force on the body upon tightening of the fasteners.

10. The component of claim 1, wherein the body comprises a plurality of stacked laminate plates, each plate comprising the ceramic matrix composite material.

11. A method for forming a hybrid component comprising:

mating a body comprising a ceramic matrix composite material with a metal skeleton structure such that the metal skeleton structure encompasses at least a portion of the body and extends between a base and a top of the body; and

supplying a compressive force on the body via a retaining structure carried by the metal skeleton structure which limits movement of the body and the metal skeleton structure relative to one another and allows the metal skeleton structure to carry a greater amount of an external load than the body.

12. The method of claim 11, wherein the supplying is done by:

disposing a retaining ring about the metal skeleton structure; and

tightening a plurality of fasteners on the retaining ring to induce a compressive force on the body.

13. The method of claim 11, wherein the metal skeleton structure comprises a plurality of ribs, and wherein on of the body and the ribs comprises a plurality of channels configured to receive a portion of the other of the body and the ribs therein.

14. The method of claim 13, wherein the body comprises a plurality of channels, and wherein the method further comprises slidably inserting the ribs into the channels of the body.

15. The method of claim 11, wherein the metal skeleton structure comprises an alloy material.

16. The method of claim 11, wherein the alloy material has a melting point of from 450-600° C.

17. The method of claim 11, wherein the metal skeleton structure comprises a mating structure such that the component can be connected to another structure.

18. The method of claim 11, wherein the mating structure comprises a circumferential flange for attachment of the component to another structure.

19. The method of claim 11, wherein the body comprises a plurality of stacked laminate plates, each plate comprising the ceramic matrix composite material.