WO2019194860A2

WO2019194860A2 - 3d cmc material having a thermal protection layer

Info

Publication number: WO2019194860A2
Application number: PCT/US2018/051276
Authority: WO
Inventors: Jay A. Morrison; Marco Claudio Pio Brunelli; Gary B. Merrill
Original assignee: Siemens Aktiengesellschaft; Siemens Energy, Inc.
Priority date: 2017-09-27
Filing date: 2018-09-17
Publication date: 2019-10-10
Also published as: WO2019194860A3

Abstract

A component (10) is disclosed having an outer surface (22) of a ceramic matrix composite material (12), wherein the outer surface (22) is part of a thermal protective layer (24) that is 10-50% of a total 3D CMC thickness. The component further includes an inner surface (23) of the ceramic matrix composite material (12). Reinforcing fibers (20) extend throughout the ceramic matrix composite material (12), wherein the reinforcing fibers (20) extend unitarily or interconnectedly from the outer surface (22) to the inner surface (23).

Description

3D CMC MATERIAL HAVING A THERMAL PROTECTION LAYER

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to and the benefit of the filing date of U.S. Provisional Application No. 62/563,908, filed September 27, 2017, the entirety of which is hereby incorporated by reference herein.

FIELD

[0002] Disclosed embodiments are generally related to turbine engines and in particular to materials used in the construction of components for the turbine engines.

BACKGROUND

[0003] Gas turbine engines 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 high temperature and high pressure (working) gas. This working gas then travels through the transition and into the turbine section of the turbine.

[0004] The turbine section typically 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 a rotor attached thereto. The rotor is also attached to the compressor section, thereby turning the compressor and is also operatively connected to an electrical generator for producing electricity.

[0005] High efficiency of a combustion turbine is improved by heating the gas flowing through the combustion section to as high a temperature as is practical. However, the hot gas may degrade various metal turbine components, such as the combustor, transition ducts, vanes, ring segments, and turbine blades as it flows through the turbine.

[0006] High temperature resistant ceramic matrix composite (CMC) materials have been developed and increasingly utilized in gas turbine engines. Typically, CMC materials include a ceramic or a ceramic matrix material, either of which hosts a plurality of fibers. The fibers may have predetermined orientations to provide the CMC materials with additional mechanical strength. Generally, fiber reinforced ceramic matrix composites are manufactured by the infiltration of a matrix slurry (e.g., alumina, mullite, YAG, silicon-containing polymers, molten silicon, or the like) into a fiber preform, but can be manufactured in a variety of other ways. Most commercially available oxide ceramic fibers and their respective oxide-matrix CMCs are temperature limited for long life applications and, therefore, should be cooled to enable operation at temperatures exceeding this limit. At operating gas temperatures well above the normal CMC temperature limit, a thermal barrier coating (TBC) is typically employed to further minimize the cooling requirement. When applied to 2D laminate CMCs, TBC durability is limited. Overcoming the limitations discussed above is desired.

SUMMARY

[0007] Briefly described, aspects of the present disclosure relate to providing a CMC material that has improved capability to withstand degradation that occurs during operation of the gas turbine engine.

[0008] An aspect of the present disclosure comprises a component formed with a 3D CMC material, wherein the 3D CMC material comprises: an outer surface of the ceramic matrix material, wherein the outer surface is part of a thermal protective layer that is 10-50% of a total 3D CMC thickness; an inner surface of the ceramic matrix material; and reinforcing fibers extending throughout the ceramic matrix material, wherein the reinforcing fibers extend unitarily or interconnectedly from the outer surface to the inner surface, and wherein the outer surface does not have a thermal barrier coating.

[0009] Another aspect of the present disclosure may comprise a component formed with a 3D CMC material, wherein the 3D CMC material comprises: an outer surface formed of ceramic matrix material, wherein the outer surface is part of a thermal protective layer that is 10-50% of a total 3D CMC thickness; an inner surface formed of the ceramic matrix material; reinforcing fibers extending throughout the ceramic matrix material, wherein the reinforcing fibers extend unitarily or interconnectedly from the outer surface to the inner surface; and first fibers and second fibers embedded in the ceramic matrix material, wherein the first fibers and the second fibers do not extend unitarily or interconnectly from the outer surface to the inner surface, and wherein the outer surface does not have a thermal barrier coating.

[0010] Still yet another aspect of the present disclosure may comprise a 3D CMC material. The 3D CMC material may have an outer surface of ceramic matrix material, wherein the outer surface is part of a thermal protective layer that is 10-50% of a total 3D CMC thickness, an inner surface of the ceramic matrix material; and reinforcing fibers extending throughout the ceramic matrix material, wherein the reinforcing fibers extend unitarily or interconnectedly from the outer surface to the inner surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 is a diagram of a 2D CMC material having a thermal barrier coating.

[0012] Fig. 2 is a graph illustrating the strength of the 2D CMC material.

[0013] Fig. 3 is a diagram of a 3D CMC material having a reinforcing fiber extending unitarily from an outer surface to an inner surface.

[0014] Fig. 4 is a flow chart setting forth the method for forming a 3D CMC material.

[0015] Fig. 5 is a diagram of a 3D CMC material further illustrating the thermal protective layer.

[0016] Fig. 6 is another graph illustrating the strength of the 3D CMC material.

[0017] Fig. 7 is a diagram illustrating a layer-to-layer angled weave.

[0018] Fig. 8 is a diagram illustrating a braided weave.

DETAILED DESCRIPTION

[0019] To facilitate an understanding of embodiments, principles, and features of the present disclosure, they are disclosed hereinafter with reference to implementation in illustrative embodiments. Embodiments of the present disclosure, however, are not limited to use in the described systems or methods and may be utilized in other systems and methods as will be understood by those skilled in the art.

[0020] The components described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components that would perform the same or a similar function as the components described herein are intended to be embraced within the scope of embodiments of the present disclosure.

[0021] Components in gas turbine engines may be made of a two-dimensional (2D) CMC material. Prior Art Fig. 1 shows a section of a component 1 formed with a conventional 2D CMC material 2. The 2D CMC material 2 is made of fibers 4 located within a ceramic matrix material 6. The 2D CMC material 2 is formed of layers 5 that may be stacked on top of each other. The top layer of the 2D CMC material 2 may have a thermal barrier coating (TBC) 7 sprayed thereon. The thermal barrier coating is typically a material such as yttria-stabilized-zirconia, mullite, YAG, alumina, etc.

[0022] There are problems with using the arrangement set forth in Fig. 1. Conventional TBCs do not adhere well to 2D CMC materials 2 or without surface modification. The TBC tends to spall at interfaces. With various forms of surface engineering, TBC adhesion to the CMC surface is improved, but subsurface delamination within the 2D CMC then becomes a predominant failure mechanism.

[0023] Fig. 2 is a diagram illustrating the strength of the 2D CMC material 2. The diagram illustrates that at certain temperatures and at certain radial thermal stresses the strength of the 2D CMC material 2 is insufficient. This can result in structural damage at too high a temperature.

[0024] The inventors recognized that using a material for the components that utilizes the existing CMC material as the heat protective layer may provide better protection for the component and extend its lifespan. However, using only layers to form a 2 dimensional structure can result in whole or partial delamination.

[0025] Turning to Fig. 3 in order to form an improved CMC component 10, in an aspect of the present invention, a three-dimensional (3D) 3D CMC material 12 is formed and used for the component. By“3D CMC material” it is meant that the ceramic matrix material has a structure that is not limited to layers, but instead has reinforcing fibers 20 that extend either unitarily or interconnectedly from an outer surface 22 to an inner surface 23 of the 3D CMC material 12.

[0026] Still referring to Fig. 3, the 3D CMC material 12 may be formed by creating a weave of fibers 4 that can form planes 15. In addition to planes 15 having a weave of fibers 4 there is the added feature of the reinforcing fibers 20. The fibers 4 and the reinforcing fibers 20 are located within a ceramic matrix material 6.

[0027] The 3D CMC material 12 is formed so that reinforcing fibers 20 pass from the outer surface 22 to the inner surface 23, through the planes 15. The reinforcing fibers 20 shown in Fig. 2 are unitary in nature. This means that a single reinforcing fiber 20 moves from the outer surface 22 to the inner surface 23 without having to be interlocked with another reinforcing fiber 20.

[0028] In some embodiments the reinforcing fibers 20 may be an interconnected reinforcing fiber 20, such as illustrated by the weaves in Fig. 7 and Fig. 8. When the reinforcing fiber 20 is an interconnected reinforcing fiber, it means that the reinforcing fiber 20 may be woven and/or intertwined with another reinforcing fiber 20 so that there is a continuous interwoven chain extending from the outer surface 22 to the inner surface 23. Whether the reinforcing fiber 20 is a unitary or interconnected reinforcing fiber 20, the reinforcing fiber 20 provides enhanced structural integrity for the 3D CMC material 12. Unlike the simple plies that exist with 2D CMC materials, the reinforcing fibers 20 help inhibit shearing.

[0029] Still referring to Fig. 3, in an embodiment, the reinforcing fibers 20 are oriented in such a manner that the dimension L of the reinforcing fiber 20 extends in a direction that is at an angle with respect to the outer surface 22 of the 3D CMC material 12. As discussed above, the reinforcing fibers 20 help inhibit delamination of the CMC component 10.

[0030] The weave shown in Fig. 3 is an angle interlock weave. The reinforcing fiber 20 passes through multiple planes 15. In Fig. 2 the reinforcing fiber 20 passes through all of the planes 15 of the 3D CMC structure 12. In an embodiment, the angle at which the reinforcing fiber 20 is oriented with respect to the outer surface 22 of the 3D CMC material 12 is a 45° angle. However, while a 45° angle is shown, it should be understood that an angle within the range of l0°-90° would be effective with the use of the reinforcing fiber 20. [0031] In the embodiment shown in Fig. 3, the reinforcing fiber 20 weaves its way from the outer surface 22 to the inner surface 23 multiple times. In weaving from the outer surface 22 to the inner surface 23, the orientation of the reinforcing fiber 20 changes direction from extending inwardly from the outer surface 22 through all the to then extending back towards the outer surface 22 of the 3D CMC structure 12.

[0032] To manufacture the 3D CMC material 12, in an embodiment, a matrix slurry (e.g., alumina, mullite, YAG, silicon-containing polymers, molten silicon, or the like) is infiltrated into a fiber preform. While this is one manner in which the 3D CMC material 12 may be manufactured there are other manners in which the 3D CMC material 12 may be made.

[0033] Fig. 4 shows a flow chart illustrating an embodiment of a process for the manufacture of the 3D CMC material 12 shown in Fig. 3. In step 102, the fibers 4 are manufactured or otherwise provided. In step 104, the reinforcing fibers 20 are woven through the matrix of fibers 4 using a near net shape (NNS) preform weaving or braiding operation. The weaving of the fibers 4 and the reinforcing fibers 20 form a preform that will then be infiltrated with a ceramic matrix material 6.

[0034] In step 106, the preform is then infiltrated with the ceramic matrix material 6. In step 108, the preform is compacted. Steps 106 and 108 may be reversed in some processes. In step 110, the matrix is dried or cured to a“green” state. In step 112, the green preform is fired. The firing of the preform solidifies the preform. In step 114, the fired preform may undergo an additional step of infiltrating or otherwise coating of a vapor resistant layer (VRL). Optionally, this VRL may be applied prior to final firing and after a bisque-firing step. These steps produce a 3D CMC material 12. This formed 3D CMC material 12 can be used for a gas turbine engine component.

[0035] In some embodiments, an intermediate temperature treatment to enhance and improve the rate of degradation resulting from high pressure moisture attack may optionally be applied in the formation of the 3D CMC material 12. This forms the vapor resistant layer (VRL). The gradual recession of alumina and alumina/silicate composition can be can be improved by the addition of certain rare earth oxides that have been shown to substantially slow the recession rates of such chemical species. Such constituents are described in US Patent No. 9,328,028, herein incorporated by reference. Such examples include but are not limited to: pyrochlore structures; HfSi0₄; ZrSi0₄; Y2S12O7; Y2O3; Zr02, Hf02; yttria and/or ZrCtefully or partially stabilized by rare earth elements; yttria and/or HfCh partially or fully stabilized by rare earth elements, yttria and/or ZrCh/HfCh partially or fully stabilized by rare earth elements; yttrium aluminum garnet; rare earth silicates of the form RE2S12O7; rare earth oxides of the form RE2O3; rare earth zirconates or hafnates of the form REhZnO^ or RE₄Hf₃0i2, wherein the rare earth elements may be one or more of the following: Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. A functionally graded concentration may be applied through the application of a specifically prepared slurry at intermediate sintering temperatures to improve the recession behavior of the outer surface 22 of the 3D CMC material 12, especially when exposed to high velocity combustion gases in excess of 1200 °C. This creates a vapor resistive layer (VPL), the use of which is discussed below with respect to Fig. 5.

[0036] Some of the benefits of producing the 3D CMC material 12 in the manner discussed above with respect to Fig. 4 are lower infiltration costs and no manual layup cost. Additionally, there are no surface preparation costs and the cost of a vapor resistive layer as described herein is lower than the costs associated with a conventional thermal barrier coating. Also, there is no need for a post thermal barrier coating heat treatment.

[0037] Turning to Fig. 5, there is a diagram of the 3D CMC material 12 having a thermal protective layer 24 in accordance with an aspect of the present invention. The thermal protective layer (TPL) 24 is formed in the uppermost planes 15 of the 3D CMC material 12. The TPL 24 comprises the outer surface 22 and portions of the 3D CMC material 12 beneath the outer surface 22. This may include one or more planes 15 in those embodiments that have identifiable planes 15. In those embodiments that are formed with a more complex weave or braiding of reinforcing fibers 20, such as shown in Figs. 7 and 8, the top millimeter of formed material may act as the thermal protective layer 24. In general, the TPL 24 is between 10-50% of the total 3D CMC thickness.

[0038] The thickness (T) of the 3D CMC material 12 is the shortest distance from a point on the outer surface 22 to the inner surface 23. The 3D CMC material 12 may be subjected to a temperature exceeding the maximum temperature limit for the component and applying cooling to achieve a thermal gradient, wherein the TPL 24 exceeds this temperature limit, but the bulk of the 3D CMC material 12 remains below the temperature limit.

[0039] During the use of the component formed with the 3D CMC material 12, the thermal protective layer 24 functions as a non- structural or semi-structural layer. The thermal protective layer 24 protects the underlying layers without the need for having a thermal barrier coating. In certain embodiments, the TPL 24 may be infused with a rare earth oxide as described above to protect from moisture-related recession. This forms a TPL 24 that is also a VPL.

[0040] When the 3D CMC material 12 is exposed to surface temperatures greater than 1200 °C but is also cooled, a thermal gradient can be achieved such that the 3D CMC material 12 below the TPL 24 remains below 1200 °C, or whatever the maximum temperature of the CMC component 10 is. The threshold temperature limit of the CMC component 10 may be determined by the performance of mechanical property behaviour such as creep and thermo-mechanical fatigue. While the temperature of 1200 °C is discussed herein, it should be understood that it is in reference to one component 10. The temperature threshold may vary for different components 10 made of the 3D CMC material 12. The result is that the TPL 24 may be exposed to temperatures above the maximum threshold for the CMC component, while the 3D CMC material 12 below the TPL 24 remains below the maximum threshold temperature for the CMC component 10.

[0041] As an example, three layers 15 are indicated in Fig. 5; a first layer 17, a second layer 19, and a third layer 21. The outer surface 22, the first layer 17, and the second layer 19 may function as the TPL 24. The TPL 24 functions in a similar manner as a thermal barrier coating without the associated costs. Additionally, the TPL 24 provides additional protection from heat while not suffering from some issues associated with the use of TBCs, such as the delamination of planes of weakness of 2D. The reinforcing fibers 20 improve the out of plane strength of the 3D CMC material 12.

[0042] Fig. 6 is a diagram illustrating the strength of the 3D CMC material 12. The 3D CMC material 12 shows a strength margin even after thermal degradation.

[0043] In addition to the use of the reinforcing fiber 20 shown in Fig. 5, it is possible to have reinforcing fibers 20 located or woven with the other fibers 4 in different manners. For example, Fig. 7 illustrates a layer-to-layer angled weave. Fig. 8 is a diagram illustrating a braided weave. Of course, as understood by those skilled in the art, there are other types of 3D fiber architectures that may be used as well, for example orthotropic weaves, knitted or stitched structures, and the like.

[0044] While embodiments of the present disclosure have been disclosed in exemplary forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents, as set forth in the following claims.

Claims

What is claimed is:

1. A component (10) compri sing :

an outer surface (22) of a ceramic matrix composite material (12), wherein the outer surface (22) is part of a thermal protective layer (24) that is 10-50% of a total 3D CMC thickness;

an inner surface (23) of the ceramic matrix composite material (12);

reinforcing fibers (20) extending throughout the ceramic matrix composite material (12), wherein the reinforcing fibers (20) extend unitarily or interconnectedly from the outer surface (22) to the inner surface (23).

2. The component (10) of claim 1, wherein the outer surface (22) does not have a thermal barrier coating (7).

3. The component (10) of claim 1, wherein at least some of the reinforcing fibers (20) extend at an angle of between l0°-90° with respect to the outer surface (22).

4. The component (10) of claim 1, wherein at least some of the reinforcing fibers (20) extend at an angle of 90° with respect to the outer surface (22).

5. The component (10) of claim 1, wherein the reinforcing fibers (20) form an angle interlock weave.

6. The component (10) of claim 1, wherein the reinforcing fibers (20) form a layer-to-layer angle interlock weave.

7. The component (10) of claim 1, wherein the reinforcing fibers (20) are braided.

8. The component (10) of claim 1, wherein the 3D CMC material (12) further comprises addition of rare earth oxides to protect the thermal protection layer (24) from moisture-related recession.

9. The component (10) of claim 1, further comprising second fibers (4) embedded in the ceramic matrix composite material (12), wherein the second fibers (4) do not extend unitarily or interconnectedly from the outer surface (22) to the inner surface (23).