WO2018164693A1

WO2018164693A1 - Three-dimensional printing of ceramic fiber composite structures for improved thermal barrier coating adhesion

Info

Publication number: WO2018164693A1
Application number: PCT/US2017/021795
Authority: WO
Inventors: Ramesh Subramanian
Original assignee: Siemens Aktiengesellschaft
Priority date: 2017-03-10
Filing date: 2017-03-10
Publication date: 2018-09-13

Abstract

Processes are described herein which 3D print a ceramic fiber composite (24, 48) in a printed pattern (308) on a ceramic matrix composite (CMC) component (300) in order to define a plurality of channels (312) between adjacently deposited segments (314) of the ceramic fiber composite (24, 48). A thermal barrier coating (TBC) (318) is deposited within the channels (312), and optionally over the segments (314), to mechanically interlock the TBC (318) to the CMC component (300), thereby improving the adhesion of the TBC (318) to the component (300) and the high temperature performance of the component (300).

Description

THREE-DIMENSIONAL PRINTING OF CERAMIC FIBER COMPOSITE STRUCTURES FOR IMPROVED THERMAL BARRIER COATING ADHESION

FIELD

The present invention relates to systems and processes for improving thermal protection for components, including gas turbine components. More particularly, the present invention relates to methods for three-dimensional (3D) printing a scaffold of a ceramic matrix composite (CMC) material on a CMC body and depositing a thermal barrier coating (TBC) material into the scaffold in order to effectively interlock the TBC with the CMC body. This interlocking will substantially reduce crack propagation and spalling of the TBC coating.

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 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 past the combustor transition and into the turbine section of the turbine.

Generally, 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 a rotor associated therewith. The rotor is also attached to the compressor section, thereby turning the compressor and also an electrical generator for producing electricity. 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 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 turbine 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. State of the art superalloys with additional protective coatings are commonly used for hot gas path components of gas turbines. In view of the substantial and longstanding development in the area of superalloys, however, it figures to be extremely difficult to further increase the temperature capability of superalloys.

For this reason, ceramic matrix composite (CMC) materials have been developed and increasingly utilized. Typically, CMC materials include a ceramic or a ceramic matrix material, either of which hosts a plurality of reinforcing fibers. The fibers may have a predetermined orientation 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, silicon- containing polymers, molten silicon, or the like) into a fiber preform. While these materials may offer a high temperature resistance than superalloys, fiber grains of the CMC may coarsen and lead to crack propagation at the fiber/matrix interface as firing temperatures increase. Accordingly, there is still a need to provide CMC materials with added thermal protection strategies, particularly in high temperature environments, e.g., 1600-1700° C.

One such strategy is the application of a thermal barrier coating (TBC) to the CMC substrate surface. In certain applications, the TBC material is applied directly to an external surface of the substrate to be coated or over a previously-applied intermediate metallic bond coat. Once applied, the TBC provides an insulating layer over the component surface, which may reduce the temperature the substrate is subjected to in a high temperature environment. A number of methods have been developed for applying a TBC coating to a CMC material, such as by (hot) thermal spraying or vapor deposition (e.g., electron beam physical vapor deposition (EB-PVD)). In thermal spraying (e.g., plasma spraying), ceramic particles or the like are heated to an elevated temperature to form a molten material, and the molten material is directed at the component surface and allowed to cool to form the desired coating.

Although the thermal spraying of coatings on a CMC material has improved, the application of thermally sprayed TBCs on CMC materials continues to produce numerous challenges. For one, depending on the local macro-roughness of the ceramic fibers and matrix infiltration characteristics of the substrate CMC material, the adhesion of thermally sprayed TBCs may be poor. As a result, the TBC coating is especially prone to rapid crack propagation and spallation issues. Further, other methods, such as vapor deposition, may also result in insufficient deposition, uneven distribution, and inadequate bonding of the TBC to the desired CMC substrate.

Accordingly, there is a need to improve the application of TBC coatings to substrates comprising a CMC material.

SUMMARY

In accordance with yet another aspect, there are provided processes for improving the performance of thermal barrier coatings (TBCs) applied to the surfaces of CMC components, including gas or steam turbine components. In one aspect, a CMC material (ceramic fiber composite) may be three-dimensionally (3D) printed onto a component surface (also comprising a CMC material) in a scaffold (e.g., grid-like) fashion, thereby forming a plurality of channels into which a TBC may be applied. The application of the TBC to the channels results in a mechanical interlocking of the TBC to the CMC component surface. In addition, the use of the 3D printing to define the channels does not damage the integrity of the CMC surface as compared to methods which mechanically cut into a surface of the CMC component.

Further, in certain aspects, the 3D printing of the CMC scaffold and formation of channels is done with a CMC material identical to or similar to the underlying CMC component. In this way, thermal mismatch between the scaffolding and the substrate CMC material is avoided. In another aspect, the formation of the plurality of channels aids in localizing and confining thermal stress- or foreign object damage (FOD)-induced crack propagation within the TBC that might otherwise allow excessive TBC spallation and subsequent thermal exposure damage to the component's underlying substrate.

In accordance with another aspect, there is provided a component comprising a body comprising a ceramic matrix composite material; a three-dimensionally printed pattern of a ceramic fiber composite on a surface of the body, the printed pattern comprising channels defined between adjacently deposited segments comprising the ceramic fiber composite; and a thermal barrier coating disposed within the channels so as to mechanically interlock the thermal barrier coating to the body.

In accordance with yet another aspect, there is provided a process for improving adhesion of a thermal barrier coating to a substrate comprising a ceramic matrix composite material. The process comprises introducing a ceramic material into a solid fiber material to produce a ceramic fiber composite; depositing a plurality of segments of the ceramic fiber composite onto the substrate in a printed pattern so as to form a plurality of channels defined between adjacently deposited ones of the segments; and depositing a thermal barrier coating within the plurality of channels.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 1 is a schematic view of a 3D printing system for manufacturing a

component from a ceramic matrix composite in accordance with an aspect of the present invention;

FIG. 2 is a cross-section of a fiber material comprising an uptake enhancement structure in accordance with an aspect of the present invention;

FIG. 3 is a schematic showing further components for a 3D printing system in accordance with an aspect of the present invention;

FIG. 4 illustrates a fiber material loaded with two ceramic materials in distinct portions thereof in accordance with an aspect of the present invention.

FIG. 5 illustrates a fiber material having a first and a second ceramic coating layer in accordance with an aspect of the present invention;

FIG. 6 is a schematic showing further components for a 3D printing system in accordance with an aspect of the present invention;

FIG. 7 is a schematic showing still further components for a 3D printing system in accordance with an aspect of the present invention;

FIG. 8 illustrates a cutting mechanism associated with a dispensing head in accordance with an aspect of the present invention; FIG. 9 illustrates a stationary vane formed by a system in accordance with an aspect of the present invention;

FIG. 10 illustrates a dispensing head having a laser source attached thereto in accordance with an aspect of the present invention.

FIGS. 1 1 -12 illustrate steps in a 3D printing process of a ceramic fiber composite in accordance with an aspect of the present invention;

FIG. 13 illustrates the printing and cutting of a ceramic fiber composite in a predetermined pattern in accordance with an aspect of the present invention;

FIG. 14 illustrates the printing and cutting of a ceramic fiber composite in a predetermined pattern in accordance with another aspect of the present invention;

FIG. 15 illustrates a printing pattern in accordance with an aspect of the present invention.

FIG. 16 illustrates a component of a ceramic matrix composite material having a defect therein.

FIG. 17 illustrates the repair of the defect of FIG. 16 via application of a ceramic fiber composite in accordance with aspects of the present invention.

FIG. 18 illustrates a robotic arm having a dispensing head associated therewith in accordance with an aspect of the present invention.

FIG. 19 illustrates a top view of a 3D printed scaffold (printed pattern) of a ceramic fiber composite on a CMC substrate in accordance with an aspect of the present invention.

FIG. 20 is a cross-sectional view of a component with the printed pattern and a TBC disposed therein in accordance with another aspect of the present invention.

FIG. 21 is a cross-sectional view of a component with the printed pattern and a TBC disposed over the deposited segments of the printed segments in accordance with an aspect of the present invention.

FIG. 22 is a cross-sectional view of a component with the printed pattern and a TBC forming a continuous layer a top surface of the printed pattern in accordance with an aspect of the present invention. FIG. 23 illustrates a TBC having a plurality of hollow ceramic particles disposed over and within the printed pattern in accordance with an aspect of the present invention.

FIG. 24 illustrates a TBC and a bond coat disposed over the printed pattern in accordance with an aspect of the present invention.

FIG. 25 is a side view showing a component with the printed pattern, a TBC over the printed pattern, and grooves in the TBC for strain relief.

FIG.26-27 illustrate the effects of spallation on a PRIOR ART CMC component having a TBC thereon with having no engineered surface.

FIG. 28-29 illustrate (with comparison to FIGS. 26-27) a CMC component having an engineered surface (scaffolding) in accordance with an aspect of the present invention.

DETAILED DESCRIPTION

Referring now to the Figures, FIG. 1 illustrates a system 10 comprising a source 12 of a first solid fiber material 14 (or fiber material 14), a source 16 of a first ceramic material 18, a first injector 20 in fluid communication with the source 16 of the first ceramic material 18 configured to introduce an amount of the first ceramic material 18 into the first solid fiber material 14 to form a first ceramic fiber composite 24; and a first dispensing head 22 configured to deposit the first ceramic fiber composite 24 therefrom in a predetermined pattern onto a working surface 25. By way of example, the working surface 25 may be a substrate, a layer of ceramic material, or a previously deposited layer of a ceramic fiber composite. As used herein, the term "ceramic fiber composite" is understood to refer to a material formed from a combination, e.g., extrusion, of a ceramic or ceramic matrix material with a solid fiber material.

The source 12 of first solid fiber material 14 may be in any form, such as a spool (with fibers wound about a mandrel) or the like, which conveys an amount of the first ceramic fiber material 14 for the system 10 as needed. In addition, the first solid fiber material 14 may comprise any suitable fiber material which provides a degree of added strength for the ceramic fiber composite. The first solid fiber material 14 also has a desired thickness and a longitudinal length (L), which may extend through at least a portion of the system 10.

In an embodiment, the first solid fiber material14 comprises a ceramic material. Without limitation, exemplary ceramic materials include alumina, mullite,

aluminosilicate, yttria alumina garnet, silicon carbide, silicon nitride, silicon carbon nitride, molydisicilicide, zirconium oxide, titanium oxide, combinations thereof, and the like. In an embodiment, the first solid fiber material 14 comprises an oxide material. In another embodiment, the first solid fiber material 14 comprises a non-oxide material. In a particular embodiment, the first solid fiber material 14 may comprise ceramic fibers sold under the trademark Nextel, such as Nextel 610, and 720 fibers. In addition, the first solid fiber material 14 may be in any suitable form, such as a straight filament, a bundle or a roving of multiple fibers, a braid, or a rope. In still other embodiments, the fiber material may comprise non-ceramic materials, including but not limited to carbon, glass, polymeric, metal, or any other suitable fiber materials.

In an embodiment, the first solid fiber material 14 is delivered from the fiber source 12 such that a longitudinal section (L) of the fiber is repeatedly exposed (e.g., within a loading region 15) to the first injector 20 as one of the first solid fiber material 14 and the first injector 20 is advanced past the other. As needed, an amount of a first ceramic material 18 may be introduced into the first solid fiber material 14 by the first injector 20, or alternatively by any other suitable method or device. In this way, the first ceramic material 18 may be absorbed by and/or coated on the first solid fiber material 14 along all or a portion of its longitudinal length to provide a first ceramic fiber composite 24. The amount of first ceramic material 18 introduced may be any suitable amount, such as from about 1 to about 500 μΙ_ per millimeter of length (L) of the associated fiber material, e.g., first solid fiber material. As used herein, the term "about" refers to an amount that is ± 5 % of the stated amount.

Alternatively, the ceramic material 18 may be introduced into the first solid fiber material 14 by any other suitable process and in any suitable form, such as a slurry or the like, to form the first ceramic fiber composite 24. In certain embodiments, the amount of ceramic material introduced to the first ceramic solid fiber composite may be a predetermined volume (vol.) % of the first solid fiber material 14, such as from 1 to 75 vol. %, and in a particular embodiment, from 20 to 50 vol. %.

In an embodiment, the first solid fiber material 14 may comprise an uptake enhancement feature 26 associated therewith to facilitate uptake of the first ceramic material 18. In an embodiment, referring to FIG. 2, the uptake enhancement feature 26 may comprise a physical structure which facilitates uptake of the first ceramic material 18 (or other material) into the first solid fiber material 14. For example, the uptake enhancement feature 26 may comprise a member selected from the group consisting of tubes, whiskers, flyfeet, and scoops associated with the first solid fiber material 14. In the embodiment shown, there is illustrated a longitudinal portion of the first solid fiber material 14 having scoops 28 integrated therewith for enhancing uptake of the first ceramic material 18, or any other suitable material. The uptake enhancement feature 26 may be associated with a surface of the first solid fiber material 14, or may be incorporated within the first solid fiber material 14 by any suitable method. In a certain embodiment, the first solid fiber material 14 may be manufactured with the uptake enhancement feature 26 incorporated therein.

The source 16 of the first ceramic material 18 may comprise any suitable housing, such as a vessel or a syringe with a plunger, for containing a quantity of the first ceramic material 18. Similar to the first solid fiber material 14, the first ceramic material 18 may comprise an oxide material or a non-oxide material. In an

embodiment, the first ceramic material 18 comprises an oxide material, such as zirconium oxide, titanium oxide, aluminum oxide, mullite, combinations thereof, and the like. In another embodiment, the first ceramic material 18 comprises a non-oxide material, such as a carbide material (e.g., a SiC material). In yet another embodiment, the first ceramic material 18 may comprise a ceramic-polymer mixture. In yet another embodiment, the ceramic material 18 may comprise a silicon-containing polymer, which may also comprise an oxide or non-oxide material. In certain embodiments, the first ceramic material 18 may comprise a mixture of two or more ceramic materials.

Additionally, in some embodiments, the first solid fiber material 14 and the first ceramic material 18 may be of the same oxide or non-oxide material (e.g., oxide/oxide or non- oxide/non-oxide) or different materials of the same type (e.g. oxide1/oxide2, non- oxide 1 /non-oxide2). In other embodiments, the first solid fiber material 14 and the first ceramic material 18 may be of different types (e.g., oxide/non-oxide).

In accordance with an aspect, the first injector 20 is in fluid communication with the source 16 of the first ceramic material 18 such that the first injector 20 introduces the first ceramic material 18 to the first solid fiber material 14 in a loading region 15 thereof. The amount of first ceramic material 18 delivered to the first solid fiber material 14 is without limitation and may, for example, be an amount which fully saturates the first solid fiber material 14 as portions of the first solid fiber material 14 travel past the first injector 20. In an embodiment, the amount of the first ceramic material 18 delivered to the first solid fiber material 14 by the first injector 20 may be from 1 to 500 μΙ_ per millimeter of length (L) of the fiber material, e.g., first solid fiber material 14. Further, in an embodiment, the first ceramic material 18 has a solids fraction of from about 1 to about 90 wt %.

The skilled artisan would also readily appreciate that the amount of ceramic material 18 introduced to the first solid fiber material 14 may be dependent on properties of the first solid fiber material 14 and the first ceramic material 18, such as density, fiber thickness, viscosity, and the like. The first injector 20 may comprise any suitable structure that will allow for the active or passive introduction of a ceramic material, e.g., a first ceramic material 18, into an associated fiber material, e.g., first solid fiber material 14. In an embodiment, the first injector 20 comprises one or more nozzles 29, each of which may have any suitable outlet diameter and outlet shape suitable for the particular application. Further, in an embodiment, the first injector 20 may comprise a syringe comprising a suitable housing for storing an amount of a ceramic material therein, at least one nozzle 29, and a plunger for directing the ceramic material out of the syringe through the nozzle 29. The first injector 20 may further comprise any suitable valves, lines, pumps, controllers, sensors, or other components associated therewith as are necessary or desired for operation thereof.

In accordance with an aspect, the first injector 20 may be disposed at any suitable angle relative to a longitudinal length (L) of the first solid fiber material 14 in order to introduce the first ceramic material 18 into the first solid fiber material 14 in the loading region 15 thereof to provide the ceramic fiber composite 24. In an embodiment, the angle is normal to the longitudinal length (L) of the first solid fiber material 14 as shown in FIG. 1 , although it is understood that the present disclosure is not so limited. In other embodiments, the first injector 20 may be oriented at an angle other than 90 degrees relative to the longitudinal length (L) of the first solid fiber material 14.

The above embodiment describes a single ceramic material being introduced to the first solid fiber material 14. It is also understood, however, that the present invention is not so limited. In other embodiments, the system 10 may include one or more additional ceramic sources in communication with first injector 20 and optionally one or more additional injectors for introducing the additional ceramic material(s) into the first solid fiber material 14. Referring to FIG. 3, for example, there is shown a source 30 of a second ceramic material 32 in fluid communication with a second injector 34, which may also include one or more nozzles 29 through which the second ceramic material 32 can exit. In this embodiment, the second injector 34 may configured to introduce a selected amount of the second ceramic material 32 into the first solid fiber material 14 in a loading region 15 thereof. The loading region 15 may progress up (toward the fiber source) as the first ceramic fiber composite 24 is deposited by the system 10. The first ceramic fiber composite 24 (though now loaded instead or also with a second ceramic material vs. a first ceramic material) may be deposited from the first dispensing head 22 onto the working surface 25. For ease of illustration, all of the components of FIG. 1 are not shown as being included in FIG. 3; however, it is understood that the components of FIG. 1 may also be present in the embodiment shown in FIG. 3, as well in the other figures showing further components of the system 10.

In an embodiment, as shown in FIG. 4, the second ceramic material 32 may be introduced to the first solid fiber material 14 such that a first longitudinal portion 36 of the first solid fiber material 14 has the first ceramic material 18 and a second (distinct) longitudinal portion 38 of the first solid fiber material 14 includes the second ceramic material 32. A line is shown dividing the two portions; however, it is understood that the separation of the two ceramic materials may not be so distinct, and that there may be some mixing of materials at or near the intersection of the two materials. Alternatively, a first length of the fiber material 14 could be provided with the first ceramic material 18, the first length cut (as will be described below), and a second length of the fiber material 14 could be provided with the second ceramic material 32. In this way, the first solid fiber material 18 and resulting ceramic matrix composite may be provided with more than one type of ceramic material, such as ceramic materials having differing porosities. This may be useful, for example, when higher temperature fibers are more desirable in a portion of the component vs. another portion. Aspects of the present invention thus provide numerous design options in the formation of ceramic fiber composite materials and components therefrom.

In still other embodiments, as shown in FIG. 5, the second ceramic material 32 may be added to the first solid fiber material 14 in a same region 15 of the first solid fiber material 14 such that the first ceramic material 18 forms a first ceramic layer 40 on the fiber material 14 and the second ceramic material 32 forms a second ceramic layer 42 over the first ceramic layer 40. FIG. 5 is a cross-sectional view of a portion of a fiber (fiber material 14) having a first ceramic layer 40 and a second ceramic layer 42 thereover. In this embodiment, the second ceramic material 32 may be different from that of the first ceramic material 18 in terms of composition, porosity, or the like. In this way, in certain embodiments, the first solid fiber material 14 may be provided with the beneficial properties of two distinct ceramic materials.

In other embodiments, one or more ceramic materials may be mixed by a suitable mixing device and introduced into the first solid fiber material 14 by the first injector 20, the second injector 34, or a like device. In this way also, novel materials may further be created, such as a fiber material being combined with a ceramic blend having desired properties from each of a plurality of distinct ceramic materials, or having new properties altogether.

In accordance with another aspect, the system 10 allows for more than one type of fiber material to be deposited therefrom. To accomplish this, in an embodiment (and referring now to FIG. 6), the system 10 may further include a source 44 of a second solid fiber material 46, a second injector 34 in communication with the source 30 of a second ceramic material 32 (as previously described herein), the second injector 34 configured for introducing the second ceramic material 32 into the second solid fiber material 46 in a loading region 15 thereof to produce a second ceramic fiber composite 48. In addition, the system 10 may further describe a second dispensing head 50 for dispensing the second ceramic fiber composite 48 onto the working surface 25 (which may be a substrate, a previously laid down layer of a ceramic material, first ceramic fiber composite 24, second ceramic fiber composite 48, or the like) in a predetermined pattern. Again, for ease of illustration, the other components described herein for system 10 are not shown in FIG. 6, but it is understood that they may be included therein.

Further, for ease of discussion, the source 44 of second solid fiber material 46, the second solid fiber material 46, the second ceramic fiber composite 48, the source of second ceramic material 30, the second ceramic material 32, the second injector 34, and the second dispensing head 50 may be the same or similar in structure or composition as described above for the corresponding first ones of each like component (12, 14, 16, 18, 20, 22, 24). It is understood in the interest of brevity that the possible embodiments for each composition will not be re-explained for the second of these elements. It is further understood that each component may be of the same

structure/type as that of its corresponding first component, or may be different in kind. By way of example only, the second solid fiber material 46 may be different from the first solid fiber material 14. Still further, it is further understood that the present invention is not so limited to first and second ones of the above components. In certain embodiments, still further fiber or ceramic materials (and corresponding components for the same) may be provided.

In accordance with another aspect, when the first ceramic fiber composite 24 or the second ceramic fiber composite 48 are printed (deposited), the first ceramic fiber composite 24 and the second ceramic fiber composite 48 may be deposited on or incorporated into an existing working surface 25 that comprises a ceramic material (note: the term "ceramic" is understood herein to include a ceramic or ceramic matrix material). In an embodiment, the working surface 25 comprises a ceramic material without fibers incorporated therein. In certain aspects, the system 10 may further include a structure for dispensing the ceramic material without fibers in a predetermined pattern. The ceramic fiber composite(s) may then be added onto/into the deposited ceramic only material. In this way, aspects of the present invention may not only print a ceramic fiber composite, but also add a fiber material to a ceramic material to build a component in contrast to known systems and processes, wherein a ceramic material is incorporated into a fiber material, typically a fiber layup or preform.

Referring now to FIG. 7, to provide a ceramic material to the working surface 25, the system 10 may further include a ceramic only dispensing head 52 in fluid

communication with a source 54 of a ceramic material 56. As with dispensing heads 22, 50, the dispensing head 52 may include at least an inlet and an outlet, such as a nozzle 31 , for dispensing of the ceramic material 56 therefrom. In addition, the source 54 of ceramic material 56 may be the same as the source of ceramic material (16 or 30) for the fiber materials (14 or 46) or may comprise an independent source of a different ceramic material as shown. In an embodiment, the ceramic material 56 may comprise either or both of the first ceramic material 18 and the second ceramic material 32.

As will be discussed below, in certain embodiments, the ceramic only dispensing head 52 may deposit the ceramic material 56 in a predetermined pattern in one or more layers on the working surface 25. Thereafter, an amount of a first or second ceramic fiber composite (24 or 48) may be deposited on the ceramic material 56 (or vice-versa). Further thereafter, an additional layer of a ceramic material 56 or a ceramic fiber composite (24 or 48) may be deposited on the previously deposited layer(s) in a predetermined pattern. These steps may be repeated in any desired order until the component is formed. It is appreciated that any desired number of fiber dispensing heads or ceramic only dispensing heads may be provided in the system 10, or as modules to be added/removed from existing systems.

In accordance with another aspect, as mentioned, the dispensing heads (22, 50, or 52) deposit the ceramic fiber composites or the ceramic material in a predetermined pattern. To accomplish this, a motor or other drive mechanism 58 may be associated with each dispensing head (22, 50, or 52) to allow for deposition of the associated material on the working surface 25 in any coordinate position at a point in time. In an embodiment, the working surface 25 is configured to move with respect to one or more of the dispensing heads (22, 50, and/or 52). In another embodiment, one or more the dispensing heads (22, 50, and/or 52) may be configured to move with respect to the working surface 25. In certain embodiments, as shown in FIG. 18, the drive mechanism 58 comprises a robotic arm 75, and any one or more of the dispensing heads described herein (22, 50, or 52) may be associated with the robotic arm 75 such that the associated dispensing heads have a freedom of movement in any desired direction (e.g., rotationally and in any or all of an x, y, or z direction (FIG. 12). Without limitation, the robotic arm 75 may comprise a 5-axis or a 6-axis robotic arm as are known in the art.

In addition, the system 10 may further comprise one or more controllers (e.g., controller 60) in electrical (wired or wireless) in communication with the drive

mechanism 58 to facilitate the amounts, concentrations, order, location of, and extent of deposition of the materials, as well as the operation of any pumps, values, or the like, positions of the working surface 25 and/or dispensing heads (22, 50, or 52), or other parameter(s). For purposes of illustration, FIG. 7 shows a controller 60 in electrical communication with a drive mechanism 58 for controlling a position of the ceramic only dispensing head 52, although it is understood the remaining dispensing heads (22, 50) may have the same or a distinct drive mechanism 58 and/or controller 60 associated therewith.

The controller 60 may comprise a general or special purpose computer programmed with or software/hardware to carry out an intended function as described herein. As used herein, the term "computer" may include a processor, a

microcontroller, a microcomputer, a programmable logic controller (PLC), a discrete logic circuit, an application specific integrated circuit, or any suitable programmable circuit or controlling device. The memory may include a computer-readable medium or a storage device, e.g., floppy disk, a compact disc read only memory (CD-ROM), or the like. In an embodiment, the controller 60 executes computer readable instructions for performing any aspect of the methods or for controlling any aspect of the systems or process steps described herein. As such, the controller 60 may be configured to execute computer readable instructions to monitor and/or adjust parameters such as: timing of deposition steps, the amounts, concentrations, order, location of, and extent of deposition of materials; the operation of pumps, valves, or the like; positions of the working surface and/or dispensing heads, or any other parameter(s). If necessary, the systems and processes described herein may employ one or more sensors for monitoring a desired parameter. Correspondingly, the controller 60 may comprise one or more inputs for receiving information from the one or more sensors.

In accordance with another aspect, when the first ceramic fiber composite 24, the second ceramic fiber composite 48, and/or fiber material alone is deposited onto the working surface 25, any of these components (which include a fiber material) may need to be cut, such as at an edge of the predetermined pattern in which it is deposited. To accomplish this, as shown in FIG. 8, the system 10 may further include a cutting mechanism 62 to cut the fiber material (e.g., first or second ceramic fiber composite 24, 48) at a point of time after deposition of the fiber material from its associated dispensing head (22 or 50). In certain embodiments, the cutting mechanism 62 may be associated with a particular (fiber) dispensing head (22 or 50) so as to be able to cut the ceramic fiber composite (24 or 48) close to the outlet of the nozzle 29 where it is deposited so as to leave little slack after cutting.

The cutting mechanism 62 may comprise any suitable component effective to cut the desired material at a desired time and location. In an embodiment, the cutting mechanism 62 comprises a device that cuts the fiber material mechanically. Without limitation, as shown in FIG. 8, the cutting mechanism 62 may comprise two opposable arms 64, one or both housing a cutting tool 66, such as a cutting (razor) blade, which acts to cut the ceramic fiber composite upon closure of the arms 64 with respect to one another (with the fiber material therebetween). Alternatively, the cutting mechanism 62 may comprise any other structure configured to cut the ceramic fiber composite (24 or 48) or fiber material deposited from an associated dispensing head (22 or 50) at a predetermined time and position along a length of the ceramic fiber composite (24 or 48) or fiber material. The cutting mechanism 62 may also include a laser-based approach. For example, as shown in FIG. 10, the cutting mechanism 62 may also comprise a laser source 65, which may be (but not necessarily) associated with a particular dispensing head (22 or 50), and which is configured to deliver a suitable amount of energy 67 for cutting the ceramic fiber composite (24 or 48) at a desired position.

In particular embodiments, activation of the cutting mechanism 62 may be automated, and thus programmed to cut the associated fiber material (e.g., ceramic fiber composite 24 or 48) when the associated dispensing head or working surface 25 reaches a desired location/position or at a predetermined point in time. The cutting mechanism 62 may itself have a controller/microprocessor (of the type described above for controller 60) for automating these functions, or alternatively may be in electrical communication with an external controller, e.g., controller 60, for control of the operation thereof.

The apparatuses and products described herein may be suitable for

manufacturing any suitable ceramic matrix composite structure. The structure may be a newly manufactured component or a repair or addition to an existing component. In an aspect of the invention, the apparatuses and processes described herein are suitable for the manufacture of components having a complex 3D shape, e.g., an airfoil, shape. Thus, in an embodiment, the structure formed by the systems and processes described herein may comprise a gas turbine component. In certain embodiments, the gas turbine component may comprise a rotating component, such as a blade. In other embodiments, the gas turbine component may comprise a stationary component, such as a vane. By way of example, FIG. 9 illustrates a component 70, e.g., a stationary vane 71 , having an airfoil portion 72 of a ceramic fiber composite formed by any of the processes and systems described herein. As shown, the airfoil portion 72 may be disposed between an inner and outer platform 74, 76, and secured to each by any suitable method or structure to provide the stationary vane 71 .

In other embodiments, the systems and processes may be configured for 3D printing the material to repair/augment an existing component, such as any of the gas turbine components described herein. By way of example, FIG. 16 illustrates a portion of an existing component 200 formed from a typical ceramic matrix composite 202. In this embodiment, as is typical for high strength components, the ceramic matrix composite 202 may comprise a fibrous layup or weave 204 into which a ceramic or ceramic matrix material is impregnated. For ease of illustration, the ceramic material is considered to be removed from FIGS. 16-17.

When the component 200 is damaged through operation and include one or more defects 206 formed therein, it of course may be desirable to repair the defect(s) 206 to restore it to a desirable operating condition. In the case of the weave 204 shown in FIG. 16, however, it is well-appreciated that restoration of the original weave structure may be completely impossible as the weave structure cannot be recreated at the location of the defect(s) 206. Currently known systems and methods thus do not provide an adequate method of repairing ceramic matrix composite structures where the weave structure has been compromised. Aspects of the present invention, however, provide a system and method for providing localized ceramic-reinforced fibers where necessary to repair the defect. As shown in FIG. 17, where the defect(s) 206 lie in the fibrous weave 204, a ceramic solid fiber composite, e.g., first ceramic fiber composite 24, can be printed within the area of the defect(s) 206 via any system or process described herein so as to reestablish a fiber reinforced ceramic (repair 208) with a comparable, if not stronger, ceramic (solid) fiber composite at the location of the defect(s) 206.

The operation of the systems as described herein, and the components therein, will be briefly described in the below paragraphs. It is however understood that the processes for operating the systems described herein and manufacturing component(s) therefrom is not so limited to the below description. Accordingly, the processes may include any additional or alternative steps that would be appreciated from the disclosure of the components described herein. Further, any component(s) or process step(s) described herein with respect to one embodiment may be combined with component(s) or process step(s) of any other embodiment described herein.

Referring now to FIGS. 1 1 -12, there are shown exemplary steps in a process for forming a ceramic matrix composite component in accordance with an aspect of the present invention. As shown in FIG. 1 1 , an amount of a ceramic material 56 is first delivered from the ceramic only dispensing head 52 onto a substrate 102 to form a first (cross-sectional) layer 104 thereon (working surface 25). The substrate 102 may comprise any suitable structure. In certain embodiments, the substrate 102 may comprise a platform for a blade or vane, a substrate intended to be removed upon completion of the component, or alternatively may be an initial cross-section of the structure or component to be formed. In an embodiment, a ceramic material 56 may be deposited on the substrate 102 by the ceramic only dispensing head 52 in a

predetermined pattern to form the first layer 104. Next, as shown in FIG. 12, an additional ceramic layer may be deposited from dispensing head 52, or a layer of a ceramic fiber composite (24 or 48) may be deposited from an associated dispensing head (22 or 50) onto the first layer 104 to form the next cross-sectional layer 106 and an updated working surface 25. Alternatively, one or more ceramic fiber composite layers may be first deposited on the substrate 102, and thereafter layer(s) of a ceramic material, e.g., ceramic material 56, may be deposited thereon.

To accomplish the deposition of the ceramic fiber composite, as was shown in FIGS. 1 and 3, a suitable amount of a fiber material, e.g., first solid fiber material 14, may be deposited from its corresponding fiber material source, e.g., source 16. An amount of a ceramic material (e.g., first and/or second ceramic materials 18, 32) may be introduced onto/into the fiber material 14 from a corresponding injector (e.g., injector 20 or 34). The resulting ceramic fiber composite (24 or 48) may be fed to a

corresponding dispensing head (22 or 50).

To deposit the ceramic fiber composite(s) (24 or 48) onto the working surface 25 in the predetermined pattern, the associated dispensing head (22 or 50) may deposit the desired material and be moved with respect to the working surface 25 in any direction as shown in FIG. 1 1 , or alternatively, the working surface 25 may be caused to move in any of the direction with respect to the associated dispensing head (22 or 50). In any case, the ceramic fiber composite (24 or 48) may be deposited from its associated dispensing head (22 or 50) so as to deposit the ceramic fiber composite (24 or 48) onto the working surface 25 in a predetermined pattern to form the next cross- sectional layer 106.

Thereafter, an additional ceramic only layer or an additional ceramic fiber composite layer may be deposited on the next cross-sectional layer 106 to form a yet further cross-sectional layer. It is appreciated that this process may be repeated several times until the desired structure is formed. Still further, the combination of ceramic materials, fiber materials, ceramic fiber composites, and order of printing (deposition) of components may be quite large in number and is without limitation herein. In certain embodiments, the fiber material (14 or 46) may even be deposited on the working surface 25 without loading of a ceramic material therein. As noted above, when a fiber material as described herein (ceramic fiber composite or fiber material without ceramic material) is deposited, it may be desirable to cut the fiber material at a point in its path of deposition. Referring again to FIGS. 8 and 10, the deposited ceramic fiber composite (24 or 48) may be cut at a desired position along a longitudinal length thereof by the cutting mechanism 62, which may be mechanical or laser-based. For example, as shown in FIG. 13, the ceramic fiber composite (e.g., first ceramic fiber composite 24) may be cut upon reaching an edge of the component to be formed as indicated by the solid lines 105. The solid lines 105 refer to locations where a cut may be made. The arrows in this instance refer to the direction of deposition of the material. Spacing between deposited tracks is illustrated in FIG. 13 to better show the path of deposition; however, it is appreciated that the spacing between tracks is not necessary or may not be desired. Typically, an overlap is desired of approximately 10-20 % of the roving diameter when the fiber material is in the form of a roving.

In accordance with another aspect, as shown in FIG. 14, the systems and processes described herein may allow for turning of the fiber material (e.g., ceramic fiber composite 24) as indicated by reference numeral 107 without cutting of the material. In certain embodiments, the fiber material is not cut until deposition of the subject cross-sectional layer is complete as is indicated by solid line 105. The skilled artisan would readily appreciate whether turning of the fibers would be suitable for a particular application may be dependent on fiber thickness, fiber stiffness, the length of the deposition path, degree of turn, and the like. Moreover, to reiterate, spacing between deposited tracks is illustrated in FIG. 14 to better show the path of deposition; however, it is appreciated that the spacing between tracks (or turns) is not necessary or may not be desired.

When ceramic fiber composites are printed as described herein, the cutting step allows complex geometries to be formed as the component's shape is not limited to an existing preform fiber shape. In accordance with another aspect, the deposition of the materials described herein can be provided in any desired order layer by layer until the component having a final desired composition, shape, and size is formed. Nothing in this disclosure is intended to limit the order of deposition of layers herein, each of which may comprise any of the material(s) described herein.

It is further contemplated that the deposited materials need not all be

printed/deposited in the same direction and pattern. In accordance with another aspect, it is contemplated that a "weave-like" structure may be formed by depositing a first layer of the loaded ceramic material in a first x, y, or z direction, and thereafter 3D printing a second layer over the first layer in a second x, y, or z direction distinct from the first direction. For example, as shown in FIG. 15, a first layer 120 of a fiber loaded ceramic material (24 or 48) may be printed in at least a first direction 122 and a second layer 124 of the fiber loaded ceramic material (24 or 48) may be printed over the first layer 120 in at least a second direction 126, e.g. transverse to the first direction 122.

In the manufacture of a typical ceramic matrix composite material, a fiber preform is utilized which includes a weave structure, wherein fibers extending in one direction are loomed over and under fibers extending in another direction (e.g., transversely) to add strength to the overall material. In an aspect, the 3D printing of ceramic fiber composite material(s) as described herein improves upon these conventional techniques. As mentioned above, the weaving process may, in fact, significantly weaken the mechanical strength of the fibers. In contrast, the systems and processes described herein allow fibers to be oriented in different directions in the same material yet eliminate processing steps that weaken the fibers as in typical weaving processes.

In accordance with another aspect, once all the desired layers are deposited to form the component 70 as described in any of the systems and processes described herein, the component 70 may be sintered or otherwise heated to a desired

temperature. The sintering, for example, may take place by the application of energy, such as the application of heat, for any suitable duration at any desired temperature. In an embodiment, the component 70 (upon printing of all the layers) is sintered at a temperature of at least about 500°C, and in particular embodiment from 500°C to 1200°C - either isothermally or with a temperature gradient.

In accordance with an aspect, any existing system configured for the free form extrusion of ceramic materials can be modified with the components described herein to provide a system which deposits a ceramic fiber composite. Further, although aspects of the present invention have been explained in the context of manufacturing or repairing gas turbine components, as easily understood by those skilled in the art, the instant manufacturing concepts may be applied to other suitable fields and components.

In accordance with an aspect of the present invention, the processes and materials for 3D printing a ceramic fiber composite (CMC material) as described herein may be utilized to improve the adhesion of a thermal barrier coating (TBC) directly or indirectly to a CMC component. In an embodiment, the CMC component is one formed by a 3D printing process as described herein. In another embodiment, the CMC component may be manufactured by another non-3D printing process and/or is a commercially available component. In any case, aspects of the present invention may also enhance the performance of TBCs applied to the surfaces of CMC components.

In accordance with one aspect, a ceramic fiber composite as described herein is three-dimensionally (3D) printed onto a component surface (also formed from a CMC material) in a pattern (e.g., a grid-like pattern). The pattern of 3D printed ceramic fiber composite defines a plurality of channels between adjacently deposited segments of the ceramic fiber composite. Thereafter, a TBC may be deposited at least within the channels, and in some embodiments over and within the printed segments, such that the TBC is mechanically interlocked to the underlying CMC component. The deposition of the TBC in the pattern and the mechanical interlocking of the TBC to the component has several benefits. For example, the confinement of the TBC by the channels aids in localizing crack propagation (whether by thermal stress or otherwise) that might otherwise result in excessive TBC spallation and subsequent thermal exposure damage to the underlying substrate.

Referring again to the figures, FIG. 19 shows a component 300, which may be made by a process as described herein or is otherwise provided from a suitable source. For example, in an embodiment, the component 300 may be formed from repeated deposition of the first and/or second ceramic fiber composites 24, 48 as described herein, and optionally also a ceramic only material or fiber only material. Accordingly, in an embodiment, the component 300 includes a body 302 having at least a portion 304 that comprises a ceramic matrix composite (CMC) material 306. In this embodiment, the CMC portion 304 of the body 302 also comprises a printed pattern 308 of a ceramic fiber composite 24, 48 on a surface 310 thereof. The printed pattern 308 is selected such that a plurality of channels 312 are defined on the surface 310 between adjacently deposited segments 314 of a ceramic fiber composite (24 and/or 48). In this way, the printed pattern 308 provides a scaffold-like or grid-like framework on the surface 310 of the component 300. Over this surface, a thermal barrier coating (TBC) 318 is deposited (FIG. 20).

To explain further, in an embodiment and as shown in FIG. 20, a TBC 318 may be provided at least within the channels 312 and between adjacent segments 314 so as to at least fill in all or a portion of a depth (D) of the channels 312. In some

embodiments, the TBC 318 may also be disposed over the segments 314 as shown in FIG. 21 . In other embodiments, as shown in FIG. 22, the TBC 318 may also extend above a top surface 320 of the printed segments 314 to form a continuous layer portion 322 over the printed segments 314. With the TBC 318 disposed within the channels 312 and optionally over the printed segments 314, the TBC 318 may be mechanically interlocked with the body 302 of the component 300 comprising the CMC material 306. Moreover, the pattern 308 may be effective to reduce crack propagation of the TBC 318 as any crack forming in the TBC 318 may be contained within respective channels 312 bounded by the segments 314. As would be appreciated by reference to FIG. 19, the TBC 318 may be bounded on four sides by four segments 314, thereby providing a barrier on each side to crack propagation. It is noted that FIGS. 19-20 illustrate the channels 312 as having a relatively rectangular shape merely for ease of illustration in this instance; however, the present invention is not so limited.

The component 300 may be any structure, such as a gas turbine component, comprising a CMC material and for which a thermal barrier coating 318 may be of benefit. In an embodiment, the component 300 comprises a gas turbine component, such as vane or a blade for a gas turbine, which is in a hot gas path of the turbine engine. In an embodiment, the body 302 of the component (to which the TBC 318 is applied) is solely formed from a ceramic matrix composite (CMC) material. In other embodiments, the body 302 of the component 300 may comprise an inner core of a metal material or the like which extends radially through the body 302 for structural support thereof, with an outer portion formed from a CMC material 306. The printed pattern 308 may comprise any suitable arrangement of printed segments 314 of a ceramic fiber composite material (24 or 48) effective to provide a plurality of channels 312 between adjacently printed segments 314. Note, as used herein, the term "or" as used herein may refer to "and/or," and thus include one, both, or all possibilities listed. The 3D printing of the segments 314 to define the channels 312 by the dispensing heads (22, 50, or 52) as described herein will be described in greater detail below. In an embodiment, the printed pattern 308 comprises a grid pattern 316 (FIG. 19) having a plurality of intersecting segments 314 at right angles to one another; however, it is understood that the present invention is not so limited. In other embodiments, the pattern 308 may comprise any other desired configuration other than a grid, such as a pattern which provides channels 312 having a diamond shape. In addition, in an embodiment, the segments 314 are relatively linear as shown. In other embodiments, the segments 314 may have a degree of curvature thereto, such as when printing on a curved surface. The segments 314 may be printed at any desired distance from one another to define the channels 312. By way of example only, a given segment 314 may be spaced form 1 to 20 mm apart from an adjacent parallel segment 314.

The channels 312 may be of any suitable size so as to contain an amount of the TBC 318 within a depth of the channels 312. By way of example only, the channels 312 may have a depth of from 0.5 to 20 mm, and in a particular embodiment from 0.5 to 5 mm. In the same way, the channels 312 may have any suitable width and length, such as from 0.5 to 20 mm. As mentioned above with respect to the printed pattern 308, the channels 312 may further be of any suitable shape. For example, in an embodiment, the channels 312 may have a substantially rectangular or square shape (e.g., FIG. 19) in cross-section or as viewed from above. Alternatively, the channels 312 may comprise a diamond shape or the like. In certain embodiments, the segments 314 defining the channels 312 may be oriented at an angle other than 90 degrees relative to a plane extending across a top surface 320 of the segments 314.

The TBC 318 may comprise any suitable material which provides an increased temperature resistance to the body 302 when applied to a surface of the body 302. In an embodiment, the TBC layer 318 comprises a stabilized zirconia material. For example, the TBC layer 318 may comprise an yttria-stabilized zirconia (YSZ), which includes zirconium oxide (Zr0₂) with a predetermined concentration of yttrium oxide (Y₂O₃), pyrochlores, or other TBC material known in the art. In another embodiment, the TBC 318 may comprise a magnesia stabilized zirconia, ceria stabilized zirconia, aluminum silicate, or the like.

In yet another embodiment, as shown in FIG. 23, the TBC 318 may comprise a dimensionally stable, abradable, ceramic insulating material 319 comprising a plurality of hollow ceramic particles 321 dispersed in the material 319. The hollow particles 321 may be of any suitable dimension, and in one embodiment may be from 1 -100 micron in diameter. In an embodiment, the hollow ceramic particles 321 are spherical and comprise one or more of zirconia, alumina, mullite, ceria, and yttrium aluminum garnet (YAG), for example. In one aspect, the ceramic insulating material 319 comprising the hollow particles 321 may be added to the channels 312, and optionally over the scaffolding (segments 314) by slurry-based infiltration or the like. Following deposition on the associated component and sintering, the ceramic insulating material 319 comprising hollow particles 321 may be strain relieved by laser engraving or the like as set forth below.

In accordance with another aspect, a bond coat as is known in the art may be disposed between the surface 310 of the body 302 and the TBC 318 in order to improve the adhesion of the TBC 318 to the body 302. For example, FIG. 24 illustrates a bond coat layer 323 disposed over the pattern 308 (defined by segments 314) and within the channels 312. The TBC 318 as previously described herein is deposited over the bond coat layer 323. The material for the bond coat layer 323 may comprise any suitable material. For example, an exemplary bond coat layer 323 may comprise an MCrAIY material, where M denotes nickel, cobalt, iron, or mixtures thereof, Cr denotes chromium, Al denotes aluminum, and Y denotes yttrium. In other embodiments, the bond coat layer 323 may comprise alumina, yttrium aluminum garnet (YAG), or other suitable ceramic-based material, e.g., a rare earth oxide and/or rare earth garnet material. The bond coat layer 323 may also be applied by any known process, such as via a thermal spraying or a slurry-based deposition process. Alternatively, the bond coat layer 323 may be omitted and the TBC 318 may be applied directly onto the surface 310 as described above.

The manufacture of an exemplary component 300 having at least channels 312 and a TBC 318 will described below. In operation (referring again to FIGS. 1 , 3, and 19), a component 300 may be manufactured from a ceramic fiber composite (24 or 48) as described previously herein. To accomplish this, a suitable amount of a fiber material, e.g., first solid fiber material 14, may be deposited from its corresponding fiber material source, e.g., source 16. An amount of a ceramic material (first or second ceramic materials 18, 32) may be introduced onto/into the fiber material, e.g., fiber material 14, from a corresponding injector (injector 20 or 34). The resulting ceramic fiber composite (24 or 48) may be fed to a corresponding dispensing head (22 or 50).

To deposit the ceramic fiber composite(s) (24 or 48) onto the working surface 25 in the predetermined pattern, the associated dispensing head (22 or 50) may deposit the desired material and be moved with respect to the working surface 25 in any direction as shown in FIG. 1 1 , or alternatively, the working surface 25 may be caused to move in any of the direction with respect to the associated dispensing head (22 or 50). In any case, the ceramic fiber composite (24 or 48) may be deposited from its associated dispensing head (22 or 50) so as to deposit the ceramic fiber composite (24 or 48) onto the working surface 25 in a predetermined pattern to form the next cross- sectional layer 106. Thereafter, an additional ceramic only layer or an additional ceramic fiber composite layer may be deposited on the next cross-sectional layer 106 to form a yet further cross-sectional layer. It is appreciated that this process may be repeated several times until the desired structure (e.g., component 300) is formed.

To add a scaffold (printed pattern 308) of the ceramic fiber composite (24 or 48), the associated dispensing head (22 or 50) may likewise deposit the desired ceramic fiber composite (24 or 48) and be moved with respect to the working surface 25 in any direction as was shown in FIG. 1 1 , or alternatively, the working surface 25 may be caused to move in any of the direction with respect to the associated dispensing head (22 or 50). Contrary to the formation of the component 300, in forming the scaffold (printed pattern 308), any deposited segment 314 is necessarily spaced apart by a predetermined distance from an adjacent or parallel segment 314 as shown in FIG. 19. In this way, the printed pattern 308 may define the plurality of channels 312 having a depth between adjacently deposited segments 314.

In an embodiment, after deposition of one or more segments 314, the deposited ceramic fiber composite (forming the segments 314) may be cut by the cutting mechanism 62 as described herein at one or more selected positions on the material. For example, in an embodiment, after the formation of each segment 314, each segment 314 may be cut by the cutting mechanism 62 at a desired end of the segment 314 (see FIGS. 8, 10, 13, and 14). In certain embodiments, any of the segments 314 may be cut at or near an edge of the component 300.

In certain embodiments, each segment 314 need not be cut after it is deposited. For example, a plurality of ceramic fiber composite segments 314 may be added to a surface of the component by depositing one segment 314 and then allowing turning of deposited ceramic fiber composite (24 or 48) at a desired location (by suitable movement of the dispensing head or working surface) to allow for deposition of an adjacent segment 314 without cutting. This process may be repeated until a desired number of segments 314 are deposited. Thereafter, the deposited ceramic fiber composite material (24 or 48) may be cut by cutting mechanism 62 as desired.

Thereafter, if further segments 314 are desired that extend in a different direction (such as a direction transverse to the previously deposited segments 314), those further segments 314 may be deposited, turned in the same manner, and cut by cutting mechanism 62 where desired. As discussed, a desired spacing between adjacent segments 314 is selected which is sufficient to define the channels 312.

Once the ceramic fiber composite (24 or 48) has been fully deposited to provide the desired pattern 308 and define the desired number and shape of channels 312, in an embodiment, the pattern 308 of the ceramic fiber composite (24 or 48) may be sintered or otherwise heated to a desired temperature to join the pattern 308 to its underlying substrate (body 302). The sintering, for example, may take place by the application of energy, such as the application of heat, for any suitable duration at any desired temperature. In an embodiment, the component 300 (upon printing of all the layers and/or pattern 308) is sintered at a temperature of at least about 500°C, and in particular embodiment from 500°C to 1200°C - either isothermally or with a temperature gradient.

At this point, the scaffolding (pattern 308) is now ready for the application of the bond coat 323 (if present) and TBC 318 therein and/or thereon. When a boat coat layer 323 is utilized, the bond coat layer 323 may be applied by any suitable technique, such as a thermal spray or slurry-based technique. The TBC 318 may be applied by any suitable process, such as a thermal spray process, a slurry-based coating deposition process, or a vapor deposition process as is known in the art. In an embodiment, the TBC 318 is applied via a thermal spray process, such as a plasma spray process. In another embodiment, the TBC 318 is applied by a vapor deposition process such as an electron beam physical vapor deposition process (EBPVD). An EBPVD process typically provides the TBC layer 318, such as an YSZ coating, with a columnar microstructure having sub-micron sized gaps between adjacent columns of YSZ material as shown, for example, in U.S. Patent No. 5,562,998, the entirety of which is incorporated by reference herein. In further embodiments, the TBC 318 may be applied via any other suitable deposition technique in the art.

In accordance with another aspect, the TBC 318 may be modified, e.g., during processing or in a post-processing step, so as to provide a degree of strain relief to the TBC 318. Porous TBCs, in particular, tend to have a low strain tolerance. This relatively low strain tolerance limits the thickness of the TBC that can be deposited on a component. Accordingly, as the thickness of a porous TBC increases, the accumulation of residual stresses diminishes the ability of the TBC to accommodate the strain without spalling. In accordance with an aspect, the TBC 318 is thus modified or otherwise provided with a degree of strain relief.

In one embodiment, as shown in FIGS. 23 and 25 for example, the TBC 318 is provided with a degree of strain relief by forming a plurality of channels or grooves 324 into a depth of a TBC 318. The grooves 324 may be formed by laser engraving, etching, or any suitable technique which provide grooves 324 in the TBC 318 in a desired pattern. In an embodiment, the pattern the grooves 324 are formed in may be substantially similar to the pattern 308 of the segments 314 of the ceramic fiber composite are formed in. For example, the grooves 324 may be formed in a similar grid pattern in the TBC 318 as the pattern 308. In this way, the grooves 324 also will provide a controlled path for crack propagation to take place if it occurs, as well as provide a degree of strain relief.

One difference between channels 312 and grooves 324 is that channels 312 are defined by the positive printing of a ceramic fiber composite in the pattern 308 to define the channels 312. Grooves 324, however, are formed by the inverse (negative) removal of an amount of TBC material in a desired pattern. In any case, instead of allowing cracks to propagate along an entire interface between the TBC 318 and a substrate, the grooves 324 may also confine crack propagation, which may significantly reduce the size and scale of any actual or potential spallation of the TBC 318. In addition, the grooves 324 may relieve a degree of thermal expansion mismatch between the TBC 318 and the CMC substrate (body 302). Further, the presence of the grooves 324 may reduce stress in the TBC 318 to a degree similar to the reduction of a thickness of the TBC 318. The grooves 324 may be provided by any suitable process and in any suitable size, shape, and pattern as described in Published PCT Application No. 2016/105327, for example, the disclosure of which is hereby incorporated by reference. In an embodiment, the grooves 324 are provided by laser engraving the grooves 324 in the TBC 318 in a desired pattern. In addition, in an embodiment, the plurality of grooves 324 in the TBC 318 comprise a predetermined configuration selected from the group consisting of circles, semi-circles, diamond shapes, straight segments, curved segments, and a grid pattern.

In accordance with another aspect, the TBC 318 may be formed as a dense vertically cracked (DVC) TBC as is known in the art to provide the degree of strain relief. See U.S. Published Patent Application No. 2003/0203224, for example, the entirety of which is also incorporated by reference. As set forth in US 2003/0203224, DVC TBCs typically have less than 5% porosity and include a series of vertical crack generally traveling through an entire cross-sectional thickness of the TBC. The low porosity gives the coating excellent tensile adhesion strength, while the vertical cracks give the coating the ability to accommodate strains in the substrate plane.

To illustrate the benefits of the 3D printed and engineered surface described herein, attention is drawn to FIGS. 26-29. FIG. 26 illustrates a CMC substrate 400 having a TBC layer 402 thereon with no engineered surface. As shown in FIG. 27, subjecting the component to temperatures greater than 1200° C will result in complete elimination or recession of the TBC layer 402, plus fiber degradation and further structural damage to the underlying component. Conversely, a component 300 formed according to an aspect of the present invention may have a TBC 318 which continues to protect the underlying CMC substrate - even under typical spallation conditions. As shown in FIG. 28, the body 302 comprising CMC material 306 has a TBC 318 overlaying a printed pattern 308 of a ceramic fiber composite (24 or 48) as described herein. Upon being subjected to temperatures > 1200°C, while the TBC 318 may show some recession (although not necessarily so), the bulk of the TBC 318 is maintained within the channels 312 and is able to protect the underlying CMC body from structural damage as shown in FIG. 29.

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 (300) comprising:

a body (302) comprising a ceramic matrix composite material (306);

a three-dimensionally printed pattern (308) of a ceramic fiber composite (24,48) on a surface (310) of the body (302), the printed pattern (308) comprising channels (312) defined between adjacently deposited segments (314) comprising the ceramic fiber composite (24, 48); and

a thermal barrier coating (318) disposed within the channels (312) so as to mechanically interlock the thermal barrier coating (318) to the body (302).

2. The component of claim 1 , wherein the ceramic matrix composite material (306) of the body (302) and the ceramic fiber composite (24, 48) of the printed pattern (308) comprise the same material.

3. The component of claim 1 , wherein the body (302) and the ceramic fiber composite (24, 48) of the printed pattern (308) each comprise an oxide material.

4. The component of claim 1 , wherein the thermal barrier coating (318) is further disposed over a top surface of the printed pattern (308).

5. The component of claim 1 , wherein the deposited segments (314) comprise a height of from about 0.5 mm to about 5 mm.

6. The component of claim 1 , wherein the thermal barrier coating (318) further comprises a plurality of grooves formed therein for strain relief of the thermal barrier coating (318).

7. The component of claim 6, wherein the plurality of grooves (324) in the thermal barrier coating (318) comprise a configuration selected from the group consisting of circles, semi-circles, diamond shapes, straight segments, curved segments, and a grid pattern.

8. The component of claim 6, wherein the thermal barrier coating (318) comprising a ceramic material (319) comprising a plurality of hollow ceramic particles (321 ) dispersed therein, wherein the hollow ceramic particles (321 ) have a diameter of from 1 -100 micron.

9. A process for improving adhesion of a thermal barrier coating (318) to a substrate (302) comprising a ceramic matrix composite material (306), the process comprising:

introducing a ceramic material (18, 32) into a solid fiber material (14, 46) to produce a ceramic fiber composite (24, 48);

depositing a plurality of segments (314) of the ceramic fiber composite (24, 48) onto the substrate (302) in a printed pattern (318) so as to form a plurality of channels (312) defined between adjacently deposited ones of the segments (314); and

depositing a thermal barrier coating (318) within the plurality of channels (312).

10. The process of claim 9, wherein the depositing of the thermal barrier coating (318) is done by a process selected from the group consisting of thermal spraying, vapor deposition, and slurry infiltration.

1 1 . The process of claim 9, further comprising cutting the ceramic fiber composite (24, 48) after at least one of the segments (314) is deposited on the substrate (302).

12. The process of claim 9, wherein the substrate (302) is formed by a three- dimensional printing process, the three-dimensional printing process for forming the substrate (302) comprising:

introducing a ceramic material (18, 32) into a solid fiber material (14, 46) to produce a ceramic fiber composite (24, 50);

depositing the ceramic fiber composite (24, 48) onto a working surface (25); and repeating the introducing of a ceramic material (18, 32) and depositing of the ceramic fiber composite (24, 48) until the substrate (302) is formed.

13. The process of claim 9, wherein the thermal barrier coating (318) is deposited within the plurality of channels (312) and over the printed pattern (308).

14. The process of claim 9, wherein the deposited segments (314) comprises a height of from about 0.5 mm to about 5 mm.

15. The process of claim 9, further comprising depositing a bond coat layer (323) over the printed pattern (308) prior to depositing the thermal barrier coating (318) within the plurality of channels (312).