THREE-DIMENSIONAL PRINTING OF A CERAMIC FIBER COMPOSITE TO FORM A

TURBINE ABRADABLE LAYER

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 forming a thermally protective abradable surface on a hot gas component which comprises a three-dimensionally (3D) printed ceramic fiber composite and a thermal barrier coating (TBC) deposited thereover.

BACKGROUND

Axial gas turbines typically contain rows of turbine blades, referred to as stages, coupled to disks that rotate on a rotor assembly. The turbine blades extend radially and terminate in turbine blade tips. Ring seal segments are positioned radially outward from the turbine blade tips, but in close proximity to the tips of the turbine blades to limit gases from passing through the gap created between the turbine blade tips and the inner surfaces of the ring seal segments. The gaps between the turbine blade tips and the ring seal segments are designed to be as small as possible between the blade tips and the surrounding segment because the larger that gap, the more inefficient the turbine engine.

When the turbine blades and the ring seal segments are formed from materials having different coefficients of thermal expansion relative to one another, the size of the gap between the tips of the turbine blades and the ring seal segments must account for the same. As a turbine engine begins to heat up during startup procedures, the length of the turbine blades typically increases radially outward while the ring seal segments move radially outward as well. The gap size may thus change during the thermal growth. To account for the thermal growth, the gap is sized such that at steady state operating conditions in which the turbine blades are heated to an operating

temperature, the gap is a small as possible without risking significant damage from the tips contacting the ring seal segments. As the gap is reduced, the incidences of rubbing between the turbine blade tips and the ring seal segments increase upon thermal growth. For example, if the gap is too small, the turbine blade tips may undergo excessive wear due to excessive contact with the ring segments.

Attempts have been made to minimize the clearance gap to improve efficiency while avoiding excessive wear on the turbine blade tips. For instance, some

conventional turbine engines include thermal barrier coatings (TBCs) on the ring seal segments that are designed to abrade when contacted by the blade tips. The TBCs also insulate the underlying turbine components from the hot gases present during operation, which may be approximately 2500° F. Use of the TBCs can reduce the temperature of the underlying substrate to a temperature of less than approximately 1800 ° F.

While the gap between the tips of the turbine blade and the ring seal segments may be designed to enable smooth startup from a cold engine, problems are typically encountered during a warm restart. In particular, a warm restart occurs when a turbine engine running at steady state operating temperatures is shut down, allowed to cool for two to three hours, and then restarted. During the restart, the turbine blade tips often contact the abradable coating on the ring seal segments because during the shutdown period turbine disks remain hot and thermally expanded radially, while the thermally insulated turbine shroud ring has cooled and retracted somewhat, thereby reducing the gap. With the gap reduced, the turbine blade tips often contact the abradable coating.

Abradable coatings are designed such that when contacted by a turbine blade, a portion of the coating will break away to prevent damage to the turbine blade tips. One widespread problem with abradable coatings is that the coatings generally sinter after exposure to turbine engine operating temperatures of about 2,500° F (1371 ° C) after about 50 to 100 hours. Sintering of the abradable coating significantly reduces the abradable coatings ability to shear when contacted by tips of turbine blades.

Further, in addition to abradable TBCs alone, back-filled honeycombs have been utilized on a turbine component surface in order to allow deposition of a TBC to a metallic substrate and in an attempt to limit/prevent gases from passing through the aforementioned gap spaces. Typically, metallic honeycombs are attached to a superalloy substrate surface, which is then filled with a TBC material. Examples of this technology are found in U.S. Pat. Nos. 6,846,574; 6,641 ,907; 6,235,370; and 6,013,592, the entirety of each of which is hereby incorporated by reference. In some embodiments, a prefabricated honeycomb structure is welded to the substrate.

Alternatively, a honeycomb may be fabricated by depositing a metal-ceramic material in a mask on the substrate and heating it to produce cohesion and a solid-state diffusion bond with the substrate. In any case, however, these technologies typically require high processing times and expenditures, and may result in incomplete attachment to the underlying substrate. In addition, the type of material to which these honeycomb structure may be applied is currently limited to superalloy substrates or like metals.

SUMMARY

In accordance with an aspect of the present invention, the processes and systems described herein allow for the three-dimensional (3D) printing of a ceramic fiber composite engineered surface to which an abradable and (additionally) thermally protective material (e.g., TBC) may be applied. The ceramic fiber composite described herein may advantageously be printed onto any suitable substrate, e.g., either of a superalloy substrate or a CMC substrate. In one aspect, the resulting abradable surface (comprising a ceramic fiber composite and a TBC) is printed on an inner layer of a thermal barrier coating (TBC), which has been applied on a superalloy substrate. Since the abradable surface is partially composed of a ceramic fiber composite, and not entirely a thermal barrier coating, it is believed the temperature resistance of the abradable surface is improved. Further, due to the 3D printed ceramic fiber composite underlying the TBC, the likelihood of sintering of the TBC at higher operating

temperatures desired in modern engines is significantly reduced. In addition, because the CMC abradable surface is less prone to sintering than a TBC alone, the abradable surfaces described herein provide for improved turbine performance due to increased abradability and less undesired wear on components, such as blade tips. Still further, in certain aspects, the 3D printed ceramic fiber composite allows for the deposition of an abradable surface that behaves like a metallic honeycomb, but without the processing times, attachment issues, and the like of the prior art.

In accordance with an aspect, there is provided a process for forming a three- dimensional abradable surface on a gas turbine component comprising: introducing a ceramic material into a solid fiber material to produce a ceramic fiber composite;

printing a plurality of segments of the ceramic fiber composite onto a body of the component in a pattern; and depositing a thermal barrier coating over the plurality of segments to define the three-dimensional abradable surface comprising the thermal barrier coating. In an embodiment, the 3D abradable surface comprises a plurality of spaced apart ridges of a predetermined height and shape.

In accordance with another aspect, there is provided a gas turbine component comprising a three-dimensionally (3D) printed pattern of a plurality of segments of a ceramic fiber composite disposed on a body of the component; and a thermal barrier coating (TBC) disposed over the plurality of segments to define a three-dimensional abradable surface for the component.

In accordance with yet another aspect, there is provided a turbine engine comprising:

a turbine casing having an inner circumference;

a rotor having blades rotatively mounted within the turbine casing inner circumference, distal tips of which forming a blade tip circumferential swept path in a blade rotation direction; and

an abradable component associated with the turbine casing, the abradable component comprising:

a three-dimensionally printed pattern of a plurality of segments of a ceramic fiber composite disposed on a body of the component; and

a thermal barrier coating disposed over the plurality of segments and defining a three-dimensional abradable surface;

wherein contact of the distal tips with the three-dimensional abradable surface upon movement of the blades in the blade tip circumferential swept path results in removal of the three dimensional abradable surface by the distal tips.

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 illustrates a component comprising a 3D abradable surface in

accordance with an aspect of the present invention.

FIG. 21 illustrates a component comprising a 3D abradable surface in

accordance with another aspect of the present invention.

FIG. 22 illustrates a component comprising a superalloy portion and a thermal barrier coating thereon in accordance with an aspect of the present invention.

FIG. 23 illustrates a component comprising a 3D abradable surface in

accordance with another aspect of the present invention.

FIG. 24 illustrates a turbine engine comprising a component having an abradable surface in accordance with an aspect of the present invention.

FIGS. 25-26 illustrate the manufacture of a component having an abradable surface in accordance with an aspect of the present invention.

FIG. 27-28 illustrate the manufacture of another component having an abradable surface in accordance with an aspect of the present invention.

FIG. 29 illustrate an embodiment of an abradable surface in accordance with an aspect of the present invention.

DETAILED DESCRIPTION

Referring now to the Figures, FIG. 20 illustrates a component 300 comprising a body portion 302 having a printed pattern 308 comprising segments 314 of a ceramic fiber composite 24 and/or 48 (hereinafter 24, 48) on a surface thereof. Over the printed pattern 308 of the ceramic fiber composite 24, 48, there is provided an amount of a thermal barrier coating (TBC) 318 effective to define a three dimensional (3D) abradable surface 322 as shown on the body 302. In an embodiment, the 3D

abradable surface 322 comprises a plurality of spaced apart ridges 324 as shown.

Turning now to FIG. 1 , FIG. 1 illustrates a system 10 for printing the ceramic fiber composite 24, 48 in the printed pattern 308 referred to above. The system 10

comprises 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 material 14 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- oxide1/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 (see e.g., FIGS. 1 , 3 and 8), 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 as described above may be utilized to instead or further build a three-dimensional (3D) abradable surface 322 on a surface of the component 70 described above, or alternatively on a distinct existing

(manufactured) component. In an embodiment, the component on which the 3D abradable surface 322 is formed is produced by a 3D printing process as described herein. In another embodiment, the component on which the abradable surface 322 is formed is one manufactured by another non-3D printing process and/or is a commercially available CMC component. In still other embodiments, as set forth below, the component on which the abradable surface 322 is formed is one comprising a superalloy body and a layer of a thermal barrier coating on the superalloy body.

In any case, the abradable surface described herein provides numerous benefits, including enhanced temperature resistance and improved abradability performance When, for example, a TBC 318 is deposited over the pattern of the ceramic fiber composite to form the abradable surface 322, the abradable surface 322 also

comprises a ceramic fiber composite material, and not just a TBC 318. Since the 3D printed ceramic fiber composite may be less prone to sintering than a TBC, the 3D printed ceramic fiber composite may provide improved turbine performance due to increased abradability of the TBC and less undesired wear on components, such as blade tips, at the higher operating temperatures (e.g., > 2500° C) found in more modern turbine engines. In addition, the 3D printing of the fiber ceramic composite is not limited to particular surfaces so long as the 3D printed ceramic fiber composite can be effectively bonded thereto. In certain embodiments, the 3D ceramic fiber composite can thus enhance the application and performance of a TBC coating applied to a superalloy substrate, which has been difficult to date.

Referring to FIGS. 19-20, in an aspect, a plurality of spaced apart segments 314 of the ceramic fiber composite 24, 48 may be three-dimensionally (3D) printed onto a surface 310 of the component 300 in a printed pattern 308 by the processes/systems described herein. In this way, the pattern 308 of 3D printed ceramic fiber composite 24, 48 defines a plurality of channels 312 between the 3D printed segments 314 of the ceramic fiber composite. The printed pattern 308 of the ceramic fiber composite 24, 48 may comprise any suitable arrangement of segments 314 of the ceramic fiber composite material 24, 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 printed 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 (spacing) from one another to define the channels 312. By way of example only, a given segment 314 may be spaced from 1 to 20 mm apart from an adjacent parallel segment 314, and in certain embodiments from 4 to 6 mm apart.

The segments 314 and thus channels 312 defined thereby may be of any suitable size. By way of example only, the segments 314 may be printed so as to have a height 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 (FIG. 25).

A TBC 318 is deposited over and/or within the printed segments 314 so as to define a three-dimensional abradable surface 322 comprising the deposited TBC 318 and the 3D printed ceramic fiber composite 24, 48 in the printed pattern 308. In certain embodiments, the resulting three dimensional abradable surface 322 (comprising pattern 308 and TBC 318) comprises a plurality of spaced apart ridges 324. In some embodiments, the deposited TBC 318 may follow the printed pattern 308 of the 3D printed ceramic fiber composite 24, 48. In other words, in an embodiment, the formed abradable ridges may be vertically aligned with or over the printed segments 314 as shown in FIG. 20. In other embodiments, as shown in FIG. 21 , the deposited TBC 318 may provide a three dimensional profile which is distinct from the 3D printed ceramic fiber composite. For example, the ridges 324 may not be vertically aligned over the printed segments 314.

The component 300 may comprise any suitable structure, such as a gas turbine component. In an embodiment, the component 300 comprises a gas turbine

component, such as vane, ring segment, or a blade for a gas turbine, which is in a hot gas path of the turbine engine. In an embodiment, the body 302 comprises a CMC material and is formed by a process as described herein or is otherwise provided from a suitable source. In certain 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. In another embodiment, the body 302 comprises a superalloy portion 304 and an inner thermal barrier coating (TBC) 306 disposed over the superalloy portion 304 as is particularly shown in FIG. 22. In still further embodiments, the body 302 may simply comprise a superalloy material. In any case, a printed pattern 308 of a ceramic fiber composite 24, 48 as described herein may be deposited on a surface 310 of the body 302 of the component 300. Advantageously, the ceramic fiber composite 24, 48 can be printed on either a superalloy material (with or without a TBC) or on a CMC substrate, or alternatively on any other suitable substrate so long as there is sufficient attachment of the 3D printed ceramic fiber composite to the substrate.

When the component 300 comprises a superalloy portion 304 (FIG. 22), the term "superalloy" is used herein as it is commonly used in the art to refer to a highly corrosion-resistant and oxidation-resistant alloy that exhibits excellent mechanical strength and resistance to creep even at high temperatures. Exemplary superalloys include, but are not limited to alloys sold under the trademarks and brand names Hastelloy, Inconel alloys (e.g., IN 738, IN 792, IN 939), Rene alloys (e.g. Rene N5, Rene 41 , Rene 80, Rene 108, Rene 142, Rene 220), Haynes alloys, Mar M, CM 247, CM 247 LC, C263, 718, X-750, ECY 768, 262, X45, PWA 1483, CMSX (e.g. CMSX-4) single crystal alloys, GTD 1 1 1 , GTD 222, MGA 1400, MGA 2400, PSM 1 16, CMSX-8, CMSX-10, PWA 1484, IN 713C, Mar-M-200, PWA 1480, IN 100, IN 700, Udimet 600, Udimet 500, and titanium aluminide. The inner TBC 306 (when present) and 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 306 and/or 318 (hereinafter 306, 308) may comprise a degree of porosity suitable for the desired application. In an embodiment, the TBC 306, 318 may comprise a stabilized zirconia material. For example, the TBC 306, 318 may comprise an yttria-stabilized zirconia (YSZ), which includes zirconium oxide (Zr02) with a predetermined concentration of yttrium oxide (Y2O3). In another embodiment, the TBC 306, 318 may comprise a magnesia stabilized zirconia, ceria stabilized zirconia, aluminum silicate, or the like.

In still other embodiments, the TBC 316, 318 may comprise a pyrochlore structure. In an embodiment, the pyrochlore structure has the empirical formula A2B2O7 or in general terms A _v B _x O _z where v = 2, x = 2 and z = 7. Deviations from this

stoichiometric composition for v, x and z may occur as a result of vacancies or minor, deliberate or undeliberate doping. In the formula A _v B _x O _z where v = 2, x = 2 and z = 7, gadolinium (Gd) is typically used for A, and hafnium and/or zirconium (Hf, Zr) are typically used for B. In this case too, minor deviations from this stoichiometry may occur. When Hf and Zr are used as B (e.g., Gdv(Hf _x Zr _y )Oz), x + y = 2. In other embodiments, B = Zr or Hf individually, and the pyrochlore structure may comprise one of gadolinium zirconate (Gd ₂ Zr ₂ 07) or gadolinium hafnate (Gd ₂ Hf ₂ 07). In still other embodiments, the TBC 316, 318 may comprise a bilayer 8YSZ/59 weight percent gadolinium stabilized zirconia (8YSZ/59GZO) coating, a bilayer 8YSZ/30-50 weight percent yttria stabilized zirconia ("30-50 YSZ") coating, or the like.

In yet another embodiment, as shown in FIG. 23, the TBC 306, 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. The ceramic insulating material 319 may comprise any suitable ceramic material as described herein, such as a suitable oxide or non-oxide material. In one aspect, the ceramic material 319 comprising the hollow spheres 321 may be added to the channels 312 defined by segments 314 and over the scaffolding (segments 314) by slurry-based infiltration or the like so as to define the abradable surface 322 (comprising ridges 324).

In accordance with another aspect, a bond coat (not shown) as is known in the art may be utilized to improve adhesion of the TBC (306, 318) to its underlying surface. For example, when a superalloy having an inner TBC 306 thereover is provided as the component 300, the bond coat may be disposed of between the superalloy portion 304 and the inner TBC 306. In addition or instead, a bond coat layer may be disposed over the printed pattern 308 (defined by segments 314) and within the channels 312. The TBC 318 as previously described herein may then be deposited over the bond coat layer. The material for the bond coat layer may comprise any suitable material. For example, an exemplary bond coat layer may comprise a MCrAIY material, where M is a metal such as nickel, cobalt, iron, or mixtures thereof, Cr denotes chromium, Al denotes aluminum, and Y denotes yttrium. In other embodiments, the bond coat layer may comprise alumina. In still other embodiments, the bond coat layer may comprise a rare earth garnet material (e.g., yttrium aluminum garnet (YAG)), a rare earth oxide, or combinations thereof. The bond coat may also be applied by any known process, such as via a thermal spraying or a slurry-based deposition process. Alternatively, the bond coat may be omitted and the TBC 306, 318 may be applied directly onto an exposed surface as described above.

Without wishing to be bound by theory, it is believed that the 3D printed ceramic fiber composite segments 314 provide a degree of mechanical stability to the abradable surface 322 (relative to a TBC alone). In addition, since the abradable surface 322 is at least partially composed of a ceramic fiber composite material, it is believed the temperature resistance of the abradable surface is improved relative to an abradable coating formed from a TBC alone as is known in the art. Further, with the ceramic fiber composite segments 314 in combination with the TBC 318, the likelihood of sintering of the TBC at higher operating temperatures desired in modern engines is significantly reduced. In addition, because the abradable surface 322 described herein is less prone to sintering than a TBC layer alone, components comprising the abradable surfaces described herein may improve turbine performance due to increased abradability and less undesired wear on components, such as blade tips.

To further illustrate an application of a component 300 having the described abradable surface 322, FIG. 24 is a simplified cross-sectional view of a portion of a turbine engine 400 comprising a turbine casing 402 having an inner circumference 404. The engine 400 further includes a rotor having a plurality of blades 408 mounted within the turbine casing inner circumference 404. Typically, there are rows of blades with corresponding vanes - the vanes mounted on the casing 402. For ease of illustration, one row of blades is shown and the vanes are omitted. The blades have distal tips 410 which in operation form or define a blade tip circumferential swept path thereof in a blade rotation direction (R) as shown. In an embodiment, the blade tips 410 also include a lower pressure side downstream of the blade rotational direction and a higher pressure side upstream of the blade rotational direction.

A component 300, e.g., a ring segment 412 is secured to and associated with or otherwise carried by the casing 402. In some embodiments, an intermediate support structure is provided between the ring segment 412 and the casing 402. Each ring segment 412 may comprise an abradable surface 322 as described herein which comprises a three-dimensionally printed pattern 308 of a plurality of segments 314 of a ceramic fiber composite 24,48 disposed on a surface 310 of a body 302 of the component 300. Over the segments 314, there is provided at least a TBC 318 in an amount and pattern effective to provide a three dimensional abradable surface 322 thereon as was shown in FIGS. 20-21 , for example. In this instance, thermal growth of the ring segments 412 and/or the blades 408 may result in contact of the distal tips 410 of the blades 408 with the three-dimensional abradable surface 322 of each ring segment 412 upon movement of the blades 402 in the blade tip circumferential swept path. The contact of the distal tips 410 with the abradable surface 322 will result in the removal of the three dimensional abradable surface 322 by the distal tips 410.

The manufacture of an exemplary component 300 will be 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. In certain embodiments, however, the component 300 may be pre-assembled or pre- manufactured such as when the component 300 comprises a superalloy portion 304 having an existing (inner) TBC layer 306 thereon. To form a 3D printed ceramic fiber composite component, 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 an abradable surface 322 on a surface of the component 300, a printed pattern 308 of the ceramic fiber composite (24 or 48) may be deposited on the component 300. FIG. 20 illustrates a component 300 formed from a ceramic fiber composite (24 or 48). To provide the printed pattern 308, 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 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 certain embodiments, the printed segments 314 are spaced 1 to 10 mm apart; however, it is understood that the present invention is not so limited.

In an embodiment, after deposition of one or more segments 314 on the surface 310 of the component 300, 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 (if present) and TBC 318 therein and/or thereon. When a boat coat layer is utilized, the bond coat layer may be applied by any suitable technique, such as a thermal spray or slurry-based technique. With or without a bond coat, 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 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.

As is shown in FIG. 25, for example, the segments 314 are printed on the body 302 (in this case a CMC body) and the TBC 318 may be deposited thereover as shown in FIG. 26 such that the TBC 318 covers the printed segments 314 and defines a three dimensional abradable surface 322 having a plurality of ridges 324. In the embodiment shown in FIG. 26, the TBC 318 disposed above the printed ceramic fiber composite material (segments 314) provides a textured surface for abradability while the TBC 318 within the channels 312 (between adjacent segments 314) provides additional thermal protection for the underlying component 300.

In another embodiment, as shown in FIG. 27 a printed pattern 308 of the ceramic fiber composite 24, 48 is deposited on a TBC-coated superalloy component 300 having a superalloy portion 304 and a TBC 306 thereon. The materials may then be fired or otherwise heated to a desired temperature to join / bind the printed pattern 308 to the (inner) TBC layer 306. The heating 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 TBC-coated superalloy component 300 is heated 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.

Thereafter, as shown in FIG. 28, an additional TBC material (TBC 318) may be deposited over the inner TBC 306 to form the desired 3D abradable surface 322 comprising abradable ridges 324. The TBC 318 may again 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. The amount of TBC 318 applied may be any amount necessary in order to provide the desired total thickness of TBC material, the desired height/dimensions of the ridges 324, and the desired spacing between adjacent ridges 324.

In accordance with another aspect and as is best shown in FIG. 29, the TBC 318 may be applied over a component (regardless of material) such that TBC 318 fully encompasses the deposited ceramic fiber composite segments 314 and forms a continuous layer 326 thereover, wherein any spacing between adjacent segments 314 is filled with TBC 318 (and optionally bond coat material when present). Upon this continuous layer 326, the 3D abradable surface 322, such as one comprising abradable ridges 324, may be formed by depositing the TBC 318 in a desired amount and in a suitable pattern 328. In certain embodiments, this pattern 328 of TBC 318 deposition may be distinct from the printed pattern 308 of the ceramic fiber composite 24, 48, such as by having greater or lesser spacing between adjacent ridges 324 as compared to the spacing between adjacent segments 314.

In any of the embodiments set forth herein, the abradable ridges 324 may have any desired dimension, such as height, and any suitable cross-sectional shape. In addition, the ridges 324 may have any desired spacing therebetween. Without limitation, the ridges 324 may have any suitable height such as from 0.5 to 20 mm, and in a particular embodiment from 0.5 to 5 mm. In addition, the ridges 324 may have any suitable spacing therebetween, such as from 1 to 20 mm apart from an adjacent ridge, and in a particular embodiment from 3 to 5 mm. It is further contemplated that a variety of different shaped / sized ridges 324 may be applied on a single component 300 to provide the desired abradable surface 322. In certain embodiments, the abradable ridges 324 may comprise one or more rows of first ridges of a first height followed by one or more rows of second ridges of a second height. In addition, the ridges 324 may comprise any suitable orientation or mixture of orientations, such as the angle of the ridges 324 relative to the surface on which they are formed.

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.