U.S. patent application number 17/092541 was filed with the patent office on 2021-02-25 for method of densifying a ceramic matrix composite using a filled tackifier.
The applicant listed for this patent is Raytheon Technologies Corporation. Invention is credited to Jeremy R. Hart, Richard Wesley Jackson, Andrew J. Lazur, Kathryn S. Read.
Application Number | 20210053882 17/092541 |
Document ID | / |
Family ID | 1000005199297 |
Filed Date | 2021-02-25 |
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United States Patent
Application |
20210053882 |
Kind Code |
A1 |
Jackson; Richard Wesley ; et
al. |
February 25, 2021 |
METHOD OF DENSIFYING A CERAMIC MATRIX COMPOSITE USING A FILLED
TACKIFIER
Abstract
A method of producing an enhanced ceramic matrix composite
includes applying a tackifier compound to a fiber preform. The
tackifier compound includes inorganic filler particles. The method
further includes modifying the tackifier compound such that the
inorganic filler particles remain interspersed throughout the fiber
preform, and occupy pores of fiber preform.
Inventors: |
Jackson; Richard Wesley;
(Mystic, CT) ; Read; Kathryn S.; (Marlborough,
CT) ; Hart; Jeremy R.; (Middletown, CT) ;
Lazur; Andrew J.; (Laguna Beach, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Raytheon Technologies Corporation |
Farmington |
CT |
US |
|
|
Family ID: |
1000005199297 |
Appl. No.: |
17/092541 |
Filed: |
November 9, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16422223 |
May 24, 2019 |
10829419 |
|
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17092541 |
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|
15823016 |
Nov 27, 2017 |
10829418 |
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16422223 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B 35/565 20130101;
C04B 35/62863 20130101; C04B 35/634 20130101; C04B 35/515 20130101;
C04B 35/589 20130101; C04B 35/62884 20130101; C04B 35/638 20130101;
C04B 2235/5296 20130101; C04B 35/6264 20130101; C04B 35/63416
20130101; C04B 2235/616 20130101; C04B 35/01 20130101; C04B 35/532
20130101; C04B 2235/5276 20130101; C04B 35/584 20130101; C04B
35/63424 20130101; C04B 35/117 20130101; C04B 35/62871 20130101;
C04B 35/83 20130101; C04B 35/571 20130101; C04B 35/488 20130101;
C04B 35/583 20130101; C04B 35/63432 20130101; C04B 35/64 20130101;
C04B 2235/528 20130101 |
International
Class: |
C04B 35/515 20060101
C04B035/515; C04B 35/589 20060101 C04B035/589; C04B 35/571 20060101
C04B035/571; C04B 35/583 20060101 C04B035/583; C04B 35/117 20060101
C04B035/117; C04B 35/83 20060101 C04B035/83; C04B 35/634 20060101
C04B035/634; C04B 35/01 20060101 C04B035/01; C04B 35/584 20060101
C04B035/584; C04B 35/628 20060101 C04B035/628; C04B 35/565 20060101
C04B035/565; C04B 35/488 20060101 C04B035/488; C04B 35/626 20060101
C04B035/626 |
Claims
1. A method of producing an enhanced ceramic matrix composite, the
method comprising: applying a tackifier compound to a fiber
preform, the tackifier compound comprising inorganic filler
particles; and modifying the tackifier compound such that the
inorganic filler particles remain interspersed throughout the fiber
preform and occupy pores of the fiber preform.
2. The method of claim 1 and further comprising: coating the fiber
preform with an interface coating using a chemical vapor
infiltration or chemical vapor deposition process.
3. The method of claim 1 and further comprising: forming a matrix
surrounding the fiber preform using a chemical vapor infiltration
or chemical vapor deposition process.
4. The method of claim 3 and further comprising: applying a thermal
barrier coating or an environmental barrier coating to the ceramic
matrix composite.
5. The method of claim 1, wherein the tackifier compound further
comprises a solvent and a resin.
6. The method of claim 5, wherein the solvent comprises water,
acetone, ethanol, isopropanol, or toluene.
7. The method of claim 5, wherein the resin comprises
polyvinyl-alcohol, polyvinyl-styrene, or polyacrylate.
8. The method of claim 5, wherein applying the tackifier compound
comprises a technique selected from the group consisting of
spraying, painting, filming, dip-coating, and combinations
thereof.
9. The method of claim 1, wherein the inorganic filler particles
comprise a ceramic material or a preceramic polymer.
10. The method of claim 9, wherein the ceramic material is formed
from a material selected from the group consisting of silicon
carbide, silicon nitride, pure silicon, boron carbide, pure carbon,
aluminum oxide, hafnia, and combinations thereof.
11. The method of claim 9, wherein the preceramic polymer is formed
from a material selected from the group consisting of
polycarbosilane, polycarbosiloxane, polycarbosilazane,
polycarbodiimides, and combinations thereof.
12. The method of claim 11, wherein modifying the tackifier
compound comprises a thermochemical decomposition technique or a
crosslinking technique.
13. An enhanced ceramic matrix composite comprising: a fiber
preform interspersed with inorganic filler particles; and a matrix
formed over the fiber preform and the inorganic filler particles;
wherein the ceramic matrix composite has a porosity of less than
20%.
14. The ceramic matrix composite of claim 13, wherein the inorganic
filler particles comprise spherical particles, chopped fibers, and
combinations thereof.
15. The ceramic matric composite of claim 13, wherein the inorganic
filler particles comprise a ceramic material.
16. The ceramic matrix composite of claim 15, wherein the ceramic
is formed from a material selected from the group consisting of
silicon carbide, silicon nitride, pure silicon, boron carbide, pure
carbon, aluminum oxide, hafnia, and combinations thereof.
17. The ceramic matrix composite of claim 15, wherein the ceramic
is formed from a decomposed preceramic polymer, the preceramic
polymer being formed from a material selected from the group
consisting of polycarbosilane, polycarbosiloxane,
polycarbosilazane, polycarbodiimides, and combinations thereof.
18. The ceramic matrix composite of claim 13, wherein the inorganic
filler particles comprises spherical particles, elongated
particles, and combinations thereof.
19. The ceramic matrix composite of claim 18, wherein a diameter of
the inorganic filler particles ranges from 0.1 micrometer to 500
micrometers.
20. The ceramic matrix composite of claim 18, wherein an aspect
ratio of the inorganic filler particles ranges from 1 to 100.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is a continuation of U.S. application Ser.
No. 16/422,223, filed May 24, 2019, for "Method of Densifying A
Ceramic Matrix Composite Using A Filled Tackifier" by R. W.
Jackson, K. S. Read, J. R. Hart, and A. J. Lazur, which is a
continuation-in-part of U.S. application Ser. No. 15/823,016 filed
Nov. 27, 2017 for "Method of Densifying A Ceramic Matrix Composite
Using a Filled Tackifier" by R. W. Jackson, K. S. Read, J. R. Hart,
and A. J. Lazur.
BACKGROUND
[0002] The present invention relates to the fabrication of ceramic
matrix composites and more particularly, to a ceramic matrix
composite having improved properties for operating in gas turbine
engines.
[0003] Ceramic matrix composites may be fabricated using a chemical
vapor infiltration process, in which a matrix is deposited on a
fiber preform. Deposition occurs more easily on fiber surfaces
rather than in open spaces between fibers. Thus, the open spaces
remain in the resulting composite structure, which can negatively
impact strength and thermal conductivity.
SUMMARY
[0004] A method of producing an enhanced ceramic matrix composite
includes applying a tackifier compound to a fiber preform. The
tackifier compound includes inorganic filler particles. The method
further includes heating the tackifier compound such that the
inorganic filler particles remain interspersed throughout the fiber
preform, and occupy pores of the fiber preform.
[0005] An enhanced ceramic matrix composite includes a fiber
preform interspersed with inorganic filler particles, and a matrix
formed over the fiber preform and the inorganic filler particles.
The ceramic matrix composite has a porosity of less than 6%.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a flow chart illustrating a method of forming an
enhanced ceramic matrix composite using a tackifier.
[0007] FIG. 2 illustrates the composition of the tackifier.
[0008] FIG. 3 is a simplified cross-section of an arrangement of
fiber plies interspersed with inorganic filler particles.
DETAILED DESCRIPTION
[0009] A method of forming a ceramic matrix composite (hereinafter
"CMC") having improved mechanical and thermal properties is
disclosed herein. The method includes applying a tackifier compound
to a fiber preform made up of one or more fiber plies or other
subcomponents. The tackifier compound includes inorganic filler
particles that, after a modification step, remain interspersed
throughout the structure The preform can be subjected to subsequent
processing steps, such as infiltration with reactant vapors to form
a matrix. The inorganic filler particles serve as nucleation sites
for the vaporous deposits, thus forming a more uniform matrix with
increased resistance to environmental degradation.
[0010] FIG. 1 is a flow diagram illustrating selected steps of
method 10, used to produce an enhanced CMC. FIG. 2 illustrates a
tackifier used to produce the enhanced CMC. FIG. 3 is a simplified
cross-section showing a preform as an arrangement of fiber plies to
which a silicon carbide or other ceramic matrix can be applied. At
step 12, a plurality of fiber plies 34 (shown in FIG. 3) are
arranged in a desired manner, such as in a stacked arrangement.
Plies 34 can be formed from woven and/or non-woven ceramic fibers
or tows, which in an exemplary embodiment, can be formed from
silicon carbide. Other suitable ceramics are contemplated herein.
Plies 34 can further be formed from unidirectional and/or
multidirectional (including randomly oriented) fibers. In the
embodiment shown in FIG. 3, plies 34 are generally uniform in their
design, however, alternative embodiments can include any
combination of woven and/or non-woven plies 34, as well as any
combination of fiber orientations.
[0011] At step 16, tackifier 26 is applied to plies 34. As is shown
in FIG. 2, tackifier 26 includes resin 28, carrier solvent 30, and
inorganic filler particles 32. Resin 28 can include a polymer-based
material, such as polyvinyl-alcohol, polyvinyl-styrene, and
polyacrylate, to name a few, non-limiting examples. Carrier solvent
30 can be an organic or inorganic solvent such as water, acetone,
ethanol, isopropanol, toluene, or any compound suitable for
dissolving resin 28. Filler particles 32 can be, in one embodiment,
formed from a stable ceramic material, such as silicon carbide,
boron carbide, silicon nitride, pure silicon, pure carbon, aluminum
oxide, or hafnia. In another embodiment, filler particles 32 can be
formed from a preceramic polymer, such as polycarbosilane,
polycarbosiloxane, polycarbosilazane, or polycarbodiimides, which
pyrolyze to form a silicon-based ceramic. Other suitable
organosilicon compounds are contemplated herein. In yet another
embodiment, filler particles 32 can include preceramic polymers
which decompose to form non-silicon ceramics (zirconium carbide,
hafnium carbide, etc.). Filler particles 32 can account for about
5-60 wt % of tackifier 26, and in an exemplary embodiment, about
20-40 wt % of tackifier 26.
[0012] Filler particles 32 are intended to infiltrate plies 34, and
more specifically, the open spaces/pores 36 of plies 34.
Accordingly, particle dimensions can be tailored to a specific
application. The width of filler particles 32 can range from 0.1
micrometer to 500 micrometers, depending on, for example, the size
of pores 36 needing to be filled. Filler particles 32 can be
spherical particles having an aspect ratio (ratio of particle width
to length) of 1. Filler particles 32 can also be elongated
particles, such as chopped fibers, having aspect ratios ranging
from greater than 1 to 10. In some embodiments, the aspect ratio
can be as great as 100. Tackifier 26 can include filler particles
32 having roughly uniform sizes/dimensions, or it can include
filler particles 32 having varied sizes/dimensions, based on
factors such as the porosity of the individual plies 34, and the
arrangement of plies 34 with respect to one another. For example, a
mixed tackifier 26 (having more than one type of filler particle
32) can be advantageous in certain embodiments where spherical
particles 32 are better suited to fill intra-ply pores 36, while
elongated particles 32 are better suited to fill inter-ply
gaps.
[0013] There are a number of ways to apply tackifier 26 to plies
34. For example, tackifier 26 can be painted or sprayed onto plies
34 as a mixture of each of resin 28, carrier solvent 30, and filler
particles 32. A suitable spraying technique can be, for example, a
slurry coating technique. The mixture can also be formed as a film
adhesive and applied to plies 34. Alternatively, a mixture of resin
28 and carrier solvent 30 can be prepared and applied to plies 34
as described above, while filler particles 32 are subsequently
applied over the wet film or mixture. A dip-coating application
technique is also contemplated herein. In most cases, plies 34
require only a single application of tackifier 26, however,
multiple applications of tackifier 26 can be carried out if
necessary.
[0014] Step 16 further includes modifying tackifier 26 after it is
applied to plies 34, such that filler particles 32 remain
associated with plies 34. The modification step can include a
thermal and/or chemical decomposition technique, such as pyrolysis,
dissolution, or calcination. For example, in embodiments having
ceramic filler particles 32, pyrolysis can be used to burn off
resin 28 and carrier solvent 30 to leave behind the ceramic
particles. In embodiments having preceramic polymer filler
particles 32, pyrolysis can be used to burn off resin 28 and
carrier solvent 30, and also to decompose the preceramic polymer to
a ceramic material. FIG. 3 illustrates plies 34 after the
modification step with filler particles 32 remaining attached to
fiber tows 38 and in pores 36 of plies 34. It is further envisioned
that depending on the composition of tackifier 26, alternative
modification techniques can be used without departing from the
scope of the present invention. Such techniques can include one or
a combination of crosslinking, heating, drying, exposure to
radiation, applying a vacuum, and more.
[0015] At step 20, plies 34 undergo matrix formation and
densification using a chemical vapor infiltration or deposition
(CVI or CVD) process. Plies 34 are infiltrated by reactant vapors,
and a gaseous precursor deposits on the fiber tows 38 and filler
particles 32. Filler particles 32, disposed along all surfaces of
the fiber tows 38 and within pores 36, act as nucleation sites for
the gaseous precursor, thus allowing for a more uniform
distribution of a matrix within plies 34. Vapor infiltration is
carried out until the resulting CMC has reached the desired
residual porosity. In some embodiments, CMCs formed using method 10
can have a residual porosity of 10-20%. In other embodiments,
residual porosity can be below 10%, and in some cases, as low as
3-5%. Further, a fiber volume fraction of a CMC formed using method
10 can range from about 20-75%, and in an exemplary embodiment,
from about 30-60%.
[0016] At step 24, additional coatings can be applied to the CMC.
For example, one or more protective coatings, such an environmental
and/or thermal barrier coatings, can be applied. A bond coat can
also be applied to facilitate bonding between the CMC and
protective coating. Other protective coatings, especially those
suitable for use in a gas turbine engine environment, are
contemplated herein.
[0017] Method 10 further includes optional, intermediate steps 14,
18, and 22, which can be performed variously between steps 12, 16,
20, and 24. For example, step 14 can be a fiber coating step during
which an interface coating is applied to fiber plies 34 using
chemical vapor infiltration. Step 14 can additionally or
alternatively include a preforming/shaping step, as well an initial
round of matrix formation and densification using chemical vapor
infiltration. Depending on the process performed at step 14, step
18 can be any of preforming, interface coating, secondary matrix
formation, or machining. Machining can additionally or
alternatively be performed at step 22. The use and order of
intermediate steps 14, 18, and 22 depends on a number of factors,
such as operating environment, component dimensions, cost, and
labor availability.
[0018] While the disclosed method and tackifier have been described
for use with fiber plies 34 as the fiber preform structure, it
should be understood that the method and tackifier can also be used
on three-dimensional fiber structures. Such three-dimensional
structures can be formed from woven, braided, needled, or stitched
fibers, loosely-associated chopped fibers, and chopped-fiber or
continuous-strand mats, to name a few, non-limiting examples.
Three-dimensional structures can further be formed by joining
together a plurality of individual three-dimensional structures of
any combination, or any combination of one, two, and
three-dimensional fiber structures.
[0019] The disclosed method produces CMCs with reduced porosity
over CMCs produced using other methods. These enhanced CMCs have
improved mechanical and thermal properties ideal for harsh
operating environments like the hot section of a gas turbine
engine. Other aerospace applications include exhaust systems,
ducting, and external systems. The disclosed method can also be
used to produce enhanced CMCs for maritime, power generation, and
industrial applications.
Discussion of Possible Embodiments
[0020] The following are non-exclusive descriptions of possible
embodiments of the present invention.
[0021] A method of producing an enhanced ceramic matrix composite
includes applying a tackifier compound to a fiber preform. The
tackifier compound includes inorganic filler particles. The method
further includes modifying the tackifier compound such that the
inorganic filler particles remain interspersed throughout the fiber
preform, and occupy pores of the fiber preform.
[0022] The method of the preceding paragraph can optionally
include, additionally and/or alternatively, any one or more of the
following features, configurations and/or additional
components:
[0023] The method can further include coating the fiber preform
with an interface coating using a chemical vapor infiltration or
chemical vapor deposition process.
[0024] Any of the above methods can further include forming a
matrix surrounding the fiber preform using a chemical vapor
infiltration or chemical vapor deposition process.
[0025] Any of the above methods can further include applying a
thermal barrier coating or an environmental barrier coating to the
ceramic matrix composite.
[0026] In any of the above methods, the tackifier compound can
further include a solvent and a resin.
[0027] In any of the above methods, the solvent can include water,
acetone, ethanol, isopropanol, or toluene.
[0028] In any of the above methods, the resin can include
polyvinyl-alcohol, polyvinyl-styrene, or polyacrylate.
[0029] In any of the above methods, applying the tackifier compound
can include a technique selected from the group consisting of
spraying, painting, filming, dip-coating, and combinations
thereof.
[0030] In any of the above methods, the inorganic filler particles
can include a ceramic material or a preceramic polymer.
[0031] In any of the above methods, the ceramic material can be
formed from a material selected from the group consisting of
silicon carbide, silicon nitride, pure silicon, boron carbide, pure
carbon, aluminum oxide, hafnia, and combinations thereof.
[0032] In any of the above methods, the preceramic polymer can be
formed from a material selected from the group consisting of
polycarbosilane, polycarbosiloxane, polycarbosilazane,
polycarbodiimides, and combinations thereof.
[0033] In any of the above methods, modifying the tackifier
compound can include a thermochemical decomposition technique or a
crosslinking technique.
[0034] An enhanced ceramic matrix composite includes a fiber
preform interspersed with inorganic filler particles, and a matrix
formed over the fiber preform and the inorganic filler particles.
The ceramic matrix composite has a porosity of less than 20%.
[0035] In the above composite, the inorganic filler particles can
include spherical particles, chopped fibers, and combinations
thereof.
[0036] In any of the above composites, the inorganic filler
particles can be a ceramic material.
[0037] In any of the above composites, the ceramic can be formed
from a material selected from the group consisting of silicon
carbide, silicon nitride, pure silicon, boron carbide, pure carbon,
aluminum oxide, hafnia, and combinations thereof.
[0038] In any of the above composites, the ceramic can be formed
from a decomposed preceramic polymer, and the preceramic polymer
can be formed from a material selected from the group consisting of
polycarbosilane, polycarbosiloxane, polycarbosilazane,
polycarbodiimides, and combinations thereof.
[0039] In any of the above composites, the inorganic filler
particles can include spherical particles, elongated particles, and
combinations thereof.
[0040] In any of the above composites, a diameter of the inorganic
filler particles can range from 0.1 micrometer to 500
micrometers.
[0041] In any of the above composites, an aspect ratio of the
inorganic filler particles can range from 1 to 100.
[0042] While the invention has been described with reference to an
exemplary embodiment(s), it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
* * * * *