U.S. patent application number 16/897486 was filed with the patent office on 2021-02-04 for method for making hybrid ceramic/metal, ceramic/ceramic body by using 3d printing process.
The applicant listed for this patent is General Electric Company. Invention is credited to Brian Peterson, Xi Yang.
Application Number | 20210031404 16/897486 |
Document ID | / |
Family ID | 1000005164035 |
Filed Date | 2021-02-04 |
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United States Patent
Application |
20210031404 |
Kind Code |
A1 |
Yang; Xi ; et al. |
February 4, 2021 |
METHOD FOR MAKING HYBRID CERAMIC/METAL, CERAMIC/CERAMIC BODY BY
USING 3D PRINTING PROCESS
Abstract
This invention relates to a product and a method of preparing
ceramic and/or ceramic hybrid materials through the construction of
a printed die. The printed die being made by three dimensional
printing or additive manufacturing processes possesses both an
external geometry and an internal geometry.
Inventors: |
Yang; Xi; (Mason, OH)
; Peterson; Brian; (Madeira, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
1000005164035 |
Appl. No.: |
16/897486 |
Filed: |
June 10, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14991413 |
Jan 8, 2016 |
10697305 |
|
|
16897486 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B 2237/341 20130101;
C04B 2237/345 20130101; B32B 18/00 20130101; C04B 35/14 20130101;
C04B 2235/945 20130101; B28B 11/24 20130101; B28B 7/342 20130101;
C04B 2235/94 20130101; F05D 2300/603 20130101; F01D 5/18 20130101;
C04B 35/111 20130101; B29K 2101/12 20130101; C04B 2235/6028
20130101; C04B 35/505 20130101; C04B 35/622 20130101; B28B 1/008
20130101; B28B 1/14 20130101; C04B 2237/84 20130101; B28B 23/02
20130101; F05D 2300/20 20130101; B29L 2031/757 20130101; C04B
2237/343 20130101; C04B 35/48 20130101; C04B 2235/483 20130101;
C04B 2235/6022 20130101; F05D 2220/30 20130101; C04B 37/021
20130101; C04B 37/001 20130101; F05D 2230/211 20130101; B29K
2101/10 20130101 |
International
Class: |
B28B 1/00 20060101
B28B001/00; B28B 1/14 20060101 B28B001/14; B28B 11/24 20060101
B28B011/24; B28B 23/02 20060101 B28B023/02; F01D 5/18 20060101
F01D005/18; C04B 37/02 20060101 C04B037/02; B28B 7/34 20060101
B28B007/34; C04B 37/00 20060101 C04B037/00; B32B 18/00 20060101
B32B018/00; C04B 35/14 20060101 C04B035/14; C04B 35/111 20060101
C04B035/111; C04B 35/505 20060101 C04B035/505; C04B 35/48 20060101
C04B035/48; C04B 35/622 20060101 C04B035/622 |
Claims
1. A ceramic composite comprising a ceramic body including external
features corresponding to a mold pattern and at least one internal
cavity; and at least a second material within the internal cavity
that is different than the ceramic body, wherein the geometry of
the at least one internal cavity includes at least one of an aspect
ratio in the range of 100:1 to 5:1 or a diameter in the range of
approximately 0.010 inch to 0.100 inch.
2. The ceramic composite of claim 1, wherein the second material
includes a metal insert of a geometry that matches the geometry of
the at least one internal cavity.
3. The ceramic composite of claim 1, wherein the second material
includes a ceramic material that is different than the ceramic
body.
4. The ceramic composite of claim 1, wherein the second material is
a rod of alumina or quartz.
5. The ceramic composite of claim 4, wherein the rod includes a
ceramic coating that is sintered to the ceramic body such that a
sintered bond exists between the ceramic body and the rod and
wherein the rod reinforces the ceramic body.
6. The ceramic composite of claim 1, wherein the second material is
sintered to the ceramic body such that the first and second
materials together form a contiguous structure in which the second
material reinforces the ceramic body.
7. The ceramic composite of claim 6, wherein the internal cavity is
non-linear.
8. The ceramic composite of claim 1, wherein the internal cavity is
non-linear and the geometry of the second material matches the
geometry of the at least one internal cavity.
9. A ceramic composite comprising a ceramic body including external
features corresponding to a mold pattern and at least one
non-linear internal cavity having an aspect ratio in the range of
100:1 to 5:1; and at least a second material within the internal
cavity that is different than the ceramic body, wherein the second
material is sintered to the ceramic body such that the first and
second materials together form a contiguous structure in which the
second material reinforces the ceramic body.
10. The ceramic composite of claim 9, wherein the second material
is a ceramic-coated metal or ceramic insert in which the ceramic
coating is sintered to the ceramic body.
11. The ceramic composite of claim 9, wherein the second material
is an injected ceramic material cured and sintered to the ceramic
body.
12. A ceramic composite comprising a ceramic body including
external features corresponding to a mold pattern and at least one
internal cavity, the internal cavity having a diameter in the range
of 0.010 inch to 0.100 inch; and an insert within the internal
cavity that includes at least one material that is different than
the ceramic body, wherein the insert is a ceramic-coated rod of
alumina, quartz, or metal with the ceramic coating sintered to the
ceramic body such that a sintered bond exists between the ceramic
body and the rod and wherein the rod reinforces the ceramic
body.
13. The ceramic composite of claim 12, wherein the insert is a
ceramic-coated alumina rod.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. application Ser.
No. 14/991,413, filed on Jan. 8, 2016, titled "METHOD FOR MAKING
HYBRID CERAMIC/METAL, CERAMIC/CERAMIC BODY BY USING 3D PRINTING
PROCESS", which is hereby expressly incorporated herein by
reference in its entirety.
INTRODUCTION
[0002] This invention generally relates to reinforced ceramic or
ceramic composite materials, and methods for preparing said
materials, components, and/or structures through additive printing
techniques, where the composite materials have both internal and
external geometries, and more particularly to methods of using
additive printing technologies to make functional composite or
hybrid components.
BACKGROUND
[0003] The present invention generally relates to a method of using
additive manufacturing processes to produce reinforced ceramic or
ceramic composite materials, such as but not limited to
ceramic-ceramic or ceramic-metal hybrid (i.e., cermet)
materials.
[0004] Many modern engines and next generation turbine engines
require components and parts having intricate and complex
geometries, which require new types of materials and manufacturing
techniques. One such material includes ceramic components and
parts, which reduce the need for cooling and are much lighter than
conventional alloy materials in current engines. Integration of
ceramics into next generation engine thus has the advantages of
being lighter, chemically inert, and highly heat resistant.
However, ceramics are also known to be weak in shearing and
tension, and too brittle for use in certain applications. Thus,
there is a need to develop new ceramic composites and methods of
manufacturing these ceramic parts.
[0005] Conventional techniques for manufacturing engine parts and
components involve the laborious process of investment or lost-wax
casting. One example of investment casting involves the manufacture
of a typical rotor blade used in a gas turbine engine. A turbine
blade typically includes hollow airfoils that have radial channels
extending along the span of a blade having at least one or more
inlets for receiving pressurized cooling air during operation in
the engine. Among the various cooling passages in the blades,
includes serpentine channel disposed in the middle of the airfoil
between the leading and trailing edges. The airfoil typically
includes inlets extending through the blade for receiving
pressurized cooling air, which include local features such as short
turbulator ribs or pins for increasing the heat transfer between
the heated sidewalls of the airfoil and the internal cooling
air.
[0006] The manufacture of these turbine blades, typically from high
strength, superalloy metal materials, involves numerous steps.
First, a precision ceramic core is manufactured to conform to the
intricate cooling passages desired inside the turbine blade. A
precision die or mold is also created which defines the precise 3-D
external surface of the turbine blade including its airfoil,
platform, and integral dovetail. The ceramic core is assembled
inside two die halves which form a space or void therebetween that
defines the resulting metal portions of the blade. Wax is injected
into the assembled dies to fill the void and surround the ceramic
core encapsulated therein. The two die halves are split apart and
removed from the molded wax. The molded wax has the precise
configuration of the desired blade and is then coated with a
ceramic material to form a surrounding ceramic shell. Then, the wax
is melted and removed from the shell leaving a corresponding void
or space between the ceramic shell and the internal ceramic core.
Molten metal is then poured into the shell to fill the void therein
and again encapsulate the ceramic core contained in the shell. The
molten metal is cooled and solidifies, and then the external shell
and internal core are suitably removed leaving behind the desired
metallic turbine blade in which the internal cooling passages are
found.
[0007] The cast turbine blade may then undergo additional post
casting modifications, such as but not limited to drilling of
suitable rows of film cooling holes through the sidewalls of the
airfoil as desired for providing outlets for the internally
channeled cooling air which then forms a protective cooling air
film or blanket over the external surface of the airfoil during
operation in the gas turbine engine. However, these post casting
modifications are limited and given the ever increasing complexity
of turbine engines and the recognized efficiencies of certain
cooling circuits inside turbine blades, the requirements for more
complicated and intricate internal geometries is required. While
investment casting is capable of manufacturing these parts,
positional precision and intricate internal geometries become more
complex to manufacture using these conventional manufacturing
processes. Accordingly, it is desired to provide an improved
casting method for three dimensional components having intricate
internal voids.
[0008] Additive manufacturing processes have simplified the above
described process by allowing the manufacture of synthetic model
casting. In particular, a model of a component may be created by
additive manufacturing techniques or 3D printing. A core is cast
inside a synthetic model. The synthetic model may then be removed
from the cast core, and then the cast core is used for casting an
authentic component therearound. The core is removed from inside
the authentic component, with an authentic component precisely
matching the original synthetic model. This technology effectively
creates a disposable core die (or "DCD"). U.S. Pat. No. 7,413,001
describes one application of this process.
[0009] The immediate application of this DCD technology allows the
industry to produce complex components, structures, and parts using
new combinations of materials or hybrid materials that can be
incorporated into next generation engines. The DCD process has been
demonstrated with success to accomplish this endeavor by utilizing
additive manufacturing methods to produce master dies or DCDs that
have geometries not previously achieved or at the very least more
efficiently than previously accomplished through conventional
investment casting processes.
[0010] The present invention applies the DCD additive printing
technologies previously described to create a new family of hybrid
materials and functional components that were previously never
possible to produce by conventional manufacturing processes. In
particular, the current invention overcomes the problems associated
with investment and/or lost-wax casted products that lack intricate
or complex internal geometries, cavities, or hollows. Particularly
valuable materials would be ceramic-ceramic and ceramic-metal
composite/hybrid systems. The present invention also solves some of
the problems associated with conventional casting techniques, such
as but not limited to core kissout, tipping, cracking scraps.
BRIEF DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION
[0011] The disclosure is generally directed to a method of
manufacturing complex components, structures, or parts by
additively printing a die. An illustrative embodiment of the method
includes additively manufacturing a disposable die, in particular,
three dimensionally printing a disposable die. In another
embodiment, the die has an internal opening or void, which defines
a particular three dimensional internal cavity or body. In another
aspect, the core has an internal opening defining a three
dimensional body in addition to having an external geometry.
[0012] In one aspect, the invention relates to a process of
manufacturing materials, components, parts, or structures having
complex hollow internal geometries manufactured through an additive
manufacturing (also known as 3D printing) process. Subsequently,
the hollow internal geometries or cavities may be further injected
or filled with a slurry, fluid or solid material(s).
[0013] In another aspect, the invention relates to a process of
manufacturing materials, components, or structures having
particular internal or external geometries or features by first
creating a die through the additive manufacturing or three
dimensional printing process, followed by incorporating or
injecting one or more slurries, such as ceramic, into the die,
resulting in a three dimensional body. The three dimensional body
may, in one embodiment, have a hollow cavity defining a three
dimensional internal shape or geometry into which another liquid,
semi liquid, or solid material may be incorporated. In another
embodiment, the three dimensional body may be a solid material such
as but not limited to alumina, aluminum titanate, magnesium oxide,
or nickel oxide.
[0014] In yet another aspect, the die may be used to produce a
composite material having both a first phase of ceramic material
and a second phase of either solid or liquid materials. In one
embodiment, the second phase material may be the same or different
type of ceramic material. In another embodiment, the second phase
material may be a solid material (e.g., metal). The produced
composite material may include ceramic materials in both the first
and second phase to generate a ceramic-ceramic material. In an
alternative embodiment, the produced composite material may include
a ceramic material in the first phase and a solid, such as a metal
made of alumina, aluminum titanate, magnesium oxide, or nickel
oxide, for example, as the second phase.
[0015] In another aspect, the invention relates to a process of
manufacturing a DCD that is used to create materials that are
hybrid composites having both a ceramic phase and a metal phase.
First, a slurry of ceramic material is injected into the DCD, which
can be made of a variety of plastics and cured, thereby forming a
three dimensional shell. In one embodiment, the DCD is manufactured
in a way that would allow for the formation of a hollow cavity
after the ceramic material is injected into the DCD. Second, after
curing and firing the ceramic material, a metal component or phase
is incorporated into the hollow cavity. In another embodiment, the
metal phase is a preformed metal composition that matches the
internal geometry of the formed ceramic cavity.
[0016] In yet another embodiment, the invention relates to an
additive manufacturing process (e.g., three dimensional or 3D
printing) to produce a die containing a complex internal hollow
cavity or geometry having a certain internal and external
geometrical aspect. The portions surrounding the hollow cavity may
be filled with a first type of ceramic material, while the hollow
internal geometry may be injected or filled during a second phase
with the same or different type of ceramic material. In yet another
embodiment, the ceramic body containing the hollow or cavity may
further comprise a second phase that is a metal component having a
geometry that matches the internal geometry created using the DCD
such that the metal component fits in a lock and key fashion.
[0017] In one aspect of the invention, additive printing
technologies are utilized in a method to manufacture and create
novel families of hybrid materials and functional components not
previously possible using conventional manufacturing processes. In
particular, one aspect of the invention includes hybrid
ceramic-ceramic materials, whereby the first ceramic material is
the same as the second ceramic material. In another aspect, the
hybrid ceramic-ceramic material may be at least two different types
of ceramic materials. In yet another aspect, the invention includes
a hybrid ceramic-metal composite.
[0018] In another embodiment, the invention relates to a component,
part, or structure manufactured according to the present invention.
In particular, the component, part or structure includes an
external surface, shape, or geometry that is formed by
incorporating or injecting a first phase of liquid or semi-solid
material, such as ceramic, into an additively printed die. The
first phase occupies the portion of the printed die corresponding
to the external portion of the component, part, or structure. In
addition, the component, part or structure will also include an
internal void, cavity, or hollow that may be filled or injected
with a second phase of material. The material present in the second
phase may include solid, semi-liquid, or liquid material. The
internal void, cavity, or hollow is created and separated from the
first phase by a disposable die, which is removed following the
incorporation of the first phase.
[0019] In yet another embodiment, the invention relates to a method
of forming a composite structure comprising the steps of: (a)
printing a die (10) having an external shape portion (300, 400)
defining a three dimensional body and an internal shape portion
(100, 200); (b) injecting a first material into the external shape
portion (300, 400) of the die, wherein the external shape leaves a
hollow within the internal shape portion (100, 200); (c) curing the
first material to form the three dimensional body; (d) inserting or
injecting at least one other material into the hollow portion of
the internal shape portion (100, 200); and (e) sintering the three
dimensional body after step (d) to form the composite
structure.
[0020] In yet another embodiment, the invention relates to a method
of forming a composite structure comprising adding a first material
into a die having a cavity, wherein the cavity includes at least
one protrusion within the cavity, and curing the first material to
form a three dimensional body. Additional embodiments of this
method include the following: [0021] wherein the first material is
added by injection; [0022] wherein the first material is an
inorganic material; [0023] wherein the cavity is produced by
additive manufacturing the die, preferably by three dimensional
printing; [0024] wherein the die is fabricated from thermoset or
thermoplastic polymer; [0025] wherein the at least one protrusion
within the cavity is a hollow or a solid protrusion; [0026] wherein
the at least one protrusion is hollow; [0027] wherein the at least
one protrusion is of a non-linear geometry; [0028] wherein the die
is removed during the curing of the first material, thereby leaving
at least one void where the at least one protrusion once existed;
[0029] wherein the die is removed by heating in the range of
300-600.degree. C.; [0030] further comprising adding at least one
other material into the at least one void; [0031] wherein the at
least one other material is a solid or liquid material; [0032]
wherein the at least one other material is ceramic or metal; [0033]
wherein the metal is rod of alumina or quartz; [0034] further
comprising incorporating a binder prior to adding the at least one
other material; [0035] wherein the binder is applied to the at
least one void, the at least one other material, or to both; [0036]
further comprising sintering or curing the at least one other
material; and [0037] wherein the sintering or curing occurs at a
temperature in the range of 1,000-1,600.degree. C., preferably
1,600.degree. C.
[0038] In still yet another embodiment, the invention relates to a
ceramic-metal composite comprising a ceramic body representing an
external portion (300, 400) of the composite, wherein the ceramic
body includes an internal hollow cavity (100, 200) having an aspect
ratio in the range of 100:1 to 5:1; and a metal insert capable of
being inserted into the internal hollow cavity; and a ceramic-metal
composite comprising a ceramic body representing an external
portion, wherein the ceramic body includes an internal hollow
cavity (100, 200) with an outside diameter in the range of
approximately 0.010 inch to 0.100 inch and a depth of approximately
1 inch to 40 inches; and a metal insert capable of being inserted
into the internal hollow cavity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1: A perspective view of a representative component
(10) having both simple internal (200) and external geometries
(400) and complex internal (100) and external (300) geometries.
[0040] FIG. 2: A perspective view as described in FIG. 1
demonstrating the addition of a slurry material into the component
prior to curing.
[0041] FIG. 3: A perspective view as described in FIG. 1
demonstrating the cured first phase of material in the complex
external portion (300) and the simple external portion (400)
wherein the complex internal portion (100) and the simple internal
portion (200) remain unfilled provide for a channel for addition of
a second phase of material.
[0042] FIG. 4: A perspective view as described in FIG. 1
demonstrating the addition or insertion of a second phase of
material into complex internal portion (100) and into simple
internal portion (200).
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0043] Further features and advantages of the invention will be
seen from the following detailed description, which shows various
embodiments of the invention. Those of skill in the art will
recognize that other embodiments may be utilized, which include
changes that do not alter or depart from the scope of the
invention.
[0044] In one preferred embodiment of the invention, an additive
manufacturing, an additive printing, a sequential printing or a
three dimensional (3D) printing process is used to form a variety
of geometrical shapes, cores and moulds which may be used in the
fabrication of ceramic or ceramic composite materials. In one
embodiment, a slurry of ceramic material is injected into an
additively manufactured DCD, resulting in the formation of a three
dimensional ceramic body. In one aspect, the resulting ceramic body
contains an internal hollow or cavity into which a second phase or
second fabrication process is used to introduce another ceramic
material or metallic material to form a composite material. In one
aspect, the second phase may include the same or different ceramic
material. In another aspect the second phase may include a metal
material, such as a rod, thereby producing a composite material or
hybrid material. After the second phase, the materials may be
sintered at elevated temperatures to result in a dense material
(i.e., densification). The resulting hybrid material, for example
containing the metal rod, is reinforced having higher structural
integrity when compared to components or parts lacking the metal
rod.
[0045] The reinforcement, which may have been previously
accomplished by incorporating a metal rod into a simple geometry
(e.g., straight or non-curved) by drilling, for example, is now
possible in more intricate or complicated geometries or shapes
through the present invention.
[0046] As an example, FIG. 1 demonstrates a part or component
having a complex external geometry, 300, a complex internal
geometry 100, a simple external geometry 400, and a simple internal
geometry 200. Previously, simple internal geometries created by
investment or lost-wax casting, such as 200, were created by
methods such as drilling, however, more complex geometries, such as
100, were not possible given the difficulty in drilling, for
example curved holes. The present invention overcomes these issues
by fabricating complex internal geometry through additively
printing a DCD structure such that a hollow cavity is incorporated
into the external geometry 300, 400.
[0047] In FIG. 1, a representative component, part or structure
(10) is designed and additively printed such that the component,
part or structure has an external (300, 400) and internal (100,
200) shell made of a resin, such as but not limited to plastics. As
seen from the cut out portions, the additively manufactured
component includes hollow channels (100, 200) such that when a
first phase of material is cured and the disposable die is removed,
channels (100, 200) are created within the cured material of the
external portions (300, 400).
[0048] In FIG. 2, the external portions (300, 400) of the
additively printed component are filled with a slurry of, for
example, ceramic material, such that the slurry leaves a void,
hollow or cavity (100, 200) created by the internal void, hollow,
or cavity. The component, part or structure at this stage includes
an additively printed shell, having both external and internal
dimensions, and a slurry of materials that will be cured at a
temperature of approximately 300.degree. C.-500.degree. C. This
temperature serves two purposes, (1) to cure the slurry material of
the external portion of the component and (2) to burn off (i.e.,
remove) the additively printed plastic die.
[0049] In FIG. 3, the external portions (300, 400) of the
component, part or structure have undergone curing and the die is
removed through leaving a cured ceramic external three dimensional
body (300, 400) and an internal void, hollow, or cavity (100, 200).
The cut away of the external portion shows that the internal void,
hollow or cavity remains after the burn off.
[0050] In FIG. 4, the second phase of material (e.g., a liquid
material or a solid material) is added or inserted to the internal
portions (100, 200) of the body. Once again, the component, part or
structure is heat to a temperature of approximately 1600.degree. C.
to sinter the first and second phase of material together to form a
singular composite or hybrid material.
[0051] In one aspect, the invention relates to a method of forming
a composite structure comprising additively manufacturing a DCD;
injecting a first material into the disposable core die; curing or
firing the first material to form a three dimensional body;
removing the disposable core die to form a hollow body or cavity
that has a specific geometry; inserting (injecting) at least one
other material into the hollow body (e.g., a liquid or solid); and
sintering the materials to form the composite or hybrid
structure.
[0052] Additive manufacturing technology is a manufacturing process
where a structure is built layer-by-layer with the assistance of
computer programs, such as a Computer Aided Design (CAD) program.
The CAD software, for example, helps in fabricating each planar
layer by depositing a building material in certain X, Y, and Z
coordinates until a final three dimensional structure is complete.
With additive manufacturing, there is no need to develop or
manufacture patterns or tools (i.e., casts or molds) to fabricate
parts, thereby significantly decreasing the build times. In one
aspect of the present invention, those of skill in the art will
appreciate that a variety of computer software programs, such as
CAD, may be used, so long as it is capable of programming specific
coordinates in the fabrication of the DCD during the build process.
Encompassed within the scope of this invention is a method of using
an additive printing process that moves and fabricates in three
dimensions (e.g., in the X, Y, and Z directions). Also encompassed
in this invention is a fabrication process that moves in two
dimensions where the manufacturing process produces the product in
strips, one layer at a time. Therefore, movement is only required
in the Y direction to form a layer, and then the Z direction to
build the next layer. Finally, some emerging technologies are using
a two dimensional array of mirrors to form an entire part layer at
once, requiring movement in only one direction, the Z
direction.
[0053] There are various types of additive manufacturing
technologies available to those of skill in the art and the
particular type selected for the fabrication of the DCD will depend
entirely on the material used in its production. One type of 3D
printing may include liquid-based methods, which apply photocurable
polymer resins to form each part layer. These might include
stereolithography (SLA), jetted photopolymer, or ink jet printing.
For example, SLS printing is a well known technique that can be
described as a process that utilizes a liquid plastic resin that is
selectively cured with ultraviolet light in thin cross sections.
The thin cross sections are formed layer-by-layer.
[0054] Another type of additive printing includes powder based
printing process, such as selective laser sintering (SLS), direct
metal laser sintering (DMLS) and three dimensional printing (3DP).
In each of these powder based fabrication methods, powdered
material is melted or sintered to form each part layer. For
example, the SLS process utilizes powdered plastic materials that
are selectively sintered by a laser layer-by-layer.
[0055] Another form of additive printing includes a solid-based
process, which use non-powdered materials that are layered one on
top of another and subsequently cut out. This method includes
laminated object manufacturing (LOM), or fused deposition modeling
(FDM).
[0056] Generally, the additive manufacturing process takes on the
same sequence of steps, which as described at custompartnet.com,
includes:
[0057] 1. Create CAD model--For all additive processes, the
designer must first use Computer-Aided Design (CAD) software to
create a 3-D model of the part.
[0058] 2. Convert CAD model into STL model--Each form of CAD
software saves the geometric data representing the 3-D model in
different ways. However, the STL format (initially developed for
Stereolithography) has become the standard file format for additive
processes. Therefore, CAD files must be converted to this file
format. The STL format represents the surfaces of the 3-D model as
a set of triangles, storing the coordinates for the vertices and
normal directions for each triangle.
[0059] 3. Slice STL model into layers--Using specialized software,
the user prepares the STL file to be built, first designating the
location and orientation of the part in the machine. Part
orientation impacts several parameters, including build time, part
strength, and accuracy. The software then slices the STL model into
very thin layers along the X-Y plane. Each layer will be built upon
the previous layer, moving upward in the Z direction.
[0060] 4. Build part one layer at a time--The machine builds the
part from the STL model by sequentially forming layers of material
on top of previously formed layers. The technique used to build
each layer differs greatly amongst the additive process, as does
the material being used. Additive processes can use paper,
polymers, powdered metals, or metal composites, depending upon the
process.
[0061] 5. Post-processing of part--After being built, the part and
any supports are removed from the machine. If the part was
fabricated from a photosensitive material, it must be cured to
attain full strength. Minor cleaning and surface finishing, such as
sanding, coating, or painting, can be performed to improve the
part's appearance and durability.
[0062] The additive manufacturing process can fabricate dies or
master dies out of virtually any type of material generally known
and used in the additive manufacturing process. These materials may
include, for example, plastics, metals, ceramics, or wood. It is
also possible that the additive manufacturing process can fabricate
the DCD out of a combination of materials. For example the
manufacturing process can be made from a polymeric material, such
as ultraviolet curable thermosets (e.g., epoxy, resin, urethane,
cyanoacrylate, photopolymers, etc.) and powdered materials (e.g.,
nylon, glass filled nylon, polycarbonate, wax, metal, and sand
bonded with heat cured resin). Other materials which would be
readily apparent to those in the field may also be used in the
process.
[0063] Representative materials used in the 3D printing process
include polymers, such as thermoset and thermoplastic polymers.
Representative thermoset polymers may include, for example,
polymers belonging to the class of polyester, polyurethane,
vulcanized rubber, a phenol-formaldehyde resin, duroplast, urea
formaldehydes, melamine resin, diallyl-phthalate (DAP), epoxy
resin, polyimides, or cyanate esters or polycyanurates or
combinations thereof.
[0064] Representative thermoplastic polymers may include, for
example, polymers belonging to the class acrylic, acrylonitrile
butadiene styrene, nylon, polylactic acid, polybenzimidazole,
polycarbonate, polyether sulfone, polyetherether ketone,
polyetherimide, polyethylene, polyphenylene oxide, polyphenylene
sulfide, polypropylene, polystyrene, polyvinyl chloride, Teflon, or
combinations thereof.
[0065] In another aspect of the present invention, ceramic or
ceramic hybrid components, parts or structures are created that
have intricate or complex internal and external geometries. In
conventional investment casting techniques, injection of materials
into a cast results in the production of structures, components, or
parts that have specific external geometries. However, should a
specific internal geometry be required, a separate core having the
mirror image of the shape is required. These specific geometries
are dictated by the external mold or internal core in which they
are injected. In one aspect of the invention, the fabrication of a
core die used in the casting process results in a product having
specific internal and external geometries without the need to
separately produce an external and/or internal mold and/or
core.
[0066] The term "internal geometry" is generally understood to mean
any cavity, hollow, opening having a complex or simple shape or
geometry that is within an external geometry. A representative
example, of an internal geometry may be found in FIG. 1, 100 or
200.
[0067] The term "external geometry" is generally understood to mean
an outer shape or configuration of a body or three dimensional
body. A representative example of an external geometry may be found
in FIG. 1, 300 or 400.
[0068] Following the additive manufacturing of the die (e.g., DCD),
a first slurry of materials is incorporated into the die. This
portion of the fabrication process may be the first phase of
fabrication. The first slurry may include a variety of material
that can be cured and injected into the die. In one aspect of the
invention, the slurry of material is an inorganic material, such as
but not limited to a ceramic slurry. The ceramic material may be a
powder or fibrous material. A variety of ceramic materials may be
used including, but not limited to, metallic oxides (e.g., alumina,
beryllium oxides, and zirconia), glass ceramics, nitrides and
carbides (e.g., silicon nitrides, boron carbide, silicon carbides,
and tungsten carbides), glass (e.g., oxide (silica), silicates,
phosphates, borosilicates), carbon and graphite (e.g.,
carbon-carbon composites), porcelain, yttria, and ceramic fibers.
Upon injection of the ceramic material into the core die, the
ceramic slurry forms a three dimensional structure or green ceramic
body. The "green ceramic body" or "green body" is generally
understood by those of skill in the art to represent a three
dimensional body that is composed of a weakly bonded ceramic
material prior to curing, sintering or firing. The curing,
sintering or firing may occur at temperatures now known or future
developed. In one embodiment, the curing temperature is less than
about 100.degree. C.
[0069] Once the green body is formed, the die can or may be removed
through heating. In one embodiment, the elevated temperature
simultaneously removes the die and sinters or cures the first
slurry (e.g., ceramic). In another embodiment, the elevated
temperature is sufficient to remove the die, but less than the
required temperature to cure the first slurry. The removal of the
die may be accomplished in a range of at least 300.degree. C., in a
more preferred embodiment, the die is removed at a temperature
range of approximately a temperature range of 300-600.degree. C.,
in an even more preferred embodiment, the die is removed at a
temperature range of 400-500.degree. C. The heating or firing to
remove the die can be performed one, two, three, four, five, ten,
or as many times as needed to accomplish the removal and/or
densification of the first slurry.
[0070] In another embodiment, a second phase of fabrication for
introducing a second type of materials may be combined with the
first phase of materials. For example, between each heating or
firing step a second slurry of ceramic or solid material may be
incorporated. In one embodiment, a second slurry of material, such
as ceramic, may be incorporated. In another embodiment, the second
ceramic slurry may be same or different from the first slurry. In
another aspect, the hollow cavity may be fabricated to accept a
solid material, such as but not limited to metal component (e.g., a
rod) which in one aspect can be preformed to match the internal
geometry of the hollow cavity. The various alternative embodiments
for materials (e.g., ceramics) and processes described for previous
embodiments are equally applicable during the second phase of
fabrication.
[0071] In another aspect of the invention, following the curing of
the first slurry of materials, a binder may be applied before,
during or after the injection of the second phase of the
fabrication process. The binders that may be used include organic
and inorganic materials. These binder materials are generally known
in the art and described in, for example, U.S. Pat. No.
5,204,055.
[0072] The binder material may be such that the bonded particles
have a high binding strength as each layer is deposited so that,
when all the layers have been bonded, the component formed thereby
is ready for use without further processing. In other cases, it may
be desirable, or necessary, to perform further processing of the
part. For example, while the process may be such as to impart a
reasonable strength to the component which is formed, once the part
is formed it can be further heated or cured to further enhance the
binding strength of the particles. The binder in some cases can be
removed during such heating or firing process, while in others it
can remain in the material after firing. Which operation occurs
depends on the particular binder material which has been selected
for use and on the conditions, e.g., temperature, under which the
heating or firing process is performed. Other post-processing
operations may also be performed following the part formation.
[0073] Organic binders have been used in the ceramics industry and
are typically polymeric resins obtained from a variety of sources.
They can be either water soluble, such as celluosic binders, as
used in extrusion technology, or they can be soluble in only
volatile organic solvents, such as the butyral resins, as used in
tape casting technology. The latter water soluble systems can be
removed relatively quickly and seem particularly useful in the
technique of the invention. Another type of organic binder would be
a ceramic precursor material such as polycarbosilazane.
[0074] Inorganic binders are useful in cases where the binder is to
be incorporated into the final component. Such binders are
generally silicate based and are typically formed from the
polymerization of silicic acid or its salts in aqueous solution.
Another exemplary inorganic binder which can be used is TEOS
(tetraethylorthosilicate). During drying, the colloidal silica
aggregates at the necks of the matrix particles to form a
cement-like bond. During firing, the silica flows and acts to
rearrange the matrix particles through the action of surface
tension forces and remains after firing. Soluble silicate materials
have been used as binders in refractory castable materials, for
example, and have the advantage, when used in the technique of the
invention, of producing substantially the same type of molded
refractory body that is used in the casting industry.
[0075] In some applications, it may be preferable that the binder
harden relatively rapidly upon being deposited so that the next
layer of particles placed on a surface of the previous layer is not
subject to particle rearrangement due to capillary forces.
Moreover, a hardened binder is not subject to contamination from
solvents which may be used in powder deposition. In other cases, it
may not be necessary that the binder be fully hardened between
layers and a subsequent layer of powder particles may be deposited
on a previous layer which is not yet fully hardened.
[0076] Where hardening occurs at the time the binder is deposited,
thermal curing, i.e., evaporation of the binder carrier liquid, for
such purpose would generally require that the component being
formed be warmed as the printing of the binder material is
performed, while the printhead itself is cooled so that unprinted
binder material in the reservoir of the ink-jet head retains its
desired properties. Such hardening can be achieved by heating the
binder material indirectly, as by heating the overall apparatus in
which the part is being formed using an appropriate external heat
source, for example, or by heating the binder material directly as
by applying hot air to the binder material or by applying infra-red
energy or microwave energy thereto. Alternatively, a variety of
thermally activated chemical reactions could also be used to harden
the binder. For example, gelation of alkali silicate solutions can
be made to occur by a change in pH accompanying the decomposition
of organic reagents. Thus, a mixture of alkali silicate and
formamide could be printed on to a hot component being formed. The
rapid increase in temperature would greatly increase the formamide
decomposition rate and, therefore, rapidly change the pH of the
binder. Other thermally or chemically initiated techniques for
hardening of the binder upon deposit thereof could be devised
within the skill of those in the art.
[0077] While liquid and colloidal binder materials have been
discussed above, in some applications binder material may be
deposited in the form of binder particles entrained in a liquid.
Such binder materials can be supplied via specially designed
compound ink-jet structures capable of providing such entrained
binder materials. An example of such a composite structure is
discussed, for example, in the article "Ink-Jet Printing," J.
Heinzle and C. H. Hertz, Advances In Electronics and Electron
Physics, Vol. 65.
[0078] Moreover, in some applications in the fabrication of a part,
the binder material which is used need not be a single binder
material, but different binder materials can be used for different
regions of the part being formed, the different materials being
supplied by separate binder deposition heads.
[0079] Using the method described herein, component parts and
structures having intricate internal surfaces and geometries or
microstructures are now feasible. Due to the brittle nature of
ceramic material, parts made from this material will need
reinforcement. U.S. Pat. No. 5,626,914 describes ceramic materials
infiltrated by molten metals within microporous regions of the
ceramic. The infiltration of metal into pores of the ceramic
material, however, does not allow for precise placement of
reinforcement parts at known stress or fracture points. One
application of producing intricate internal surfaces and
microstructures described herein includes, for example, ceramic
parts having high aspect ratio microstructured holes capable of
receiving metal reinforcement materials. In one embodiment,
products produced according to the process of the present invention
will include internal micro or small voids or micro-cavities having
aspect ratios in the range of 5:1 to 100:1, or more specifically,
an aspect ratio of 5:1, 10:1, 25:1, 50:1, or 100:1. In another
embodiment, the products produced according to the method described
herein include small internal voids, micro-cavities, or hollows
having an internal diameter of approximately 0.010 inch to 0.100
inch, more specifically, 0.025 inch to 0.050 inch, and a depth of
approximately 1 inch to 40 inches.
[0080] Many possible combinations of powder and binder materials
can be selected in accordance with the invention. For example,
ceramic powders or ceramic fibers can be used with either inorganic
or organic binder materials or with a metallic binder material; a
metal powder can be used with a metallic binder or a ceramic
binder; and a plastic powder can be used with a solvent binder or a
plastic binder, e.g., a low viscosity epoxy plastic material. Other
appropriate combinations of powder and binder materials will occur
to those in the art for various applications.
[0081] These and other embodiments will become more apparent during
the description of a specific example.
EXAMPLES
Example 1
General Procedure
[0082] First phase: To produce a ceramic structure in accordance to
the method of the present invention, a photopolymer printer (e.g.,
3D SYSTEMS VISIJET) is used to fabric a plastic die having a
structure forming an external surface and an internal hollow
cavity. The internal hollow cavity will be fabricated by printing a
structure with an internal diameter of 0.016 inch and a depth of
0.5 inch to 1 inch long. The plastic die is produced using a tipcap
pin having 0.045 inch diameter through an additive printing
process. A slurry of ceramic materials, such as siloxane, silica,
zircon, alumina, yttria is injected into the portion of the plastic
die representing the external surface such that the slurry forms
around the internal hollow cavity. Following one or more rounds of
sintering at a temperature of about 1600.degree. C., the green body
is cured and the plastic die is removed or burned off leaving an
internal hollow cavity having a diameter of approximately 0.016
inches and a depth of 0.5 inches to 1 inch.
[0083] Second phase: the internal hollow cavity created during the
first phase may be filled with another slurry of material or a
solid material. In the case of a slurry material, the material may
be injected into the internal hollow cavity created in the first
phase and cured using the same procedure described above. In the
case of a solid material, a quartz rod, alumina rod, or metal rod
or any other solid material having a diameter of approximately
0.014 inch and a length of 0.4 inch to 0.75 inch is incorporated
into the internal hollow cavity.
[0084] Whether the material incorporated into the internal cavity
is another ceramic slurry or a solid material, the product having
both first and second phase materials is again heated at a
temperature of approximately 1600.degree. C. thereby sintering the
first and second phase materials together to form a contiguous
object or structure.
Example 2
Alumina Rod Insertion
[0085] A plastic die is printed in accordance with the procedure
set forth in Example 1. The plastic die will be designed to include
both an external surface and an internal cavity having an outside
diameter of 0.013 inch and a depth of 0.5 inch. As described
before, a ceramic slurry is injected into the external portion of
the plastic die. The ceramic portion now within the external
portion of the die is heated to a temperature of 500.degree. C. to
cure the ceramic matrix as well as to burn off the plastic die. An
alumina rod having a diameter of approximately 0.011 inch and a
length of 0.5 inch that is coated in ceramic-based slurry is
inserted into the internal cavity created by the internal hollow
cavity. The combined ceramic and alumina rod is heated at a
temperature of approximately 1600.degree. C. to sinter the ceramic
matrix and alumina rod, where the sintering creates a bond at the
interface of the matrix and the rod. The resulting product is a
reinforced ceramic body.
* * * * *