U.S. patent application number 16/163460 was filed with the patent office on 2019-04-18 for binder jetting in additive manufacturing of inhomogeneous three-dimensional parts.
The applicant listed for this patent is Desktop Metal, Inc.. Invention is credited to Alexander C. Barbati, Michael Andrew Gibson, Brian Daniel Kernan, Nihan Tuncer.
Application Number | 20190111480 16/163460 |
Document ID | / |
Family ID | 64184217 |
Filed Date | 2019-04-18 |
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United States Patent
Application |
20190111480 |
Kind Code |
A1 |
Barbati; Alexander C. ; et
al. |
April 18, 2019 |
BINDER JETTING IN ADDITIVE MANUFACTURING OF INHOMOGENEOUS
THREE-DIMENSIONAL PARTS
Abstract
Devices, systems, and methods are directed to binder jetting for
forming three-dimensional parts having controlled, macroscopically
inhomogeneous material composition. In general, a binder may be
delivered to each layer of a plurality of layers of a powder of
inorganic particles. An active component may be introduced, in a
spatially controlled distribution, to at least one of the plurality
of layers such that the binder, the powder of inorganic particles,
and the active component, in combination, form an object. The
object may be thermally processed into a three-dimensional part
having a gradient of one or more physicochemical properties of a
material at least partially formed from thermally processing the
inorganic particles and the active component of the object.
Inventors: |
Barbati; Alexander C.;
(Cambridge, MA) ; Gibson; Michael Andrew; (Boston,
MA) ; Tuncer; Nihan; (Cambridge, MA) ; Kernan;
Brian Daniel; (Andover, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Desktop Metal, Inc. |
Burlington |
MA |
US |
|
|
Family ID: |
64184217 |
Appl. No.: |
16/163460 |
Filed: |
October 17, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62573410 |
Oct 17, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B 2235/6026 20130101;
C04B 35/111 20130101; B22F 2207/01 20130101; B22F 2207/11 20130101;
B33Y 10/00 20141201; C04B 35/565 20130101; C04B 35/63488 20130101;
B22F 3/008 20130101; B33Y 50/02 20141201; B33Y 30/00 20141201; B22F
1/0059 20130101; B33Y 80/00 20141201; B33Y 70/00 20141201 |
International
Class: |
B22F 3/00 20060101
B22F003/00; B33Y 10/00 20060101 B33Y010/00; B33Y 30/00 20060101
B33Y030/00; B33Y 50/02 20060101 B33Y050/02; B33Y 70/00 20060101
B33Y070/00 |
Claims
1. An object comprising: a plurality of layers of a powder, the
powder including inorganic particles; at least one binder along a
respective two-dimensional pattern in each layer of the plurality
of layers, the at least one binder binding each layer to one or
more adjacent layers; and an active component at one or more target
locations of one or more layers of the plurality of layers, wherein
the at least one binder, the inorganic particles of the powder, and
the active component, in combination, form the object, and the
object is thermally processable to form a three-dimensional part
having, in areas of the three-dimensional part corresponding to the
target locations of the active component of the object, a gradient
of one or more physicochemical properties of a material at least
partially formable from thermal processing of the inorganic
particles and the active component of the object.
2. The object of claim 1, wherein the inorganic particles include
metallic particles.
3. The object of claim 2, wherein the metallic particles are
alloyable with the active component.
4. The object of claim 3, wherein an alloy formable from the
metallic particles and the active component has greater corrosion
resistance than the metallic particles alone.
5. The object of claim 4, wherein active component includes a
chromate solution.
6. The object of claim 3, wherein the metallic particles and the
active component are alloyable to form steel, and the active
component includes any one or more of sulfur, phosphorus, antimony,
fluorine, bismuth, arsenic, tin, lead, tellurium, or manganese.
7. The object of claim 3, wherein the metallic particles and the
active component are alloyable to form an aluminum alloy, and the
active component includes gallium.
8. The object of claim 3, wherein the metallic particles and the
active component are alloyable to form a copper alloy, and the
active component includes one or more of bismuth, antimony, or
tellurium.
9. The object of claim 3, wherein the metallic particles and the
active component are alloyable to form a free-machining
material.
10. The object of claim 3, wherein the metallic particles and the
active component are alloyable to form an alloy having a lower
melting point than a melting point of a metal formed from the
metallic particles alone.
11. The object of claim 10, wherein the metallic particles and the
active component are alloyable to form steel, and the active
component includes carbon.
12. The object of claim 1, wherein the target locations of the
active component are at least partially along a surface of the
object formed by the at least one binder, the plurality of layers,
and the active component.
13. The object of claim 1, wherein the target locations of the
active component are at least partially within the object formed by
the at least one binder, the plurality of layers, and the active
component.
14. The object of claim 1, wherein the object is sinterable to form
the three-dimensional part.
15. The object of claim 1, wherein the object is infiltratable with
a liquid metal to form the three-dimensional part.
16. The object of claim 1, wherein the object is thermally
processable to densify the object into the three-dimensional
part.
17. The object of claim 1, wherein, as compared to the at least one
binder, the active component resists removal through thermal
processing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 62/573,410, filed Oct. 17, 2017, the entire
contents of which are incorporated herein by reference.
BACKGROUND
[0002] Binder jetting is an additive manufacturing technique useful
for rapid fabrication of parts, including parts made of metal and
having complex geometry. In particular, binder jetting is a
layer-by-layer fabrication process in which a binder is jetted onto
successive layers of a powder in a powder bed such that the layers
of the powder adhere to one another, along the areas of
distribution of the binder, to form a three-dimensional green part.
Through subsequent processing, the three-dimensional green part can
be formed into a finished three-dimensional part having a generally
homogeneous composition and, thus, generally homogenous material
properties. While parts with homogenous material properties are
useful in certain applications, there are a number of applications
in which it is desirable to form a three-dimensional part having
controlled spatial variation of material properties. Such
controlled spatial variation of material properties, however, is
difficult to achieve with binder jetting techniques. Accordingly,
there remains a need for improved spatial control over material
properties in finished three-dimensional parts formed using binder
jetting processes.
SUMMARY
[0003] Devices, systems, and methods are directed to binder jetting
for forming three-dimensional parts having controlled,
macroscopically inhomogeneous material composition. In general, a
binder may be delivered to each layer of a plurality of layers of a
powder of inorganic particles. An active component may be
introduced, in a spatially controlled distribution, to at least one
of the plurality of layers such that the binder, the powder of
inorganic particles, and the active component, in combination, form
an object. The object may be thermally processed into a
three-dimensional part having a gradient of one or more
physicochemical properties of a material at least partially formed
from thermally processing the inorganic particles and the active
component of the object.
[0004] According to one aspect, an object may include a plurality
of layers of a powder, the powder including inorganic particles, at
least one binder along a respective two-dimensional pattern in each
layer of the plurality of layers, the at least one binder binding
each layer to one or more adjacent layers, and an active component
at one or more target locations of one or more layers of the
plurality of layers, wherein the at least one binder, the inorganic
particles of the powder, and the active component, in combination,
form the object, and the object is thermally processable to form a
three-dimensional part having, in areas of the three-dimensional
part corresponding to the target locations of the active component
of the object, a gradient of one or more physicochemical properties
of a material at least partially formable from thermal processing
of the inorganic particles and the active component of the
object.
[0005] In some implementations, the inorganic particles may include
metallic particles. The metallic particles may be, for example,
alloyable with the active component. For example, an alloy formable
from the metallic particles and the active component (e.g., a
chromate solution) may have greater corrosion resistance than the
metallic particles alone. As an additional or alternative example,
the metallic particles and the active component may be alloyable to
form steel, and the active component may include any one or more of
sulfur, phosphorus, antimony, fluorine, bismuth, arsenic, tin,
lead, tellurium, or manganese. As still a further or alternative
example, the metallic particles and the active component may be
alloyable to form an aluminum alloy, and the active component may
include gallium. Further, or instead, the metallic particles and
the active component may be alloyable to form a copper alloy, and
the active component includes one or more of bismuth, antimony, or
tellurium. Additionally, or alternatively, the metallic particles
and the active component are alloyable to form a free-machining
material. Further, or instead, the metallic particles and the
active component may be alloyable to form an alloy having a lower
melting point than a melting point of a metal formed from the
metallic particles alone. As an example, the metallic particles and
the active component may be alloyable to form steel, and the active
component includes carbon.
[0006] In certain implementations, the target locations of the
active component may be at least partially along a surface of the
object formed by the at least one binder, the plurality of layers,
and the active component. Additionally, or alternatively, the
target locations of the active component may be at least partially
within the object formed by the at least one binder, the plurality
of layers, and the active component.
[0007] In some implementations, the object may be sinterable to
form the three-dimensional part. Further, or instead, the object
may be infiltratable with a liquid metal to form the
three-dimensional part. Additionally, or alternatively, the object
may be thermally processable to densify the object into the
three-dimensional part.
[0008] In certain implementations, as compared to the at least one
binder, the active component may resist removal through thermal
processing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The devices, systems, and methods described herein are set
forth in the appended claims. However, for the purpose of
explanation, several implementations are set forth in the following
drawings:
[0010] FIG. 1 is a schematic representation of an additive
manufacturing system for binder jetting to form an object from a
powder in a powder bed.
[0011] FIG. 2 is a flowchart of an exemplary method of delivering
multiple fluids to one or more layers of a plurality of layers of a
powder to form an object.
[0012] FIG. 3A is a side view of the object of FIG. 1.
[0013] FIG. 3B is a cross-sectional view of the object of FIG. 3A,
the cross-section taken along the line 3B-3B in FIG. 3A.
[0014] FIG. 3C is a schematic representation of inorganic particles
dispersed in a least one binder in a layer of the object of FIG.
3A, the schematic representation corresponding to the area of
detail 3C, shown in FIG. 3B.
[0015] FIG. 4 is a schematic representation of an additive
manufacturing plant including the additive manufacturing system of
FIG. 1.
[0016] FIG. 5 is a flowchart of an exemplary method of using an
active component to form a gradient of one or more physiochemical
properties in a three-dimensional part.
[0017] FIG. 6 is a flowchart of an exemplary method of using a salt
as an active component to form a gradient of one or more
physiochemical properties in a three-dimensional part.
[0018] FIG. 7 is a flowchart of an exemplary method of additive
manufacturing of a three-dimensional part using a stable additive
including particles of an active component.
[0019] FIG. 8 is a flowchart of an exemplary method of additive
manufacturing based on selective decomposition of at least one
binder to form an active component.
[0020] FIG. 9 is a flowchart of an exemplary method of additive
manufacturing based on selective chemical modification of at least
one binder to form an active component.
DESCRIPTION
[0021] Embodiments will now be described with reference to the
accompanying figures. The foregoing may, however, be embodied in
many different forms and should not be construed as limited to the
illustrated embodiments set forth herein.
[0022] All documents mentioned herein are hereby incorporated by
reference in their entirety. References to items in the singular
should be understood to include items in the plural, and vice
versa, unless explicitly stated otherwise or clear from the text.
Grammatical conjunctions are intended to express any and all
disjunctive and conjunctive combinations of conjoined clauses,
sentences, words, and the like, unless otherwise stated or clear
from the context. Thus, the term "or" should generally be
understood to mean "and/or" and so forth.
[0023] Recitation of ranges of values herein are not intended to be
limiting, referring instead individually to any and all values
falling within the range, unless otherwise indicated herein, and
each separate value within such a range is incorporated into the
specification as if it were individually recited herein. The words
"about," "approximately," or the like, when accompanying a
numerical value, are to be construed as indicating a deviation as
would be appreciated by one of ordinary skill in the art to operate
satisfactorily for an intended purpose. Ranges of values and/or
numeric values are provided herein as examples only, and do not
constitute a limitation on the scope of the described embodiments.
The use of any and all examples, or exemplary language ("e.g.,"
"such as," or the like) provided herein, is intended to better
illuminate the embodiments and, unless otherwise indicated or made
clear from the context, should not be understood to impose a
limitation on the scope of the embodiments. No language in the
specification should be construed as indicating any unclaimed
element as essential to the practice of the embodiments.
[0024] In the following description, it is understood that terms
such as "first," and "second" and the like, are words of
convenience and are not to be construed as limiting terms.
[0025] As used herein, "binder jetting" shall be understood to
refer, generally, to a layer-by-layer additive manufacturing
technique in which a powder of particles is spread across a powder
bed in successive layers and formed into a plurality of
two-dimensional slices stacked on top of one another to define,
collectively, a shape of a three-dimensional object. For example,
each two-dimensional slice corresponding to a given layer may be
formed by delivering one or more binders to at least a portion of
the given layer in a respective controlled two-dimensional pattern
associated with the layer. The binder may be any of various
different materials suitable for substantially maintaining the
particles of the powder in place along the two-dimensional slice of
a given layer and for adhering the two-dimensional slice of the
given layer to the two-dimensional slices of one or more adjacent
layers. Thus, for example, as used herein a binder may include any
one or more of a polymer or a gel. Additionally, or alternatively,
the binder may include nanoparticles that sinter at a lower
temperature than the particles of the powder such that the
nanoparticles act to hold the particles of the powder in place.
Further or instead, while the binder may be jetted from one or more
printheads to each layer of the powder of the particles, it should
be appreciated that binder jetting does not necessarily require
jetting of the binder, as the term jetting is generally understood
in fluid mechanics. That is, binder jetting techniques described
herein may include any manner and form of controlled delivery of at
least one binder from one or more printheads in a direction toward
a layer of the powder of the particles on top of a powder bed.
Thus, in certain instances, such as instances in which the binder
includes a gel, binder jetting techniques described herein may
include extrusion of the binder in a controlled-two-dimensional
pattern to the layer of the powder on top of the powder bed.
Further or instead, unless otherwise indicated or made clear from
the context, the binder jetting techniques described herein shall
be understood to be applicable to any manner and form of imparting
force to a binder for jetting the binder in a direction toward a
layer of the powder of the particles. Therefore, depending on
composition of the binder, this may include imparting any one or
more of mechanical force, thermal excitation, pneumatic force,
magnetohydrodynamic force, electrohydrodynamic force, or
acoustophoresis to the binder.
[0026] In general, the present disclosure is directed to binder
jetting-based techniques for additive manufacturing of
three-dimensional parts advantageously having a gradient of one or
more physicochemical properties. As used herein, physicochemical
properties may include any manner and form of physical properties,
chemical properties, or combinations thereof, characteristic of a
three-dimensional part formed from thermally processing an object
formed through the binder jetting techniques described herein. The
one or more physicochemical properties may be scalar or
tensor-valued. Examples of physicochemical properties, therefore,
may include, but are not limited to: melting point, hardness,
density, ductility, chemical composition, chemical stability in a
given environment, Young's modulus, Poisson's ratio, preferred
oxidation state, or combinations thereof.
[0027] As used herein, unless otherwise specified or made clear
from the context, a gradient of the one or more physicochemical
properties shall be understood to include any controlled,
macroscopic variation of one or more material properties or
material functions in a three-dimensional part. The controlled,
macroscopic variation may be distinguishable from nominal
variations associated with design tolerances at least because the
controlled, macroscopic variation is not random or otherwise
uncontrolled and, thus, may be reliably repeated in multiple
instances of fabrication of the three-dimensional part. Further, or
instead, the gradient of the one or more physicochemical properties
may be along any predetermined direction or path defined by the
three-dimensional part. For example, at least a portion of the
gradient may be along one or more surfaces of the three-dimensional
part. As an additional or alternative example, at least a portion
of the gradient may be within the three-dimensional part, away from
surface of the three-dimensional part.
[0028] In certain implementations, the gradient of the one or more
physicochemical properties may vary according to a continuous
function (e.g., sinusoidally or monotonically in at least one
direction of the three-dimensional part) producing a smooth
variation of the one or more physicochemical properties over a
distance of the predetermined path defined by the three-dimensional
part. Such a continuous function may be particularly advantageous,
for example, for reducing or eliminating certain mechanical failure
modes (e.g., resulting from stress concentration) that may be
associated with certain abrupt variations in composition in a
part.
[0029] In some implementations, however, the gradient of the one or
more physicochemical properties may include a sharp change (e.g.,
substantially a step function to within spatial resolution
limitations of a binder jetting system) in the one or more
physicochemical properties along the predetermined path defined by
the three-dimensional part.
[0030] As an example, such a sharp change in the one or more
physicochemical properties may exist at a transition between an
interior portion of the three-dimensional part adjacent to a
surface of the three-dimensional part. Continuing with this
example, such a sharp change may be useful for forming with one or
more physicochemical properties that differ substantially on a
surface of the part as compared to along the interior portion of
the three-dimensional part.
[0031] For the sake of clarity of explanation, a single gradient of
one or more physicochemical properties of a material in a
three-dimensional part is described. However, unless otherwise
indicated or made clear from the context, it should be appreciated
that the principals applicable to the single gradient case may be
used to form a plurality of gradients of any number of
physicochemical properties without departing from the scope of the
present disclosure.
[0032] Referring now to FIG. 1, an additive manufacturing system
100 may be used to form an object 102 at least partially from a
combination of a powder 104 including inorganic particles (e.g.,
metallic particles, ceramic particles, or a combination thereof),
at least one binder 106, and an active component of an additive
108. The object 102, as described in greater detail below, may be
thermally processed to form a three-dimensional part (e.g.,
three-dimensional part 410 in FIG. 4) having a gradient of one or
more physicochemical properties of a material at least partially
formed from thermally processing the inorganic particles of the
powder 104 and the active component of the object 102. As also
described in greater detail below, forming a gradient of one or
more physicochemical properties in a three-dimensional part formed
from thermally processing the object 102 may be useful for
fabricating a unitary part suitable for meeting disparate material
requirements previously requiring a trade-off in performance in
many applications. By way of example, and not limitation, the
gradient of the one or more physicochemical properties in the
three-dimensional part may facilitate resisting corrosion along one
or more surfaces of the three-dimensional part while achieving a
high degree of electrical conductivity within the three-dimensional
part. By way of further non-liming example, the gradient of the one
or more physicochemical properties in the three-dimensional part
may provide structural reinforcement to the three-dimensional part,
as compared to an analogous three-dimensional part formed without
the use of the active component and, thus, does not include the
gradient.
[0033] The additive manufacturing system 100 may include a powder
supply 112, a powder bed 114, a spreader 116, a first printhead
118a, and a second printhead 118b. The spreader 116 may be movable
from the powder supply 112 to the powder bed 114 and along the
powder bed 114 to spread successive layers of the powder 104 across
the powder bed 114. The first printhead 118a and the second
printhead 118b may be movable (e.g., in coordination with one
another and, optionally, in coordination with movement of the
spreader 116) across the powder bed 114.
[0034] In general, the first printhead 118a may define one or more
orifices (e.g., in a first nozzle) through which the at least one
binder 106 may be delivered from the first printhead 118a along a
controlled two-dimensional pattern in each layer of the powder 104
along the powder bed 114, and the second printhead 118b may define
one or more orifices (e.g., in a second nozzle) through which the
additive 108 may be delivered from the second printhead 118b to
target locations in at least one layer of a plurality of layers
forming the object 102. The at least one binder 106 and the
additive 108 may be directed to the powder 104 along the powder bed
114 along individually controlled patterns such that the at least
one binder 106, the additive 108, or both may be present in a given
layer of the powder 104 forming the object 102 in any of various
different patterns suitable for interacting with one another and/or
with the powder 104 to form the object 102 such that the object 102
has a material distribution suitable for forming a
three-dimensional part meeting predetermined design specifications.
That is, as described in greater detail below, the object 102 may
be formed, at least in part, by the at least one binder 106, the
additive 108 (or, at least, the active component of the additive
108), and the inorganic particles of the powder 104, collectively,
and each component of the object 102 has a distribution in the
object 102 suitable for forming the gradient of the one or more
physicochemical properties in the three-dimensional part formed by
thermally processing the object 102.
[0035] The spreader 116 may span at least one dimension of the
powder bed 114 such that movement of the spreader 116 across the
powder bed 114 forms a single layer of the powder 104 along the top
of the powder bed 114. The spreader 116 may include, for example, a
roller rotatable about an axis perpendicular to an axis of movement
of the spreader 116 across the powder bed 114. The roller may be,
for example, substantially cylindrical. In use, rotation of the
roller about the axis perpendicular to the axis of movement of the
spreader 116 may spread the powder 104 from the powder supply 112
to the powder bed 114 and form a layer of the powder 104 along the
powder bed 114. More generally, it should be appreciated that the
plurality of sequential layers of the powder 104 may be formed in
the powder bed 114 through repeated movement of the spreader 116
across the powder bed 114.
[0036] In certain implementations, the first printhead 118a and the
second printhead 118b may be substantially similar--that is,
operating according to the same operating principle. For example,
the first printhead 118a and the second printhead 118b may be based
on piezoelectric activation for the distribution of fluid.
Continuing with this example, the first printhead 118a and the
second printhead 118b may each include one or more piezoelectric
elements. The one or more piezoelectric elements of the first
printhead 118a may be actuated to expel the at least one binder 106
from the respective one or more orifices defined by the first
printhead 118a and, similarly, the one or more piezoelectric
elements of the second printhead 118b may be actuated to expel the
additive 108 from the respective one or more orifices defined by
the second printhead 118b. In certain implementations, one or both
of the first printhead 118a and the second printhead 118b may expel
a respective single liquid formulation from the one or more
orifices defined by the respective printhead. In some
implementations, however, one or both of the first printhead 118a
and the second printhead 118b may expel a plurality of liquid
formulations from the one or more orifices. For example, the first
printhead 118a may expel a plurality of solvents, a plurality of
components of a binder system, or both from the one or more
orifices. As another example, while the first printhead 118a and
the second printhead 118b may be separate printheads, it should be
appreciated that the first printhead 118a and the second printhead
118b may be combined into a single printhead operable to jet the at
least one binder 106 and the additive 108 according to any one or
more of the methods described herein.
[0037] In general, the first printhead 118a may be controlled to
deliver (e.g., jet or otherwise distribute) the at least one binder
106 to a layer of the powder 104 along the top of the powder bed
114 in a controlled (e.g., predetermined) two-dimensional pattern
associated with the given layer. As used herein, unless otherwise
indicated or made clear from the context, the at least one binder
106 may include a liquid or other flowable component such that the
at least one binder 106 may be metered (e.g., through the
controlled application of force) through one or more orifices
defined by the first printhead 118a for controlled deposition along
a two-dimensional layer of the powder 104 along the top of the
powder bed 114. Additionally, or alternatively, the first printhead
118a may be controlled to control volumetric flow rate of the at
least one binder 106 such that concentration of the at least one
binder 106 along a layer of the powder on the top of the powder bed
114 may be controllably varied along the two-dimensional pattern of
the at least one binder 106 along the layer. Thus, for example, the
first printhead 118a may vary concentration of the at least one
binder 106 along the layer to achieve a distribution of the at
least one binder 106 that facilitates uniform shrinkage of the
object 102 as the object 102 undergoes thermal processing.
[0038] The second printhead 118b may include any one or more of the
features of the first printhead 118a described herein and, thus, in
some implementations, may be substantially identical to the first
printhead 118a. Further, or instead, while the additive
manufacturing system 100 is described as including the first
printhead 118a and the second printhead 118b, other configurations
are additionally or alternatively possible for directing the at
least one binder 106 and the additive 108 to the powder bed 114 to
form the object 102. As an example, any one or more features of the
second printhead 118b may be incorporated into the first printhead
118a such that the at least one binder 106 and the additive 108 may
be delivered through a single printhead. As another example, the at
least one binder 106 and the additive 108 may be directed to the
powder bed 114 through any number of printheads. More generally,
any number of components may be directed to the powder bed 114
through any number of printheads to form the object 102 having any
one or more of the various different properties described
herein.
[0039] The second printhead 118b may be controlled to directly or
indirectly deposit an active component to one or more target
locations along a layer of the powder 104 on top of the powder bed
114. For example, in certain instances, the active component may
form at least a portion of an additive 108 such that delivery of
the additive 108 to a given layer of the powder 104 directly
introduces the active component to the given layer of the powder
104. Such direct introduction may be useful, for example, for
tightly controlling concentration of the active component which, in
turn, may be useful for controlling a gradient of material
properties in a three-dimensional part formed from the object 102.
While direct introduction of the active component to the powder 104
may provide certain advantages, it should be appreciated that the
additive 108 distributed by the second printhead 118b may further
or instead introduce a precursor of the active component to the
powder 104 such that the precursor may chemically react with or
decompose the one or more binders to form the active component in
situ in the layer of the powder 104. In this context, the precursor
distributed by the second printhead 118b may be generally referred
to herein as an ink, although the ink is not necessarily limited to
fluid including color or otherwise used for printing images. The
ink may be a fluid with or without a material dissolved or
suspended therein. More generally, unless otherwise indicated or
made clear from the context, the additive 108 may be any medium
distributable from the second printhead 118b to a layer of the
powder 104 to directly or indirectly introduce an active component,
such as any one or more of the various active components described
herein, into the layer of the powder 104.
[0040] The additive manufacturing system 100 may include a
controller 120 in electrical communication with the powder supply
112, the powder bed 114, the spreader 116, the first printhead
118a, and the second printhead 118b. The controller 120 may include
one or more processors 121 operable to control the powder supply
112, the powder bed 114, the spreader 116, the first printhead
118a, the second printhead 118b, and combinations thereof. In use,
the one or more processors 121 of the controller 120 may execute
instructions to control z-axis movement of one or more of the
powder supply 112 and the powder bed 114 relative to one another as
the object 102 is being formed in the powder bed 114. For example,
the one or more processors 121 of the controller 120 may execute
instructions to move the powder supply 112 in a z-axis direction
toward the spreader 116 to direct the powder 104 toward the
spreader 116 as each layer of the object 102 is formed. The one or
more processors 121 may, also or instead, execute instructions to
move the powder bed 114 in a z-axis direction away from the
spreader 116 to accept each new layer of the powder 104 along the
top of the powder bed 114 as the spreader 116 moves across the
powder bed 114. Additionally, or alternatively, the one or more
processors 121 of the controller 120 may control movement of the
spreader 116 from the powder supply 112 to the powder bed 114 to
move successive layers of the powder 104 across the powder bed
114.
[0041] Further or instead, the one or more processors 121 of the
controller 120 may control movement of the first printhead 118a and
the second printhead 118b over the powder bed 114 as the object 102
is being formed. Additionally or alternatively, the one or more
processors 121 of the controller 120 may control various different
delivery parameters associated with delivery of the at least one
binder 106 from the first printhead 118a as the first printhead 118
moves over a layer of the powder 104 on top of the powder bed 114.
Similarly, the one or more processors 121 of the controller 120 may
control various different distribution parameters of the additive
108 over a layer of the powder 104 on top of the powder bed 114.
More generally, the one or more processors 121 of the controller
120 may control the first printhead 118a and the second printhead
118b (e.g., independently of one another) to deliver the at least
one binder 106 and the additive 108 to the layer of the powder 104
on top of the powder bed 114 in any manner and form of combination
useful for carrying out any one or more of the various different
techniques described herein for forming a three-dimensional part
having a gradient of one or more physicochemical properties. In
certain implementations, the first printhead 118a may precede the
second printhead 118b across the powder bed 114 such that the at
least one binder 106 may be delivered onto a given layer of the
powder 104 before the additive 108 is distributed onto the given
layer of the powder 104. It should be appreciated, however, that
the at least one binder 106 and the additive 108 may be directed
toward the powder bed 114 in the reverse order in certain
implementations. Further or instead, the at least one binder 106
and the additive 108 may be directed onto the powder at the same
time or at substantially the same time, such as in implementations
in which the first printhead 118a and the second printhead 118b are
implemented as a single printhead.
[0042] The additive manufacturing system 100 may further include a
non-transitory, computer readable storage medium 122 in
communication with the controller 120 and having stored thereon a
three-dimensional model 124 and instructions for causing the one or
more processors 121 to carry out any one or more of the methods
described herein. In general, as a plurality of sequential layers
of the powder 104 are introduced to the powder bed 114 and the at
least one binder 106 and the additive 108 are delivered from the
first printhead 118a and the second printhead 118b, respectively,
to the powder 104 in the powder bed 114, the object 102 may be
formed according to the three-dimensional model 124 stored in the
non-transitory, computer readable storage medium 122. In certain
implementations, the controller 120 may retrieve the
three-dimensional model 124 in response to user input, and generate
machine-ready instructions for execution by the additive
manufacturing system 100 to fabricate the object 102.
[0043] FIG. 2 is a flowchart of an exemplary method 200 of
delivering multiple fluids to one or more layers of a plurality of
layers of a powder to form an object, such as the object 102 (FIG.
1). Unless otherwise specified or made clear from the context, the
exemplary method 200 may be implemented using any one or more of
the various different additive manufacturing devices and systems
described herein. Thus, for example, the exemplary method 200 may
be at least partially implemented as computer-readable instructions
stored on the computer readable storage medium 122 (FIG. 1) and
executable by the controller 120 (FIG. 1) to operate the additive
manufacturing system 100 (FIG. 1) to form the object 102 (FIG. 1)
according to the three-dimensional model 124 (FIG. 1).
[0044] As shown in step 202, the exemplary method 200 may include
spreading a layer of a powder across a powder bed. The powder may
include inorganic particles and, more generally, may include any
one or more of the powders described herein.
[0045] As shown in step 204, the exemplary method 200 may include
delivering one or more binders along the layer of the powder. The
one or more binders may be, for example, any one or more of the
binders described herein. Additionally, or alternatively, each
binder may be jetted or otherwise delivered to the layer in a
respective controlled two-dimensional pattern associated with the
respective binder and the layer onto which the binder is
introduced.
[0046] As shown in step 206, the exemplary method 200 may include
distributing an active component along the layer of the powder. The
active component may be directly or indirectly distributed along
the layer of the powder according to any one or more of the various
different techniques described herein for achieving controlled
distribution of an active component. Accordingly, introduction of
the active component may include direct or indirect introduction of
the active component along the layer in a respective controlled
two-dimensional arrangement associated with the active component
and the layer onto which the second component is introduced. A
predetermined gradient of one or more physicochemical properties of
a material in a three-dimensional part formed from thermally
processing the object being formed may be achieved by selectively
controlling, for example, one or more of a two-dimensional
distribution pattern and a local concentration of the one or more
binders, the active component (e.g., as delivered through an
additive or as formed through a reaction or decomposition of the
one or more binders or another fluid), or both along a given layer.
Thus, as an example, the one or more binders and the active
component may be distributed in at least partially overlapping
two-dimensional patterns or in segregated patterns in a given
layer, with the distribution generally dictated by the gradient of
one or more physicochemical properties desired in the
three-dimensional part formed by thermally processing of the
object.
[0047] As shown in step 208, the exemplary method 200 may include
repeating, as necessary to form the object, one or more of the
steps of spreading a layer of the powder across the powder bed,
delivering the one or more binders along a given layer of powder,
and distributing the active component along a given layer.
[0048] Having described the exemplary method 200 that may be
carried out by the additive manufacturing system 100 (FIG. 1) to
form the object 102 (FIG. 1) through binder jetting, attention is
now turned to various different aspects of the object 102 (FIG. 1).
More specifically, it should be appreciated that the object 102
includes features that facilitate fabrication through the use of
binder jetting techniques while also being processable into a
three-dimensional part having controlled spatial variation, also
referred to herein as a gradient, of one or more physicochemical
properties. These features of the object 102 are described in
greater detail in the description that follows.
[0049] Referring now to FIGS. 1 and 3A-3C, the object 102 may be
formed by the additive manufacturing system 100 according to any
one or more of the methods described herein and, more specifically,
may be formed by a combination of components including, but not
limited to, the at least one binder 106, the inorganic particles of
the powder 104 in a plurality of layers 302, and an active
component 304. For example, each layer 302 may include the powder
104 of the inorganic particles held together by the at least one
binder 106 along a respective two-dimensional pattern associated
with a given instance of the layer 302, and the at least one binder
106 may bind each instance of the layer 302 to one or more adjacent
instances of the layer 302. The active component 304 may be
disposed along one or more target locations 306 of at least one
instance of the layer 302. Thus, in general, the at least one
binder 106 may hold the inorganic particles of the powder 104 of
the plurality of layers 302 in an overall three-dimensional shape
of the object 102, and the selective distribution of the active
component 304 along the one or more target locations 306 of the
plurality of layers 302 may be useful for imparting a desired
distribution of physicochemical properties to a three-dimensional
part formed from thermally processing the object 102. That is, as
described in greater detail below, the object 102 may be thermally
processable to form a three-dimensional part having, in areas of
the three-dimensional part corresponding to the target locations
306 of the active component 304 of the object 102, a gradient of
one or more physicochemical properties of a material at least
partially formable from thermally processing the inorganic
particles and the active component 304 of the object 102.
[0050] In general, the inorganic particles of the powder 104 may be
any of various different types of inorganic material thermally
processable to form the three-dimensional part with a desired
distribution of physicochemical properties. More specifically, the
inorganic material may be suitable for interaction with the active
component 304 through thermal processing. As used herein, such
interaction between the inorganic material and the active component
304 may include any of various different forms of changes in the
solid-state chemistry of the inorganic material at least partially
resulting from thermally processing the inorganic material in the
presence of the active component 304.
[0051] In certain implementations, the inorganic particles may
include metallic particles. The metallic particles may be, for
example, a single composition. As an additional or alternative
example, however, the metallic particles may include a plurality of
metal compositions in a predetermined ratio, such as may be useful
for forming an alloy (e.g., according to an industry-standard
specification). In some instances, the metallic particles may have
a substantially uniform size distribution, which may facilitate
substantially uniform spreading. In other instances, the metallic
particles may have different sizes, such as may be useful for
achieving a range of sintering temperatures based on the size
distribution.
[0052] In some implementations in which the inorganic particles of
the powder 104 include metallic particles, the interaction between
the metallic particles of the powder 104 and the active component
304 may include alloying the metal of the metallic particles with
the active component 304 during thermal processing. In such
instances, variation of local concentration of the active component
304 relative to the metallic particles in the object 102 may
facilitate forming a predetermined variation in alloy composition
in the three-dimensional part formed by thermally processing the
object 102. In turn, this variation in alloy composition may
correspond to variations in one or more physicochemical properties
of the three-dimensional part. Advantageously, the variations in
physicochemical properties achievable through thermally processing
the object 102 are numerous, given the ability to form the object
102 using a large number of combinations of materials. Examples of
some useful variations in physicochemical properties achievable
through such variation in alloy composition may include, but are
not limited to, one or more of the following: corrosion resistance,
melting point, hardening, thermal conductivity, electrical
conductivity, or machinability. Some specific examples of alloys
are described below to facilitate explanation of certain concepts,
but these should not be considered limiting.
[0053] As an example, the metallic particles and the active
component 304 may be alloyable with one another to form steel as
the object 102 is thermally processed. Continuing with this
example, the active component 304 may include any one or more of
sulfur, phosphorus, antimony, fluorine, bismuth, arsenic, tin,
lead, tellurium, chromium (e.g., in a chromate solution) manganese,
or carbon, such as may be useful for achieving a gradient in one or
more physicochemical properties associated with changes in
concentrations of one or more of these materials in alloys of
steel. That is, as a more specific example, one or more of
concentration or composition of the active component 304 may be
varied along the object 102 such that thermal processing of the
object 102 may result in a three-dimensional part being stainless
steel in certain regions (e.g., where corrosion resistance is a
primary design consideration) and being tool steel in other regions
(e.g., where wear resistance is a primary design
consideration).
[0054] As an additional or alternative example, the metallic
particles and the active component 304 may be alloyable to form an
aluminum alloy. In certain instances, the active component 304 may
include gallium, with areas of higher concentrations of gallium
associated with an increase in weakness. By producing the object
102 with a variation in local concentration of gallium, the object
102 may be thermally processed to form a three-dimensional part
having a predetermined gradient in weakness, which may be useful
for forming the three-dimensional part with a preferential region
of bending or failure. This may be useful, for example, in the
fabrication of structural support members.
[0055] As further or alternative example, the metallic particles
and the active component 304 may be alloyable to form a copper
alloy. In certain instances, the active component 304 may include a
variation in local concentration of one or more of bismuth,
antimony, or tellurium, with this variation being useful for
forming a desired gradient in one or more physicochemical
properties in a three-dimensional part formed from thermally
processing the object 102. As an example, in instances in which the
active component 304 includes bismuth, the active component 304 may
be selectively distributed such that the object 102 is thermally
processable to form a three-dimensional part having desired regions
of corrosion resistance. Antimony may be used in a similar manner
to impart hardening to selected areas of a three-dimensional part
formable through thermal processing of the object 102. Further or
instead, tellurium may be used to impart machinability to
predetermined areas of a three-dimensional part formable through
thermal processing of the object 102.
[0056] In some instances, the metallic particles and the active
component may be alloyable through thermal processing of the object
102 to form a free-machining material in specific regions of the
three-dimensional part formed from the object 102. As used herein,
free-machining shall be understood to refer to a material that
forms small chips when machined. As compared to a material that
does not form such small chips, a free-machining material is less
likely to interfere (e.g., through unintended entanglement) with
operation machinery and, thus, is generally considered to have
improved machinability.
[0057] While the inorganic particles of the powder 104 have been
described as including metallic particles, it should be appreciated
that other compositions of inorganic particles are additionally or
alternatively possible. For example, in certain applications, the
inorganic particles of the powder 104 may include ceramic
particles. Specific examples of ceramic particles that may be
useful for formation of the object 102 include, but are not limited
to, aluminum oxides or silicon carbide. In certain implementations,
the ceramic particles may remain ceramic as the object 102 is
thermally processed to form the three-dimensional part. However, in
some implementations, the ceramic particles in the object 102 may
be a metal oxide subjected to a reduction reaction to form a metal
as the object 102 is thermally processed to form the
three-dimensional part.
[0058] In general, the one or more target locations 306 of the
active component 304 may be along any one or more portions of the
object 102, which includes internal or otherwise inaccessible
portions of the object 102. That is, the one or more target
locations 306 of the active component 304 and, thus, the associated
variations in physicochemical properties are generally not limited
by external access afforded by geometry of the object 102. This is
a significant advantage, as compared to techniques requiring
introduction of one or more materials from a position external to
an object.
[0059] In certain implementations, the one or more target locations
306 of the active component 304 may be at least partially within
(e.g., away from at least one surface) the object 102. As a more
specific example, the one or more target locations 306 of the
active component 304 may be along internal channels, or other
similar geometric features, defined by the object 102 and generally
inaccessible from outside of the object 102. Continuing with this
example, the one or more target locations 306 of the active
component 304 along these internal channels may facilitate
imparting wear-resistance, or another useful change in
physicochemical properties, along these channels.
[0060] In some implementations, the one or more target locations
306 of the active component 304 may be at least partially along an
outer surface of the object 102. Such positioning of the one or
more target locations 306 of the active component 304 may be
particularly useful for imparting changes in physicochemical
properties in areas including intricate geometric features along
the outer surface of the object 102. That is, as compared to the
placement of material on intricate surface features of a part, the
formation of the one or more target locations 306 of the active
component 304 as part of the object 102 itself may offer more
accurate control over a gradient of one or more physicochemical
properties in the area of intricate detail.
[0061] Having described certain features of the object 102,
attention is now turned to aspects of thermally processing the
object 102 to form a three-dimensional part having a predetermined
gradient of one or more physicochemical properties.
[0062] Referring now to FIGS. 1, 3 and 4, an additive manufacturing
plant 400 may include the additive manufacturing system 100, a
conveyor 404, and a post-processing station 406. The powder bed 114
containing the object102 may be moved along the conveyor 404 and
into the post-processing station 406. The conveyor 404 may be, for
example, a belt conveyor movable in a direction from the additive
manufacturing system 100 and toward the post-processing station
406. Additionally, or alternatively, the conveyor 404 may include a
cart on which the powder bed 114 is mounted and, in certain
instances, the powder bed 114 may be moved from the additive
manufacturing system 100 to the post-processing station 406 through
movement of the cart (e.g., through the use of actuators to move
the cart along rails or by an operator pushing the cart). More
generally, however, the conveyor 404 may be understood to include
any manner and form of moving the object 102 to a post-processing
station 406 for thermal processing the object 102 into a
three-dimensional part 410 having a gradient 412 of one or more
physicochemical properties.
[0063] In the post-processing station 406, the object 102 may be
removed from the powder bed 114. The powder 104 remaining in the
powder bed 114 upon removal of the object 102 may be, for example,
recycled for use in subsequent fabrication of additional parts.
[0064] Additionally, or alternatively, in the post-processing
station 406, the object 102 may be cleaned (e.g., through the use
of pressurized air) of excess amounts of the powder 104.
[0065] In certain instances, post-processing of the object 102 may
include one or more debinding processes in the post-processing
station 406 to remove all or a portion of the at least one binder
106 from the object 102. In general, it shall be understood that
the nature of the one or more debinding processes may include any
one or more debinding processes known in the art and may be a
function of the constituent components of the at least one binder
106. Thus, as appropriate, the debinding may include, for example,
one or more of a thermal debinding process, a supercritical fluid
debinding process, a catalytic debinding process, or a solvent
debinding process. For example, in instances in which the at least
one binder 106 includes a binder system of more than one binder, a
plurality of debinding processes may be staged to remove components
of the binder system in corresponding stages as the object 102 is
formed into the three-dimensional part 410 having the gradient 412
of the one or more physicochemical properties.
[0066] Additionally, or alternatively, the object 102 may undergo
any one or more of various different types of thermal processing in
the post-processing station 406. For example, the post-processing
station 406 may include, a furnace 408 in which at least a portion
of the thermal processing of the object 102 may be carried out to
form the object 102 into the three-dimensional part 410 having the
gradient 412 of one or more physicochemical properties. As an
example, in the furnace 408, the object 102 may be subjected to a
thermal process having a peak temperature of greater than about
500.degree. C. and less than about 2100.degree. C., with this
temperature range being particularly useful for sintering metals or
ceramics.
[0067] In general, thermally processing the object 102 forms the
three-dimensional part 410 having, in at least an area of the
three-dimensional part corresponding to a distribution of the
active component 304 of the object 102, a gradient of one or more
physicochemical properties of a material at least partially formed
from thermally processing the inorganic particles of the powder 104
and the active component 304 of the object 102. In certain
instances, the material may be formed from a reaction of the
inorganic particles of the powder 104 and the active component 304.
However, more generally, it should be appreciated that the
inorganic particles of the powder 104 and the active component 304
may be adjacent (e.g., on a microscopic level) to one another in
the object 102, and thermal processing the object 102 may produce
an interaction between the inorganic particles and the active
component 304. This interaction may include any of various
different forms of changes in the solid-state chemistry of the
inorganic material at least partially resulting from thermally
processing the inorganic material in the presence of the active
component 304. Thus, for example, the material may be formed from a
reaction of the inorganic particles of the powder 104 and the
active component 304 in the presence of a process gas used as part
of the thermal processing of the object 102.
[0068] In certain instances, thermally processing the object 102 in
the post-processing station 406 may densify the object 102 to form
the three-dimensional part 410. That is, in this context, the
object 102 should be understood to have a first density, and the
three-dimensional part 410 should be understood to have a second
density greater than the first density associated with the object
102. For certain applications, the second density may be at least
90 percent of a theoretical density of the material formed from
thermally processing the inorganic particles and the active
component.
[0069] Densification of the object 102 may include removal of the
at least one binder 106 in one or more debinding processes. In such
instances, it should be appreciated that, as compared to the at
least one binder 106, the active component 304 may resist removal
from the object 102 through the thermal processing. That is, the
active component 304 may remain in the object 102 following the
removal of the at least one binder 106, which may facilitate
reacting the active component 304 with one or more of the inorganic
particles of the powder 104 or a process gas used as part of the
thermal processing.
[0070] Further or instead, densification of the object 102 may
include reducing void space between the inorganic particles of the
powder 104 in the object 102. This reduction in void space may be
achieved, for example, through sintering the inorganic particles of
the powder 104 to one another and/or to the active component 304.
In certain implementations, the reduction in void space may be
non-uniform throughout the object 102 to produce the gradient in
one or more physicochemical properties sought to be achieved in the
three-dimensional part 410.
[0071] In some instances, the object 102 may be sinterable to form
the three-dimensional part 410, and thermally processing the object
102 may include any one or more sintering processes known in the
art. That is, through the one or more sintering processes, the
inorganic particles of the powder 104 may bond with one another
and, optionally, with other substances to form at least a portion
of the three-dimensional part formed from the object 102. Examples
of such sintering processes include, but or not limited to, bulk
sintering the inorganic particles in the solid state, liquid phase
sintering, and transient liquid phase sintering.
[0072] In some implementations, the object 102 may be infiltratable
with a liquid metal to form the three-dimensional part 410 and,
therefore, thermally processing the object 102 may include
infiltration of the liquid metal through the object 102. As a
specific example, the inorganic particles of the powder 104 forming
the object 102 may be pre-sintered or otherwise bound to form a
substantially solid powdered preform. A liquid metal may be
infiltrated into the substantially solid, powdered preform as part
of the thermal processing to form a final part from the object
102.
[0073] In the sections that follow, various different methods
useful for forming three-dimensional parts, such as the
three-dimensional part 410 having the gradient 412, are described.
In general, each of these methods may be carried out using the
additive manufacturing plant 300. More specifically, unless
otherwise specified or made clear from the context, each of the
methods described in the sections that follow may be carried out
using the additive manufacturing system 100 to form an object
(e.g., the object 102) using binder jetting techniques (e.g.,
techniques described with respect to the exemplary method 200 in
FIG. 2), and thermally processing the object in the post-processing
station 406 to form a three-dimensional part having a gradient of
one or more physicochemical properties. The gradient of the one or
more physicochemical properties may be generally controlled through
appropriate distribution of an active component in the object. In
turn, thermally processing the object forms the three-dimensional
part having the desired gradient of the one or more physicochemical
properties. The methods described below are described separately
for the sake of clarity of explanation and, unless a contrary
intention is explicitly indicated or is made clear from the
context, any of various different aspects of these methods may be
used in combination with one another to form a three-dimensional
part having a controlled gradient of one or more physicochemical
properties.
[0074] Thermally Processable Active Component
[0075] FIG. 5 is a flowchart of an exemplary method 500 of using an
active component to form a gradient of one or more physiochemical
properties in a three-dimensional part. As described in greater
detail below, the exemplary method 500 may facilitate accurate
control of a gradient of one or more physicochemical properties of
a three-dimensional part through accurate placement of an active
component in an object that is thermally processable to form the
three-dimensional part.
[0076] As shown in step 502, the exemplary method 500 may include
forming a plurality of layers of a powder along a powder bed. These
layers may be formed, for example, through spreading of each layer
of the powder across the powder bed as part of a layer-by-layer
process, such as described above with respect to the exemplary
method 200 (FIG. 2), in which the layers are stacked on top of one
another to form successive two-dimensional slices of an object
being formed. Each of the layers may have a thickness of greater
than about 30 microns and less than about 70 microns (e.g., about
50 microns). Further, or instead, the powder may include any one or
more of the various different particles described herein and, thus,
may include any manner and form of ceramic particles or metallic
particles described herein.
[0077] As shown in step 504, the exemplary method 500 may include
delivering one or more binders to the plurality of layers. For
example, the one or more binders may be deposited to the plurality
of layers of the powder between formation of successive layers of
the plurality of layers of the powder. Additionally, or
alternatively, depositing the one or more binders to the layer may
include jetting the one or more binder to the plurality of layers.
That is, continuing with this example, the one or more binders may
be jetted to each layer of the plurality of layers from one or more
nozzles of a printhead moving over each layer of the plurality of
layers. More generally, depositing the one or more binders to the
layer should be understood to include any of various different
forms of delivery of binders described herein for depositing a
binder to a layer in a controlled two-dimensional pattern
associated with the given layer. Thus, delivering the one or more
binders to the plurality of layers may include the use of one or
more of piezoelectric jetting, thermal jetting, pneumatic jetting,
magnetohydrodynamic jetting, electrohydrodynamic jetting, or
acoustophoretic jetting. The applicability of such delivery
techniques should be understood to be at least partially determined
by the one or more binders to be delivered. More specifically, the
one or more binders may include at least one of a polymer (e.g.,
one or more of poly(acrylic acid), a latex suspension, or
poly(vinyl alcohol)), a salt, nanoparticles, or a gel, and the
suitability of a particular delivery technique should be generally
understood to be based at least partially based on one or more
physical or chemical characteristics of each of these forms of the
one or more binders.
[0078] In general, each binder of the one or more binders may be
delivered to one or more layers of the plurality of layers in a
respective controlled two-dimensional pattern based on the
respective binder and a given layer. As used herein, a controlled
two-dimensional pattern shall be generally understood to include a
two-dimensional geometric pattern and, in some instances, a
variation in local concentration along the geometric pattern. For
example, the controlled two-dimensional patterns of the one or more
binders in a given layer may be formed to achieve a predetermined
shape, local concentration, or a combination thereof, of a
particular binder in the given layer. Further, or instead, the
controlled two-dimensional patterns of the one or more binders in
the given layer may be formed to achieve a predetermined overlap
with one another to achieve a predetermined pattern of local
formulations of binder in the given layer.
[0079] As shown in step 506, the exemplary method 500 may include
depositing an additive to the one or more layers of the plurality
of layers. In general, the additive may include an active
component, and an object may be formed by a combination of at least
the one or more binders, the plurality of layers of the powder, and
the active component. It should be understood that other materials
may also be present in the object, such as in instances in which
the additive includes a carrier in which the active component is
dispersed. For the sake of clarity of explanation, the exemplary
method 500 is described with respect to deposition of a single
additive. However, unless otherwise specified or made clear from
the context, it should be generally understood that any number of
additives may be distributed to the one or more layers of the
plurality of layers to produce material distributions useful for
forming any manner and form of gradients of physicochemical
properties in three-dimensional parts formed from thermally
processing the object.
[0080] The additive may include an active component in a higher
volumetric concentration in the additive than in each of the one or
more binders. That is, the additive may have the same constituent
components as one or more of the binders, provided that a
volumetric concentration of the active component in the additive is
greater than a volumetric concentration of the active component in
the binder. This is the case, for example, in instances in which
the additive and one or more of the binders are identical, except
that the additive includes an active component and the one or more
binders do not include the active component. Stated differently, as
compared to the one or more binders individually, the additive may
facilitate more efficient delivery of the active component to a
given layer.
[0081] The additive may be deposited to the one or more layers of
the plurality of layers according to any one or more techniques
described herein as being useful for controlled delivery of a
material (e.g., the one or more binders) in a controlled
two-dimensional pattern along the one or more layers. Thus, like
the one or more binders, the additive may be jetted to the one or
more of the layers from a nozzle associated with a printhead moving
over the one or more layers. More generally, however, the additive
may be jetted to the one or more layers according to any one or
more of various different techniques described herein and
compatible with the physical and chemical properties of the
additive.
[0082] In some implementations, the additive may be deposited to
the one or more layers of the plurality of layers according to a
controlled two-dimensional pattern suitable for achieving a
predetermined spatial distribution of the active component in the
object being formed. This controlled two-dimensional pattern
associated with the additive may be substantially Thus, in certain
implementations, the additive may at partially overlap all or a
portion of the one or more binders in at least one of the layers of
the plurality of layers. Further, concentration of the active
component may be varied along the overlap, which may be useful for
providing an additional degree of control over the gradient of
physicochemical properties of the three-dimensional part formed
from thermally processing the object.
[0083] The additive may be deposited to the one or more layers of
the plurality of layers separately from delivery of the one or more
binders to the plurality of layers. Such separate delivery of the
additive and the one or more binders may be useful, for example,
for achieving a high degree of flexibility in combinations of the
one or more binders with the active component of the additive in a
given layer. As a specific example, the one or more binders may be
delivered to the plurality of layers from a first printhead, and
the additive may be deposited to one or more layers from a second
printhead, separately controllable with respect to control of the
first printhead.
[0084] In some instances, the additive may include a binder. In
such instances, because the additive itself may act as a binder,
the additive may be segregated from the one or more binders in a
given layer. In this context, segregation of the additive from the
one or more binders in the given layer should be understood to
include a distribution in which the additive and the one or more
binders are non-overlapping but adjacent to one another in the
given layer. While such segregation may be useful in some
applications, it should be understood the additive may be combined
with the one or more binders, as may be necessary or useful for
particular applications. Additionally, or alternatively, a binder
included in the additive to be selectively deposited to one or more
layers may be different from the one or more binders delivered to
the plurality of layers. Further, or instead, at least one of the
first binder and the second binder may include one or more of
poly(acrylic acid), a latex suspension, or poly(vinyl alcohol).
[0085] In general, composition of the active component included in
the additive may be based at least upon the composition of the
inorganic particles of the powder and the one or more
physicochemical properties to be varied within the
three-dimensional part ultimately formed from the object being
fabricated through binder jetting. Thus, in some instances, the
active component may include one or more interstitial elements of
at least one phase of the three-dimensional part. In this context,
the term "phase" is used in the metallurgical sense and, thus,
should be understood to be part of the three-dimensional object
having a uniform chemical composition and physical characteristics
(e.g., state of matter and crystal structure). As an example, in
instances in which the three-dimensional part includes a ferrous
phase and/or a nickel phase, the active component may include one
or more of the following interstitial elements: carbon, sulfur,
nitrogen, hydrogen, boron, phosphorous, oxygen, or silicon. As
another example, in instances in which the three-dimensional object
includes an aluminum phase, the active component may include one or
more of the following interstitial elements: nitrogen, oxygen, or
hydrogen. As yet another example, in instances in which the
three-dimensional part includes a titanium phase, the active
component may include one or more of the following interstitial
elements: nitrogen, oxygen, hydrogen, iron, nickel, cobalt,
chromium, manganese, hydrogen, or oxygen. As still another example,
in instances in which the three-dimensional part includes a copper
phase, the active component may include one or more of the
following interstitial elements: carbon, sulfur, nitrogen, boron,
phosphorous, oxygen, or silicon. Other types of active components
may additionally or alternatively include one or more of tungsten
or molybdenum.
[0086] While the active component may include a single material in
certain instances, it should be appreciated that the active
component may, further or instead, include a plurality of
materials. An active component including a plurality of materials
may be useful, for example, for facilitating local formation of a
particular material in a three-dimensional part. Thus, returning to
the example of steel, the active component may include certain
components of stainless steel such that selective deposition of the
active component may result in local formation of stainless steel
in predetermined portions of the three-dimensional part.
[0087] In general, given that the active component of the additive
may be any of various different materials useful for imparting a
desired gradient of physicochemical properties, it should be
appreciated that the active component may be in any one or more of
various different physical forms. To facilitate delivery of certain
forms of the active component, the additive may include a carrier
in which the active component is disposed. In this context, a
carrier may include any medium in which the active component may be
stably dispersed and which is amenable to accurate delivery using
any one or more of the delivery techniques described herein. Thus,
for example, the carrier may facilitate delivery (e.g., jetting) of
the active component from a printhead as described herein.
[0088] In certain implementations, the active component may be
undissolved in the carrier, which may be useful for working with
certain material compositions of the active component. For example,
certain material compositions may be ubiquitously available and,
thus particularly useful, in particle form. Accordingly, in some
instances, the active component may include particles stably
suspended in the carrier. Unless otherwise indicated or made clear
from the context, such stably suspended particles may have any of
various different compositions described herein and, thus, may be
any one or more of various different metals introducible into the
object to produce a desired gradient of one or more physicochemical
properties in a three-dimensional part formed from the object.
Thus, by way of example, the stably suspended particles may be one
or more of iron or chromium, which may be useful for, among other
things, imparting a gradient of one or more physicochemical
properties in a three-dimensional part formed of steel. In some
instances, the particles of the active component may differ in
composition from the inorganic particles of the powder, which may
be useful for imparting gradients in certain physicochemical
properties associated with changes in local composition, rather
than local concentration, of material.
[0089] In some implementations, the particles of the active
component may be hydrophobic (e.g., carbon particles) and the
carrier may include water and at least one surfactant (e.g., one or
more of an anionic surfactant, a cationic surfactant, a
zwitterionic surfactant, or a non-ionic surfactant) such that the
particles of the active component may remain stably suspended in
water at least for a period of time suitable for a binder jetting
fabrication process used to form the object.
[0090] In some instances, the particles of the active component
stably suspended in the carrier may have a controlled size
distribution (e.g., a size distribution ranging from greater than
about 1 nm to less than about 5000 nm). As an advantage, such a
controlled size distribution may reduce the likelihood of damage to
hardware components (e.g., a printhead) used to deliver the
additive including the particles of the active component. Further,
or instead, the controlled size distribution of the particles of
the active component may facilitate accurately varying local
concentrations of the active component along the object being
fabricated.
[0091] While the active component has been described as being
undissolved in a carrier, other approaches to carrying the active
component in a carrier are additionally or alternatively possible.
For example, the carrier may include a solvent, and the active
component may be dissolved in the solvent, which may accurate more
accurate metering of the active component as compared to instances
in which the active component is suspended in a carrier. It should
be generally understood that the nature of the carrier as a solvent
in this context depends on the composition of the carrier and
active component and, more specifically, whether the active
component is soluble in the carrier. Examples of solvents suitable
for dissolving active components may include one or more of water,
an aromatic organic substance, an aliphatic organic substance
(e.g., an alcohol). Further, or instead, the solvent may include a
surfactant.
[0092] As shown in step 508, the exemplary method 500 may include
thermally processing the object into a three-dimensional part.
Given that the three-dimensional part is formed from thermally
processing the object, it should be generally understood that
locations on the object correspond (e.g., in a one-to-one mapping)
to locations on the three-dimensional part in a known manner, even
though the three-dimensional part may be smaller than the object
due to shrinking in certain instances. Accordingly, through
thermally processing the object into the three-dimensional part,
the three-dimensional part may have, in at least an area of the
three-dimensional part corresponding to a distribution of the
active component of the object, a gradient of one or more
physicochemical properties of a material at least partially formed
from thermally processing the inorganic particles and the active
component of the object.
[0093] The gradient of the one or more physicochemical properties
may have any one or more of the variations different spatial
variations (e.g., varying according to a continuous function or
varying according to a step change) described herein and may be
along any one or more portions of the three-dimensional part. By
way of example, the gradient of the one or more physicochemical
properties may include formation of a three-dimensional part having
different physicochemical properties on different faces of the
three-dimensional part (e.g., corrosion resistance on one face of
the three-dimensional part and high hardness on another face of the
three-dimensional part). As another example, the gradient of the
one or more physicochemical properties may be in the form of
wear-resistant channels defined by the three-dimensional part. More
generally, the gradient of the one or more physicochemical
properties may be of any direction and nature along the
three-dimensional part as may be useful for achieving specific
design criteria, which may be, for example, a function of one or
more of geometry or end use of the three-dimensional part.
[0094] In some implementations, at least a portion of the gradient
of the one or more physicochemical properties of the material may
be along a surface of the three-dimensional part. For example, at
least a portion of the gradient of the one or more physicochemical
properties of the material may be perpendicular to the surface of
the three-dimensional part (e.g., such that the gradient extends
from the surface of the three-dimensional part in a direction into
an interior portion of the three-dimensional part). In instances in
which the surface of the three-dimensional part is curved, the
gradient of the one or more physicochemical properties of the
material may be perpendicular to a plane tangential to the curved
surface of the three-dimensional part. Further, or instead, at
least a portion of the gradient of the one or more physicochemical
properties may be parallel to the surface of the three-dimensional
part.
[0095] In certain implementations, at least a portion of the
gradient of the one or more physicochemical properties of the
material may be within the three-dimensional part, away from
surfaces of the three-dimensional part. Such positioning of at
least a portion of the gradient within the three-dimensional part
is a significant advantage of the techniques of the present
disclosure, as compared to modification approaches based on
external access to a part. Thus, for example, the gradient of the
one or more physicochemical properties may be formed entirely
within the three-dimensional part and/or may extend to geometric
details that are inaccessible or difficult to access from an
external surface of the three-dimensional part.
[0096] In general, the material having the gradient of the one or
more physicochemical properties in the three-dimensional part may
be formed from any manner and form of direct or indirect
interaction described herein between the inorganic particles and
the active component during thermal processing. That is, the
inorganic particles and the active component may be adjacent to one
another (e.g., on a microscopic level) in the object as the object
is thermally processed, such that the presence of the active
component influences a change in the inorganic particles during
thermal processing. As an example, the material having the gradient
may be formed by chemically reacting at least the inorganic
particles and the active component with one another during thermal
processing carried out to form the object into the
three-dimensional part. Further, or instead, the material having
the gradient may be at formed through a process including
chemically reacting the inorganic particles or the active component
with one or more process gases used in thermally processing the
object to form the three-dimensional part.
[0097] In general, thermally processing the object may include any
manner and form of exposure of the object to elevated temperature
suitable to form the object into the three-dimensional part
including the material having the gradient of physicochemical
properties. Examples of thermal processing, therefore, include any
manner and form of sintering the object or infiltrating the object
with a liquid metal. Elevated temperatures associated with the
thermal processing may be based on the inorganic particles and the
active component used to form the material. The lower end of a peak
temperature range for a given combination of the inorganic
particles and the active component may be based on achieving
suitable sintering or requirements associated with achieving
suitable infiltration of an infiltrant (e.g., a liquid metal). The
upper end of this peak temperature range may be based on retaining
useful material properties of the material formed at least
partially from the inorganic particles and the active component.
For instances in which the material having the gradient is formed
from metals and/or ceramics, thermally processing the object may
include exposing the inorganic particles and the active component
to a peak temperature of greater than about 500.degree. C. and less
than about 2100.degree. C.
[0098] Thermally processing the object may include densifying the
object into the three-dimensional part. That is, the object may
have a first density prior to thermal processing, the
three-dimensional part may have a second density after thermal
processing, and the second density may be greater than the first
density. While the amount of densification may depend on particular
use cases, the second density may advantageously be at least 90
percent of a theoretical density of the material formed from
thermally processing the inorganic particles and the active
component.
[0099] While thermal processing of the object to form the
three-dimensional part may result in densification in certain
instances, it should be understood that thermal processing may
further or instead result in other salient differences between the
object and the three-dimensional part. That is, in some instances,
the three-dimensional part may remain porous, with the thermal
processing produces other differences in properties between the
object and the three-dimensional part. For example, thermal
processing may increase resistance to tension, which may be useful
for maintaining the shape of the three-dimensional part through
subsequent processing. That is, the object may have a first
resistance to tension along a direction, the three-dimensional part
may have a second resistance to tension along the direction, and
the second resistance to tension may be greater than the first
resistance to tension along the direction. Further, or instead, the
object may have a first thermal conductivity and the
three-dimensional part may have a second thermal conductivity
greater than the first conductivity. Still further or instead, the
object may have a first electrical conductivity and the
three-dimensional part may have a second electrical conductivity
greater than the first conductivity.
[0100] The material at least partially formed from thermally
processing the inorganic particles and the active component may be
any one or more of the various different materials described herein
as being formable through thermally processing the inorganic
particles and the active component. Thus, for example, this
material may be any one or more of various different alloys
described herein. In some instances, the alloy may be steel, with
the active component including any one or more of various different
materials useful for changing properties of steel (e.g., one or
more of carbon, boron, sulfur, phosphorus, antimony, fluorine,
bismuth, arsenic, tin, lead, tellurium, or manganese). In certain
instances, the alloy may be an aluminum alloy, and the active
component of the additive may include gallium. In some instances,
the alloy may be a copper alloy, and the active component may
include one or more of bismuth, antimony, tellurium, zirconium, or
chromium. In some instances, the alloy may be a free-machining
material. As an additional or alternative example, the material at
least partially formed from thermally processing the inorganic
particles and the active component of the object may be a matrix
material. Continuing with this example, the active component may be
unreacted in the matrix material.
[0101] Salt as an Active Component
[0102] FIG. 6 is a flowchart of an exemplary method 600 of using a
salt as an active component to form a gradient of one or more
physiochemical properties in a three-dimensional part. As described
in greater detail below, the exemplary method 600 may facilitate
forming a gradient of one or more physicochemical properties of a
three-dimensional part through the use of a stable additive that is
thermally processable to form the three-dimensional part. Unless
otherwise specified or made clear from the context, it should be
generally understood that the exemplary method 600 may include one
or more aspects of the exemplary method 500 (FIG. 5) described
above and, for the sake of clarity and efficient description, these
aspects are not repeated below with respect to the exemplary method
600, except to highlight differences or to elaborate on certain
features.
[0103] As shown in step 602, the exemplary method 600 may include
forming a plurality of layers of a powder along a powder bed. In
general, step 602 may be analogous to step 502 (FIG. 5) described
above.
[0104] As shown in step 604, the exemplary method 600 may include
delivering one or more binders to the plurality of layers. In
general, step 604 may be analogous to step 504 (FIG. 5) described
above.
[0105] As shown in step 606, the exemplary method 600 may include
depositing an additive to one or more layers of the plurality of
layers. The additive may include at least one salt. An object may
be formed from a combination of materials including at least the
one or more binders, the plurality of layers, and the at least one
salt. As compared to other forms of introducing an active component
into an object being formed through a binder jetting technique, the
use of a salt may be particularly useful at least because salts may
be stable over long periods of time and through conditions
associated with shipping and storage. That is, the use of a salt
may provide a robust solution to the challenge of introducing an
active component into an object for thermal processing, as
described herein, to form a material having a gradient of one or
more physicochemical properties.
[0106] In certain implementations, the additive may include a
solvent, and the at least one salt may be dissolved in the solvent.
In certain instances, the solvent may be water, which may be
particularly useful for forming the additive at the point of
fabrication of the object. This has the advantage of reducing
storage requirements associated with the additive.
[0107] In some implementations, the at least one salt may be a
metal-containing salt (e.g., a boron-containing salt, a
tungsten-containing salt such as any one or more of ammonium
paratungstate and ammonium heptamolybdate, or a
molybdenum-containing salt such as any one or more of ammonium
orthomolybdate, ammonium heptamolybdate, ammonium phosphomolybdate,
and ammonium tetrathiomolybdate). Through thermal processing or
another reaction taking place in the object, metal derived from the
metal-containing salt may at least partially form the material
having the gradient of physicochemical properties in the
three-dimensional part. For example, in instances in which the
inorganic particles of the powder include metallic particles, the
material at least partially formed from the inorganic particles and
the at least one salt is an alloy at least partially formed from
the metallic particles and the metal of the metal-containing
salt.
[0108] As shown in step 608, the exemplary method 600 may include
thermally processing the object into a three-dimensional part
having, at least an area of the three-dimensional part
corresponding to a distribution of the at least one salt of the
object, a gradient of one or more physicochemical properties of a
material at least partially formed from the inorganic particles and
the at least one salt through thermal processing of the object. In
general, thermally processing the object may include carrying out
any one or more of various different thermal processes described
herein (including sintering and/or infiltrating the object with a
liquid metal) at elevated temperature to form the object into the
three-dimensional part.
[0109] In general, the gradient of the three-dimensional part
formed according to the exemplary method 600 may have any one or
more characteristics of the various different gradients described
herein. Thus, for example, along a first portion of the gradient,
the three-dimensional part may be stainless steel, and along a
second portion of the gradient different from the first portion of
the gradient, the alloy may be tool steel. That is, in such
implementations, the exemplary method 600 may be used to form a
part having corrosion resistance along a portion of the
three-dimensional object likely to encounter corroding agents and
having wear resistance along a portion of the three-dimensional
object likely to be subjected to wear.
[0110] Sterically Stabilized Active Component
[0111] FIG. 7 is a flowchart of an exemplary method 700 of additive
manufacturing of a three-dimensional part using a stable additive
including particles of an active component. Unless otherwise
specified or made clear from the context, it should be generally
understood that the exemplary method 700 may include one or more
aspects of the exemplary method 500 (FIG. 5) or the exemplary
method 600 (FIG. 6) described above and, for the sake of clarity
and efficient description, these aspects are not repeated below
with respect to the exemplary method 700, except to highlight
differences or to elaborate on certain features.
[0112] As shown in step 702, the exemplary method 700 may include
forming a plurality of layers of a powder along a powder bed. In
general, step 702 may be analogous to step 502 (FIG. 5) described
above.
[0113] As shown in step 704, the exemplary method 700 may include
delivering one or more binders to the plurality of layers. In
general, step 704 may be analogous to step 504 (FIG. 5) described
above.
[0114] As shown in step 706, the exemplary method 700 may include
depositing an additive to one or more layers of the plurality of
layers such that an object is formed from a combination of at least
the one or more binders, the plurality of layers, and the additive.
The additive may include a first polymer and particles of an active
component attached to the first polymer such that the particles of
the active component are sterically stabilized in the additive. In
certain implementations, it may be desirable, or even necessary, to
deliver an active component in the form of particles, rather than
in another form (e.g., a salt) that may exhibit inherent stability.
This may be the case, for example, in instances in which a
particular size distribution or average size of particles is
desirable. As such, the additive including particles of an active
component attached to the first polymer addresses the challenge of
delivering particles of a particular size distribution or average
size while maintaining those particles in a stable form with a
shelf-life suitable for transportation and storage in commercial
applications.
[0115] In certain implementations, a volumetric concentration of
the particles of the active component may be higher in the additive
than in the one or more binders. For example, the one or more
binders may be free of the particles of the active component such
that the additive is the only source of the particles. Further, or
instead, the one or more binders may include a second polymer,
which may be different from the first polymer in some cases. For
example, the first polymer may be formed of a material particularly
suitable for attachment to the particles of the active component
while the second polymer may be formed of a material particularly
suited to holding the inorganic particles together in a given layer
of the plurality of layers. In certain implementations, one or both
of the first polymer and the second polymer may be poly(ethylene
glycol). Additionally, or alternatively, the one or more binders
may include at least one of a salt, nanoparticles, or a gel.
[0116] The first polymer may be attached to the particles of the
active component in any manner suitable for achieving steric
stabilization of the additive. Thus, for example, the first polymer
may be covalently grafted to the surfaces of the particles of the
active component. Further, or instead, the first polymer may be
physically adsorbed to surfaces of the particles of the active
component. Such physical adsorption may be, for example, ionic.
[0117] In general, it should be appreciated that the particles of
the active component and the polymer are formed of materials that
are attachable to one another through surface chemistry on the
surfaces of the particles. In some instances, therefore, the
particles of the active component may be silicon-based and include
a silicon dioxide surface group. Further, or instead, the particles
of the active component may have a metal oxide surface chemistry.
Still further, or instead, surfaces of the particles of the active
component may include an oxide coating, and the first polymer may
be silane-terminated. As yet another, non-exclusive example, the
first polymer may be thiol-terminated, and the particles of the
active component may have a surface group of at least one of gold,
platinum, silver, silicon, and silicon dioxide. As an additional or
alternative example, the first polymer may be carboxyl-terminated,
and the particles of the active component have a surface group of
at least one of gold, silver, silver oxide, aluminum oxide,
silicon, silicon dioxide, copper, and a copper oxide.
[0118] As shown in step 708, the exemplary method 700 may include
thermally processing the object into a three-dimensional part
having in at least an area of the three-dimensional part
corresponding to a distribution of the particles of the active
component of the object, a gradient of one or more physicochemical
properties of a material at least partially formed from thermally
processing the inorganic particles and the active component of the
object. Such thermal processing may be carried out according to any
one or more of various different techniques described herein and,
thus, may include one or more of sintering the object or
infiltrating the object with a liquid metal. In certain instances,
thermally processing the object according to any one or more of the
techniques described herein may separate the particles of the
active component from the first polymer, which may be useful for
facilitating interaction between the inorganic particles and the
particles of the active component as part of thermal processing to
form the material having a gradient of the one or more
physicochemical properties in the three-dimensional part.
[0119] Decomposing a Binder to Form an Active Component
[0120] FIG. 8 is a flowchart of an exemplary method 800 of additive
manufacturing based on selective decomposition of at least one
binder to form an active component. Unless otherwise specified or
made clear from the context, it should be generally understood that
the exemplary method 800 may include one or more aspects of the
exemplary method 500 (FIG. 5), the exemplary method 600 (FIG. 6),
or the exemplary method 700 (FIG. 7) described above and, for the
sake of clarity and efficient description, these aspects are not
repeated below with respect to the exemplary method 800, except to
highlight differences or to elaborate on certain features.
[0121] As shown in step 802, the exemplary method 800 may include
forming a plurality of layers of a powder across a powder bed. In
general, step 802 may be analogous to step 502 (FIG. 5) described
above.
[0122] As shown in step 804, the exemplary method 800 may include
delivering at least one binder to the plurality of layers of the
powder. In general, step 804 may be analogous to step 504 (FIG. 5)
described above.
[0123] As shown in step 806, the exemplary method 800 may include
selectively decomposing the at least one binder to form an active
component. In general, such selective decomposition of the at least
one binder to form the active component may facilitate forming the
active component in situ, which may offer significant advantages in
terms of simplicity with respect to simplification of the process
used to form a three-dimensional part having a gradient of one or
more physicochemical properties. For example, by forming the active
component in situ, the exemplary method 800 may be less prone to
challenges associated with maintaining stability of additives
including the active component. Further or instead, forming the
active component in situ may facilitate the use of lower cost
materials to deliver the active component to target locations
within the object.
[0124] In general, the active component may be any one or more
materials formable from decomposition of the at least one binder.
For example, the active component yielded from selective
decomposition of the at least one binder may include carbon. That
is, selective decomposition of the at least one binder to form the
active component may increase a local concentration of carbon in
the object. Such an increase in local concentration of carbon may
be useful for imparting a gradient of one or more physicochemical
properties in certain instances, such as in the formation of a
steel part having a gradient in one or more physicochemical
properties. Further, or instead, selective decomposition of the at
least one binder may form a second component, in addition to or as
an alternative to the formation of carbon. As an additional or
alternative example, the at least one binder may include an oxygen
containing material such that decomposition of that at least one
binder in the presence of aluminum or titanium creates areas of
relative weakness as compared to regions of the object along which
the oxygen-containing material is not decomposed. Such engineered
weakness may be useful, for examples, in implementations in which
an area of reduced strength of the three-dimensional part is
desirable, such as shear pins or bolts.
[0125] The active component formed from selective decomposition of
the at least one binder may be formed from any one or more
different decomposition mechanisms, with the suitability of a given
decomposition mechanism based at least in part on a combination of
a chemical composition of the at least one binder and a chemical
composition of the active component yielded from the at least one
binder. Thus, for example, the at least one binder may include a
salt and decomposing at least a portion of the at least one binder
may include selectively decomposing a portion of the salt (e.g.,
through local thermal decomposition of the salt) such the
decomposed portion of the salt forms the active component in
certain target areas along the one or more layers and, thus, in the
object formed from the one or more layers. Continuing with this
example, the portion of the salt that is not decomposed may remain
as a binder in the one or more layers and, thus, in the object
formed from the one or more layers. Further, or instead, the at
least one binder may include a polymer, and decomposing at least a
portion of the at least one binder may include thermal pyrolysis of
the polymer in certain target locations of the object.
[0126] As shown in step 808, the exemplary method 800 may include
thermally processing the object into a three-dimensional part
having, in at least an area of the three-dimensional part
corresponding to the active component of the object, a gradient of
one or more physicochemical properties of a material at least
partially formed from thermally processing the inorganic particles
and the active component of the object. In general, thermally
processing the object into the three-dimensional part may be
carried out using any one or more of the various different thermal
processing techniques described herein and, therefore, may include
sintering the object, infiltrating the object with an infiltrant
(e.g., a liquid metal), or a combination thereof.
[0127] In certain implementations, thermally processing the object
according to step 808 may be carried out separately from one or
more techniques used to selectively decompose the at least one
binder according to step 806. That is, thermally processing the
object according to step 808 may be a global process carried out on
the entire object, whereas selective decomposing the at least one
binder according to step 806 may be carried out locally, at target
locations in one or more layers as the object is being formed in a
layer-by-layer binder jetting process.
[0128] Chemically Modifying a Binder to Form an Active
Component
[0129] FIG. 9 is a flowchart of an exemplary method 900 of additive
manufacturing based on selective chemical modification of at least
one binder to form an active component. Unless otherwise specified
or made clear from the context, it should be generally understood
that the exemplary method 900 may include one or more aspects of
the exemplary method 500 (FIG. 5), the exemplary method 600 (FIG.
6), the exemplary method 700 (FIG. 7), or the exemplary method 800
(FIG. 8) described above and, for the sake of clarity and efficient
description, these aspects are not repeated below with respect to
the exemplary method 900, except to highlight differences or to
elaborate on certain features.
[0130] As shown in step 902, the exemplary method 900 may include
forming a plurality of layers of a powder across a powder bed. In
general, step 902 may be analogous to step 502 (FIG. 5) described
above.
[0131] As shown in step 904, the exemplary method 900 may include
delivering at least one binder to the plurality of layers of the
powder. In general, step 904 may be analogous to step 504 (FIG. 5)
described above.
[0132] As shown in step 906, the exemplary method 900 may include
depositing an ink to one or more layers of the plurality of layers.
The ink may be any one or more of various different inks described
herein and, further or instead, may include any material having a
phase controllably distributable to the one or more layers as part
of a layer-by-layer binder jetting process. Thus, for example, the
ink may be any material deliverable (e.g., jettable) from a nozzle
of a printhead moving over the one or more layers. Further, or
instead, the ink may chemically react with the at least one binder
to form an active component having a composition and concentration
suitable for producing an appropriate gradient in one or more
physicochemical properties of a three-dimensional part. In general,
deposition of the ink to form the active component along target
locations of one or more layers to chemically react with the at
least one binder may be particularly useful for forming the active
component in situ as a layer-by-layer binder jetting process is
carried out to form the object. Such in situ formation of the
active component may, for example, reduce material handling
requirements as compared to maintaining stability of an active
component that includes particles. Additionally, or alternatively,
the chemical reaction of the ink with the at least one binder may
produce advantageous changes in the at least one binder. For
example, the binder may include a colloid of a finely divided
inorganic element that is stable only in a finely dispersed form
that may be undesirable for thermal processing. Continuing with
this example, the ink may chemically react with the finely divided
inorganic element, prior to thermal processing, to form an active
component including an aggregate the finely divided inorganic
element, with this aggregate being more suitable for thermal
processing. Further, or instead, chemical modification of the at
least one binder at target locations in at least one layer may
facilitate achieving modifications that may not otherwise be
achievable through local delivery of an active component including
particles.
[0133] In certain implementations, the at least one binder may
include a salt (e.g., vanadium salt), and the chemical modification
produced by depositing the ink on the salt may change volatility of
the salt. In such implementations, the salt with the altered
volatility is the active component, as this altered salt may
respond differently to subsequent processing as compared to the
salt with unaltered volatility. In certain instances, the ink may
include an ionic solution (e.g., an ionic solution including
vanadium chloride) that increases volatility of the salt.
Additionally, or alternatively, the ink may include an ionic
solution that decreases volatility of the vanadium salt.
[0134] While chemical modification of the at least one binder has
been described as changing volatility of the binder, other types of
volatility-related changes are additionally or alternatively
possible. For example, chemical modification of the binder through
selective deposition of the ink may include changing a volatility
response of the binder to thermal processing. Continuing with this
example, in areas of changed volatility response of the binder, the
binder may be debound differently than the binder in areas of
unchanged volatility response. In turn, such variation in the
debinding characteristics of the binder along the object may
produce a gradient in one or more physicochemical properties in the
three-dimensional part formed from thermally processing the
object.
[0135] As shown in step 908, the exemplary method 900 may include
thermally processing the object into a three-dimensional part
having, in at least an area of the three-dimensional part
corresponding to the active component of the object, a gradient of
one or more physicochemical properties of a material at least
partially formed from thermally processing the inorganic particles
and the active component of the object. In general, thermally
processing the object may be carried out using any one or more of
the various different thermal processing techniques described
herein. Accordingly, thermally processing the object may include
sintering the object, infiltrating the object with an infiltrant
(e.g., a liquid metal), or a combination thereof.
[0136] The above systems, devices, methods, processes, and the like
may be realized in hardware, software, or any combination of these
suitable for a particular application. The hardware may include a
general-purpose computer and/or dedicated computing device. This
includes realization in one or more microprocessors,
microcontrollers, embedded microcontrollers, programmable digital
signal processors or other programmable devices or processing
circuitry, along with internal and/or external memory. This may
also, or instead, include one or more application specific
integrated circuits, programmable gate arrays, programmable array
logic components, or any other device or devices that may be
configured to process electronic signals. It will further be
appreciated that a realization of the processes or devices
described above may include computer-executable code created using
a structured programming language such as C, an object oriented
programming language such as C++, or any other high-level or
low-level programming language (including assembly languages,
hardware description languages, and database programming languages
and technologies) that may be stored, compiled or interpreted to
run on one of the above devices, as well as heterogeneous
combinations of processors, processor architectures, or
combinations of different hardware and software. In another aspect,
the methods may be embodied in systems that perform the steps
thereof, and may be distributed across devices in a number of ways.
At the same time, processing may be distributed across devices such
as the various systems described above, or all of the functionality
may be integrated into a dedicated, standalone device or other
hardware. In another aspect, means for performing the steps
associated with the processes described above may include any of
the hardware and/or software described above. All such permutations
and combinations are intended to fall within the scope of the
present disclosure.
[0137] Embodiments disclosed herein may include computer program
products comprising computer-executable code or computer-usable
code that, when executing on one or more computing devices,
performs any and/or all of the steps thereof. The code may be
stored in a non-transitory fashion in a computer memory, which may
be a memory from which the program executes (such as random access
memory associated with a processor), or a storage device such as a
disk drive, flash memory or any other optical, electromagnetic,
magnetic, infrared or other device or combination of devices. In
another aspect, any of the systems and methods described above may
be embodied in any suitable transmission or propagation medium
carrying computer-executable code and/or any inputs or outputs from
same.
[0138] The method steps of the implementations described herein are
intended to include any suitable method of causing such method
steps to be performed, consistent with the patentability of the
following claims, unless a different meaning is expressly provided
or otherwise clear from the context. So, for example performing the
step of X includes any suitable method for causing another party
such as a remote user, a remote processing resource (e.g., a server
or cloud computer) or a machine to perform the step of X.
Similarly, performing steps X, Y and Z may include any method of
directing or controlling any combination of such other individuals
or resources to perform steps X, Y and Z to obtain the benefit of
such steps. Thus, method steps of the implementations described
herein are intended to include any suitable method of causing one
or more other parties or entities to perform the steps, consistent
with the patentability of the following claims, unless a different
meaning is expressly provided or otherwise clear from the context.
Such parties or entities need not be under the direction or control
of any other party or entity, and need not be located within a
particular jurisdiction.
[0139] It should further be appreciated that the methods above are
provided by way of example. Absent an explicit indication to the
contrary, the disclosed steps may be modified, supplemented,
omitted, and/or re-ordered without departing from the scope of this
disclosure.
[0140] It will be appreciated that the methods and systems
described above are set forth by way of example and not of
limitation. Numerous variations, additions, omissions, and other
modifications will be apparent to one of ordinary skill in the art.
In addition, the order or presentation of method steps in the
description and drawings above is not intended to require this
order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. Thus, while
particular embodiments have been shown and described, it will be
apparent to those skilled in the art that various changes and
modifications in form and details may be made therein without
departing from the spirit and scope of this disclosure and are
intended to form a part of the invention as defined by the
following claims, which are to be interpreted in the broadest sense
allowable by law.
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