U.S. patent application number 16/507700 was filed with the patent office on 2021-01-14 for tailored particles for power-based additive manufacturing.
The applicant listed for this patent is Lawrence Livermore National Security, LLC. Invention is credited to Nikola DUDUKOVIC, Eric DUOSS, Seth Evan WATTS.
Application Number | 20210008615 16/507700 |
Document ID | / |
Family ID | 1000004202206 |
Filed Date | 2021-01-14 |
United States Patent
Application |
20210008615 |
Kind Code |
A1 |
WATTS; Seth Evan ; et
al. |
January 14, 2021 |
TAILORED PARTICLES FOR POWER-BASED ADDITIVE MANUFACTURING
Abstract
The present disclosure relates to a plurality of powder
particles configured to be joined in an additive manufacturing
process to form a part, and wherein each one of the powder
particles comprises a three dimensional, non-spherical shape. The
non-spherical shape of each one of the plurality of powder
particles may be at least one of identical in three dimensional
shape, or at least partially complementary in three dimensional
shape, to each other. The plurality of powder particles may further
be of dimensions enabling fitting individual ones of the plurality
of particles in abutting relationship with one another with
substantially no voids between them.
Inventors: |
WATTS; Seth Evan;
(Collingswood, NJ) ; DUDUKOVIC; Nikola; (Hayward,
CA) ; DUOSS; Eric; (Danville, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lawrence Livermore National Security, LLC |
Livermore |
CA |
US |
|
|
Family ID: |
1000004202206 |
Appl. No.: |
16/507700 |
Filed: |
July 10, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y 70/00 20141201;
B22F 1/0011 20130101; B33Y 10/00 20141201; B22F 10/00 20210101 |
International
Class: |
B22F 1/00 20060101
B22F001/00; B33Y 70/00 20060101 B33Y070/00 |
Goverment Interests
STATEMENT OF GOVERNMENT RIGHTS
[0001] The United States Government has rights in this invention
pursuant to Contract No. DE-AC52-07NA27344 between the U.S.
Department of Energy and Lawrence Livermore National Security, LLC,
for the operation of Lawrence Livermore National Laboratory.
Claims
1. A plurality of powder particles configured to be joined in an
additive manufacturing process to form a part, each one of said
powder particles comprising: a determined three dimensional,
non-spherical shape; the non-spherical shape of each one of the
plurality of powder particles being at least one of identical in
three dimensional shape or at least partially complementary in
three dimensional shape to each other; and the plurality of powder
particles further being of dimensions enabling fitting individual
ones of the plurality of particles in abutting relationship with
one another with substantially no voids between them.
2. The powder particles of claim 1, wherein the powder particles
all have a uniform three dimensional shape.
3. The powder particles of claim 1, wherein the powder particles
all have uniform dimensions.
4. The powder particles of claim 1, wherein the powder particles
all have uniform dimensions and a uniform three dimensional
shape.
5. The powder particles of claim 1, wherein the plurality of powder
particles have differing but at least partially complementary
shapes.
6. The powder particles of claim 5, wherein the plurality of powder
particles include first particles and second particles having
differing but at least partially complementary shapes, and wherein
the first and second powder particles further include dimensions
which enable them to be fit together in abutting relationship with
substantially no voids between them.
7. The powder particles of claim 6, wherein the first powder
particles comprise an octahedral shape.
8. The powder particles of claim 7, wherein the second powder
particles comprise a cuoboctahedral shape.
9. The powder particles of claim 1, wherein the powder particles
each comprise a non-convex stellation of a rhombic
dodecahedron.
10. The powder particles of claim 9, wherein the powder particles
are all of the same dimensions.
11. The powder particles of claim 1, wherein the powder particles
all comprise a cubic square shape.
12. The powder particles of claim 1, wherein the powder particles
comprise first and second groups of powder particles; the first
group of powder particles having a first magnetic dipole
arrangement; and the second group of powder particles having a
second magnetic dipole arrangement different from the first
magnetic dipole arrangement.
13. The powder particles of claim 12, wherein the powder particles
of the first group are attracted to one another, but are repelled
from the powder particles of the second group.
14. The powder particles of claim 13, wherein the powder particles
of the first and second groups all have the same shape.
15. The powder particles of claim 13, wherein the powder particles
of the first and second groups all have the same dimensions.
16. The powder particles of claim 1, wherein at least one of a
porosity or a material of a first subplurality of the powder
particles differs from at least one of a porosity or material of a
second subplurality of the powder particles.
17. A plurality of powder particles configured to be joined in an
additive manufacturing process to form a three dimensional part,
each one of said powder particles comprising: first and second
three dimensional, non-spherical shapes which differ from one
another; the first and second non-spherical shapes being at least
partially complementary in three dimensional shape to each other;
and dimensions of the first and second non-spherical shapes further
enabling fitting individual ones of the plurality of particles in a
layered configuration, and in abutting relationship with one
another, with substantially no voids between them.
18. The powder particles of claim 17, wherein at least one of a
porosity or a material of a first subplurality of the powder
particles differs from at least one of a porosity or material of a
second subplurality of the powder particles.
19. The powder particles of claim 17, wherein the powder particles
comprise first and second groups of powder particles; the first
group of powder particles having a first magnetic dipole
arrangement; and the second group of powder particles having a
second magnetic dipole arrangement different from the first
magnetic dipole arrangement.
20. A method of constructing a three dimensional part using a
plurality of powder particles configured to be joined in an
additive manufacturing process, the method comprising: forming a
plurality of powder particles each having a determined three
dimensional, non-spherical shape; the non-spherical shape of each
one of the plurality of powder particles being at least one of
identical in three dimensional shape or at least partially
complementary in three dimensional shape to each other; the
plurality of powder particles further being formed with dimensions
enabling fitting individual ones of the plurality of particles in
abutting relationship with one another with substantially no voids
between them; arranging the powder particles on a support structure
in an ordered arrangement having substantially no voids between the
particles; and joining the particles to form at least a layer of a
finished 3D part.
Description
FIELD
[0002] The present disclosure relates to feedstock materials used
with additive manufacturing systems, and more particularly to
powder feedstock materials having unique shapes, dimensions and
material characteristics which significantly improve the
densification of 3D parts and structures made using additive
manufacturing processes.
BACKGROUND
[0003] The statements in this section merely provide background
information related to the present disclosure and may not
constitute prior art.
[0004] Additive manufacturing (AM) of parts comprised of one
material or multiple materials, where the feedstock is comprised of
one or more materials (or mixtures of materials) in a granular
form. This may include, but is not limited to, powder-bed methods
like selective laser melting (SLM), selective laser sintering
(SLS), and binder jet printing, or methods in which the particles
themselves are transported like electrophoretic deposition (EPD)
and direct ink writing (DIW) with colloidal inks.
[0005] Powder-based additive manufacturing processes have
historically only used spherical or near-spheroidal particles as
feedstock material, since these are easiest to manufacture.
Spherical or near-spherical powder, for example, is typically
created by grinding a bulk material, by precipitation of particles
from a solution, or by atomization of a molten sample. In
powder-based additive manufacturing methods, the goal is to
agglomerate these particles in locations of one's choosing to
create a part. This can be accomplished in many ways, for example,
by compacting the particles around an electrode in electrophoretic
deposition ("EPD"), depositing them in a direct ink write ("DIW")
operation, or by melting them together in selective laser melting
("SLM").
[0006] Regardless of the above operations employed, spheroidal
particles cannot pack with 100% density. In fact, the theoretical
maximum packing density for uniformly-sized spheres is only 74%,
and randomly-packed spheres typically pack to only 64% density. The
remaining void space manifests directly as porosity of the final
part in some AM methods like EPD. The void space may contribute to
residual stress formation in AM processes like SLM that involve
phase change that can partially fill in the porous space. Even in
this latter case, porosity remains to at least some degree, where
it can nucleate cracks and otherwise contribute to degraded part
performance and longevity.
[0007] Accordingly, further efforts to explore the design of
particles for AM purposes is needed to reduce the porosity in AM
constructed parts. Significantly reducing the porosity of such
parts is expected to significantly improve the resistance to cracks
which weaken the finished AM constructed 3D part.
SUMMARY
[0008] This section provides a general summary of the disclosure,
and is not a comprehensive disclosure of its full scope or all of
its features.
[0009] In one aspect the present disclosure relates to a plurality
of powder particles configured to be joined an additive
manufacturing process to form a part. Each one of the powder
particles may comprise a determined three dimensional,
non-spherical shape. The non-spherical shape of each one of the
plurality of powder particles may be at least one of identical in
three dimensional shape or at least partially complementary in
three dimensional shape to each other. The plurality of powder
particles further may be of dimensions enabling fitting individual
ones of the plurality of particles in abutting relationship with
one another with substantially no voids between them.
[0010] In another aspect the present disclosure relates to a
plurality of powder particles configured to be joined in an
additive manufacturing process to form a three dimensional part.
Each one of the powder particles may comprise first and second
three dimensional, non-spherical shapes which differ from one
another. The first and second non-spherical shapes may be at least
partially complementary in three dimensional shape to each other.
The dimensions of the first and second non-spherical shapes enable
fitting individual ones of the plurality of particles in a layered
configuration, and in abutting relationship with one another, with
substantially no voids between them.
[0011] In still another aspect the present disclosure relates to a
method of constructing a three dimensional part using a plurality
of powder particles configured to be joined in an additive
manufacturing process. The method may comprise forming a plurality
of powder particles each having a determined three dimensional,
non-spherical shape. The method may further include forming the
non-spherical shape of each one of the plurality of powder
particles at least one of identical in three dimensional shape or
at least partially complementary in three dimensional shape to each
other. The plurality of powder particles may further be formed with
dimensions enabling fitting individual ones of the plurality of
particles in abutting relationship with one another with
substantially no voids between them. The method may include
arranging the powder particles on a support structure in an ordered
arrangement having substantially no voids between the particles,
and joining the particles to form at least a layer of a finished 3D
part.
[0012] Further areas of applicability will become apparent from the
description provided herein. It should be understood that the
description and specific examples are intended for purposes of
illustration only and are not intended to limit the scope of the
present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and are not intended to limit the scope of the present
disclosure.
[0014] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings, in which:
[0015] FIG. 1 is a perspective view of one shape of powder
particles in accordance with the present disclosure, which
theoretically enables up to 100% densification in a finished 3D AM
part or structure;
[0016] FIG. 2 is an isometric illustration of two additional
differently shaped powder particles which are designed such that,
when used together in an AM process, can create a larger 3D
structure of virtually any dimension while providing up to
theoretically 100% densification in the finished 3D part;
[0017] FIG. 2a is a diagram illustrating one example of the
dimensions for an octahedral particle in order to enable fitting in
with the cuoboctahedral particles shown in FIG. 2;
[0018] FIG. 3 is an isometric illustration of another powder
particle in accordance with the present disclosure being used to
form a 3D part, which in this example makes use of first
stellations of rhombic dodecahedra, which fit together to form a 3D
part with theoretically up to 100% densification; and
[0019] FIG. 4 shows another embodiment of the present disclosure
which makes use of self-aligning, self-assembling cubes with
patterned complex magnetic polarizations on their faces, enabling
the cubes to bond together in desired orientations to form a 3D
part with theoretically up to 100% density.
DETAILED DESCRIPTION
[0020] Example embodiments will now be described more fully with
reference to the accompanying drawings.
[0021] The present disclosure involves systems and methods for
tailoring one or more of the shape, size, composition, and surface
properties of one or more types of particle for powder-based AM
methods. Particles designed using the teachings presented herein
can significantly reduce porosity in a finished AM manufactured
part, aide agglomeration of particles during a fusing or melting
process while making the part, and improve control over gradients
in material composition within the finished part. The net effect is
to improve the final part to more closely match the ideal
properties assumed in its design. Tailored particles can
additionally help the additive manufacturing process itself, for
example, by improving thermal management in SLM, allowing for
quicker solidification of parts and improved surface finish. Thus,
the design of the printing process can also be improved.
[0022] Tailoring the design of the powder particles can
additionally enable the use of powder-based AM methods in
environments where they would otherwise not be possible or
practical, for example in the reduced gravity or microgravity found
on the Moon or in Earth orbit, respectively. Reuse or recycling of
a part when it is no longer needed can also be facilitated by
tailored particles, allowing it to be decompiled into granular
feedstock with lower energy and cost than traditional
approaches.
[0023] The present disclosure involves the creation of powder
particles having shapes and characteristics making them ideally
suited for improving densification in powder-based additive
manufacturing applications. By controlling one or more important
characteristics including particle shape, particle size, and
particle surface properties and/or material characteristics, the
particles may be optimized for use in creating a wide range of 3D
AM-created parts and structures. Replacing spheroidal particles by
particles with non-spherical, but controlled shapes, allows the
latter to pack with significantly improved density, and potentially
up to 100% density to virtually eliminate voids within the finished
3D part.
[0024] Referring to FIG. 1, powder particles 10 in accordance with
one embodiment of the present disclosure are shown. The powder
particles 10 in this example are made exclusively from identical,
cubical, square-shaped particles having the same dimensions. The
square-shaped particles 10 pack with potentially up to 100% density
when deposited as a powder layer on a support table or surface "S"
during an AM process just prior to heating, and can be used to form
a larger structure 12 of virtually any desired shape and dimensions
when fused or melted together. The particles 10 may all be of
exactly the same material composition or may differ slightly in
composition depending on the needs of the finished 3D part.
Potentially, the dimensions of the particles 10 could be varied
while still achieving potentially up to 100% density. The particles
10 can be tailored to provide a varying degree of porosity through
the part, if a variable porosity is desired in the finished 3D
part. Variable porosity may be achieved by either using particles
of varying porosity, by using particles of different materials, or
through a combination of both processes. For example, one could use
micron-scale particles with nano-scale porosity which could be
preserved, for example, during a sintering operation. One could
also use particles of the same shape but differing compositions,
such that one would expect a slight volumetric change in, say, one
of the types of particles, due to a phase change during a melting
operation, for example, by a steel alloy converting from a
martensitic to a pearlitic form after melting. Also, sintering or
binder-jetting could be used to join particles with shapes
intentionally chosen to pack with less than 100% density, as for
example spheres if their packing density matched the desired final
density (or porosity).
[0025] In this regard it will be appreciated that the term "part"
or "3D" part as used herein includes any form of 3D "structure"
which can be manufactured using an AM process but which might not
normally be termed or viewed as a "part".
[0026] FIG. 2 shows another embodiment of the powder particle
design of the present disclosure in which two differently, but at
least partially complementary, shaped particles 14 and 16 are used
to form a larger structure 18 on the support structure S. The
particles 14 and 16 in this example are shaped as octahedral
(powder particle 14) and cuoboctahedral (powder particle 16) shaped
particles, which form at least partially complementary 3D shapes.
FIG. 2a shows the octahedral particle 14; its wall angles 20 are
selected to match the wall angles 16a (see FIG. 2) of the
cuoboctahedral 16 so that a perfect fit can be achieved. The
particles 14 and 16 are also made of dimensions which enable eight
ones of the particles 16 to be fitted in abutting relationship
around one of the particles 14 without creating any voids, and such
that the octahedral particle 14 is fully encased within eight ones
of the cuoboctahedral. In this example, that is achieved by making
the octahedral particle 14 with the same height "H" and length "L"
dimensions (FIG. 2a), and such that the H and L dimensions are
one-half of the overall L and W dimensions of the cuoboctahedral
particles 16. As seen in FIG. 2, each octahedral particle 14 is
perfectly encased with no voids or gaps between eight
cuoboctahedral particles 16.
[0027] It will be appreciated that a number of other particle
shapes, either all of the same shape or having different shapes,
may be constructed such that they are easily fit together to form a
larger structure with few or zero voids. FIG. 3 shows another
particle design 22 in accordance with the present disclosure. The
particle 22 forms a non-convex stellation of the rhombic
dodecahedron. The particles 22 may be identical in construction and
fit together in an interlocking manner with virtually zero voids.
In this example the particles 22 all have exactly the same
dimensions, however, it is possible that the dimensions of the
particles 22 could be varied while still enabling them to fit
together with theoretically up to 100% density. In FIG. 3 the
particles 22 are fitted together on a support structure S by
shifting them one-half of their length or height dimension relative
to an immediately adjacent particle 22, along each layer. Powders
comprised of such particles may be fully-dense before the additive
manufacturing process per se begins, that is, before a laser is
turned on in SLM process, or may become fully-dense during the AM
process, such as in an EPD process. Such fully dense solids
eliminate porosity in the finished part, which increases the
strength of the finished part, as well as its expected lifespan,
its heat conduction, and potentially other performance metrics or
characteristics of the finished part. The finished part will also
better match the ideal case properties assumed in the design of the
part, meaning that the "as-built" part more closely achieves is
predicted performance. This in turn may lead to faster
certification of AM parts in critical applications, for example
with airborne structures.
[0028] In addition, a fully-dense powder bed under the melt pool of
AM processes like the SLM process improves the heat conduction away
from the melted material, solidifying it faster. This results in a
faster overall manufacturing process, particularly if the walls
around the powder bed are plumbed to act as a heat sink.
Furthermore, a present day surface finish limitation of the SLM
process results from the high mismatch in thermal conductivity
between the solidified regions and the powder regions in previous
layers in the build volume. Reducing the mismatch in thermal
conductivity by using densified powders significantly reduces, and
in some instances may even completely eliminate, this thermal
conductivity mismatch. The elimination of the thermal conductivity
mismatch can be expected to improve surface finishes, and thus the
need for post-processing (polishing, etc.) after the additive
manufacturing.
[0029] Still another approach to achieving fully-dense powders is
to tailor the size distribution of the particles. Even for
spheroidal shapes, a carefully chosen size distribution can achieve
nearly 100% density in a finished 3D part by mixing particle sizes,
for example, as in the Apollonian gasket problem (i.e., a fractal
design in which a circular domain is 100% filled with smaller
circles of varying sizes).
[0030] When spatially-tailored micro porosity is a desirable
feature, e.g. for parts through which a fluid phase will percolate,
then the control of the size(s) and shapes(s) of the particle(s) in
the powder are tuning parameters that can be chosen to achieve
gradients in porosity below the particle size, laser spot size, or
other processing parameters. The use of particles which themselves
are highly porous, as created for example by removal of a
sacrificial phase, allows one to create hierarchical porosity.
Three dimensional parts with a hierarchical porosity are expected
to be important in applications involving bio-compatible materials,
since structures made from bio-compatible materials mimic natural
materials like bone, pulmonary alveoli, and so forth.
[0031] Selective or spatially-varying functionalization of the
powder particles provides another axis of control of the powder
particles. For example, creating a magnetic dipole moment on each
powder particle allows the particles to be aligned during
fabrication by the application of an external magnetic field. This
may be either be an integral part of the AM process, as in EPD, or
an additional method of control by which aligning powder particles
to be adhered in a binder jet method. For example, an external
magnetic field could be used to align the particles as they are
being added to the build volume of an AM machine before the
solidification step begins. For example, an oscillating magnetic
field could be used to help align the fresh layer of powder with
previously-deposited layers. Such functionality could also be used
to improve alignment under shear, e.g. when the powder particles
are delivered to the build area or to the part itself by a tube,
nozzle, or other such channel that would impose shear on the
granular medium, as is the case in DIW methods. Such shear
alignment would allow a free-flowing colloidal ink to be deposited
as a near-net-shape part within a build volume, with the particles
aligned yet separated by the ink's solvent. The solvent could then
be evaporated, leaving densely-packed, aligned particles, which
could then be solidified by various means, including heat
treatment, RF welding or other methods.
[0032] Complex magnetic polarization of the particle surfaces is
another construction/methodology that enables tailored particle
matching to facilitate particle alignment and dense packing. For
example, FIG. 4 shows another embodiment of the present disclosure
in which particles 24 and 26 are of the same shape, but particle 24
has magnet dipole moments 24a1 which are arranged differently from
magnetic dipole moments 26a1 of particles 26. This enables
particles 26 to be attracted to one another because of their
magnetic dipole moments, while particle 24 is repelled from the
particles 26 (because of differing/repulsive magnetic dipole
elements). This enables self-assembly and self-alignment of the
particles in an ordered arrangement on the support structure S
which achieves a highly dense (up to or including 100%
densification). Thus, patterns and structures can be formed, even
in a powder bed, before the AM joining process (i.e., melting or
fusion of particles through heat) has begun. Means to reduce the
energy barrier to such pattern or structure formation may include,
but are not limited to, the addition of a wetting agent,
application of a vibration signal, application of heat, flowing a
gas through the powder particles, solvent evaporation-driven
assembly and steady or oscillatory shear.
[0033] The particles may be constructed by growing them with
nano-scale control over feature sizes, for example by photoresist
silicon wafer patterning. Such patterning may also be used to
produce particles which have pits on one or more surfaces. Using
such silicon wafer patterning, and then adding magnetic material in
the pits, provides the magnetic dipoles required to control
attraction and repulsion of the different types of particles.
[0034] It will be appreciated that other approaches to forming
particles with magnetic or other functionalized surfaces exist.
Within the academic literature, these are known as "patchy
particles" and have been formed, for example, by colloidal fusion
(see, e.g., Gong et al., Nature 550, October 2017). These known
fabrication processes may potentially be applied in manufacturing
powder particles for AM applications.
[0035] Another approach would be to use AM processes which can
fabricate with two or more materials simultaneously. One would then
build both the main body of the particle as well as the magnetic or
other functionalized pattern at once. Multi-material projection
micro-stereolithography is one such approach and may be used to
print such particles in the tens to hundreds of microns size range.
Still another approach may be to make the particles with prescribed
nanoscale porosity, then wicking a magnetic material precursor
(e.g., in solution) through these pores.
[0036] While the illustration of FIG. 4 shows square shaped
particles 24 and 26a/26b being used, it will be appreciated that
the use of selectively positioned magnetic dipoles is not limited
to use with only square shaped particles. For example, pyramidal,
octahedral, cuboctahedral, or other shapes of particles may be
incorporated, and two or more differently shaped particles may be
used as well, with selective magnetic dipole arrangements which
facilitate alignment and aggregation/clustering of the particles in
a desired order, or repulsion of different types of particles or
particles of different shapes. Still further, the use of magnetic
dipoles on some particles may be combined with the use of particles
which have no dipoles, to achieve different degrees of density
throughout a part. The use of magnetic dipoles may also be combined
with material selection of different types of particles to cause
aggregation/clustering of materials of different constructions,
and/or separation of materials of different types of constructions,
to thus tailor a specific performance aspect (e.g., strength,
porosity; flexibility, etc.) of the finished 3D part.
[0037] The introduction of controllable magnetic binding between
particles additionally enables the use of powder-based AM methods
in environments where the use of powders would otherwise be
impractical or impossible. One such case is in low gravity
environments, such as one would find at a colony on the Moon or on
Mars, where the lower-than-Earth gravity may be insufficient to
pack a powder bed, e.g., for an SLM method, without unacceptably
high porosity. This porosity will be remedied by self-assembling,
densely packing particles as describe above. Another such case is
in microgravity ("zero gravity"), such as one would find aboard a
space ship in Earth orbit, or in transit from Earth to Mars. Here,
a traditional powder bed would be impossible to form since it would
not settle into the bed but would instead float above or around it.
The introduction of controllable magnetic or other binding between
the particles, and possibly between the particles and the bed,
allows the formation of such a bed, and would additionally make
handling of the powder safe since it would not float throughout the
space ship interior.
[0038] Selectively coating particles with compounds that promote or
inhibit agglomeration allows further control over the "as-built"
part via powder patterning. For example, selectively coating some
particles but not others with a heat-setting adhesive, or with
different solders that melt at varying temperatures, and
distributing these selected particles spatially, allows for the
creation of a solid part without using directed energy like SLM, by
simply heating the build area (for example with isostatic
compression). This also enables the manufacture of parts by novel
means, for example, by deformation of the entire build volume of
metal powder as in roll welding, or by solvent or RF welding of
polymers when inhibitors are spatially distributed.
[0039] Additionally, such spatially-distributed compounds could
serve to improve the reusability or recyclability of the part back
into its granular feedstock. Consider for example a solder with a
particular stoichiometry which partially melts at one temperature,
agglomerating nearby particles and forming a solid part when
cooled. Then when the part is no longer needed, it is heated to a
higher temperature, melting a solid phase in the solder with an
accompanying volumetric change, leading to re-pulverization of the
part back into granular feedstock. This decomposition directly back
into the AM feedstock would require less energy and cost than
forming new feedstock from solid material, and additionally would
allow for a reduction in the amount of feedstock that would need to
be kept in inventory in applications where space and weight are at
a premium, e.g., in submarines on extended patrols, space missions,
and the like. The capability of the binding phase to have a
secondary, de-adhesive, property is not limited to solders, or to
activation by temperature. Other examples include an adhesive that,
once activated, is susceptible to a chemical etchant, or a chemical
composition that generates a brittle phase under high hydrostatic
pressures, allowing for the particles to be easily broken
apart.
[0040] In one or all of the above described embodiments, it may be
desirable to construct the support structure S on which the
particles are placed to allow the support structure to be vibrated
for a short time (e.g., a few seconds or longer) to help settle the
particles into a densely packed configuration, before applying heat
to melt or fuse the powder particles together in an AM process.
[0041] It will also be appreciated that the sizes of the particles
described herein may vary widely to meet the needs of a specific
application, but it is expected that in many applications the
particles will be constructed with a size on a scale of tens of
hundreds of microns.
[0042] The teachings of the present disclosure enable particles to
be formed which can provide a tailored porosity for the finished
part; that is, some portions of the part may have a greater or
lesser degree of porosity than others. The porosity can be used to
control some other quality or characteristic of the part, for
example fluid percolation through the part or through different
sections of the part.
[0043] The present disclosure thus provides particle design and
construction which significantly improve the residual porosity,
residual stress, gradients in material composition, particle
alignment, and fidelity to as-designed plans. The powder particles
described herein achieve these benefits regardless of the type,
size, or composition of the part being fabricated, and regardless
of the powder-based AM process being used.
[0044] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the disclosure. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the disclosure, and all such modifications are intended to be
included within the scope of the disclosure.
[0045] Example embodiments are provided so that this disclosure
will be thorough, and will fully convey the scope to those who are
skilled in the art. Numerous specific details are set forth such as
examples of specific components, devices, and methods, to provide a
thorough understanding of embodiments of the present disclosure. It
will be apparent to those skilled in the art that specific details
need not be employed, that example embodiments may be embodied in
many different forms and that neither should be construed to limit
the scope of the disclosure. In some example embodiments,
well-known processes, well-known device structures, and well-known
technologies are not described in detail.
[0046] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be
limiting. As used herein, the singular forms "a," "an," and "the"
may be intended to include the plural forms as well, unless the
context clearly indicates otherwise. The terms "comprises,"
"comprising," "including," and "having," are inclusive and
therefore specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. The
method steps, processes, and operations described herein are not to
be construed as necessarily requiring their performance in the
particular order discussed or illustrated, unless specifically
identified as an order of performance. It is also to be understood
that additional or alternative steps may be employed.
[0047] When an element or layer is referred to as being "on,"
"engaged to," "connected to," or "coupled to" another element or
layer, it may be directly on, engaged, connected or coupled to the
other element or layer, or intervening elements or layers may be
present. In contrast, when an element is referred to as being
"directly on," "directly engaged to," "directly connected to," or
"directly coupled to" another element or layer, there may be no
intervening elements or layers present. Other words used to
describe the relationship between elements should be interpreted in
a like fashion (e.g., "between" versus "directly between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the
term "and/or" includes any and all combinations of one or more of
the associated listed items.
[0048] Although the terms first, second, third, etc. may be used
herein to describe various elements, components, regions, layers
and/or sections, these elements, components, regions, layers and/or
sections should not be limited by these terms. These terms may be
only used to distinguish one element, component, region, layer or
section from another region, layer or section. Terms such as
"first," "second," and other numerical terms when used herein do
not imply a sequence or order unless clearly indicated by the
context. Thus, a first element, component, region, layer or section
discussed below could be termed a second element, component,
region, layer or section without departing from the teachings of
the example embodiments.
[0049] Spatially relative terms, such as "inner," "outer,"
"beneath," "below," "lower," "above," "upper," and the like, may be
used herein for ease of description to describe one element or
feature's relationship to another element(s) or feature(s) as
illustrated in the figures. Spatially relative terms may be
intended to encompass different orientations of the device in use
or operation in addition to the orientation depicted in the
figures. For example, if the device in the figures is turned over,
elements described as "below" or "beneath" other elements or
features would then be oriented "above" the other elements or
features. Thus, the example term "below" can encompass both an
orientation of above and below. The device may be otherwise
oriented (rotated 90 degrees or at other orientations) and the
spatially relative descriptors used herein interpreted
accordingly.
* * * * *