U.S. patent application number 15/029097 was filed with the patent office on 2016-08-25 for three-dimensional printed hot isostatic pressing containers and processes for making same.
This patent application is currently assigned to The ExOne Company. The applicant listed for this patent is THE EXONE COMPANY. Invention is credited to Howard A. Kuhn, Thomas Lizzi, Rick D. Lucas, Michael J. Orange.
Application Number | 20160243621 15/029097 |
Document ID | / |
Family ID | 52828629 |
Filed Date | 2016-08-25 |
United States Patent
Application |
20160243621 |
Kind Code |
A1 |
Lucas; Rick D. ; et
al. |
August 25, 2016 |
Three-Dimensional Printed Hot Isostatic Pressing Containers and
Processes for Making Same
Abstract
Methods are disclosed for making a hot isostatic pressing
container for hot isostatic pressing a powder material to form an
article comprising three-dimensionally printing the container from
a build powder, the container having a cavity for receiving the
powder material and an outer section having an outer surface, the
cavity having a surface and being shaped and sized so that hot
isostatic pressing the container with the powder material within
the cavity results in the production of the article. Methods are
also disclosed for making the hot isostatically pressed article
using the container.
Inventors: |
Lucas; Rick D.; (Belmont,
OH) ; Kuhn; Howard A.; (Butler, PA) ; Orange;
Michael J.; (Latrobe, PA) ; Lizzi; Thomas;
(Harmony, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THE EXONE COMPANY |
North Huntingdon |
PA |
US |
|
|
Assignee: |
The ExOne Company
North Huntington
PA
|
Family ID: |
52828629 |
Appl. No.: |
15/029097 |
Filed: |
October 15, 2014 |
PCT Filed: |
October 15, 2014 |
PCT NO: |
PCT/US14/60572 |
371 Date: |
April 13, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61892078 |
Oct 17, 2013 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 2302/20 20130101;
B22F 5/10 20130101; B22F 3/15 20130101; C25D 7/04 20130101; B22F
2301/35 20130101; B22F 2301/15 20130101; C23C 4/11 20160101; B22F
2003/153 20130101; B22F 2003/242 20130101; C23C 4/10 20130101; B33Y
80/00 20141201; B22F 3/008 20130101; B22F 3/1258 20130101; C23C
18/1644 20130101; B22F 3/1266 20130101; B33Y 10/00 20141201; B22F
2302/253 20130101; C23C 18/32 20130101 |
International
Class: |
B22F 3/12 20060101
B22F003/12; B22F 3/15 20060101 B22F003/15; B22F 3/00 20060101
B22F003/00 |
Claims
1. A method for making a container (20) for hot isostatic pressing
a powder material to form an article (2) comprising
three-dimensionally printing the container (2) from a build powder,
the container having a cavity (26) for receiving the powder
material and an outer section (22) having an outer surface, the
cavity having a surface and being shaped and sized so that hot
isostatic pressing the container (20) with the powder material
within the cavity (26) results in the production of the article (2)
surrounded by the container (20).
2. The method of claim 1, wherein the article (2) has an internal
passageway (8) and the step of three-dimensionally printing the
container (20) includes forming a core (24) adjacent to the cavity
(26).
3. The method of claim 1, further comprising the step of sealingly
coating at least a portion of the outer surface with at least one
layer of a gas-impervious coating (42).
4. The method of claim 3, wherein the step of sealingly coating
includes applying the gas-impervious coating (42) by at least one
selected from the group consisting of electrolplating and
electroless plating.
5. The method of claim 3, wherein the gas-impervious coating (42)
comprises nickel.
6. The method of claim 3, wherein the gas-impervious coating (42)
has a thickness in the range of 60 microns to 100 microns.
7. The method of claim 3, wherein the step of sealingly coating
includes applying the gas-impervious coating (42) by dipping the
container (20) into a bath comprising the coating material.
8. The method of claim 3, wherein the step of sealingly coating
includes applying the gas-impervious coating (42) by plasma-spray
deposition.
9. The method of claim 1, further comprising the step of increasing
the inertness of a portion of the cavity surface which is to come
in contact with the powder material.
10. The method of claim 9, wherein the step of increasing the
inertness includes contacting the cavity surface with at least one
of chemical solution and a suspension.
11. The method of claim 9, wherein the step of increasing the
inertness includes exposing the cavity surface to a gas or
combination of gasses at a preselected temperature.
12. The method of claim 9, wherein the step of increasing the
inertness includes coating the cavity surface with an inert
material.
13. The method of claim 12, wherein the inert material is at least
one selected from the group consisting of boron nitride and
alumina.
14. The method of claim 1, wherein the build powder comprises a
steel powder.
15. A method for making an article (2) including the steps of:
three-dimensionally printing a hot isostatic pressing container
(20) from a build powder, the container (20) having a cavity (26)
for receiving a powder material and an outer section (22) having an
outer surface, the cavity (26) having a surface and being shaped
and sized so that hot isostatic pressing the container with the
powder material within the cavity (26) results in the production of
the article (2) surrounded by the container (20); loading the
powder material into the cavity (26); and hot isostatically
compressing the container (20) with the powder material within the
cavity (26).
16. The method of claim 15, wherein the article (2) has an internal
passageway (8) and the step of three-dimensionally printing the
container (20) includes forming a core (24) adjacent to the cavity
(26).
17. The method of claim 15, further comprising the step of
sealingly coating at least a portion of the outer surface with at
least one layer of a gas-impervious coating (42).
18. The method of claim 17, wherein the gas-impervious coating (42)
comprises nickel.
19. The method of claim 15, further comprising the step of
increasing the inertness of a portion of the cavity surface which
is to come in contact with the powder material.
20. The method of claim 1, wherein the build powder comprises a
steel powder.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The invention relates to methods of preparing powder
containers for use in hot isostatically pressing, to the containers
themselves, and to the use of the containers to produce hot
isostatically pressed parts.
[0003] 2. Background of the Invention
[0004] Hot isostatic pressing ("HIP") involves the application of
an isostatic pressure to an object that is at a temperature at
which the pressure is sufficient to cause the object to plastically
deform. HIP is commonly used for densify parts made by casting,
powder metallurgical, and ceramic processes by closing or
diminishing the size residual porosity in the parts.
[0005] HIP is also used as a means for consolidating metal powders
directly into a dense object. The metal powders are placed into a
container which is malleable at the HIP temperature. The container
is attached to a vacuum pump to evacuate gases. Often, the
container is heated while it is attached to the vacuum pump as an
aid in removing adsorbed gases from the surfaces of the powder
particles and of the container. The container is then hermetically
sealed, e.g. by hot crimping, and then hot isostatically pressed at
a time, temperature, pressure combination selected based upon the
type of powder, the size of the container, and the objective of the
HIP process. After HIP, the container is removed from the part by
machining and/or chemical dissolution.
[0006] Over the years, variations have been developed for
performing HIP on powder encapsulated in a container. Some
variations were directed at improving the throughput efficiency
through the use of auxiliary furnaces in combination with the
vessels in which the high pressure is applied. Other variations
were directed at increasing the complexity of the resultant part
geometry. Some of these shape-related variations were directed at
increasing the complexity of the container, e.g. the use of spin
formed containers. Others employed a deformable mold, e.g. a
ceramic mold made by the lost-wax process, placed within the
container and surrounded by a secondary pressing media. These
variations, though, have their limitations and their drawbacks.
Spin formed containers are useful only for parts which have axial
symmetry. Containers made by welding sections together give rise to
problems with gas-leakage at welds, disparity in strength and
deformation at welds, and limitations on weld placement. The use of
a secondary pressing media distorts the hydrostatic pressure field
and the use of internal molds present difficulties in mold design,
preparation, and uniformity of filling.
[0007] Additional information about hot isostatic pressing can be
found in the book "Hot Consolidation of Powders and Particulates"
by Animesh Bose and William B. Eisen, published by the Metal
Powders Industry Federation, 2003, ISBN 1-878954 495-4.
SUMMARY OF THE INVENTION
[0008] The present invention provides methods for preparing
containers for use in HIP. In accordance with the present
invention, a container is formed by three dimensional printing a
build powder in the shape the container is to have and then the
container is consolidated by heat treating the printed part to
densify and strengthen the build powder. In some embodiments of the
present invention, the container is printed with internal features
which will produce passageways in the HIP part. Since these
internal features are analogous to cores that are used in the
foundry industry, they will be referred to herein as cores.
[0009] Three dimensional printing was developed in the 1990's at
the Massachusetts Institute of Technology and is described in
several United States patents, including the following United
States patents: U.S. Pat. No. 5,490,882 to Sachs et al., U.S. Pat.
No. 5,490,962 to Cima et al., U.S. Pat. No. 5,518,680 to Cima et
al., U.S. Pat. No. 5,660,621 to Bredt et al., U.S. Pat. No.
5,775,402 to Sachs et al., U.S. Pat. No. 5,807,437 to Sachs et al.,
U.S. Pat. No. 5,814,161 to Sachs et al., U.S. Pat. No. 5,851,465 to
Bredt, U.S. Pat. No. 5,869,170 to Cima et al., U.S. Pat. No.
5,940,674 to Sachs et al., U.S. Pat. No. 6,036,777 to Sachs et al.,
U.S. Pat. No. 6,070,973 to Sachs et al., U.S. Pat. No. 6,109,332 to
Sachs et al., U.S. Pat. No. 6,112,804 to Sachs et al., U.S. Pat.
No. 6,139,574 to Vacanti et al., U.S. Pat. No. 6,146,567 to Sachs
et al., U.S. Pat. No. 6,176,874 to Vacanti et al., U.S. Pat. No.
6,197,575 to Griffith et al., U.S. Pat. No. 6,280,771 to Monkhouse
et al., U.S. Pat. No. 6,354,361 to Sachs et al., U.S. Pat. No.
6,397,722 to Sachs et al., U.S. Pat. No. 6,454,811 to Sherwood et
al., U.S. Pat. No. 6,471,992 to Yoo et al., U.S. Pat. No. 6,508,980
to Sachs et al., U.S. Pat. No. 6,514,518 to Monkhouse et al., U.S.
Pat. No. 6,530,958 to Cima et al., U.S. Pat. No. 6,596,224 to Sachs
et al., U.S. Pat. No. 6,629,559 to Sachs et al., U.S. Pat. No.
6,945,638 to Teung et al., U.S. Pat. No. 7,077,334 to Sachs et al.,
U.S. Pat. No. 7,250,134 to Sachs et al., U.S. Pat. No. 7,276,252 to
Payumo et al., U.S. Pat. No. 7,300,668 to Pryce et al., U.S. Pat.
No. 7,815,826 to Serdy et al., U.S. Pat. No. 7,820,201 to Pryce et
al., U.S. Pat. No. 7,875,290 to Payumo et al., U.S. Pat. No.
7,931,914 to Pryce et al., U.S. Pat. No. 8,088,415 to Wang et al.,
U.S. Pat. No. 8,211,226 to Bredt et al., and U.S. Pat. No.
8,465,777 to Wang et al. In essence, three-dimensional printing
involves the spreading of a layer of particulate material and then
selectively jet-printing a fluid onto that layer to cause selected
portions of the particulate layer to bind together. This sequence
is repeated for additional layers until the desired part has been
constructed. The material making up the particulate layer is often
referred as the "build material" and the jetted fluid is often
referred to as a "binder", or in some cases, an "activator".
Post-processing of the three-dimensionally printed part is often
required in order to strengthen and/or densify the part.
[0010] In some embodiments of the present invention, the
consolidation of the printed container includes the infiltrating of
the printed container with a liquid metal. In some embodiments of
the present invention, the consolidated printed container is plated
with a metal to seal its external surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The criticality of the features and merits of the present
invention will be better understood by reference to the attached
drawings. It is to be understood, however, that the drawings are
designed for the purpose of illustration only and not as a
definition of the limits of the present invention.
[0012] FIG. 1 is a schematic perspective view of a valve body that
is to be made according to an embodiment showing the internal
passages in dashed lines.
[0013] FIG. 2 is an elevation cross-sectional view taken along a
vertical midplane of a container according to an embodiment for
making the valve body of FIG. 1.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0014] The criticality of the features and merits of the present
invention will be better understood by reference to the attached
drawings. It is to be understood, however, that the drawings are
designed for the purpose of illustration only and not as a
definition of the limits of the present invention. It is to be
understood that whenever a range of values is described herein or
in the appended claims that the range includes the end points and
every point therebetween as if each and every such point had been
expressly described. Unless otherwise stated, the word "about" as
used herein and in the appended claims is to be construed as
meaning the normal measuring and/or fabrication limitations related
to the value which the word "about" modifies. Unless otherwise
specified, the term "embodiment" is used herein to refer to
embodiments of the present invention.
[0015] The present invention provides novel and useful methods for
making HIP containers as well as the parts resulting from the use
of those HIP containers. FIG. 1 shows an example of a valve body 2
that is to be made by HIP consolidation of a metal powder. The
valve body 2 has a top flange 4 and a bottom flange 6 with a
passage 8 extending therebetween. The valve body 2 also has a neck
10, for accommodating a handle stem, having internal threads
12.
[0016] FIG. 2 shows a cross-sectional elevation view of a first HIP
container 20 for making the valve body 2 according the present
invention. The first HIP container 20 includes an outer section 22
and an inner core 24 with a cavity 26 being situated therebetween.
The cavity 26 is shaped and sized so that use of the first HIP
container 20 would result in the production of the valve body 2. As
shown, the first HIP container 20 has two ports, first and second
ports 28, 30 through which the metal powder, which after being
consolidated by HIP is to constitute the valve body 2, may be
loaded into the cavity 26 and gas extracted from the cavity 26. It
is within the scope of the present invention for the first HIP
container 20 to include a single port or any number of ports, the
design features of which are selected to permit the powder filling
and/or the gas evacuation of the cavity 26. The first and second
ports 28, 30 have been chosen to have different designs in this
exemplary embodiment in order so illustrate some of the port design
variations encompassed by the present invention. The first port 28
has a collar 32 protruding from the outer section 22. The collar 32
is adapted to receive a crimpable tube 36 (shown in phantom) which
is fastened to collar 32 by weld 38 (shown in phantom) which is of
a length and size so as to be adapted to be attached to a vacuum
hose. The second port 30 includes a crimpable, pipe-like protrusion
40 that is of a length and size so as to be adapted to vacuum hose.
The first HIP container 20 also has an optional gas-impervious
coating 42 which is best seen in the expanded view of section A.
The coating 42 covers the exterior of first HIP container 20 and is
designed to prevent gas leakage into the cavity 30 during the gas
evacuation of the cavity 30 and during the hot isostatic pressing
of the first HIP container 20. A coating such as coating 42 is
necessary only in cases in which the first HIP container 20 has
interconnected porosity which would cause a vacuum leak in cavity
26 or would permit gas to enter the cavity 26 during the hot
isostatic pressing of first HIP container 20.
[0017] The first HIP container 20 is made according to the present
invention by three dimensional printing followed by post-printing
processing. The build powder used for three dimensional printing
the first HIP container 20 is selected to be compatible with the
three dimensional printing process, the post-printing processing of
the printed container, the metal powder that is to be contained
within the cavity 26 of the first HIP container 20, and the HIP
condition. For example, the build powder may be chosen to be a low
carbon steel powder of a powder size and distribution that allows
it be readily spread in a three dimensional printer and then
sintered into a strong monolithic body or sintered and infiltrated
with a bronze into a strong composite body. The low carbon steel is
also amenable to being hot crimped to form a vacuum-tight seal
after powder has been filled into the cavity 26 and the gases have
been evacuated out of cavity 26. Though strong at room temperature,
the low carbon steel flows easily under common HIP temperature and
pressure conditions to allow a metal powder contained within the
cavity 26 to consolidate into a dense part. Low carbon steel is
also easily machined and/or chemically removed from the valve body
2 that was formed as a result of the hot isostatic pressing of the
metal powder in the cavity 26.
[0018] The compatibility of the build powder with the metal powder
that is to be consolidated within cavity 26 may be enhanced by
adjusting the character of the portion of the surface of the cavity
26 that comes into contact with the build powder. The character may
be adjusted by chemically altering that surface by chemical means
to make the surface relatively inert. This may be done by
contacting the surface with chemical solutions or suspensions, by
exposing the surface to an appropriate gas or combination of gases
at an appropriate temperature, or a combination of these methods.
The character of the surface also be adjusted by coating the
surface with a relatively inert material, e.g., alumina, boron
nitride, etc. The coating may be applied by exposing the surface to
a suspension of the inert material in an appropriate carrier fluid.
The surface character may also be adjusted through a combination of
the use of a chemical means and the application of a coating
material.
[0019] The optional gas-impervious coating 42, when used, must
adhere well to the underlying surface of the first HIP container
20. It must also be capable of extending over and sealing any
porosity on that underlying surface and to maintain a gas-tight
seal even during the pressure and temperatures applied during the
HIP. Thus, both the thickness and the material properties of
coating 42 must be chosen with care. It is within the scope of the
present invention that the coating 42 consist of a single layer or
of multiple layers. When coating 42 consists of multiple layers,
the layers may be of the same material or they may be of different
materials each of which is chosen so that the overall coating 42
has the aforementioned adherence and performance characteristics.
The coating 42 may be applied by a number of different methods and
by a combination of methods. One method is to apply the coating 42
by electroplating or electroless plating or a combination thereof.
An example of such a coating may be a nickel plated coating having
a thickness about 60 to 100 microns. Another method is to apply the
coating 42 by dipping the first HIP container 20 into a molten
metal bath of the coating material or a succession of baths of one
or more coating materials, using whatever preheating and
atmospheric protections against undesirable chemical reactions as
are necessary. Another method is to apply the coating by plasma
spray deposition. Two or more of these methods may be combined to
form the coating 42. Appropriate cleaning and other surface
preparations, e.g., surface roughness adjustments, the application
of transient interfacial layers, etc., are to be used during the
application of coating 42. Precautions are to be taken during the
formation of the coating 42 to achieve the desired amount of
cleanliness of the cavity 26 and its surfaces. In some embodiments,
the coating 42 may cover a portion or all of the surface of cavity
26. Additional information concerning the means for the application
of coating 42 can be found in ASM "Handbook Volume 5: Surface
Engineering" published by ASM International in 1994 as ISBN
978-0-87170-384-2.
[0020] The present invention may employed to make any desired part
by means of HIP. The container is provided with a cavity that is
configured and dimensioned to result in the desired hot
isostatically pressed part. The outer surface of the container is
designed to conform to the cavity so as to subject the cavity to an
isostatic pressure that is undistorted. The thickness of the
container wall between the cavity and the outer surface is
preferably chosen to be as thin as is practicable taking into
regard the material from which the container is constructed, the
container's design, and the need to maintain the structural
integrity of the container during construction and processing.
Preferably, the wall thickness is in the range of between about
0.01 inches (0.25 millimeters) and 0.5 inches (12.7
millimeters).
[0021] The sintering of the build powder may be by solid state
sintering, reactive sintering, transient liquid phase sintering, or
liquid phase sintering. Additional information about sintering may
be found in "Sintering Theory and Practice" by Randal M. German,
which was published by John Wiley & Sons, Inc. in 1996 with
ISPB 0-471-05785-X.
[0022] All United States patents and patent applications, all
foreign patents and patent applications, and all other documents
identified herein are incorporated herein by reference as if set
forth in full herein to the full extent permitted under the
law.
* * * * *