U.S. patent application number 14/029002 was filed with the patent office on 2015-01-01 for method for manufacturing metal nanopowder by wire-explosion and apparatus for manufacturing the same.
This patent application is currently assigned to SAMSUNG ELECTRO-MECHANICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRO-MECHANICS CO., LTD.. Invention is credited to Kwan LEE, Sung Ho LEE, Jung Wook SEO.
Application Number | 20150000469 14/029002 |
Document ID | / |
Family ID | 52114303 |
Filed Date | 2015-01-01 |
United States Patent
Application |
20150000469 |
Kind Code |
A1 |
LEE; Sung Ho ; et
al. |
January 1, 2015 |
METHOD FOR MANUFACTURING METAL NANOPOWDER BY WIRE-EXPLOSION AND
APPARATUS FOR MANUFACTURING THE SAME
Abstract
There are provided a method and an apparatus for manufacturing a
metal nanopowder having a uniform particle size distribution by
uniformly applying current to a center portion of the metal wire
and a surface portion thereof. The method includes increasing a
surface roughness of a metal wire; supplying the metal wire having
the increased surface roughness to an electrode in a reaction
chamber; and wire-exploding the metal wire by supplying electrical
energy to the electrode.
Inventors: |
LEE; Sung Ho; (Suwon,
KR) ; LEE; Kwan; (Suwon, KR) ; SEO; Jung
Wook; (Suwon, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRO-MECHANICS CO., LTD. |
Suwon |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRO-MECHANICS CO.,
LTD.
Suwon
KR
|
Family ID: |
52114303 |
Appl. No.: |
14/029002 |
Filed: |
September 17, 2013 |
Current U.S.
Class: |
75/354 ;
266/137 |
Current CPC
Class: |
B22F 1/0018 20130101;
B22F 9/14 20130101; B22F 2999/00 20130101; B22F 2999/00 20130101;
B22F 9/14 20130101; B22F 3/003 20130101 |
Class at
Publication: |
75/354 ;
266/137 |
International
Class: |
B22F 9/14 20060101
B22F009/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2013 |
KR |
10-2013-0076064 |
Claims
1. A method for manufacturing a metal nanopowder by wire-explosion,
the method comprising: increasing a surface roughness of a metal
wire; supplying the metal wire having the increased surface
roughness to an electrode in a reaction chamber; and wire-exploding
the metal wire by supplying electrical energy to the electrode.
2. The method of claim 1, wherein the increasing of the surface
roughness of the metal wire is performed to cause the surface
roughness of the metal wire to be in a range of 0.2 .mu.m to 6.3
.mu.m.
3. The method of claim 1, wherein the increasing of the surface
roughness of the metal wire is performed by at least one selected
from the group consisting of a honing process, a polishing process,
a turning process, and a milling process.
4. The method of claim 1, wherein the metal wire includes at least
one selected from the group consisting of copper, nickel, aluminum,
iron, gold, and silver.
5. The method of claim 1, wherein the metal wire has a diameter of
0.01 mm to 10 mm.
6. The method of claim 1, wherein a pulse voltage of 1 kV to 100 kV
is applied to the electrode for 1 .mu.s to 10 .mu.s.
7. An apparatus for manufacturing a metal nanopowder by
wire-explosion, the apparatus comprising: a high voltage electrode
having high voltage electrical energy applied thereto to
wire-explode a metal wire; a feeding unit supplying the metal wire
to the high voltage electrode; and a surface roughness controlling
unit mounted on at least one side of the feeding unit and
increasing the surface roughness of the metal wire.
8. The apparatus of claim 7, wherein the surface roughness
controlling unit performs at least one selected from the group
consisting of a honing process, a polishing process, a turning
process, and a milling process.
9. The apparatus of claim 7, wherein the surface roughness
controlling unit includes a pair of compression rollers having
protrusions formed on a surface thereof, and the metal wire is
compressed by the pair of compression rollers, such that the
surface roughness of the metal wire is increased.
10. The apparatus of claim 7, wherein the surface roughness
controlling unit is included in the feeding unit.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority of Korean Patent
Application No. 10-2013-0076064 filed on Jun. 28, 2013, with the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method for manufacturing
a metal nanopowder by wire-explosion and an apparatus for
manufacturing the same, and more particularly, to a method for
manufacturing a nanopowder having a uniform particle size
distribution by uniformly applying electrical energy to a metal
wire, and an apparatus for manufacturing the same.
[0004] 2. Description of the Related Art
[0005] Technology has moved in a direction in which devices and
components are small-sized, lightweight, and have high strength,
due to industrial improvements. One method capable of satisfying
the functions is to manufacture a device and a component using
nanoparticles.
[0006] In general, nanoparticles have a diameter of 1 nm to 100 nm,
and even in the case that a material formed of the nanoparticles
has the same chemical composition and the same physical
crystallization structure, the material formed of nanoparticles may
have specific physical properties which are not evident in an
existing material.
[0007] Nanoparticles have great industrial potential in fields such
as the field of electronic components, the field of materials of
living, the field of medicine, the field of national defense, the
field of energy generation, the field of environmental materials,
and the like, due to the specific physical properties thereof, and
as certain nanoparticles have been commercialized, their value has
been confirmed.
[0008] Unlike the positive aspects as described above,
nanoparticles have problems to which solutions are sought, and for
example, nanoparticles may have difficulties in terms of
dispersibility due to having a large specific surface area,
difficulties in terms of chemical stability regarding particle
oxidation, and difficulties in terms of obtaining nanoparticles
having a uniform size in a manufacturing process thereof.
[0009] As a method for synthesizing nanoparticles, a chemical
synthesis method is mainly used. However, in consideration of
industrial improvements and environmental aspects such as global
warming, the chemical synthesis method has disadvantages in that
contamination caused by impurities, the generation of chemical
by-products such as waste solutions, dangers in handling chemical
materials, and the like may occur.
[0010] Therefore, systems which are environmentally friendly and
are capable of mass producing a nanopowder by using a vapor method
have been studied and developed, and as a method having a high
possibility for enabling mass-production, physical methods such as
a plasma heating method, a pulsed wire discharge (PWD) method, and
the like, may be used.
[0011] The pulsed wire discharge (PWD) method is a method in which,
after a capacitor is charged with current, a power pulse is
produced using high voltage to instantaneously discharge electrical
energy into a metal wire, such that the metal is evaporated and
condensed to produce the nanopowder. A flowchart in which wire in a
solid-phase is vaporized to form the nanopowder is illustrated in
FIG. 1.
[0012] The pulsed wire discharge (PWD) method may be utilized for
use with all metals and alloys capable of being formed into wire,
and may be easily used in producing oxides and nitrides by using
oxygen or nitrogen in the atmosphere of the process. In general,
the discharge process takes 10.sup.-6 seconds, and 10.sup.6 W of
power is consumed during this short period of time. The pulsed wire
discharge (PWD) method is appropriate for producing nanopowder
particles having a size of 50 nm to 150 nm.
[0013] However, in the pulsed wire discharge (PWD) method according
to the related art, a nanopowder having a particle size
distribution of several nm is produced on a surface portion of the
metal wire, but a nanopowder having a particle size distribution of
several .mu.m is produced in the center portion thereof.
[0014] The reason that nanoparticles having a non-uniform particle
size distribution are produced is because an electric field flowing
through the wire is not constant. In wire having a smooth surface,
the extent of disturbance with respect to current flow is different
between the surface portion of the metal wire and the center
portion thereof due to a skin effect, such that the surface portion
thereof is initially exploded and the center portion is
subsequently exploded. Here, the evaporation in the center portion
is not smooth, such that it may be difficult to produce nanopowder
particles, and therefore, relatively large micro-sized particles
are produced. The reason for this is that the current flow is small
in the center portion of the metal wire, such that Joule heating is
also low.
[0015] The manufactured nanopowder having the non-uniform particle
size distribution requires filtering having a high resolution and a
sorting process using centrifugal force in the subsequent process,
such that the process may be complicated and costs increased.
[0016] Therefore, a method for synthesizing a nanopowder having a
uniform particle size distribution by uniformly supplying
electrical energy to a metal raw material in the pulsed wire
discharge (PWD) method has been demanded.
[0017] Patent Document 1, which is directed to an apparatus for the
production of a metal nanopowder by wire-explosion, is
characterized by mounting a vibrator on a feeding unit to allow a
particle size of a nanopowder produced according to a position of a
wire to be uniform, through a mechanical resonance phenomenon and
vibration of atoms and electrons.
[Related Art Document]
(Patent Document 1) Korean Patent Laid-Open Publication No.
10-2011-0122277
SUMMARY OF THE INVENTION
[0018] An aspect of the present invention provides a method for
manufacturing a metal nanopowder having a uniform particle size
distribution by wire-explosion by uniformly applying current to a
center portion of a metal wire and a surface thereof, and an
apparatus for manufacturing the same.
[0019] According to an aspect of the present invention, there is
provided a method for manufacturing a metal nanopowder by
wire-explosion, the method including: increasing a surface
roughness of a metal wire; supplying the metal wire having the
increased surface roughness to an electrode in a reaction chamber;
and wire-exploding the metal wire by supplying electrical energy to
the electrode.
[0020] The increasing of the surface roughness Ra of the metal wire
may be performed to cause the surface roughness of the metal wire
to be in a range of 0.2 .mu.m to 6.3 .mu.m.
[0021] The increasing of the surface roughness Ra of the metal wire
may be performed by at least one selected from the group consisting
of a honing process, a polishing process, a turning process, and a
milling process.
[0022] The metal wire may include at least one selected from a
group consisting of copper, nickel, aluminum, iron, gold, and
silver.
[0023] The metal wire may have a diameter of 0.01 to 10 mm.
[0024] A pulse voltage of 1 to 100 kV may be applied to the
electrode for 1 .mu.s to 10 .mu.s.
[0025] According to another aspect of the present invention, there
is provided an apparatus for manufacturing a metal nanopowder by
wire-explosion, the apparatus including: a high voltage electrode
having high voltage electrical energy applied thereto to
wire-explode a metal wire; a feeding unit supplying the metal wire
to the high voltage electrode; and a surface roughness controlling
unit mounted on at least one side of the feeding unit and
increasing the surface roughness of the metal wire.
[0026] The surface roughness controlling unit may perform at least
one selected from a group consisting of a honing process, a
polishing process, a turning process, and a milling process.
[0027] The surface roughness controlling unit may include a pair of
compression rollers having protrusions formed on a surface thereof,
and the metal wire may be compressed by the pair of compression
rollers, such that the surface roughness of the metal wire is
increased.
[0028] The surface roughness controlling unit may be included in
the feeding unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The above and other aspects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0030] FIG. 1 is a flowchart illustrating a process of
manufacturing a nanopowder by wire-explosion;
[0031] FIG. 2 is a view illustrating examples of metal wire before
and after surface roughness (Ra) thereof is increased according to
an embodiment of the present invention;
[0032] FIG. 3 is a flowchart illustrating a mechanism by which a
nanopowder having a uniform particle size distribution is
manufactured due to increased surface roughness (Ra);
[0033] FIG. 4 is a cross-sectional view showing an apparatus for
manufacturing a metal nanopowder by wire-explosion according to an
embodiment of the present invention;
[0034] FIG. 5 is an enlarged perspective view of part A of FIG. 4;
and
[0035] FIG. 6 is a cross-sectional view illustrating an apparatus
for manufacturing a metal nanopowder by wire-explosion according to
an embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0036] Hereinafter, embodiments of the present invention will be
described in detail with reference to the accompanying
drawings.
[0037] The invention may, however, be embodied in many different
forms and should not be construed as being limited to the
embodiments set forth herein. Rather, these embodiments are
provided so that this disclosure will be thorough and complete, and
will fully convey the scope of the invention to those skilled in
the art.
[0038] In the drawings, the shapes and dimensions of elements may
be exaggerated for clarity, and the same reference numerals will be
used throughout to designate the same or like elements .
[0039] According to an embodiment of the present invention, in
order to allow current flows in a surface portion and in a center
portion of a metal wire to be uniform, a surface roughness (Ra) of
the metal wire may be increased to increase resistance on the
surface thereof. Therefore, current flow may be uniform in the
surface portion and the center portion of the metal wire, and a
metal nanopowder having a uniform particle size distribution may be
manufactured.
[0040] More specifically, a method for manufacturing a metal
nanopowder by wire-explosion according to an embodiment of the
present invention includes increasing a surface roughness Ra of a
metal wire; supplying the metal wire having the increased surface
roughness Ra to an electrode within a reaction chamber; and
wire-exploding the metal wire by supplying electrical energy to the
electrode.
[0041] First, the increasing of the surface roughness Ra of the
metal wire will be described.
[0042] FIG. 2 is a view illustrating examples of metal wire before
and after the surface roughness (Ra) thereof is increased according
to an embodiment of the present invention. As shown in FIG. 2, the
metal wire having a smooth surface may have various concave-convex
shapes through the increasing of the surface roughness Ra. As long
as the surface roughness Ra is increased to thereby increase a
distance for which current flows, the concave-convex shapes are not
particularly limited, in addition to the shapes shown in FIG.
2.
[0043] In the metal wire having the increased surface roughness Ra
as described above, the length of the surface of the metal wire may
be increased, and resistance disturbing the flow of current flowing
on the surface may be increased. As a result, the surface portion
and the center portion of the metal wire may have the uniform
current flow, and wire-explosion may be uniformly induced to
manufacture a metal nanopowder having a uniform particle size
distribution. FIG. 3 is a flowchart illustrating a mechanism by
which a nanopowder having a uniform particle size distribution is
manufactured due to increased surface roughness (Ra).
[0044] In order to induce uniform current flows in the surface
portion and the center portion of the metal wire, the surface
roughness Ra of the meta wire may be increased to be 0.2 .mu.m to
6.3 .mu.m.
[0045] In the case in which the surface roughness Ra of the metal
wire is less than 0.2 .mu.m, the surface resistance thereof may not
be sufficiently increased to generate a difference in current flows
in the surface portion and the center portion, and in the case in
which the surface roughness Ra of the metal wire is greater than
6.3 .mu.m, the metal wire may be locally discharged and may be cut,
resulting in a failure in the manufacturing of the nanopowder.
[0046] A method for increasing the surface roughness Ra of the
metal wire is not specifically limited as long as the surface
roughness Ra can be increased in order to apply a uniform electric
field to the surface portion and the center portion of the metal
wire, and more specifically, the surface roughness Ra of the metal
wire may be increased by a honing process, a polishing process, a
turning process, and a milling process.
[0047] The metal wire of which the surface roughness Ra is to be
increased is not specifically limited, and for example, copper,
nickel, aluminum, iron, gold, or silver, an alloy or mixture
thereof may be used. A diameter of the metal wire may be 0.01 mm to
10 mm, and a length thereof is not specifically limited.
[0048] Then, the metal wire having the increased surface roughness
Ra may be supplied to the electrode within the reaction
chamber.
[0049] Two electrodes for wire-explosion may be provided in the
reaction chamber, such that the wire-explosion may occur in the
reaction chamber. The metal wire having the increased surface
roughness Ra may be supplied between two electrodes in the reaction
chamber by a wire feeding unit.
[0050] After the metal wire is supplied between two electrodes, the
electrical energy may be supplied to the electrodes, thereby
wire-exploring the metal wire, and thus, the metal nanopowder is
manufactured.
[0051] The wire-explosion may occur by applying a pulse voltage to
the metal wire n times (n is a natural number) using two
electrodes. Here, N is not specifically limited.
[0052] The pulse voltage may be supplied at an interval of 0.5 to
10 seconds, and the period of the pulse voltage may be constant in
the above-described range or may be changed. For example, the pulse
voltage may be 1 kV to 100 kV, and may be constant in the above
range or may be changed. The pulse voltage may be applied for 1
.mu.s to 10 .mu.s.
[0053] The current flow may be generated to be uniform in the
surface portion and the center portion of the metal wire having the
increased surface roughness Ra, such that a metal nanopowder to be
manufactured according to a position of the wire may obtain a
uniform particle size distribution.
[0054] Then, an apparatus for manufacturing a metal nanopowder by
wire-explosion according to an embodiment of the present invention
will be described.
[0055] FIG. 4 is a cross-sectional view illustrating an apparatus
for manufacturing a metal nanopowder by wire-explosion according to
an embodiment of the present invention.
[0056] Referring to FIG. 4, a reaction chamber 100 in which
wire-explosion occurs may include a wire feeding unit in an upper
portion thereof. The wire feeding unit may include a wire roller 21
having a metal wire M wound therearound and a pair of guide rollers
22 feeding the metal wire M unwound from the wire roller 21 in a
direction toward a high voltage electrode 50 positioned at a lower
portion of the reaction chamber 100.
[0057] The metal wire M fed in the direction toward the high
voltage electrode 50 by the guide rollers 22 may pass through a
wire guide 40 having a hollow portion therein. In other words, a
route of the metal wire M may be determined by the wire guide 40 so
as to be fed to the vicinity of the high voltage electrode 50. When
pulse power is applied to the high voltage electrode 50, the pulse
power may be supplied to the metal wire, such that the metal wire
may be wire-exploded to be vaporized. The metal wire may be
vaporized, and cooled/condensed to manufacture a nanopowder.
[0058] However, as described above, in the case of a metal wire
having a smooth surface, the extent of disturbance with respect to
current flow is different between the surface portion of the metal
wire and the center portion thereof due to a skin effect, such that
particle sizes of a powder to be manufactured may not be uniform
between the surface portion of the metal wire and the center
portion thereof. In order to solve the above-described problem, the
apparatus for manufacturing a metal nanopowder by wire-explosion
according to the embodiment of the invention may include a surface
roughness controlling unit increasing the surface roughness Ra of
the metal wire.
[0059] As shown in FIG. 4, the surface roughness controlling unit
according to the embodiment of the invention includes a pair of
compression rollers 31 having protrusions formed on a surface
thereof. Referring to FIG. 5, an enlarged view of part A of FIG. 4,
it may be appreciated that the metal wire M passes through between
the pair of compression rollers 31 having the protrusions formed on
the surface thereof, and is compressed, such that the surface
roughness Ra of the metal wire is increased.
[0060] The surface roughness controlling unit according to the
embodiment of the invention is not limited to the compression
rollers 31 having the protrusions formed on the surface thereof as
shown in FIG. 4, and as long as a configuration enables the surface
roughness of the metal wire M to be increased, and a honing
process, a polishing process, a turning process, a milling process,
or the like, may be performed.
[0061] In FIG. 4, the compression rollers 31 are disposed beyond
the guide rollers 22 of the wire feeding unit, but the position
thereof is not limited thereto. The surface roughness controlling
unit may be mounted on one side of the wire feeding unit before the
metal wire is supplied to the high voltage electrode 50.
[0062] In addition, as shown in FIG. 6, while the metal wire M
unwound from the wire roller 21 may be fed to the compression
rollers 32 having the protrusions formed on the surface thereof,
the surface roughness Ra thereof may be simultaneously increased.
That is, the surface roughness controlling unit may be included in
the wire feeding unit.
[0063] In the metal wire having the increased surface roughness by
the surface roughness controlling unit, surface resistance may be
increased and as a result, the current flow may be disturbed at the
surface thereof, such that electric energy may be uniformly applied
to the surface portion of the metal wire and the center portion
thereof to allow the particle size of the manufactured metal
nanopowder to be uniform.
[0064] As set forth above, in a method and an apparatus for
manufacturing a metal nanopowder by wire-explosion according to
embodiments of the invention, current may be uniformly applied to a
center portion of the metal wire and a surface portion thereof,
whereby a metal nanopowder having a uniform particle size
distribution can be manufactured.
[0065] While the present invention has been shown and described in
connection with the embodiments, it will be apparent to those
skilled in the art that modifications and variations can be made
without departing from the spirit and scope of the invention as
defined by the appended claims.
* * * * *