U.S. patent application number 14/118446 was filed with the patent office on 2014-07-24 for metal powder production method and metal powder production device.
This patent application is currently assigned to HARD INDUSTRY YUGEN KAISHA. The applicant listed for this patent is Takuichi Yamagata, Torao Yamagata, Yoshihiko Yokoyama. Invention is credited to Takuichi Yamagata, Torao Yamagata, Yoshihiko Yokoyama.
Application Number | 20140202286 14/118446 |
Document ID | / |
Family ID | 47177047 |
Filed Date | 2014-07-24 |
United States Patent
Application |
20140202286 |
Kind Code |
A1 |
Yokoyama; Yoshihiko ; et
al. |
July 24, 2014 |
METAL POWDER PRODUCTION METHOD AND METAL POWDER PRODUCTION
DEVICE
Abstract
A metal powder production method and a metal powder production
device capable of reducing the size of the device, reducing costs,
and obtaining spherical metal powder are provided. Supply means
supplies a downward flow of molten metal, and a plurality of jet
burners emit flame jets to the downward flow of the molten metal
supplied from the supply means. Each of the jet burners is provided
to emit the flame jet from the same angle and from each of
positions rotationally symmetrical with each other with respect to
the downward flow of the molten metal.
Inventors: |
Yokoyama; Yoshihiko;
(Sendai-shi, JP) ; Yamagata; Takuichi;
(Hachinohe-shi, JP) ; Yamagata; Torao;
(Hachinohe-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yokoyama; Yoshihiko
Yamagata; Takuichi
Yamagata; Torao |
Sendai-shi
Hachinohe-shi
Hachinohe-shi |
|
JP
JP
JP |
|
|
Assignee: |
HARD INDUSTRY YUGEN KAISHA
Hachinohe-shi, Aomori
JP
TOHOKU TECHNO ARCH CO., LTD.
Sendai-shi, Miyagi
JP
|
Family ID: |
47177047 |
Appl. No.: |
14/118446 |
Filed: |
May 18, 2012 |
PCT Filed: |
May 18, 2012 |
PCT NO: |
PCT/JP2012/062736 |
371 Date: |
December 19, 2013 |
Current U.S.
Class: |
75/331 ; 266/137;
75/354 |
Current CPC
Class: |
B22F 1/0048 20130101;
C22C 33/02 20130101; B22F 9/02 20130101; B22F 2009/0848 20130101;
B22F 1/0003 20130101; B22F 2009/088 20130101; B22F 9/08 20130101;
B22F 1/0014 20130101; B22F 2202/00 20130101; B22F 9/04 20130101;
B22F 2009/0888 20130101 |
Class at
Publication: |
75/331 ; 75/354;
266/137 |
International
Class: |
B22F 9/08 20060101
B22F009/08; B22F 9/02 20060101 B22F009/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2011 |
JP |
2011-110904 |
Claims
1. A metal powder production method for obtaining metal powder by
using a principle of an atomization method, the metal powder
production method comprising the steps of: providing a circular jet
orifice for emitting a flame jet; arranging molten metal or a metal
wire on an inner side of the flame jet emitted from the jet
orifice; and emitting the flame jet to the molten metal or the
metal wire so as to obtain the metal powder.
2. The metal powder production method according to claim 1, wherein
the flame jet is emitted from a periphery of the molten metal or
the metal wire so that the flame jet collides against the molten
metal or the metal wire with an almost equal jet pressure and
without leaving any space along an outer periphery of the molten
metal or the metal wire.
3-4. (canceled)
5. A metal powder production device for obtaining metal powder by
using a principle of an atomization method, the metal powder
production device comprising: supply means for supplying molten
metal or a metal wire; and a jet burner for emitting a flame jet to
the molten metal or the metal wire supplied from the supply means,
wherein the jet burner comprises a circular jet orifice for
emitting the flame jet, and the molten metal or the metal wire is
arranged on an inner side of the flame jet emitted from the jet
orifice.
6. The metal powder production device according to claim 5, wherein
the jet burner emits the flame jet from a periphery of the molten
metal or the metal wire so that the flame jet collides against the
molten metal or the metal wire with an almost equal jet pressure
and without leaving any space along an outer periphery of the
molten metal or the metal wire.
7-10. (canceled)
11. The metal powder production method according to claim 1,
wherein the jet orifice comprises a Laval nozzle type.
12. The metal powder production device according to claim 5,
wherein the jet orifice comprises a Laval nozzle type.
13. The metal powder production method according to claim 2,
wherein the jet orifice comprises a Laval nozzle type.
14. The metal powder production device according to claim 6,
wherein the jet orifice comprises a Laval nozzle type.
Description
BACKGROUND OF INVENTION
[0001] 1. Technical Field
[0002] The present invention relates to a metal powder production
method and a metal powder production device.
[0003] 2. Background Art
[0004] Conventionally, atomization methods have been widely used
for producing metal powder (refer to, for example, MURAKAMI,
Yotaro, "Method for producing high-quality metal powder", (online),
September 2003, The New Materials Center, Osaka Science &
Technology Center (searched on Jan. 17, 2011), the Internet (URL:
http://www.ostec.or.jp/nmc/TOP/nmc_news.htm)). Typical atomization
methods include a water atomization method and a gas atomization
method that produce powder by emitting a jet of water or gas to
molten metal (metal melt), pulverizing the molten metal, and
allowing it to be solidified as droplets (refer to, for example,
Japanese Unexamined Patent Application Publication Numbers.
2006-63357, 2005-139471, and 2004-183049). In addition, the typical
atomization methods also include a disk atomization method that
produces the powder by allowing the molten metal to be dropped on a
rotating disk, and pulverizing it by applying a shear force in a
tangential direction, and a plasma atomization method that allows a
fine wire of Ti or the like to become particles by heat of plasma
and kinetic energy.
SUMMARY OF INVENTION
Technical Problem
[0005] However, the water atomization method has the problem of
increased equipment costs, because a high-pressure pump for
emitting a jet of water at high speed is expensive. In addition,
the water atomization method has such a problem that the shape of
the produced powder is irregular. The gas atomization method has
such a problem that material costs, equipment costs and other costs
are high because high-pressure gas production equipment is required
in order to use high-pressure gas, and the gas to be used is
expensive. The disk atomization method has such a problem that
equipment costs are high, because it is necessary to increase a
rotation rate of the disk in order to produce the fine metal
powder, and such a problem that technology for increasing the
rotation rate of the disk has already reached the limit. The plasma
atomization method has such a problem that a plasma torch is
expensive. In addition, the plasma atomization method also has the
problem of an increase in size of the device, because the plasma
torch is used.
[0006] The present invention is made in view of the above-described
problems, and an object of the present invention is to provide a
metal powder production method and a metal powder production device
capable of reducing the size of the device, reducing the costs, and
obtaining spherical metal powder.
Solution to Problem
[0007] In order to achieve the above-described object, a metal
powder production method according to the present invention obtains
metal powder by emitting a flame jet to molten metal or a metal
wire.
[0008] A metal powder production device according to the present
invention includes supply means for supplying molten metal or a
metal wire, and a jet burner for emitting a flame jet to the molten
metal or the metal wire supplied from the supply means.
[0009] It is possible for the metal powder production device of the
present invention to preferably implement the metal powder
production method according to the present invention. The metal
powder production method and the metal powder production device
according to the present invention can obtain the metal powder by
using the principle of an atomization method. By emitting the
high-temperature flame jet to the molten metal, the molten metal
can be pulverized. Further, by emitting the high-temperature flame
jet to the metal wire, the metal wire is melted and its molten
metal can be pulverized. As the temperature of the flame jet at
this time is higher than those of high-pressure water of a water
atomization method and high-pressure gas of a gas atomization
method, flow velocity of blowing fluid can be increased to be
higher than those of the water atomization method and the gas
atomization method. Due to its high temperature, it is not
necessary to cool the molten metal for atomization, nor to increase
the temperature of the molten metal more than necessary. Therefore,
the molten metal can be finely pulverized. Thus-pulverized molten
metal is allowed to fall or scatter in an atmosphere and statically
supercooled, so as to enable vitrification and to obtain fine metal
powder with ease. In addition, it is possible to obtain the metal
powder that is finer than those obtained by the water atomization
method and the gas atomization method.
[0010] According to the metal powder production method and the
metal powder production device of the present invention, it is
possible to obtain the spherical metal powder. The jet burners used
in the metal powder production method and the metal powder
production device according to the present invention are relatively
inexpensive and small-sized as compared with a high-pressure pump
used in the water atomization method, high-pressure gas production
equipment used in the gas atomization method, a plasma torch used
in a plasma atomization method and the like, and therefore, it is
possible to reduce the size of the device and to reduce the costs
including equipment costs, material costs and the like.
[0011] It is preferable that the metal powder production method and
the metal powder production device of the present invention are
configured to be able to emit the flame jet to the molten metal or
the metal wire at a speed faster than the speed of sound. In this
case, the molten metal can be finely pulverized by a shock wave
emitted by the flame jet, and the fine metal powder can be
obtained. According to the metal powder production method and the
metal powder production device of the present invention, the
atomization method to the molten metal or the metal wire may be a
free fall type or may be a confined type. According to the metal
powder production method and the metal powder production device of
the present invention, it is preferable that the flame jet is
emitted to obliquely intersect a flow direction of the molten metal
or an extending direction of the metal wire. In this case, the fine
metal powder can be produced efficiently.
[0012] According to the metal powder production method of the
present invention, it is preferable that the flame jet is emitted
from a periphery of the molten metal or the metal wire so that the
flame jet collides against the molten metal or the metal wire with
an almost equal jet pressure and without leaving any space along an
outer periphery of the molten metal or the metal wire. According to
the metal powder production device of the present invention, it is
preferable that the jet burner emits the flame jet from a periphery
of the molten metal or the metal wire so that the flame jet
collides against the molten metal or the metal wire with an almost
equal jet pressure and without leaving any space along an outer
periphery of the molten metal or the metal wire. This makes it
possible to prevent the molten metal or the metal wire from
scattering to escape from the flame jet at the position where the
flame jet collides against the molten metal or the metal wire.
Therefore, the uniform atomization to the molten metal or the metal
wire is possible, and the fine and uniform spherical metal powder
can be obtained. It is also possible to improve production
efficiency of the metal powder.
[0013] According to the metal powder production method of the
present invention, a circular jet orifice for emitting the flame
jet may be provided, and the flame jet may be emitted by arranging
the molten metal or the metal wire on an inner side of the flame
jet emitted from the jet orifice. According to the metal powder
production device of the present invention, the jet burner may
include a circular jet orifice for emitting the flame jet, and the
molten metal or the metal wire may be arranged on an inner side of
the flame jet emitted from the jet orifice. In this case, the flame
jet can be made to collide against the molten metal or the metal
wire with an almost equal jet pressure and without leaving any
space along an outer periphery of the molten metal or the metal
wire, with relative ease. One jet burner and one combustion chamber
will suffice, and therefore, the size of the device can be reduced
further, and the production costs can be reduced.
[0014] According to the metal powder production method of the
present invention, a plurality of flame jets may be emitted to the
molten metal or the metal wire from positions rotationally
symmetrical with each other with respect to the molten metal or the
metal wire. According to the metal powder production device of the
present invention, the jet burner may include a plurality of jet
burners and may be provided to emit the flame jets to the molten
metal or the metal wire from positions rotationally symmetrical
with each other with respect to the molten metal or the metal wire.
In this case, it is possible to pulverize the molten metal finely
and to obtain the fine metal powder, by collisions between the
plurality of flame jets.
[0015] Further, when there are plurality of jet burners, each of
the jet burners may have an elongated jet orifice for emitting the
flame jet, and a major axis direction of the jet orifice may be
arranged to correspond to an outer periphery of the molten metal or
the metal wire. In this case, the flame jet emitted from the jet
orifice of each jet burner can be spread in a plane shape or
divided into a plurality of jets, along the major axis direction of
the jet orifice. When the flame jets are emitted from the plurality
of jet burners so as to surround the molten metal or the metal
wire, the uniform atomization to the molten metal or the metal wire
is possible. It is preferable that there are three or more jet
burners so as to surround the molten metal or the metal wire.
[0016] According to the metal powder production device of the
present invention, the jet burner may have a heat-resistant nozzle
at its tip end, the heat-resistant nozzle having a through hole
therein through which the molten metal or the metal wire passes,
and the jet burner may be provided to be able to emit the flame jet
to the molten metal or the metal wire passing through the through
hole. In this case, the metal powder can be obtained by one jet
burner. The heat-resistant nozzle may divide the flame jet in its
inside into a plurality of jets, and may emit the divided jets to
the molten metal or the metal wire, passing through the through
hole, from positions rotationally symmetrical with each other. Any
material, such as carbon or water-cooled copper, may be used to
form the heat-resistant nozzle as long as the material is
heat-resistant.
Advantageous Effects of Invention
[0017] According to the present invention, it is possible to
provide the metal powder production method and the metal powder
production device capable of reducing the size of the device,
reducing the costs, and obtaining the spherical metal powder.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIGS. 1(a) and 1(b) are side views illustrating a usage
state of a metal powder production device according to a first
embodiment of the present invention where (a) shows a free fall
type, and (b) shows a confined type;
[0019] FIG. 2 is a side view illustrating a modification of the
metal powder production device according to the first embodiment of
the present invention, in which a metal wire is used;
[0020] FIG. 3 is a side view illustrating a modification of the
metal powder production device according to the first embodiment of
the present invention, in which jet burners are modified;
[0021] FIG. 4 is a vertical cross-sectional view illustrating the
metal powder production device according to a second embodiment of
the present invention;
[0022] FIG. 5(a) is a perspective view illustrating the metal
powder production device according to a third embodiment of the
present invention, and
[0023] FIG. 5(b) is a perspective view illustrating its usage
state;
[0024] FIG. 6(a) is a front view illustrating a jet orifice of the
metal powder production device as in FIG. 5, and
[0025] FIG. 6(b) is a side view illustrating the shape of an
emitted flame jet;
[0026] FIG. 7(a) is an enlarged side view illustrating a state of
the flame jets emitted from the metal powder production device as
in FIG. 1(a),
[0027] FIG. 7(b) is an enlarged side view near an emitting position
of the flame jet, illustrating a state of atomization when molten
metal is used in the metal powder production device as in FIG.
1(a),
[0028] FIG. 7(c) is an electron micrograph of
Fe.sub.75Si.sub.10B.sub.15 amorphous powder obtained from Fe--Si--B
based molten metal by the metal powder production device as in FIG.
1(a), and
[0029] FIG. 7(d) is an electron micrograph illustrating enlarged
particles of the powder;
[0030] FIG. 8(a) is an electron micrograph at 150-fold
magnification and
[0031] FIG. 8(b) is an electron micrograph at 1000-fold
magnification of metal powder obtained by the metal powder
production device as in FIG. 2 from a metal wire of stainless steel
SUS420;
[0032] FIG. 9(a) is an electron micrograph at 1500-fold
magnification and
[0033] FIG. 9(b) is an electron micrograph at 2500-fold
magnification of metal powder obtained by the metal powder
production device as in FIG. 2 from a metal wire of a TIG welding
rod (TGS50 manufactured by Kobe Steel, Ltd.);
[0034] FIG. 10(a) is an electron micrograph at 200-fold
magnification and
[0035] FIG. 10(b) is an electron micrograph at 1200-fold
magnification of metal powder obtained by the metal powder
production device as in FIG. 2 from a metal wire of SUS420 alloy;
and
[0036] FIGS. 11(a) to 11(c) are graphs illustrating particle size
distribution of metal powder produced by emitting a flame jet to
molten metal of Fe--Si.sub.10-B.sub.15 alloy by (a) the metal
powder production device as in FIG. 1(a), (b) the metal powder
production device as in FIG. 4, and (c) the metal powder production
device as in FIG. 4 having a Laval nozzle type jet orifice.
DESCRIPTION OF EMBODIMENTS
[0037] Hereinafter, embodiments of the present invention will be
explained with reference to the drawings.
[0038] FIG. 1 and FIG. 3 illustrate a metal powder production
device according to a first embodiment of the present
invention.
[0039] As illustrated in FIG. 1, a metal powder production device
10 has supply means 11 and a plurality of jet burners 12. In the
following, an explanation will be mainly given to a free fall type
that is illustrated in FIG. 1(a).
[0040] As illustrated in FIG. 1(a), the supply means 11 is formed
by a container containing molten metal. The supply means 11 has, at
the center of its bottom surface, a molten metal injection nozzle
11a that communicates with its inside. The supply means 11 is
configured to be able to discharge the molten metal contained
therein downward from the molten metal injection nozzle 11a.
[0041] Each of the plurality of jet burners 12 is able to emit a
flame jet 12a at a speed faster than the speed of sound. Each of
the jet burners 12 is arranged under the supply means 11 to be able
to emit the flame jet 12a obliquely downward. Each of the jet
burners 12 is provided to emit the jet to a downward flow 1 of the
molten metal from the molten metal injection nozzle 11a in such a
manner that the jet obliquely intersects the downward flow 1 at the
same angle, from each of positions rotationally symmetrical with
each other with respect to the downward flow 1. Thereby, the
respective jet burners 12 are made to emit the flame jets 12a to
one point of the downward flow 1 in a concentrated manner.
[0042] According to a specific example, the jet burner 12 is formed
by a jet burner manufactured by Hard Industry Yugen Kaisha, which
is small-sized, and is able to emit the flame jet 12a at the speed
faster than the speed of sound. There are three jet burners 12 that
are arranged at positions with the same distance from the downward
flow 1 and at intervals of a central angle of 120 degrees, with the
downward flow 1 of the molten metal serving as a central axis, and
that emit the jets to the downward flow 1 from an obliquely upward
direction at an angle of about 45 degrees. Further, each of the jet
burners 12 are made to emit the flame jet 12a at the same pressure
and speed.
[0043] It is possible for the metal powder production device 10 to
preferably implement a metal powder production method according to
the first embodiment of the present invention. The metal powder
production device 10 can obtain metal powder by using the principle
of an atomization method. By emitting the high-temperature flame
jet 12a to the downward flow 1 of the molten metal, the molten
metal can be pulverized. As the temperature of the flame jet 12a at
this time is higher than those of high-pressure water of a water
atomization method and high-pressure gas of a gas atomization
method, flow velocity of blowing fluid can be increased to be
higher than those of the water atomization method and the gas
atomization method. Due to its high temperature, it is not
necessary to cool the molten metal for atomization, nor to increase
the temperature of the molten metal more than necessary. For
example, the temperature of the molten metal may be set to be lower
than those of the conventional water atomization method and the gas
atomization method by about 50 to 100.degree. C. Therefore, the
molten metal can be finely pulverized under the condition in which
the molten metal is amorphized more easily. Thus-pulverized molten
metal is allowed to fall or scatter in an atmosphere and statically
supercooled, so as to enable vitrification and to obtain fine metal
powder with ease. In addition, it is possible to obtain the metal
powder that is finer than those obtained by the water atomization
method and the gas atomization method.
[0044] When each of jet burners 12 emits the flame jet 12a at the
speed faster than the speed of sound, the metal powder production
device 10 can finely pulverize the molten metal by a shock wave
emitted by the flame jet 12a. Further, each of the jet burners 12
emits the flame jet 12a to one point of the downward flow 1 in a
concentrated manner from the same angle and from each of the
positions rotationally symmetrical with each other with respect to
the downward flow 1 of the molten metal, which makes it possible to
pulverize the molten metal more finely and to obtain the finer
metal powder, by collisions between the plurality of flame jets
12a. It should be noted that the obtained metal powder can be
collected easily when a container or a chamber is provided under
the supply means 11 in such a manner to cover peripheral portions
and lower portions of the respective flame jets 12a.
[0045] As the jet burners 12 used in the metal powder production
device 10 are relatively inexpensive and small-sized as compared
with a high-pressure pump used in the water atomization method,
high-pressure gas production equipment used in the gas atomization
method, a plasma torch used in a plasma atomization method and the
like, it is possible to reduce the size of the device and to reduce
the costs including equipment costs, material costs and the
like.
[0046] Incidentally, the metal powder production device 10 may be a
confined type as illustrated in FIG. 1(b). With regard to the
confined type, efficient atomization is possible without
attenuating kinetic energy of the flame jets 12a of the respective
jet burners 12, as the confined type can supply the molten metal
directly to an atomizing zone, as well as the similar effects as
those of the free fall type can be obtained. When the conventional
gas atomization or the like is used in the confined type, there is
such a problem that the molten metal is solidified and clogging of
the molten metal injection nozzle 11a is easily caused as the
molten metal injection nozzle 11a is cooled by the emitted gas and
the like. On the contrary, with the metal powder production device
10 as illustrated in FIG. 1(b), it is possible to prevent the
solidification of the molten metal and the occurrence of the
clogging of the molten metal injection nozzle 11a because the
high-temperature flame jets 12a are emitted from the respective jet
burners 12 and the molten metal injection nozzle 11a is not
cooled.
[0047] In the metal powder production device 10, as illustrated in
FIG. 2, the supply means 11 may be provided to be able to supply a
metal wire 2 continuously to a downward direction, and the
respective jet burners 12 may be provided to emit the flame jets
12a to the metal wire 2. In this case, the high-temperature flame
jets 12a are emitted to the metal wire 2, so as to melt the metal
wire 2 and to pulverize the melted metal. Material of the metal
wire 2 may be, for example, stainless steel or SUS420 alloy.
[0048] Further, the metal powder production device 10 may include
one jet burner 12 having a heat-resistant nozzle at its tip end.
The heat-resistant nozzle may be configured to include a through
hole therein, through which the molten metal or the metal wire
passes, divide the flame jet 12a in its inside into a plurality of
jets, and emit the divided jets to the molten metal or the metal
wire, passing through the through hole, from positions rotationally
symmetrical with each other and from the same angle with respect to
the molten metal or the metal wire. In this case, it is possible to
obtain the metal powder by one jet burner 12. The heat-resistant
nozzle may be obtained by forming the nozzle used in the water
atomization method or the gas atomization method by heat-resistant
material such as carbon or water-cooled copper.
[0049] Further, in the metal powder production device 10, as
illustrated in FIG. 3, a jet nozzle 12c of each of the jet burners
12 may be bent so that an emitting direction of the flame jet 12a
has a specified angle with respect to a longitudinal direction of a
body 12b of the jet burner 12. In this case, the jet nozzle 12c can
be easily brought closer to the molten metal injection nozzle 11a
of the supply means 11. This is effective especially when the metal
powder production device 10 is the confined type.
[0050] FIG. 4 illustrates the metal powder production device and
the metal powder production method according to a second embodiment
of the present invention.
[0051] As illustrated in FIG. 4, a metal powder production device
20 is the confined type, and has the supply means 11 and the jet
burner 12.
[0052] Incidentally, in the following explanation, the same
numerals and symbols will be used to designate the same components
as those in the metal powder production device 10 according to the
first embodiment of the present invention, and the repeated
explanation will be omitted.
[0053] The supply means 11 has a container 21 containing the molten
metal, and a supply hole 21a that communicates with the outside at
the center of the bottom of the container 21. Further, the supply
means 11 has the molten metal injection nozzle 11a that
communicates with the supply hole 21a and is attached to the center
of the bottom surface of the container 21 via a heat insulating
plate 22 (an alumina plate, for example). The molten metal
injection nozzle 11a has a tapered shape, whose tip end has such an
external form that is gradually thinnes downward. The supply means
11 can supply the molten metal that is contained in the container
21 through the molten metal injection nozzle 11a.
[0054] The jet burner 12 has a combustion chamber (not illustrated)
and a circular jet orifice 24 for emitting the flame jet. The jet
burner 12 is provided under the container 21 of the supply means 11
in such a manner that the molten metal injection nozzle 11a is
arranged on an inner side of the jet orifice 24. The jet burner 12
is formed in such a manner that the jet orifice 24 corresponds to
the tapered shape of the tip end of the molten metal injection
nozzle 11a.
[0055] The jet burner 12 is configured to be able to emit the flame
jet from the jet orifice 24 toward a forward inner side and along
the circumference of the jet orifice 24 without leaving any space.
Thereby, the jet burner 12 is able to emit the flame jet
concentrically on one point of the molten metal, from the periphery
of the molten metal supplied from the molten metal injection nozzle
11a, in such a manner that the flame jet obliquely intersects a
flow direction of the molten metal. Further, with the jet burner
12, the flame jet is made to collide against the molten metal along
the outer periphery of the molten metal supplied from the molten
metal injection nozzle 11a with an almost equal jet pressure and
without leaving any space.
[0056] The jet burner 12 also has a water cooling unit 25 that
circulates water in the periphery of the jet orifice 24 and cools
the jet orifice 24. Incidentally, the jet burner 12 can also emit
the flame jet at the speed faster than the speed of sound. In the
specific example, the jet burner 12 is made to emit the jet to the
molten metal supplied downward from the molten metal injection
nozzle 11a, from the obliquely upward direction at an angle of
about 40 degrees.
[0057] It is possible for the metal powder production device 20 to
preferably implement the metal powder production method according
to the second embodiment of the present invention. With the metal
powder production device 20 and the metal powder production method
according to the second embodiment of the present invention, the
flame jet that is emitted from the periphery of the molten metal is
made to collide against the molten metal along the outer periphery
of the molten metal with the almost equal jet pressure and without
leaving any space, which makes it possible to prevent the molten
metal from scattering to escape from the flame jet at the colliding
position. Therefore, uniform atomization to the molten metal is
possible, and fine and uniform spherical metal powder can be
obtained. It is also possible to improve production efficiency of
the metal powder. According to the specific example, the diameter
of the produced metal powder is about 5 .mu.m.
[0058] With the metal powder production device 20 and the metal
powder production method according to the second embodiment of the
present invention, one jet burner 12 and one combustion chamber
will suffice, and therefore, the size of the device can be reduced
further, and the production costs can also be reduced further.
Incidentally, it is also possible for the metal powder production
device 20 and the metal powder production method according to the
second embodiment of the present invention to emit the
high-temperature flame jet to the metal wire, not to the molten
metal.
[0059] FIG. 5 and FIG. 6 illustrate the metal powder production
device and the metal powder production method according to a third
embodiment of the present invention.
[0060] As illustrated in FIG. 5 and FIG. 6, a metal powder
production device 30 has the supply means 11 and the jet burners
12.
[0061] Incidentally, in the following explanation, the same
numerals and symbols will be used to designate the same components
as those in the metal powder production device 10 according to the
first embodiment of the present invention and the metal powder
production device 20 according to the second embodiment of the
present invention, and the repeated explanation will be
omitted.
[0062] In the metal powder production device 30, there are three
jet burners 12, each of which has an elongated jet orifice 24 for
emitting the flame jet 12a. Each of the jet burners 12 is arranged
in such a manner that a major axis direction of the jet orifice 24
corresponds to the outer periphery of the downward flow 1 of the
molten metal. Each of the jet burners 12 is provided to be able to
emit the flame jet 12a at the same pressure and the same speed to
the downward flow 1, from each of the positions rotationally
symmetrical with each other and from the same angle with respect to
the downward flow 1.
[0063] In the specific example illustrated in FIG. 5 and FIG. 6,
each jet orifice 24 has a gourd shape in which two circles are
connected. Further, the respective jet burners 12 are arranged at
the positions with the same distance from the downward flow 1 and
at the intervals of the central angle of 120 degrees, with the
downward flow 1 of the molten metal serving as the central axis,
and the respective jet burners 12 emit the jets to the downward
flow 1 from the obliquely upward direction at the angle of about 40
degrees.
[0064] It is possible for the metal powder production device 30 to
preferably implement the metal powder production method according
to the third embodiment of the present invention. With the metal
powder production device 30 and the metal powder production method
according to the third embodiment of the present invention, the
flame jet 12a emitted from the jet orifice 24 of each jet burner 12
can be spread in a plane shape or divided into a plurality of jets,
along the major axis direction of the jet orifice 24, as
illustrated in FIG. 6(b). Therefore, the flame jets 12a are emitted
from the respective jet burners 12 so as to surround the downward
flow 1 of the molten metal, and thus, the flame jets 12a are made
to collide against the downward flow 1 of the molten metal along
the outer periphery of the downward flow 1 of the molten metal with
the almost equal jet pressure and without leaving any space. This
makes it possible to prevent the molten metal from scattering to
escape from the flame jet 12a at the colliding position. Therefore,
the uniform atomization to the molten metal is possible, and the
fine and uniform spherical metal powder can be obtained. It is also
possible to improve the production efficiency of the metal
powder.
[0065] Incidentally, it is also possible for the metal powder
production device 30 and the metal powder production method
according to the third embodiment of the present invention to emit
the high-temperature flame jets 12a to the metal wire, not to the
molten metal.
Example 1
[0066] The state of the flame jets 12a emitted from the metal
powder production device 10 as illustrated in FIG. 1(a) is
illustrated in FIG. 7(a). A convergence of the plurality of flame
jets can be confirmed as in FIG. 7(a). This metal powder production
device 10 was used to emit the flame jets 12a to Fe--Si--B based
molten metal, and then fine spherical Fe.sub.75Si.sub.10B.sub.15
amorphous powder was obtained. FIG. 7(b) to FIG. 7(d) illustrate
the state of the flame jet 12a near the emitting position at this
time, and electron micrographs of the obtained powder.
Example 2
[0067] The metal powder production device 10 as illustrated in FIG.
2 was used to emit the flame jets 12a to the metal wire 2 of
stainless steel SUS420, and then fine spherical metal powder was
obtained. Electron micrographs of the obtained metal powder are
illustrated in FIG. 8.
Example 3
[0068] The metal powder production device 10 as illustrated in FIG.
2 was used to emit the flame jets 12a to the metal wire 2 of a TIG
welding rod TGS50 (manufactured by Kobe Steel, Ltd.), and then fine
and spherical metal powder was obtained. Electron micrographs of
the obtained metal powder are illustrated in FIG. 9.
Example 4
[0069] The metal powder production device 10 as illustrated in FIG.
2 was used to emit the flame jets 12a to the metal wire 2 of SUS420
alloy, and then fine and spherical metal powder was obtained.
Electron micrographs of the obtained metal powder are illustrated
in FIG. 10.
Example 5
[0070] The metal powder production device 10 as illustrated in FIG.
1(a), the metal powder production device 20 as illustrated in FIG.
4, and the metal powder production device 20 as illustrated in FIG.
4 having a Laval nozzle type jet orifice 24 were used to emit the
flame jets to the molten metal of Fe--Si.sub.10-B.sub.15 alloy, so
as to produce the metal powder. Particle size distribution of the
metal powder produced in the respective devices is illustrated in
FIG. 11.
[0071] Incidentally, in the metal powder production device 10 as
illustrated in FIG. 1(a), the four jet burners 12 were arranged at
the intervals of the central angle of 90 degrees, with the downward
flow 1 of the molten metal serving as the central axis, and the
respective jet burners 12 emitted the flame jets to the downward
flow 1 from the obliquely upward direction at the angle of about 15
degrees (vertex angle of 30 degrees). With regard to combustion
parameters per one jet burner 12, air volume is 700 L/min and fuel
(kerosene) is 130 mL/min. With regard to the combustion parameters
of the metal powder production device 20 as illustrated in FIG. 4,
the air volume is 3000 L/min and the fuel (kerosene) is 550 mL/min.
With regard to the combustion parameters of the Laval nozzle type,
the air volume is 3000 L/min and the fuel (kerosene) is 550
mL/min.
[0072] With regard to the metal powder produced by the metal powder
production device 10 as illustrated in FIG. 1(a) and by the metal
powder production device 20 as illustrated in FIG. 4, the most
common diameter was 40 to 70 .mu.m, and the diameter was 100 .mu.m
or less for the most part, as illustrated in FIGS. 11(a) and 11(b).
With regard to the metal powder produced by the Laval nozzle type,
the diameter was 50 .mu.m or less for the most part. From these
results, it was confirmed that the fine powder can be obtained by
the emission of the flame jet. As the diameter of the produced
metal powder is smaller in the Laval nozzle type, it is found that
the diameter of the produced metal powder is reduced as the speed
of the flame jet is increased.
REFERENCE SIGNS LIST
[0073] 1 downward flow [0074] 2 metal wire [0075] 10 metal powder
production device [0076] 11 supply means [0077] 11(a) molten metal
injection nozzle [0078] 12 jet burner [0079] 12a flame jet
* * * * *
References