BACKGROUND OF INVENTION
Technical Field
[0001] The present invention relates to a metal powder production method and a metal powder
production device.
Background Art
[0002] 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 January
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
[0003] 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.
[0004] 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
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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 devided 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.
[0014] 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
[0015] 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
[0016] 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;
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;
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;
Fig. 4 is a vertical cross-sectional view illustrating the metal powder production
device according to a second embodiment of the present invention;
Fig. 5(a) is a perspective view illustrating the metal powder production device according
to a third embodiment of the present invention, and Fig. 5(b) is a perspective view
illustrating its usage state;
Fig. 6(a) is a front view illustrating a jet orifice of the metal powder production
device as in Figs. 5, and Fig. 6(b) is a side view illustrating the shape of an emitted
flame jet;
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), 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), Fig.
7(c) is an electron micrograph of Fe75Si10B15 amorphous powder obtained from Fe-Si-B based molten metal by the metal powder production
device as in Fig. 1(a), and Fig. 7(d) is an electron micrograph illustrating enlarged
particles of the powder;
Fig. 8(a) is an electron micrograph at 150-fold magnification and 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;
Fig. 9(a) is an electron micrograph at 1500-fold magnification and 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.);
Fig. 10(a) is an electron micrograph at 200-fold magnification and 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
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-Si10-B15 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
[0017] Hereinafter, embodiments of the present invention will be explained with reference
to the drawings.
[0018] Figs. 1 and Fig. 3 illustrate a metal powder production device according to a first
embodiment of the present invention.
[0019] As illustrated in Figs. 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).
[0020] 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.
[0021] 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.
[0022] 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.
[0023] 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°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.
[0024] 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 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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 obtaibed
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.
[0029] 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.
[0030] Fig. 4 illustrates the metal powder production device and the metal powder production
method according to a second embodiment of the present invention.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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 µm.
[0038] 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.
[0039] Figs. 5 and Figs. 6 illustrate the metal powder production device and the metal powder
production method according to a third embodiment of the present invention.
[0040] As illustrated in Figs. 5 and Figs. 6, a metal powder production device 30 has the
supply means 11 and the jet burners 12.
[0041] 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.
[0042] 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.
[0043] In the specific example illustrated in Figs. 5 and Figs. 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.
[0044] 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 devided 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.
[0045] 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]
[0046] 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
75Si
10B
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]
[0047] 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 Figs. 8.
[Example 3]
[0048] 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 Figs. 9.
[Example 4]
[0049] 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 Figs. 10.
[Example 5]
[0050] 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
10-B
15 alloy, so as to produce the metal powder. Particle size distribution of the metal
powder produced in the respective devices is illustrated in Figs. 11.
[0051] 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.
[0052] 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 µm, and the diameter was 100 µm 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 µm 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
[0053]
- 1
- downward flow
- 2
- metal wire
- 10
- metal powder production device
- 11
- supply means
- 11(a)
- molten metal injection nozzle
- 12
- jet burner
- 12a
- flame jet
1. A metal powder production method comprising
obtaining metal powder by emitting a flame jet to molten metal or a metal wire.
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. The metal powder production method according to claim 1 or claim 2,
wherein a circular jet orifice for emitting the flame jet is provided, and the flame
jet is emitted by arranging the molten metal or the metal wire on an inner side of
the flame jet emitted from the jet orifice.
4. The metal powder production method according to claim 1 or claim 2,
wherein a plurality of flame jets are 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.
5. A 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.
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. The metal powder production device according to claim 5 or claim 6,
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.
8. The metal powder production device according to claim 5 or claim 6,
wherein the jet burner comprises a plurality of jet burners that are 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.
9. The metal powder production device according to claim 8,
wherein each of the jet burners has an elongated jet orifice for emitting the flame
jet, and a major axis direction of the jet orifice is arranged to correspond to an
outer periphery of the molten metal or the metal wire.
10. The metal powder production device according to claim 5 or claim 6,
wherein the jet burner has 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 is provided to be able to emit the flame jet to the molten
metal or the metal wire passing through the through hole.