JPS59140307A - Manufacturing apparatus of ultrafine metallic particle - Google Patents

Abstract

PURPOSE:To obtain ultrafine metallic powder having uniform particle size at low cost by blowing a gas against a metallic material, an arc column and an anodic flame, and providing a cooling rod in the anodic flame to control the average particle size and the particle size distribution of the ultrafine metallic powder. CONSTITUTION:An arc column 10 is generated by arc discharge between a metallic material 11 on a water-cooled copper hearth 4 and a cathodic electrode 3. The metallic material 11 is melted by the arc column 10, and an anodic flame 12 for forming ultrafine metallic powder is generated and sent to a filter 6 by a circulation gas. At this time, the circulating gas is blown against the metallic material 11, the arc column 10 and the anodic flame 12 from nozzles 13 through an introducing tube part 13a to concentrate the arc column 10 upon the surface of the metallic material 11. A cooling rod 14 is inserted into the anodic flame 12 to attract the anodic flame to the circumference of the cooling rod 14. Thus the anodic flame 12 is throttled and sent upward in the vessel. By this method, the ultrafine metallic powder having optimum average particle size and particle size distribution is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for producing ultrafine metal particles, particularly suitable for producing ultrafine ferromagnetic metal particles using arc discharge.

Conventionally, as an example of such a device, there is one shown in FIG. 1, for example. That is, an electrode 3 made of tungsten W for a cathode or tungsten containing thorium oxide fixed to the tip of an electrode support frame 2 is inserted into a sealed container 1, and a copper electrode for an anode forming the bottom of the container 1 is inserted. The electrode 3 for a cathode is opposed to the upper surface of the hearth 4. Reference numeral 5 denotes a collection section with a built-in filter 6 for collecting ultrafine metal particles, and 7 a gas circulation purification section such as a bebon pump. It is meant to be inserted into the 1. B is a power supply, and 9 is an insulator.

First, the inside of the container 1 is made to have an atmosphere of an inert gas such as argon gas, helium gas, or pure hydrogen gas, or a mixture thereof, and the internal pressure is set to 20 to 760.
Set to the required value within the range of Torr. Thereafter, the pump of the gas circulation purification section γ is operated to chain the gas.

Under these conditions, an inter-electrode voltage is applied from electrode #8 to cause arc discharge between electrode 3 and copper hearth 4, causing arc column 1
0, this arc column 10 is concentrated at one point on the surface of the metal material 110.

As a result, the vicinity thereof becomes hot and a large amount of ultrafine metal particles are generated and rise in the direction of arrow A in the haze 12'.

Thereafter, this anode back 12' is carried in the direction of the arrow by the circulating current, and is cooled and condensed in the recovery section 5.
Ultrafine metal particles are recovered.

The gas that has passed through the recovery section 5 is purified in the gas circulation purification section 1, proceeds in the convex direction of the arrow, and is sent into the container 1 again. Further, ultrafine metal particles generated from the metal material 11 become an anodic flame 12' rising from the arc column 10.

However, in the conventional apparatus S4, the particle size and particle size distribution of the ultrafine metal particles are controlled by the gas composition and gas pressure in the container 1. However, when such apparatus S4 was used, the particle sizes of the ultrafine metal particles varied. Therefore, it has not been possible to produce magnetic powder with a particle size of several hundred micrometers and good homogeneity for use in magnetic recording.

The present invention has been made in view of the above-mentioned points, and its object is to provide metal materials, arc columns, and positive molar materials.
To provide an apparatus for producing ultrafine metal particles, in which the particle size and particle size distribution of the ultrafine metal particles are controlled by blowing gas through the K11l flame and by arranging a cooling rod within the K11l flame.

A first embodiment of the present invention will be explained below with reference to FIGS. 2 to 5. In addition, in Jin's embodiment, the same parts as shown in FIG. 1 are designated by the same reference numerals.

13 Pogas blowing nozzle, this gas blowing nozzle 13.1
3 has its distal end facing the metal material 11, and the introduction tube portion 13 on its proximal end! Since L is connected to the gas circulation purification section γ, the gas from the gas circulation purification section 1 is blown onto the metal material 11, the arc column 10, and the anode flame 12. Also, this gas jet nozzle 13.13
is movable from the position shown by the solid line in FIG. 1 to the position shown by the imaginary line.

Reference numeral 14 denotes a cooling rod disposed within the anodic flame 12 of ultrafine metal particles rising from the metal material 11, and the anodic flame 12 is cooled by this cooling rod 14 and extended upward, without also narrowing the width. It's narrowed down. The metal material 11 in this example has a composition ratio of Fθ:Ni of 8, for example.
A 6:14 weight percent Fθ-Ni alloy is used.

One embodiment of the present invention has the above-mentioned configuration, and a container 1.
Inside the container 1, a single gas such as argon gas, helium gas, pure hydrogen gas, or a mixture of these gases (in this example, pure hydrogen gas) is used, and the pressure inside the container 1 is set to 1 g g 'L'.
orr, an arc voltage of 25 V was applied to the power source 8 and an arc current of 200 people was applied to form the copper hearth 4 as the anode and the electrode 3 as the cathode formed of tungsten containing double liquid percentage of thorium oxide. Metal material 11 made of iron-nickel alloy by generating arc column 101 between
When irradiated with water, ultrafine metal particles from the metal material 11 turn into an anodic flame 12 and rise inside the container 1 . In this case, pure hydrogen gas H! is circulated by the pump of the gas circulation purification section γ, which will be described later, and is blown from the gas jet nozzle 13.13 onto the metal material 11 made of iron-nickel alloy, the arc column 10, and the anode flame 12, thereby changing the shape of the arc column 10. is self-contracted and concentrated in the metal material 11 by the magnetic pinch action and thermal pinch action, and a large number of ultrafine metal particles are generated from the metal material 11, and the average particle size of the ultrafine metal particles becomes smaller. In this case, as the flow rate of the gas increases, the average particle size becomes smaller. Also, since the cooling rod 14 is inserted inside the IW extremely long flame 12, the anodic flame 12 is cooled when passing near this cooling rod 14, and the cooling #14 is cooled.
It is narrowed around and rises. Thereafter, this anode flame 12 is carried by the circulating gas flow and condenses, so that the ultrafine metal particles are collected by the filter 6 of the collection section 5.

The particle size distribution of the ultrafine metal particles of this example produced in this way and the particle size and particle size distribution of the ultrafine metal particles produced using the conventional apparatus are shown in FIGS. 3, 4, and 5, respectively. .

Of these, Figure 3 shows the average particle diameter of ultrafine metal particles and pure hydrogen gas H! Graph (■) showing the relationship characteristics with. From the curve (@1) in this graph, it can be seen that as the pressure inside the container 1 of pure hydrogen gas H2, that is, the pressure from the gas jet nozzle 13 increases, the average particle size of the ultrafine metal particles increases.

In addition, Fig. 4 shows a characteristic diagram ■ showing the relative particle size of ultrafine metal particles and the flow rate for gas blowing, of which curve α is the third
The anode in the apparatus S- of this embodiment as shown in FIG. The curve shows a case where ultrafine metal particles are manufactured with the cooling rod 14 removed from the housing 10. From this curve α,
It can be seen that when the pure hydrogen gas H is sprayed from the gas jet nozzle 13.13, the average particle size becomes smaller as the gas flow rate increases. In addition, the curve β shows the relationship between the value obtained by dividing the median width of the Gaussian distribution curve shown in Figure 5 by the peak particle size (relative value) and the gas flow rate of the gas sprayed from the gas jet nozzle 13.13. It is. From FIG. 4, it can be seen that the particle size distribution of ultrafine metal particles becomes sharper when the gas flow rate increases.

FIG. 5 is a characteristic diagram (1) showing the particle size distribution of ultrafine metal particles, which shows a Gaussian distribution. Among these, the distribution curve a is the distribution curve of ultrafine metal particles produced by the conventional technology as shown in Figure 1, and the distribution curve o and d are gas, pure hydrogen, with the peak particle size being 1.0. When spraying, the spraying is a distribution curve depending on the difference in flow rate. In other words, the distribution curve is 20 t/miΩ, the distribution curve 0 is 50 t/++in, and the distribution curve, lid, is 1
00t/sjn, the distribution curve θ is 201/iiΩ, and the distribution curve 7f is when a gas flow rate of 201/ain is sprayed.

It can be seen from this that in spraying, as the gas flow rate of the fluid increases, the peak value of the distribution curve b r O * d of ultrafine metal particles becomes smaller. Moreover, the distribution curve e shows the case where ultrafine metal particles were produced with the gas ejection nozzles 13 and 13 removed from the apparatus S1 shown in FIG. It can be seen from this distribution curve e that the peak of the particle size of the ultrafine metal particles is small, but the particle size distribution is sharp. Furthermore, the distribution curve f shows the case where the cooling rod 14 is disposed inside both the anode 12 and the distribution curve f.

FIG. 8 shows an apparatus S1 according to a second embodiment of the present invention.

In this embodiment, the electrode 3f is arranged perpendicularly to the metal material 11, so that the arc column 10 is irradiated perpendicularly to the metal material 11, thereby generating a large amount of ultrafine metal particles from the metal material 11. This embodiment differs from the first embodiment in that Further, this embodiment differs from the first embodiment in that a pump P disposed in place of the gas circulation purification section T is operated to circulate the circulating gas and cause the gas ejection nozzles 13, 13 to eject the gas.

Furthermore, FIG. 9 is a diagram showing a third embodiment of the present invention.

In this third embodiment, the anode 12 is cooled by forming a cooling means for the support frame 2 such as by passing cooling water around the support frame 2 supporting the electrode 3. Since the metal ultrafine particles are concentrated around the support rack 2 and rise up, the generation rate of the metal ultrafine particles is higher than when both the anode and the anode 12 are spread out, and the number of parts is reduced. In addition, gas from the pump P instead of the gas circulation purification section is transferred through the support rack 2, and from the gas jet nozzle section 13.13 formed at the tip of the support rack 2 to the anode 12. This embodiment differs from the above-mentioned embodiments in that the circulating gas is spouted out.

Note that although an iron-nickel alloy is used as the metal material 11 in the above embodiment, the metal material 11 is not limited to this. Further, the gas atmosphere inside the container 1 that is ejected from the gas ejection nozzle 13.13 is H1+Mr.

He, Nx, o, , CH2, k4YIB +
7) Any one gas or a mixture of two or more gases can be used.

As mentioned above, in the present invention, a cooling rod is placed in the anode flame to cool it, so that the anode rises in a constricted state, and gas is blown onto both the anode and the anode. The particle size and particle size distribution of ultrafine metal particles can be controlled. Therefore, even in the production of ferromagnetic ultrafine metal particles, ultrafine metal particles with a high coercive force and an optimal particle size and particle size distribution can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional apparatus for producing ultrafine metal particles, FIG. 2 is a sectional view similarly showing an embodiment of the present invention, and FIG. Figure 4 is a graph showing the relationship between fine particles and their particle size. Figure 4 is a graph showing the relationship between the average particle size of ultrafine metal particles and the gas flow rate for spraying. Figure 5 is the particle size distribution curve. Figure 6 is an electron micrograph of ultrafine metal particles in the previous particle size distribution curve &, Figure 7 is an electron microscope image of ultrafine metal particles with the same particle size distribution curve fVc in Figure 5. The photograph, FIG. 8, is a cross-sectional view showing a second embodiment of the manufacturing apparatus of the present invention, and FIG. 9 is a cross-sectional view, similarly showing a third embodiment of the present invention. 1...Answer 3...Electrode 10...Arc column 11...Metal material 12... ......Sunlight flame 13...Gas jet nozzle 14...
...Cooling rod. Patent applicant Pioneer Corporation (1) Cjji91? tIslt Muneka 4 (ffi/min)
(I [) Omebun 7bemu Moku Moku Tokorozawa-shi Hanazono 4-2610 Pioneer Co., Ltd. Tokorozawa Factory Procedures Amendment (Gin June 8, 1981 Director General of the Patent Office Mr. Wakasugi Ichiguchio ■, Incident Indication Patent Application No. 13942 No. 3 of 1988, Relationship with the case of the person making the amendment Patent applicant address: 1-4-1 Meguro, Meguro-ku, Tokyo
(501) Pioneer Co., Ltd. 4, Agent 6, Description of the number of inventions increased by amendment Book 1, Name of the invention Apparatus for manufacturing ultrafine metal powder 2, Claims Placed on water-cooled copper hearth of anode In an apparatus for producing ultrafine metal powder by generating an arc between a metal material and a cathode electrode, a gas is blown into the metal material, the arc, and the anode flame, and a cooling rod is installed in the anode flame. 1. An apparatus for producing ultrafine metal powder, characterized in that the average particle size and particle size distribution of the ultrafine metal powder are controlled by arranging. 3. Detailed Description of the Invention The present invention relates to an apparatus for producing ultrafine metal powder, which is most suitable for producing ultrafine metal powder, especially ferromagnetic material, using arc discharge. Conventionally, as an example of such a device, there is one shown in FIG. 1, for example. That is, an electrode 3 such as tungsten W for a cathode or tungsten containing thorium oxide fixed to the tip of an electrode support frame 2 is inserted into a sealed container 1, and then the container 1 is closed.
The electrode 3 for the cathode is opposed above the water-cooled copper hearth 4 for the anode, which constitutes the bottom part of the inside. Reference numeral 5 denotes a collection section incorporating a filter 6 for collecting ultrafine metal particles, and 7 a gas circulation purification section operated by a pump or the like, which is used to feed the gas into the container 1. . 8 is a power supply, and 9 is an insulator. First, the inside of the container 1 is made into an atmosphere of pure hydrogen gas or a mixed gas of pure hydrogen gas and one or more inert gases such as argon and helium, and the internal pressure is set to 30 to 760 T.
Set to the required value within the range of o r r. Thereafter, the pump in the gas circulation fft 1i production section 7 is operated to circulate the gas. Then, current and voltage are applied from a power source 8 to cause arc discharge between the electrode 3 and the metal sludge 11 placed on the water-cooled copper hearth 4, thereby generating an arc column 10. At this time, by appropriately setting conditions, the arc column 10 can be
The molten surface is squeezed into a thin layer. As a result, the metal material 11 in the vicinity becomes high in temperature, and an anodic flame 12', which becomes a source of ultrafine metal particles, is generated and rises at high speed in the direction of arrow A. This anode flame 12' is carried in the direction of the arrow by the circulating gas flow, and on the way, it is cooled, condensed, and solidified to become ultrafine metal particles, which are collected and recovered in the recovery section 5. The gas that has passed through the recovery section 5 is purified in the gas circulation purification section 7.
It advances in the convex direction of the arrow and is fed into the container 1 again. However, in the conventional apparatus S described above, the average particle size and particle size distribution of the ultrafine metal particles are controlled by the gas composition and gas pressure in the container 1. However, when this apparatus S4 was used, the particle size of the ultrafine metal particles was non-uniform. Therefore, it has not been possible to produce highly homogeneous magnetic powder using several hundred people, the average particle size of which is close to that of single-magnetic particles of magnetic material, which is used in high-density magnetic recording media. The present invention has been made in view of the above-mentioned points, and its purpose is to spray a gas onto a metal material, an arc, and an anode flame, and to dispose a cooling rod within the anode flame. An object of the present invention is to provide an apparatus for producing ultrafine metal powder in which the average particle size and particle size distribution of fine particles can be controlled. A first embodiment of the present invention will be described below with reference to FIGS. 2 to 5. 13 is a gas jetting nozzle, and this gas jetting nozzle 13.1
3 has its distal end facing toward the metal material 11, and its base end introduction pipe portion 13a is connected to the gas circulation purification section 7, so that the gas from the gas circulation purification section 7 is directed toward the metal material 11, It is designed to be blown onto an arc column 10 and an anodic flame 12. Also, this gas jet nozzle 13.13
is movable from the position shown by the solid line to the position shown by the imaginary line. Reference numeral 14 denotes a cooling rod disposed within the anodic flame 12 that serves as a source of ultrafine metal particles rising from the metal material 11;
4, the anodic flame 12 is drawn nearby, forming a high-velocity air stream that extends upward. As the metal material 11 as an example, for example, Fe
: The blending composition ratio of Ni is 86:14 weight percent 1-
Fe--Ni alloy is used. One embodiment of the present invention has the above-mentioned configuration, and includes a container 1.
The interior of the container 1 is made into an atmosphere of pure hydrogen gas or a mixture of hydrogen gas and one or two gases such as argon and helium. In this example, the atmosphere is pure hydrogen gas and the internal pressure of the container 1 is set to 100 To'rr. After that, an electrode 3 as a cathode made of an iron-Nisokel alloy (containing 14 weight percent Ni) and tungsten containing 2 percent by weight thorium oxide was placed on a water-cooled copper hearth 4 as an anode.
An arc voltage of (2) is applied and an arc current of 200 A is applied to generate an arc column 10, and the metal material 11 made of iron-Ninokel alloy is melted by the arc. When the metal material 11 is melted by the arc column 10 in this manner, a high-velocity airflow that becomes a source of ultrafine metal particles called an anodic flame 12 rises inside the container 1 from the metal material 11 . In this case, pure hydrogen gas H2 is circulated by the pump of the gas circulation purification unit 7, which will be described later, and is blown from the gas jet nozzle 13.13 onto the metal material 11 made of iron-Nisokel alloy, the arc column 10, and the anode flame 12. Therefore, the arc column 10 self-contracts due to magnetic and thermal pinch effects and concentrates on the surface of the metal material 11,
A high-velocity air current that becomes a source of a large amount of ultrafine metal particles is generated from the metal material 11, which is cooled and solidified to become ultrafine metal particles. In this case, one of the effects of gas blowing is that the average particle size of the ultrafine metal particles can be reduced. in this case,
In spraying, the average particle size tends to become smaller as the gas flow rate increases. Also, a cooling rod 1 is placed inside the anode flame 12.
4 is inserted, the anode flame 12 is cooled and drawn around the cooling rod 14 when passing near this cooling rod 14, and is therefore constricted and rises. Thereafter, this anode flame 12 is carried by the circulating gas flow, cooled and solidified, and the ultrafine metal powder is collected by the filter 6 of the collection section 5. The average particle size and particle size distribution of the ultrafine metal particles of this example thus produced are shown in FIGS. 3, 4, and 5, respectively. Of these, FIG. 3 is a graph (I) showing the average particle size of ultrafine metal particles against the pressure of pure hydrogen gas H2 without blowing gas from the surroundings. From the curve β of this graph (I), it can be seen that as the atmospheric pressure in the container 1 in the atmosphere of pure hydrogen gas H2 increases, the average particle size of the ultrafine metal particles increases. Further, FIG. 4 shows a diagram (II) showing the relative particle size of ultrafine metal particles versus the flow rate of gas blowing. Here, the relative particle size α is the average particle size when ultrafine metal powder is produced by setting an arbitrary pressure on the curve l shown in Figure 3 (100 Torr here) and blowing gas from the surroundings. It shows the value divided by the average particle diameter when ultrafine metal particles were produced with the cooling rod 14 removed from the anode flame 1o in the apparatus S2 of this embodiment as shown in the figure. From this value α, it can be seen that when the pure hydrogen gas H2 is sprayed from the gas jet nozzle 13.13, the average particle diameter becomes smaller when the gas flow rate increases. Also, the curve β as a parameter is the fifth
The value obtained by dividing the half width of the Gaussian distribution curve representing the particle size distribution shown in the figure by the relative particle size α and the gas ejection nozzle 13.13
The spraying from the air shows the relationship between the gas flow rate. From FIG. 4, it can be seen that in gas spraying in particular, when the flow rate increases to 3QA/mtn, the average particle size distribution of fine metal powder becomes significantly smaller and the particle size distribution also becomes sharper. Although not shown here, in this case, if the cooling rod 14 is further inserted vertically into the anode flame 10 to produce ultrafine metal powder, this tendency will be further emphasized. Figure 5 is a diagram showing the particle size distribution of ultrafine metal powder (I
II). Among these, distribution curve a is the particle size distribution of ultrafine metal particles produced by the conventional technique as shown in FIG. 1, and is expressed with the average particle size at this time being 1. Furthermore, particle size distributions S, C, and d indicate relative particle size distributions depending on the difference in flow rate when pure hydrogen gas is sprayed. In other words, the particle size distribution is 20 I! /min, particle size distribution C is 5012/min%, and particle size distribution d is 100
A/min, particle size distribution e is 207! The results are shown when /min. From this, it can be seen that in spraying, as the gas flow rate increases, the particle size distribution of ultrafine metal particles, the peak values of c and d, tend to become smaller. In addition, the particle size distribution e is determined by the device s shown in Fig. 2.
It can be seen that when the gas ejection nozzle 13°13 is removed from 2, that is, due to the effect of the cooling rod 14 alone, the peak of the particle size of the ultrafine metal particles becomes smaller than the particle size distribution a, and the particle size distribution becomes sharper. . Furthermore, the particle size distribution f shows the case where the cooling rod 4 is disposed within the anode flame 12 with respect to the particle size distribution. In other words, this shows the synergistic effect of the cooling rod 14 and the gas blowing, and the peak of the particle size is smaller and the particle size distribution is sharper than when either one is used alone. FIG. 8 shows a device s2 according to a second embodiment of the present invention. In this embodiment, the electrode 3 is arranged perpendicularly to the metal material 11, so that the arc is discharged in a vertical shape to the metal material 11, and a large amount of ultrafine metal powder is generated from the metal material 11. This embodiment differs from the first embodiment in that Further, this embodiment differs from the first embodiment in that a pump P disposed in place of the gas circulation purification section 7 is operated to circulate the circulating gas and cause the gas ejection nozzles 13, 13 to eject the gas. Furthermore, FIG. 9 shows an apparatus showing a third embodiment of the present invention. In this third embodiment, a high-velocity air stream called an anodic flame 12 is cooled by flowing cooling gas around the support frame 2 supporting the electrode 3 and forming a gas means to the support frame 2. The speed air flow mechanism 2 is designed to stand up around the support frame 2 in a narrowed state. In addition, instead of the gas circulation purification section, gas from the pump P is transferred through the support rack 2, and is directed to the anode flame 12 from a gas jet nozzle section 13.13 formed at the tip of the support rack 2. The difference between the above embodiments is that the circulating gas is ejected. In the above embodiment, the metal material 11 is made of iron-Nisokel alloy, but is not limited to this, and may be Fe-co gold alloy, Fe-Co-Ni alloy, or Fe. It can also be applied to metal alloys such as C01Ni, Ti, Zr, Nb, Ta, and Mo. The gas atmosphere inside the container 1 that is ejected from the gas ejection nozzle 13.13 includes N2, Ar, He, N2, CH
< , NH3, or a mixture of two or more gases can also be applied. As mentioned above, in the present invention, a cooling rod is placed inside the anode flame to cool the anode flame so that the anode flame is raised in a narrow state, and gas is blown onto the anode flame. It is possible to control the average particle size and its particle size distribution by controlling the growth process of ultrafine metal particles produced from metal materials.Therefore, it is possible to control the average particle size and its particle size distribution.Therefore, it is possible to control the average particle size and its particle size distribution, which is also ideal for producing ultrafine metal powder of ferromagnetic metal alloys. Ultrafine metal powder with a particle size and particle size distribution is obtained. 4. Brief description of the drawings Figure 1 is a cross-sectional view showing an example of a conventional ultrafine metal powder manufacturing apparatus, and Figure 2 is a cross-sectional view of an example of a conventional manufacturing apparatus for ultrafine metal powder. A sectional view showing one example, Fig. 3 is a graph showing ultrafine metal particles produced using this device and their relationship, and Fig. 4 is a graph showing the relationship between the gas flow rate and the average particle size of ultrafine metal particles. Figure 5 is a graph showing the relationship characteristics of the diameter, Figure 5 is a characteristic diagram also showing the particle size distribution curve, Figure 6 is an electron micrograph of ultrafine metal particles in the previous particle size distribution curve a, and Figure 7 is the same. Particle size distribution curve f in Figure 5
FIG. 8 is a cross-sectional view showing a second embodiment of the manufacturing apparatus of the present invention, and FIG. 9 is a cross-sectional view of a third embodiment of the present invention. ■... Container, 3... Electrode, 10... Arc column, 1
DESCRIPTION OF SYMBOLS 1... Metal material, 12... Anode flame, 13... Gas jet nozzle, 14... Cooling rod. Patent applicant Pioneer Corporation■■■
■1 ==11

Claims (1)

[Claims] The device generates an arc column between a metal material placed on an anode and a cathode to produce ultrafine metal powder, and gas is ejected to the metal material, the arc column, and the sunlight, and the sunlight 1. An apparatus for producing ultrafine metal particles, characterized in that a cooling rod is disposed within the apparatus to control the particle size and particle size distribution of the ultrafine metal particles.