JPS59190302A - Method and device for producing ultrafine particle - Google Patents

Abstract

PURPOSE:To improve productivity in producing ultrafine particles by replenishing the raw material housed in a cylinder of which the open top end is disposed below an electrode by lifting the material with a piston and forming the ultrafine particles by using an arc. CONSTITUTION:An ingot of a raw material A consisting of a metal, semimetal, semiconductor or alloy is housed in a cylinder 7, and hydrogen or hydrogen- contg. gas or nitrogen or nitrogen-contg. gas is run in a furnace body 1 and is blown onto the surface A of the raw material A. A voltage is impressed between the electrode 5 fixed to the bottom end of a water-cooling copper pipe 4 and the raw material A to generate an arc. The top end of the material A is melted by the arc and the gaseous atmosphere is activated. Ultrafine particles are generated from the material A by the reaction between the molten raw material A and the activated gas and are guided with the gaseous flow which flows to a waste gas pipe 2, by which the particles are captured. An increase in the voltage owing to a decrease in the top surface of the material A is detected by a control device 17 and a piston 11 is moved upward by a screw bar 14 which is rotated by a motor 16. The material A is thus replenished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for producing ultrafine particles using an arc, and is particularly directed to improvements in raw material supply.

In recent years, the unique properties of ultrafine particles have attracted attention, and their future applications in a wide range of technical fields such as electronics and thick medium chemistry are expected.

Various methods for producing ultrafine particles have been developed, but
One method is to use an arc. Specifically, an electrode is placed in a hydrogen-containing gas or a nitrogen-containing gas, and a crucible is placed below the electrode. This crucible has four relatively shallow parts in the center), and the raw material is stored in these recesses. Then, an arc is generated between the electrode and the raw material, and the arc melts the raw material in the heating bath, simultaneously activating the gas, and the reaction between the molten raw material and the activated gas removes ultrafine particles from the molten raw material. generate.

By the way, the amount of raw materials decreases with the generation of ultrafine particles.

In the conventional method described above, the amount of raw material that can be accommodated in the crucible is relatively small, and the operation must be interrupted for a short period to open the furnace and replenish the raw material.

For this reason, continuous mass production was not possible and productivity was low.

The present invention was developed based on the above-mentioned circumstances, and its first purpose is to provide a method for producing ultrafine particles that can continuously replenish raw materials and greatly improve productivity. A second object of the present invention is to provide an ultrafine particle manufacturing apparatus that can automatically and continuously replenish raw materials.

The method and apparatus of the invention will now be described with reference to the illustrated embodiments. In the figure, reference numeral 1 denotes a furnace body whose outer periphery is water-cooled. This furnace body 1 is installed in an upright position. An exhaust gas pipe 2 is connected to the lower part of the furnace body 1. Exhaust gas pipe 2
is facing diagonally upward. A flange 3 is fixed to the lower end of the furnace body 1. A water-cooled steel pipe 4 is installed inside the furnace body 1. The water-cooled copper tube 4 is supported at the upper part of the furnace body 1 and is installed vertically along the central axis of the furnace body 1. An electrode 5 is vertically fixed to the lower end of the water-cooled steel pipe 4.

Another flange 6 is connected to the 7 flange 3. A cylinder 7 is supported at the center of the flange 6. A flange portion 8 is formed at the upper end of the cylinder 7, and the flange portion 8 of the cylinder is fixed to the 7 flange 6 for aging. The cylinder 7 is supported vertically, and the lower end a between its upper ends is located below the electrode 5 described above. Cylinder 7 is tentatively titled Case 9. The upper opening edge of the case 9 is fixed to the 7-lunge 6,
The lower end of the cylinder 7 is inserted and fixed into the bottom opening 9a. Cooling water flows inside the case 9 to cool the cylinder 7. In the figure, 10a is the cooling water inlet;
10b is an outlet section.

A piston 11 is inserted into the lower part of the cylinder 7 so as to be slidable in the vertical direction. The piston 11 is cooled by cooling water flowing inside it.

In the figure, 12a is an inlet portion of the cooling water, and 12b is an outlet portion.

A support portion 13 is fixed to the lower end of the piston 11.

A screw hole is formed in this support portion 13, and a screw hole 14 is screwed into the screw hole with the maple. The lower end of the threaded rod 14 is connected to a motor 16 (drive mechanism) via a power transmission mechanism 15.

The screw shaft 14 is rotated by the drive of the motor 16, and the piston 11 is moved up and down by the action of the screw rod 14 and the screw hole. The motor 16 is controlled by a control device 17.

In the above configuration, the raw material A is stored in the cylinder 7 in advance. As the raw material A, not only metals but also some half metals and semiconductors can be used.

For example, raw material A is in the form of a cylindrical ingot in cylinder 7.
is housed in. Hydrogen or a hydrogen-containing gas, or nitrogen or a hydrogen-containing gas flows within the furnace body l. The above-mentioned gas flows downward from the inlet at the top of the furnace body 1, is blown onto the surface of the raw material A, and further flows into the exhaust gas pipe 2. A voltage is applied between the electrode 5 and the upper surface of the raw material A by a constant voltage source or constant current source electrically connected to the water-cooled copper tube 4, and an arc is generated. For this arc,
The upper part of raw material A is melted. Further, the above-mentioned rising air gas is activated by the arc. Then, ultrafine particles are generated from the molten raw material A due to the reaction between the molten raw material A and the activated gas.

The generated ultrafine particles are guided by the gas flow to the exhaust gas pipe 2.
and is collected by a extractor (not shown).

Due to the generation of ultrafine particles, the position of the upper surface of the raw material A decreases, but this decrease can be replenished by moving the piston 11 upward and pushing up the raw material A. In this embodiment, the above-mentioned raw material supply is performed automatically. An example will be explained in which a constant current source is used as an arc power source. When the upper surface of the raw material A decreases, the voltage (arc voltage) between the electrode 5 and the upper surface of the raw material A increases in order to obtain a long arc with a constant current. This increase in voltage is detected by the control device 17. The control device 17 compares this detected voltage with a preset voltage, and outputs a control signal to the motor 16 according to the difference. When the motor 16 receives the control signal and is driven, the screw barrel 14 rotates and the piston 11 moves upward. Along with this, the raw material A is pushed up and the arc returns to a predetermined length. As a result,
The driving of the shimotor 16 is stopped when the voltage detected by the control device 17 and the set voltage are the same value. In this way, raw materials are automatically replenished so that the length of the arc is always constant. Furthermore, since the length of the arc is constant, the conditions for generating ultrafine particles are stabilized, and ultrafine particles with relatively uniform particle sizes can be produced. Note that when a constant voltage is used as the arc electric power W, the movement of the piston 11 is controlled by detecting a change in the current (arc current) flowing through the electrode 5 by the control device 17.

Further, the arc length can also be adjusted in response to variations in the speed of gas flowing within the furnace body l.

In this case, the set voltage (or current) of the control device 17 is adjusted. Then, the piston 11 is adjusted in the vertical direction so that the detected arc voltage (or arc current) becomes the set value, and as a result, a desired arc length can be obtained.

Note that the present invention is not limited to the embodiments described above, and various embodiments are possible. In the method of the present invention, the piston may be moved manually.

For example, the piston may be moved by rotating the screw barrel 14 by operating a handle without using the motor 16, or by manually operating all the on/off control switches of the motor 16. In these cases, the operator must determine the arc voltage t
- or operate manually while checking the arc current with a meter.

Although the upper y4 open lower a of the cylinder 7 must be located below the electrode 4, the cylinder 7 itself does not necessarily have to be arranged vertically, and may be arranged vertically.

Further, as the mechanism for moving the piston 11, in addition to a combination of a threaded rod and a screwdriver, a unique structure such as a rack and pinion or a worm gear can be adopted.

Furthermore, the electrode may be configured to generate all plasma arcs.

As explained above, in the method of the present invention, raw material is replenished by pushing up the raw material housed in the cylinder with a piston, so it is possible to continuously produce a large amount of ultrafine particles, greatly improving productivity. can.

In addition, in the device of the present invention, the piston is moved upward to maintain a constant arc length by detecting arc voltage or arc current, so it is possible to automatically replenish raw materials and to remove ultrafine particles. Generation conditions can be stabilized.

[Brief explanation of the drawing]

The figure is a sectional view showing an embodiment of the device of the present invention. 1... Furnace body, butt... Electrode, 7...
・Cylinder holder, 7a... Upper end opening of cylinder, 1
1...Piston, 16...Motor (drive mechanism), 17...1 Mori control device, A...
··material. Noboru Watanabe, patent attorney representing applicant Tokyo Steel Co., Ltd.

Claims (1)

[Claims] 1. Heating and bath-melting a pure metal, metalloid, semiconductor, or alloy by arc in hydrogen or a hydrogen-containing gas, or nitrogen or a nitrogen-containing gas, and activating the hydrogen gas or nitrogen gas at the same time; In the method of manufacturing ultrafine particles by reacting the activated gas and the melt, the raw material is contained in a cylinder whose upper end opening is arranged below the electrode, and the raw material is slidably inserted into the lower part of the cylinder. An ultrafine particle manufacturing method characterized by replenishing the raw material by pushing the raw material up with a piston. 2. (a) A furnace body filled with hydrogen or hydrogen-containing gas, or nitrogen or nitrogen-containing gas; (b) An electrode disposed within the furnace body; and (c) A furnace body that accommodates raw materials and has an upper end opening below the electrode. a cylinder disposed in (b) a piston slidably inserted into the bottom of the cylinder and supporting the bottom of the raw material contained in the cylinder; (e) a drive mechanism for driving the piston; It is equipped with a control device for controlling the drive mechanism, generates an arc at the lower end of the electrode, heats and melts the raw material with this arc, and simultaneously activates the gas, and by a reaction between the molten raw material and the activated gas, Ultrafine particles are generated from the melted raw material in the bath, and at this time, the control device detects the shear current or arc voltage, and outputs a control signal to the drive mechanism according to the difference between this detected value and a preset value. The piston is raised, thereby compensating for the drop in the position of the upper surface of the raw material due to the generation of ultrafine particles, maintaining the arc length between the electrode and the upper surface of the raw material at a predetermined length, and automatically replenishing the raw material. An ultrafine particle manufacturing device characterized by: