JPH059483B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for producing ultrafine powder of a high melting point substance by melting the substance and evaporating it.

In conventional equipment for producing ultrafine powder of high-melting-point substances, a long material is placed horizontally, the axis of the material is oriented in the horizontal direction, and the material is sequentially fed out, and an electron beam is applied to the outer peripheral surface of the tip of the material. An apparatus has been provided in which ultrafine powder is obtained by irradiating orthogonally from above and thereby melting and vaporizing the outer circumferential surface of the tip of the material. According to such a device, the material heated at the tip of the material tends to form a droplet shape and hang downward, so that the electron beam does not hit the material. Therefore, the above-mentioned material was cooled in a water-cooled copper mold, and the cooled material was irradiated with the above-mentioned beam (for example, see Japanese Patent Laid-Open No. 49-48541). This method can prevent the material from sagging, but the amount of evaporation is extremely small compared to the amount of energy supplied by the electron beam, and therefore only a small amount of powder is produced relative to the amount of energy and supply time. There was a big problem that made it impossible to get anything.

Therefore, the present invention provides a support for supporting the high-melting point material in the irradiation chamber, and irradiates the high-melting point material supported by the support with an electron beam from above. In an apparatus for producing ultrafine powder of a high melting point substance, the apparatus melts and evaporates the material, and collects the ultrafine powder of the material produced by the evaporation using a recovery means to obtain the ultrafine powder of the material, A plurality of concave placing parts are disposed on the upper surface of the support, each having a concave shape for placing a high melting point substance, and each placing part is pressed against the periphery of the lower part of the material. a mounting surface for fixing the material in an established state, and a recess for forming a gap under the material placed on the mounting surface; The above-mentioned problem is solved by making the plurality of above-mentioned materials fixed on the mounting part horizontally movable to enable selective irradiation with the above-mentioned electron beam. The material can be erected by supporting the sides, and as a result, the upper surface of the material can be irradiated with an electron beam, and the material can be thermally levitated and thermally isolated from the support. The amount of evaporation of the material can be extremely increased and a large amount of powder can be obtained, and in that case,
The object of the present invention is to provide a method for producing ultrafine powder of a high melting point substance, which allows a large amount of powder to be obtained compared to the amount of energy supplied, and which also improves thermal efficiency.

The drawings showing the embodiments of the present application will be described below. In Figures 1 to 3, 1 is an irradiation chamber;
The inside is designed to be airtight. Next, in the support device provided in the irradiation chamber 1, 2 is a support rod, which can move forward and backward in the direction of the arrow.
Further, the inside and outside of the irradiation chamber 1 are sealed by a sealing member 3. Reference numeral 4 denotes a support body attached to the tip of the support rod 2, and a support base 4a equipped with a roll.
It is designed to be able to move left and right on the top of Figure 1. It is preferable to use the support 4 made of the same material as the material described below in order to obtain powder with high purity. Reference numeral 5 designates a plurality of mounting portions provided on the support body 4, which are formed in a concave shape. Reference numeral 6 indicates an annular mounting surface, which is preferably formed to have a rough surface so that the surface is uneven. Reference numeral 7 indicates a recessed portion provided at the center of the mounting portion 5. Reference numeral 8 is a high melting point material and is formed into a cylindrical shape. Examples of the high melting point substance include tungsten, tantalum, zirconium, niobium, and molybdenum. The dimensions of this material 8 are approximately 5 mm to 50 mm in diameter and 5 mm to 50 mm in height.
A certain degree is used. Note that the shape of this material 8 is not limited to a cylindrical shape, but may be a prismatic shape. Next, reference numeral 10 indicates an electron beam irradiation device provided in the upper part of the irradiation chamber 1. This device 10 is well known and includes a casing 1
1 includes an electron gun 14 consisting of a cathode 12 and an anode 13.
It is also configured to include an electronic lens 15.
16 is a power source for the filament connected to the cathode 12, and is configured so that the filament current can be adjusted. Reference numeral 17 denotes a power source for accelerating the electron beam connected to the cathode 12 and anode 13, so that the voltage applied between the two electrodes 12 and 13 can be adjusted. 18
shows the electron beam emitted from the device 10. 1
Reference numerals 9a and 20 are well-known exhaust ports, which are connected to a vacuum pump (not shown) and are provided to evacuate the inside of the irradiation chamber 1, as is well-known. 19b indicates a gas inlet. Next, reference numeral 21 indicates a recovery means provided within the irradiation chamber 1. In this recovery means 21, 22
is a cylindrical container that can be freely rotated in the direction of the arrow, and is adapted to be rotated at a low speed in the direction of the arrow by a motor (not shown). Further, it is configured to be positively charged by the power source 22a. 23 is a cooling medium provided in the container body 22, and liquid nitrogen is used, for example. 24 is a scraping piece, one end 24a of which is pivotally connected to a supporting member integral with the irradiation chamber 1, and the other end 24b of which is attached to a spring 2.
It is brought into elastic contact with the outer peripheral surface of the vessel body 22 by the biasing force 4c. 24 represents a hopper, and 26 represents a collection container. Reference numeral 27 indicates a viewing window provided on the side wall of the irradiation chamber 1, which is formed to monitor the working conditions within the irradiation chamber 1. Although not shown, irradiation chamber 1
As is well known, a working opening is provided in the side wall of the container 26 for charging the material 8 or taking out the container 26 storing the manufactured fine powder.

In the case of the above structure, first, the materials 8 are respectively placed on the placing portions 5 of the support 4 to bring each material into an established state. Thereafter, the irradiation chamber 1 is evacuated through the exhaust ports 19a and 20 to reduce the pressure in the irradiation chamber 1 to a high vacuum (approximately 10 ^-6 Torr). Thereafter, an atmosphere gas is introduced into the irradiation chamber 1 through the inlet 19b as required to maintain the interior of the irradiation chamber 1 in a low pressure gas atmosphere (about 1 torr). In this state, the power supply 16,
Electricity is supplied from the electron beam 17 to the cathode 12 and the anode 13 in a well-known manner to emit an electron beam 18. Also, this electron beam 18 is transmitted to the material 8 by the electron lens 15.
It is made to converge at the top surface to a size that corresponds to the material dimensions. When the top surface of the material 8 is irradiated with the electron beam 18 by the above-described operation, the top surface of the material 8 is melted and a fused portion 8a is formed thereon as shown in FIG. The periphery of the upper surface of the melted portion 8a is rounded due to surface tension. In addition, 8b in Figure 3
indicates the solid part. When melting the top surface of the material 8 in this manner, the amount of energy supplied by the electron beam 18 is adjusted so that the entire area of the top surface is melted and the melt does not overflow from the top surface and flow down. The adjustment may be performed by adjusting the filament current by variable operation of the power source 16, or by adjusting the voltage applied between the cathode 12 and the anode 13 by variable operation of the power source 17. Good too. Also electron beam 1
Swinging the melt 8 within the top surface of the material 8 using a deflection coil (not shown) is an extremely effective means for creating a molten zone 8a with a uniform temperature in the material 8 having a large diameter. To give an example of the relationship between the dimensions of the material 8 and the amount of energy supplied, if the diameter of the material 8 is 5 mm and the height is 5 mm, the amount of energy supplied is, for example
It is 800W. Also, if the diameter is 10mm and the height is 10mm,
It is about 6.5kW. Furthermore, if the diameter is 50 mm and the height is about 5 mm, the power output is about 80 kW.

When the wide melting area 8a is formed as described above, a large amount of vapor of the above material is generated from the entire area of the melting area 8a. As is well known, the vapor condenses to produce ultrafine powder, and during the formation, the ultrafine powder is charged to a negative potential. Therefore, the ultrafine powder is attracted toward the positively charged container body 22 and adheres to its outer peripheral surface. And the vessel 2
As the roller 2 rotates, the ultrafine powder adhering to its outer peripheral surface is scraped off by the action of the scraping piece 24, and the scraped ultrafine powder is successively collected into the container 26 through the hopper 25.

When the material 8 is melted as described above,
Since the material 8 is placed on the support 4,
The thermal resistance between the material 8 and the support 4 is extremely high. Therefore, the amount of heat escaping from the material 8 toward the support 4 by conduction is kept extremely small. Furthermore, in the case of the above configuration, the recess 7 is formed in the placement section 5, reducing the area of the placement surface 6. Moreover, the placement surface 6 is also formed to have a rough surface, so that the space between it and the material 8 is reduced. Due to the larger thermal resistance, the loss of heat is kept smaller.

When one material 8 is almost completely consumed by the above-described operation, the operation of the electron beam irradiation device 10 is stopped, and the support rod 2 is operated to move the support body 4 as shown in FIG. Move it to the right so that the next material 8 is under the electron beam irradiation device 10. Then, the same operations as described above may be repeated.

After the above-described repeated operations, if all the material 8 has been consumed for powder formation, the electron beam irradiation device 10 is stopped and the irradiation chamber 1
The inside is returned to normal pressure, and a new material is charged through the working port and the produced ultrafine powder stored in the container 26 is taken out.

Next, to give an example of the results of an experiment to generate powder as described above, using a tungsten material with a diameter of 5 mm and a height of 5 mm, the amount of energy supplied was 800 W, and ultrafine powder was generated. During the production, we were able to collect 1.5g of ultrafine powder per hour.

Next, in various different embodiments, the relationship between the support 4 and the material 8 may be such that only one material is placed on the flat upper surface of the support and then melted and evaporated.

Further, as the collection means, one having another structure, such as one in which a container containing a refrigerant is placed in the irradiation chamber and powder is adhered to the surface of the container, may be used.

Next, FIG. 4 shows a different embodiment of the present application, and shows a different example of a support device provided within the irradiation chamber. In the figure, 30 is a rotating device;
Reference numeral 31 denotes a rotating shaft thereof, and a disk-shaped support 4e is attached to the upper end of the rotating shaft 31.

When using such a support device, if one material 8e is consumed, the rotating shaft 31 is rotated and the next material 8e with the support 4e placed thereon is transferred to the electron beam irradiation device. Move it so that it is below. Then, similar operations can be performed on that material.

It should be noted that the same reference numerals as those in the previous figure are appended with an alphanumeric letter "e" for parts that are functionally the same or equivalent to those in the previous figure, and redundant explanations are omitted.
(Furthermore, in the following figure, the same idea is given and the redundant explanation is omitted by adding an alphanumeric character f.) Next, FIG. 5 shows a further different embodiment of the present application. In the figure, reference numeral 32 denotes a receiving piece, around which is formed an annular recess 7f. Further, a cylindrical enclosure 33 is arranged around the material 8f. In the case of such a configuration, the mounting surface 6
The area of f, that is, the contact area between the material 8f and the support 4f becomes even smaller, making it possible to further increase the thermal resistance between the two compared to the embodiment described above, thereby further reducing the heat loss. I can do things. Furthermore, the presence of the enclosure 33 can reduce heat loss due to radiation from the peripheral side of the material 8f. It is preferable to use the same material as the material 8f for the enclosure 33 in order to maintain high purity of the powder.

As described above, in the present invention, (a) When attempting to obtain powder of material 8, a part of the material is irradiated with an electron beam to heat and melt it to evaporate its atoms. It has the advantage of being able to obtain extremely fine powder because it collects the atoms of the material in powder form.

(b) Moreover, in the above case, according to the apparatus of the present invention, the material 8 can be established, and the upper surface can be irradiated with the beam 18 while the lower side is received, and the beam 18 can be evaporated from the upper surface. This means that, unlike the conventional case in which the material is placed horizontally and its outer periphery is heated from above, the material 8 is less likely to lose its shape even when heated, increasing the amount of evaporation per unit time. There are certain effects that can be achieved.

(C) Furthermore, for the material 8 which is supported downwardly and is in a state where it is difficult to lose its shape, a gap 7 is formed in a part of the lower part of the material 8, so that the material 8 is thermally maintained as if it were floating from the support body 4. can do. As a result, even if a small amount of energy is applied to the upper surface of the material 8 by the beam 18, the thermal effect is large.
There is also an epoch-making effect in that a large amount of evaporation can be obtained from the upper surface of the material 8 compared to the amount of energy.

(d) Moreover, on the upper surface of the support 4, a plurality of materials 8,
8 and 8 can be placed side by side, so different materials 8 can be placed one after another.
By selectively irradiating the beam 18, there is also the operational effect that the evaporation work can be performed continuously using a plurality of materials 8 one after another.

[Brief explanation of the drawing]

The drawings show examples of the present application, in which Fig. 1 is a schematic vertical cross-sectional view of an ultrafine powder generating device, Fig. 2 is a cross-sectional view showing the relationship between the support and the material, and Fig. 3 is a diagram showing the melting of the material. FIG. 4 is a perspective view showing a different example of the support device; FIG. 5 is a cross-sectional view showing a different example of the relationship between the material and the support. 1... Irradiation chamber, 4... Support, 8... Material, 1
8...electron beam, 21...recovery means.

Claims (1)

[Claims] 1. A support for supporting the high melting point material is provided in the irradiation chamber, and the upper part of the material is melted by irradiating the high melting point material supported by the support with an electron beam from above. In an apparatus for producing ultrafine powder of a high-melting point substance, the ultrafine powder of the material produced by the evaporation is collected by a recovery means to obtain an ultrafine powder of the material, wherein the support A plurality of concave placing parts are arranged on the upper surface to place high melting point materials, and each placing part is pressed against the lower part of the material to place the material. A mounting surface for fixing the material in an established state, and a recess for forming a gap under the material placed on the mounting surface, and the support body An apparatus for producing ultrafine powder of a high melting point substance, characterized in that a plurality of the materials fixed thereon are movable laterally to enable selective irradiation with the electron beam.