JP3127045B2 - Micro powder continuous feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus capable of continuously supplying a small amount of raw material powder.

[0002]

2. Description of the Related Art The critical temperature (TC) is the temperature of liquid nitrogen (about 7).
As oxide superconductors having a value exceeding 7K), for example, YBaCuO-based, BiSrCaCuO-based, TlBa
An oxide superconductor such as a CaCuO-based oxide is known. Various studies have been conducted to apply these oxide superconductors to various superconducting applied devices such as power transport, superconducting magnets, and superconducting devices. As one of the manufacturing methods of such an oxide superconductor, a method of forming an oxide superconducting thin film on a substrate surface by a film forming means such as a chemical vapor deposition method (CVD method) is known. The oxide superconducting layer formed by this film forming means has a larger critical current density (Jc) than a superconductor obtained by processing a bulk material,
It is known to have excellent superconducting properties. Also,
The CVD method is attracting attention as a means capable of forming a thicker film in a shorter time than a film forming means such as sputtering.

The raw material compounds used in such a method for producing an oxide superconductor by the CVD method include acetylacetone compounds of each element constituting the oxide superconductor, diketone compounds such as hexafluoroacetylacetone compound, and cyclopentadienyl. Organometallic complexes such as compounds have been used. For example, as a raw material for producing a YBaCuO-based oxide superconductor, 2,2,6,6 tetramethyl-3,5-heptanedione (hereinafter, referred to as D) of each element of Y, Ba, and Cu is used.
PM), ie, Y (DPM) ₃ , Ba (D
PM) ₂ and Cu (DPM) ₂ .

FIG. 5 shows an example of a gas supply section of a conventional CVD apparatus used for manufacturing an oxide superconductor. This gas supply unit is provided with Y (DPM) ₃ , Ba (DP
A powder feeder 3 for transporting a mixed powder 1 obtained by mixing each compound powder of M) ₂ and Cu (DPM) ₂ by a carrier gas 2 such as argon gas, and a mixed powder 2 transported from the powder feeder 3 Is provided with a vaporizer 5 having a heater 4 for heating the vaporizer to a temperature higher than the vaporization temperature. The powder feeder 3 includes a closed container 3a containing the mixed powder 1, and a carrier gas introduction tube 3b and a discharge tube 3c inserted into the closed container 3a.

[0005] The carrier gas 2 is blown into the powder feeder 3 through an introduction pipe 3b, and then the carrier gas containing the powder is discharged through a discharge pipe 3c and conveyed to a vaporizer 5. The mixed powder 1 conveyed to the vaporizer 5 is heated by the heater 4 and vaporized, and the vaporized gas 6 is supplied to a reaction chamber (not shown) together with a carrier gas.

[0006]

However, in the oxide superconductor, in the case of the Y-based superconductor, Y ₁ Ba ₂ Cu ₃ O _7-x
Composition, Bi-based, Bi ₂ Sr ₂ Ca ₂ Cu ₃ O
_In order to produce these superconducting thin films by the CVD method, since only those having a specific composition range such as the composition of _x exhibit superconducting properties, a prescribed amount of the raw material powder is reacted in a continuously stable state. It must be supplied into the chamber and reacted in a stable state to form a film. However, in the structure of the powder feeder 3 shown in FIG. 5, the amount of the mixed powder 1 is reduced and the tip position of the introduction pipe 3b and the discharge pipe 3 are reduced.
If the relative position between the tip position of c and the position of the powder 1 changes, the amount of powder that can be conveyed fluctuates, so that there has been a problem that a prescribed amount of mixed powder cannot be conveyed for a long time.

In general, there are an ultrasonic vibration type powder feeder having a configuration shown in FIG. 6 and a brush mesh type powder feeder having a configuration shown in FIG. The apparatus shown in FIG. 6 includes a hopper 8 containing raw material powder 7, a slide 9 provided at an outlet of the hopper 8, and an ultrasonic vibrator 1 provided below the slide 9.
0, the slide 9 is vibrated using the ultrasonic vibrator 10, and the raw material powder 7 is moved and supplied along the slide 9. This device uses an ultrasonic transducer 10
Of the powder, the amplitude, the frequency, the shape of the hopper 8, the inclination angle of the slide 9 and the like are adjusted as parameters to adjust the powder supply speed. However, the conventional apparatus shown in FIG. 6 cannot supply powder to pipes or the like in a reduced-pressure atmosphere, and also has a problem in that powder cannot be supplied with an accuracy of several mg / minute.

The apparatus shown in FIG. 7 includes a hopper 13 containing powder 12, a rotary brush 14 rotatably provided at an outlet 13 a of the hopper 13, and an outlet 13 a of the hopper 13.
Is a device for supplying powder from the outlet 13a of the hopper 13 by the rotation of the rotating brush 14. This device can supply a mixed powder with an accuracy of several mg / min by adjusting the rotation speed of the rotary brush 14, the diameter of the outlet 13a of the hopper 13, and the like. However, the conventional apparatus shown in FIG. 7 cannot supply powder to piping or the like in a reduced-pressure atmosphere, and also uses a soft raw material powder (for example, in the above-described CVD apparatus) due to frictional force between the rotating brush 14 and the mesh 16. Y (DPM) ₃ , Ba (DPM) ₂ , Cu (DP) used
M) ₂ powder).

The present invention has been made in view of the above circumstances, and provides a continuous micro powder supply apparatus capable of supplying a raw material powder at a rate of several mg / min for a long time at a low speed into an apparatus in a reduced-pressure atmosphere. The purpose is to:

[0010]

According to a first aspect of the present invention, there is provided a cylindrical cylinder having a closed end and an open end, and a cylindrical end having an open end. Is closed, a cylindrical piston slidably fitted into the opening of the cylinder with the opening facing the inside of the cylinder, and a carrier that is disposed inside the piston through the cylinder. A gas introduction pipe, a discharge pipe that penetrates the cylinder and is disposed inside the piston, and a moving mechanism that slides the piston up and down along the cylinder is provided. Is provided with a storage section for raw material powder.

[0011]

A carrier gas is blown from the introduction pipe onto the raw material powder stored in the piston, so that the powder rises, and the raised powder is transferred by the discharge pipe, so that a minute amount of the raw material powder is transferred. In addition, by moving the piston to change the relative position between the introduction tube and the raw material powder, the amount of the raw material powder that flies in the piston changes, so that the amount of the raw material powder that can be transferred by the discharge tube changes. Therefore, by changing the position of the cylinder in accordance with the decrease in the amount of the raw material powder, a stable amount of the raw material powder is transferred over a long period of time, and the supply amount of the raw material powder can be adjusted by changing the cylinder position.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration of an example of a film forming CVD apparatus provided with an embodiment of a trace powder continuous supply apparatus according to the present invention. In the figure, reference numeral 20 indicates a continuous trace powder supply apparatus, to which a bubbler 21, a vaporizer 22, and a film forming apparatus 23 are connected.

The micro-powder continuous supply device 20 includes a cylindrical cylinder 25, a cylindrical piston 26 slidably inserted below the introduction pipe 25, and a moving mechanism 27 for moving the piston 26 up and down. And an introduction rod 28 attached to the upper part of the cylinder 25, and an introduction pipe 29 and an extraction pipe 30 for the carrier gas inserted into the introduction rod 28.
Are provided.

The cylinder 25 has a cylindrical shape whose upper end is closed and whose lower end is opened, and a support gas supply port 25a is formed on a side surface of the upper end. The supply port 25a is connected to a bubbler 21 containing liquid tetrahydrofuran (THF). The bubbler 21 has a supply source 3 of a support gas such as argon gas.
1 is connected so that gas containing THF can be supplied to the cylinder 25. The piston 26 has a cylindrical shape whose upper end is open and whose lower end is closed. The upper part is slidably inserted into the lower side of the cylinder 25, and the piston 26 is Is airtightly closed. Further, inside the piston 26, a raw material powder A for producing an oxide superconductor, for example, YBaCuO
(DPM) ₃ , Ba (DP) for the production of oxide-based superconductors
M) ₂ , Cu (DPM) ₂ powders and the like are stored.

The moving mechanism 27 includes a rack member 27a connected to the lower end of the piston 26, and a rack member 2a.
A pinion gear 27b meshing with the pinion 7a and a motor (not shown) for rotating the pinion gear 27b in the forward and reverse directions are provided. The piston 26 can be moved up and down by rotating the pinion gear 27b in the forward and reverse directions. The introduction rod 28 extends through the ceiling wall of the cylinder 25 to the lower end side of the cylinder 25, and its upper end is closed and its lower end is opened. A gap D is provided between the outer peripheral surface of the introduction rod 28 and the inner peripheral surface of the piston 26. The introduction pipe 29 and the extraction pipe 30 extend through the ceiling of the introduction rod 28 to near the lower end of the introduction rod 28, respectively. The introduction pipe 29 is connected to a carrier gas supply source 29 a so that the carrier gas can be supplied to the inside of the piston 26, and the extraction pipe 30 is connected to the vaporizer 22. The vaporizer 22 is provided with a heater 33 on an outer peripheral portion thereof and is connected to a film forming apparatus 23 through a lead-out pipe 34. The vaporizer 22 heats a gas containing powder carried therein to vaporize the powder, thereby evaporating the powder. The mixed gas thus obtained can be sent to the film forming apparatus 23.

As shown in detail in FIG. 4, the film forming apparatus 23 used in the present embodiment has a horizontally elongated reaction chamber 40 and a gas diffusion section 41 having a constricted shape provided at the upper center thereof.
And an exhaust pipe 4 connected to both ends of the reaction chamber 40.
2 and 42 and an exhaust pump 24 connected to the exhaust pipes 42 and 42.

At both ends of the reaction chamber 40, a substrate transfer device 43 is provided. Inside the reaction chamber 40, a horizontally long heat conduction plate 45 incorporating a heater 44 is provided. The long base material 46 sent into the reaction chamber 40 by the device 43 can be moved along the heat conduction plate 45. Further, a temperature control device 47 is connected to the heater 44 so that the temperature of the base material 46 can be controlled to a desired temperature.

The film forming apparatus 23 having the above-described structure includes the heater 4
4 and exhaust by exhaust pipes 42, 42, a reaction region 48 is formed in the center of heat conduction plate 45 shown in FIG.
Is formed, a preheating region 49 is formed on the left side of the heat conduction plate 45, a slow cooling region 50 is formed on the right side of the heat conduction plate 45, and the reaction region is formed by the constricted gas diffusion portion 41. The raw material mixed gas can be uniformly supplied to the entirety of 47.

Next, a method of manufacturing an oxide superconductor using the above-mentioned trace powder continuous supply device 20, bubbler 21, vaporizer 22, and film forming device 23 will be described. Before evacuating the inside of each device, the piston 26 is withdrawn from the cylinder 25, the mixed powder for producing oxide superconductor is charged therein, and then the piston 26 is inserted into the cylinder 25. Next, the inside of the vaporizer 22 and the film forming apparatus 23 is evacuated to a reduced pressure atmosphere convenient for film forming, and then the production is started.

First, a carrier gas such as argon discharged from a supply source 29a is supplied to a piston 26 through an introduction pipe 29.
Spray on the mixed powder A inside. Then, a part of the mixed powder A soars, and a space h in which gas and powder are mixed is formed in a space between the introduction pipe 29 and the mixed powder A as shown in FIG. At the same time, the support gas supplied from the supply source 31 is supplied into the cylinder from the supply port 25a. This support gas moves through the gap D as shown by the arrow (i) in FIG. 3 to suppress the soared mixed powder A from above,
This has the effect of confining the mixed powder in the space h.

Next, the mixed powder enclosed in the space h as described above is automatically sucked out and transferred to the decompressed vaporizer 22 through the outlet pipe 30. When the mixed powder A is discharged for a long time, the amount of the mixed powder A decreases, and the distance between the distal end of the introduction pipe 29 and the mixed powder A fluctuates. The distance between the tip of the introduction pipe 29 and the mixed powder A is maintained at an appropriate value. By doing so, a stable supply amount of the raw material powder A can be secured for a long time. When the pressure and the velocity of the gas ejected from the introduction pipe 29 are fixed, the amount of the mixed powder A sent to the vaporizer 22 changes according to the size of the interval between the tip of the introduction pipe 29 and the upper surface of the mixed powder A. . Therefore, the powder supply amount can be adjusted by adjusting the vertical position of the piston 26. However, in this case, there is an upper limit and a lower limit in the interval, and the adjustment is performed within the range.

Next, the carrier gas containing the mixed powder sent to the vaporizer 22 is heated to a predetermined temperature by the heater 33 of the vaporizer 22 to vaporize the mixed powder, whereby a raw material mixed gas can be obtained. By sending the gas to the film forming apparatus 23, an oxide superconducting layer can be formed on the base material 46 in the film forming apparatus 23.

In the film forming apparatus 23, a preheating region 49, a reaction region 48, and a slow cooling region 49 are formed by heating by a heater 44 and an exhausting operation from exhaust pipes 42, 42. The material 46 is gradually heated in the preheating zone 49, the raw material mixed gas reacts at a stable temperature in the reaction zone 48, and a film is deposited on the base material 46.
And slowly cooled. Therefore, when the base material 46 is cooled after passing through the reaction region 48, the stress due to the difference in the coefficient of thermal expansion between the base material 46 and the oxide superconducting layer hardly acts, so that the thermal stress is applied to the oxide superconducting layer. It does not take. Therefore, cracks do not occur in the oxide superconducting layer after film formation.

Further, if the powder supply device 20 having the above configuration is used, it is only necessary to design the inner diameters of the inlet pipe 29 and the outlet pipe 30 optimally so that the mixed powder A soars into the space h in the piston 26. The mixed powder can be automatically supplied to the decompressed vaporizer 22. Further, regarding the supply accuracy of the mixed powder, the supply rate can be freely changed by changing the moving speed of the piston 26 upward.
A certain upper limit and a lower limit are generated depending on the inner diameters of the inlet pipe 29 and the outlet pipe 30 and the carrier gas to be introduced, but within this limit, the moving speed of the piston 26 and the feeding speed of the mixed powder A are in a proportional relationship. . In addition, Bubbler 2
The THF gas supplied from 1 has an effect of suppressing decomposition when the mixed powder is vaporized. Further, when the mixed powder A stored in the piston 26 is discharged, unlike the conventional apparatus shown in FIGS. 6 and 7, the mixed powder A does not come into contact with the mechanical parts, so that a problem of mechanical wear occurs. Absent.

(Production Example) An oxide superconducting layer was formed on a long base material using the apparatus shown in FIG. The outer diameter of the carrier gas inlet tube connected to the mass flow controller is 0.8 m
m, the outside diameter of the outlet pipe is 0.8 mm, and the outside diameter of the introduction rod is 6
mm, and a glass cylinder was used. The inner diameter of the piston was 8 mm, the gap between the outer peripheral surface of the piston and the outer peripheral surface of the introduction rod was 1 mm, and the piston was raised at a low speed of 1 mm / min using a constant speed motor for driving the moving mechanism. In addition, 30 argon gas is supplied as a carrier gas from the supply pipe.
The gas was supplied to the cylinder at a flow rate of sccm, and THF gas / argon gas was supplied to the cylinder at a flow rate of 30 sccm as a support gas from a supply port. The temperature of the vaporizer is 250 ° C., the pressure of the system is 5 to 8 mmHg, and the temperature of the CVD reaction chamber is 800.
° C, Y (DP
A mixed powder of M) ₃ , Ba (DPM) ₂ , and Cu (DPM) ₂ was used.

When the apparatus was operated under the above conditions, 80
The raw material powder can be sent to a film forming apparatus at a rate of about 120 mg / hour, and Y _{1 is} deposited on a Hastelloy substrate with YSZ (yttrium-stabilized zirconia) sent to a reaction chamber.
A Y-based oxide superconducting layer having a composition of Ba ₂ Cu ₃ O _{7 -X and} a thickness of 0.8 μm was formed. The critical temperature of this superconducting layer was 91.5K. By moving the piston up and down while keeping the flow rates of the carrier gas and the support gas supplied to the cylinder at the above values, the supply amount of the raw material powder to be supplied through the outlet pipe is within a range of 50 to 300 mg / hour. Could be changed.

[0027]

As described above, according to the present invention, a carrier gas can be blown from the introduction pipe to the raw material powder stored in the piston so that the raw material powder rises in the piston. Can be transported by
A minute amount of raw material powder can be transferred. Also, by moving the piston to change the relative position between the introduction tube and the raw material powder, the amount of the raw material powder that flies up in the piston can be changed, so that the amount of the raw material powder that can be transferred by the discharge tube can be changed. Therefore, for example, by changing the position of the cylinder according to the decrease in the amount of the raw material powder, a stable amount of the raw material powder can be transferred for a long time.

[Brief description of the drawings]

FIG. 1 shows a CV equipped with a powder supply device according to the present invention.
It is a figure showing the whole D device composition.

FIG. 2 is a cross-sectional view showing one embodiment of a powder supply device according to the present invention.

FIG. 3 is an enlarged sectional view of a main part of the apparatus shown in FIG. 2;

FIG. 4 is a configuration diagram showing an example of a CVD chamber to which the apparatus shown in FIG. 2 is connected.

FIG. 5 is a configuration diagram showing an example of a conventional powder supply device.

FIG. 6 is a configuration diagram showing another example of a conventional powder supply device.

FIG. 7 is a configuration diagram showing another example of a conventional powder supply device.

[Explanation of symbols]

20 micro powder continuous feeder, 22
Vaporizer, 23 film forming device, 25
Cylinder, 26 piston,
27 moving mechanism, 29 supply pipe,
30 outlet pipe, A mixed powder, h space, 46
Base material,

Continuation of the front page (72) Inventor Akira Kagawa 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Electric Wire Co., Ltd. (72) Inventor Satoshi Kono 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Electric Wire Co., Ltd. (72) Inventor Shigeo Nagaya 20th Kita-Sekiyama, Midori-ku, Nagoya-shi, Aichi Prefecture Inside the Electric Power Research Laboratory, Chubu Electric Power Co., Inc. (72) Inventor Toshio Inoue, Otaka-cho, Midori-ku, Nagoya-shi, Aichi 20 at Kitaguanyama 1 Chubu Electric Power Co., Inc. Power Technology Research Institute (56) References JP-A-5-117864 (JP, A) JP-A-4-34230 (JP, U) (58) Fields surveyed ( Int.Cl. ⁷ , DB name) B65G 53/00-53/28 B65G 53/32-53/66 B65G 65/30-65/48

Claims (1)

(57) [Claims] A cylindrical cylinder having one end closed and the other end opened; a cylinder having one end opened and the other end closed;
A cylindrical piston slidably fitted into the opening of the cylinder with the opening facing the interior of the cylinder, and a carrier gas introduction pipe passing through the cylinder and disposed inside the piston And a lead-out pipe that penetrates the cylinder and is disposed inside the piston, and a moving mechanism that slides the piston up and down along the cylinder.
An apparatus for continuously supplying a minute amount of powder, wherein a storage portion for raw material powder is provided inside the piston.