JP2000337779A - Floating and melting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a floating and melting device to cool and solidify a metallic or semiconductor material while the material is in a floating state, by providing a main holding means composed of a superconducting magnet, an auxiliary holding means which controls the floating state of the material, and a heating means. SOLUTION: When a conductive material 9 is placed in the high magnetic flux density space of a superconducting coil 2, a holding force and a braking force act on the material. The coil 2 constitutes a main holding means which holds the material 9 by generating a high magnetic flux density magnetic field. When a pouring funnel 1 is placed in the high magnetic flux internal space of the superconducting coil 2 and a control gas 8 is blown at a high speed from a control gas nozzle 5 provided below the space, the material 9 which becomes a spheric shape is maintained in a floating state at a fixed point in the funnel 1. Here, the material 9 has the function of a supporting means which controls the floating state. In addition, the material 9 is melted in the floating state by heating the material 9 by supplying a high-temperature fuel gas blown from a gas burner 4 together with air as the heating means of the material 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for floating and melting a metal or semiconductor material, for example, an apparatus for floating and melting a material such as a single crystal pulling apparatus.

[0002]

2. Description of the Related Art Conventionally, as one of methods for melting a metal, there is a method of melting a metal in a crucible using induction heating.
In this method, a coil is wound around a refractory crucible, an eddy current is generated in the metal material in the crucible by applying a high-frequency current to this coil, and the metal material is heated and melted by Joule heat at that time. Things.

[0003] As an advanced technology of the induction heating melting furnace, there is a flotation melting furnace. In this flotation melting furnace, a metal material is suspended and melted by electromagnetic force due to eddy current generated in a fixed metal crucible and the metal material. This levitation melting furnace can solve the problems such as the problem that the refractory component is mixed into the molten metal and the purity of the metal decreases, and the restriction of the heat resistant temperature of the refractory.

[0004] The idea and principle of the levitation melting furnace based on induction heating has been proposed since the 1920s, and in recent years, technological progress has been made up to the point of practical use (IEEJ, 1
14, Vol. 3, No. 156, 1994).

However, in a levitation melting furnace using induction heating,
The floating state of the melted metal material is very unstable, and it is very difficult to stabilize even if the shape of the metal crucible and the configuration of the coil are improved. The cause is that the levitation means and the heating means are the same, that is, the electromagnetic force and Joule heat caused by the eddy current generated in the metal material are used, so it is difficult in principle to control them independently. It is mentioned. Further, the fact that there is no damping action for braking is also an important cause.

[0006] In the levitation melting furnace by induction heating,
The influence of the specific gravity and electric conductivity of the metal material is very large, and it is difficult to configure a general-purpose device applicable to many materials. In other words, a material having a low specific gravity, such as aluminum, is likely to be unstable in levitation, and is difficult to apply to a material having a low electric conductivity, such as a semiconductor material.

Furthermore, since it is difficult in principle to independently control the heating function and the floating function, it is impossible to cool and solidify the molten material in a floating state.

Further, since the eddy current generated in the metal crucible due to levitation generates a large amount of Joule heat, it is necessary to cool the metal crucible and the efficiency is lowered.

[0009] On the other hand, there is a problem in equipment such as a high frequency power supply which is expensive and requires environmental (electromagnetic wave, electromagnetic sound) measures.

[0010]

As described above, in the conventional levitation melting apparatus, the influence of the specific gravity and electric conductivity of the melted material is very large, and it is applied to a general-purpose apparatus applicable to many materials. It is difficult to cool and solidify the dissolved material in a floating state. In addition, since a large amount of Joule heat is generated in the metal crucible, there is a problem that cooling is required and efficiency is low, and a high-frequency power source that is expensive and requires environmental (electromagnetic wave, electromagnetic sound) measures is required.

The present invention has been made in view of the above circumstances, and solves problems such as a problem that a refractory component is mixed into a melted material to lower the purity of the material and a restriction on a heat resistant temperature of the refractory. In addition to the fact that the floating state of the dissolved material is very stable, and it has excellent damping action to brake the material,
In addition to being able to adjust the influence of the specific gravity and electrical conductivity of the material, a general-purpose device applicable to many materials can be configured, and the material can be cooled and solidified in a floating state,
It is an object of the present invention to provide a levitation melting apparatus which has high efficiency and does not require a high frequency power supply.

[0012]

According to the present invention, in order to achieve the above object, a flotation melting apparatus is constituted by the following means.

According to the present invention, there is provided a levitation melting apparatus for floating and melting a metal or semiconductor material, a main holding means using a superconducting magnet, an auxiliary holding means for controlling a floating state of the metal or semiconductor material, Means for heating the material.

Further, the present invention is provided with means for cooling a metal or semiconductor material in addition to the above means.

In the flotation / melting apparatus having the above-described structure, the metal or semiconductor material is levitated and melted, so that the refractory component is mixed into the melted material and the purity of the material is reduced. Can be solved.

Further, the present invention comprises a main holding means for holding and braking the material, an auxiliary holding means for controlling a floating state, a means for heating a metal or semiconductor material, or a means for further cooling the material. It is.

In the flotation / melting apparatus having the above configuration, the floating state of the melted material is very stable, has a damping action for damping the material, and is free from the influence of the specific gravity and electric conductivity of the material. Since the adjustment can be performed, a general-purpose device applicable to many materials can be configured, and the material can be cooled and solidified in a floating state, and the efficiency is high, and a high-frequency power supply is unnecessary.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing a first embodiment of a flotation melting apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes a refractory having an inner surface formed in a funnel shape and containing a material 9 such as a metal or a semiconductor therein. A superconducting coil (solenoid coil) 2 is provided on an outer peripheral portion of the refractory 1. A cryostat 3, which is a cryogenic container stored and held, is provided. In addition, refractory 1
A burner 4 and a control gas nozzle 5 are provided to penetrate from the bottom center toward the inside.

The burner 4 contains fuel gas 6 and air 7.
A control (cooling) gas 8 is supplied to the control gas nozzle 5.

In FIG. 1, the cryostat 3
The vacuum evacuation system for keeping the inside of the chamber evacuated, the refrigerator system for keeping the cryogenic temperature, and the excitation power supply system for supplying current to the superconducting coil 2 are omitted for easy understanding.

Next, the operation of the flotation melting apparatus configured as described above will be described.

The superconducting coil 2 is held inside a cryostat 3 which is a cryogenic container, and generates a high DC magnetic field when a current is supplied from an excitation power supply (not shown).

A recent superconducting solenoid coil is an MRI.
Even a coil having a large diameter, such as a coil of a medical diagnostic device, is manufactured on a commercial basis, and a magnetic flux density of 6 T is obtained at an inner diameter of about 200 mm even in a refrigerator directly cooled without using liquid helium (No. 50) , 1993 Fall Cryogenics Society
Superconductivity Society of Japan, D2-8-11).

When the conductive material 9 is placed in a space having a high magnetic flux density in the inner diameter portion of the superconducting coil 2, a strong holding force and a braking force act on the material 9. This is because when the material 9 moves, an eddy current flows so as to prevent a change in magnetic flux inside. Here, the superconducting coil 2 forms a main holding unit that generates a magnetic field having a high magnetic flux density and holds the material 9.

However, the material 9 drops very slowly but cannot be held in the intended fixed position space in a floating state by the main holding means alone. Therefore, the funnel-shaped refractory 1 is placed in the high magnetic flux density space inside the inner diameter of the superconducting coil 2, and the control gas nozzle 5 at the lower portion blows out the high-speed control gas 8.

Then, the spherical material 9 is subjected to such a force as to be held in a floating state at a fixed point inside the funnel-shaped refractory 1. Here, the material 9 has a function as an auxiliary control means for controlling the floating state.

Further, when the material 9 tries to vibrate due to the fluctuation of the gas flow of the control gas 8, the vibration is suppressed by the braking action in the high magnetic flux density space, and the loss due to the eddy current is effectively used for heating the material 9. Is done.

The control gas 8 can be prevented from oxidizing the material by using an inert gas such as helium, neon, argon or the like whose pressure and temperature are controlled, or a nitrogen gas which can be easily obtained.

In addition, as a heating means for heating the material 9 in FIG. 1 by supplying a high-temperature fuel gas ejected from the gas burner 4 together with air and heating, the material 9 is dissolved in a floating state. Further, since heating only needs to be performed on the material 9, the efficiency is high, and the funnel-shaped refractory 1 is
And a function to protect devices such as the cryostat 3 from high heat.

As the fuel gas, hydrogen gas, hydrocarbons such as methane, ethane and propane are used. It is also possible to use oxygen gas instead of air or to use fuel gas as a reducing agent.

In FIG. 1, the superconducting coil 2 is arranged vertically, but it is possible to obtain the function of exerting a holding force and a braking force on the material 9 even if the superconducting coil 2 is arranged horizontally or at an arbitrary angle. it can.

The present invention is not limited to the above embodiment, but may have the following configuration.

(1) In the first embodiment, as shown in FIG. 1, a part of the control gas nozzle 5 is replaced with a cooling gas nozzle for mainly cooling the material, or a cooling gas is supplied from the control gas nozzle 5. It may be possible to squirt.

With this configuration, the temperature-controlled cooling gas 8 ejected from the cooling gas nozzle 5 can be supplied as cooling means. In this case, a cooling gas such as argon which is an inert gas is supplied to the cooling gas nozzle 5.

Therefore, by adjusting the flow rates of the high-temperature fuel gas 6 and the cooling gas ejected from the burner 4, the material 9
Can be arbitrarily adjusted. In the conventional levitation melting apparatus, the function of cooling and solidifying the material in a floating state has been difficult in principle, but in the present embodiment, it is possible to realize this simple method.

(2) In the first embodiment, the cost is reduced by using a superconducting solenoid coil, which has a large number of production results up to now as the superconducting coil 2 and has the most secure production method and stability. A highly reliable flotation melting device can be configured. The direction of the magnetic flux generated by the superconducting solenoid coil is a vertical direction.

FIG. 2 is a sectional view showing a second embodiment of the flotation melting apparatus according to the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. State.

In the second embodiment, as shown in FIG. 2, a plurality of superconducting solenoid coils 2a and 2b are combined to form a magnetic field having a high magnetic flux density. That is, in FIG. 2, the combination of the superconducting solenoid coils 2a and 2b includes a combination of two solenoid coils that generate magnetic flux in the vertical direction and a combination of two solenoid coils that generate magnetic flux in the horizontal direction. In any case, it can be used as the main holding means.

With such a configuration, a plurality of superconducting coils can increase the degree of freedom in assembling and configuring devices.

In the above embodiment, the funnel-shaped refractory 1 is arranged vertically and a high-speed gas is ejected from the lower part. However, this is arranged horizontally and a high-speed gas is ejected from the lateral direction. In this case, the auxiliary holding function for controlling the floating state as described above can be obtained even if the gas is ejected at a higher speed from the upper portion by arranging it in a reverse manner.

FIG. 3 is a block diagram showing the auxiliary holding means and the heating means in the third embodiment of the flotation / melting apparatus according to the present invention. Here, only different points will be described.

In the third embodiment, as shown in FIG. 3, a straight tubular refractory 1a is used in place of the funnel-shaped refractory. Although not shown, a superconducting coil as shown in FIG. 1 or 2 is arranged on the outer periphery of the straight tubular refractory 1a.

Even with such a configuration, an auxiliary holding function for controlling the floating state of the material 9 can be obtained.

FIG. 4 is a structural view showing an auxiliary holding means and a heating means in a fourth embodiment of the flotation / melting apparatus according to the present invention. Here, only different points will be described.

In the fourth embodiment, the burner 4 and the cooling gas nozzle 5 are arranged along the inclined surface of the funnel-shaped refractory 1 as shown in FIG. Although not shown, a superconducting coil as shown in FIG. 1 or 2 is arranged on the outer periphery of the straight tubular refractory 1a.

With such a configuration, there is no structure such as a burner or a cooling gas nozzle immediately below the material 9, so that
A device that can easily supply and take out the material 9 can be provided.

In the first to fourth embodiments, a part of the configuration may be modified as follows.

(A) In FIGS. 1 to 4, the nozzle 9 is arranged such that a swirl flow (swirl flow) is generated in the gas flow ejected from the burner 4 and the control gas nozzle 5, so that a uniform gas is applied to the material 9. Since the contact is made, the temperature distribution can be easily adjusted, and the material 9 can be rotated slowly by applying the rotational force, so that the stability can be improved.

(B) In FIGS. 1 to 4, if the burner 4 and the cooling gas nozzle 5 are not separately used, but a high-temperature gas whose temperature is adjusted in advance is ejected from the nozzle, the structure of the nozzle portion is simplified. be able to.

(C) If a high-temperature inert gas heated and temperature-adjusted beforehand by an electric heater or the like is ejected from a nozzle without using a fuel gas, a flotation melting apparatus for use in which oxides are not generated can also be constructed.

(D) If a laser beam, a microwave, an electron or an ion beam is used as a heating means, and an auxiliary holding function for ejecting a gas from a nozzle is used independently, local melting of the material 9 can be prevented. A levitation melting apparatus in which oxidation is prevented can be obtained.

(E) A levitation melting apparatus in which the cooling function of the cooling gas nozzle 5 is omitted depending on the application can be configured.

(F) An auxiliary holding function for controlling the floating state only by the burner 4 and the cooling gas nozzle 5, omitting a funnel-shaped or straight-tube refractory, and protecting equipment such as the cryostat 2 from high heat. As a configuration in which a cooling pipe is installed or a heat shield plate is installed between a high-temperature object and a device to be protected, a flotation melting apparatus that does not require maintenance of a refractory can be configured.

(G) A high-frequency coil, such as a conventional levitation melting apparatus, is installed in a space having a high magnetic flux density generated by a superconducting coil, and a levitation melting apparatus having an auxiliary holding function and a heating function by a high-frequency magnetic field is also configured. it can. This is effective when reusing existing conventional equipment. However, in this case, a strong coil supporting means capable of withstanding a strong electromagnetic force acting on the coil is required.

(H) As a heating means, the characteristic that the temperature control of the electric heater is relatively easy is utilized, and it is effective when a relatively low melting point metal material needs to be finely controlled. However, in this case, a strong heater supporting means capable of withstanding a strong electromagnetic force acting on the heater is required.

In the conventional levitation melting furnace using induction heating, the material is floated by the balance between the gravitational force of the material and the levitation force due to the eddy current. Since the auxiliary holding device generates a force that holds the spherical material in a floating state at a fixed point, the auxiliary holding device can be used even in a zero gravity state obtained by a space shuttle or the like.

(I) The material supply to the levitation and melting apparatus according to the present invention is performed by a material holding means made of an insulating heat-resistant material such as ceramics so as to oppose the main holding force and the braking force to the material by the superconducting coil. While moving the material to a predetermined position, the material is supplied. A metal material can be used for the material holding means, but when it moves, an eddy current is generated and receives a braking force. The shape of the material may be granular or powdery in addition to the spherical mass as shown in FIG. 1, and these become spherical due to intermolecular force and surface tension as soon as they are dissolved. Also, at the time of the first material supply, if the material is moved and supplied by weakening the magnetic field generated by the superconducting coil, the main holding force and the braking force are reduced, so the material is moved to a predetermined position with a small force. Can be supplied.

FIG. 5 is a perspective view showing only a superconducting saddle coil which is a main holding means in a levitation and melting apparatus according to a fifth embodiment of the present invention.

In the fifth embodiment, as shown in FIG. 5, superconducting saddle type coils 2d and 2c are arranged as superconducting coils on the outer peripheral portion of a tubular refractory 1a, and the configuration of other parts Are omitted because they are the same as in FIGS.

In the superconducting solenoid coil described in each of the embodiments described above, it is difficult to generate a magnetic flux in a long cylindrical space in a direction perpendicular to the axis of the cylinder, but the superconducting saddle coil as shown in FIG. By disposing the coils 1d and 1c, it is possible to generate a magnetic flux in a direction perpendicular to the axis of the cylinder.

With such a configuration, when a magnetic flux perpendicular to the axis of the cylinder is generated in the long cylindrical space, the magnetic flux penetrates perpendicularly to the falling direction of the material. There is an advantage that the braking force works effectively. It is also possible to provide an apparatus that supplies a material from the upper part of the cylinder, melts and solidifies while slowly falling in the lower direction, and removes the material from the lower part.

FIG. 6 is a perspective view showing only a superconducting race track coil which is a main holding means in a levitation and melting apparatus according to a sixth embodiment of the present invention.

In the sixth embodiment, as shown in FIG. 6, racetrack-shaped superconducting coils 1e and 1f are arranged in a V-shape with an open lower portion, and a strong magnetic field space extending in the horizontal direction of the gravitational field is provided. Is formed.

By using the main holding means for forming a long strong magnetic field space in the horizontal direction, the auxiliary holding means and the heating means described in the first embodiment can be horizontally mounted on one main holding means. Many can be arranged in the direction.

The coils 1e and 1f are connected to the open V
Since they are arranged in the shape of a letter, the magnetic flux density in the lower space is increased, the holding force is increased, and the holding control is easy.

FIG. 7 is a perspective view showing only a main holding means and a heating means in a levitation and melting apparatus according to a seventh embodiment of the present invention.

In the seventh embodiment, as shown in FIG. 7, the auxiliary holding means and the heating means are configured to be long in the horizontal direction.

With this configuration, it is possible to obtain a flotation melting apparatus capable of processing a large amount of materials.

In the above arrangement, the V-shaped race track superconducting coil, the horizontally long auxiliary holding means and the heating means are arranged so as to be inclined with respect to the horizontal axis of the gravitational field. Thus, it is possible to configure an apparatus that supplies a material from one end having a high position potential, slowly drops, that is, melts and solidifies in the horizontal direction, and takes out the material from the other end having a low position potential.

With such a configuration, a large amount of material can be processed efficiently continuously or intermittently.

The embodiment using the race track type superconducting coil can be implemented with various modifications in the same manner as described above.

Further, there is provided a device for measuring the position of the floating material using light, ultrasonic waves or the like. Based on the position information obtained by this device, the gas flow adjustment of the auxiliary holding means and the coil current of the main holding means are performed. By adding a function to adjust, it is possible to obtain a more stable floating state of the material,
A versatile flotation-melting device that is less affected by the material of the material and changes in temperature can be configured.

Further, with respect to insulators such as metal oxides, unnecessary oxides generated on the surface of the material are removed by utilizing the fact that the high magnetic flux density magnetic field generated by the superconducting coil does not act as a main holding function. If a nozzle that blows off the gas is provided, a flotation melting apparatus that can keep the material at a high purity can be configured.

Note that the present invention is not limited to the above embodiments, and the gist of the present invention is, for example, to measure the temperature of each part of the material and add a function of adjusting the heating means based on the measured temperature. Of course, various modifications can be made without departing from the scope of the present invention.

[0077]

As described above, according to the present invention, in a device for levitating and melting a metal or semiconductor material, the refractory constituents are mixed into the melted material to reduce the purity of the material and the fire resistance. In addition to being able to solve problems such as restrictions on the heat-resistant temperature of the material, the floating state of the dissolved material is extremely stable, the damping action for braking the material is excellent, and the specific gravity of the material and the electrical conductivity In addition to being able to adjust the effect, a general-purpose device that can be applied to many materials can be configured, and it is possible to cool and solidify the material in a levitated state. Can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a flotation melting apparatus according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the flotation melting apparatus according to the present invention.

FIG. 3 is a configuration diagram showing an auxiliary holding unit and a heating unit in a third embodiment of the flotation melting apparatus according to the present invention.

FIG. 4 is a configuration diagram showing an auxiliary holding means and a heating means in a fourth embodiment of the flotation melting apparatus according to the present invention.

FIG. 5 is a perspective view showing only a superconducting solenoid coil as a main holding device in a fifth embodiment of a flotation melting apparatus according to the present invention.

FIG. 6 is a perspective view showing only a superconducting race track coil which is a main holding device in a sixth embodiment of a flotation melting apparatus according to the present invention.

FIG. 7 is a perspective view showing only an auxiliary holding device and a heating means in a levitation melting apparatus according to a seventh embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Funnel-shaped refractory 1a ... Tubular refractory 2, 2a, 2b ... Superconducting solenoid coil 2c, 2d ... Superconducting saddle coil 2e, 2f ... Superconducting race track coil 3, 3a, 3b ... Cryostat 4 ... Burner 5 ... Control ( Cooling) nozzle 6 ... Fuel gas 7 ... Air 8 ... Control (cooling) gas 9 ... Material

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/208 H01L 21/208 Z H05B 6/32 H05B 6/32 F-term (Reference) 3K059 AA08 AB00 AB07 AB09 AB16 AB22 AB28 AC10 AC78 AD03 AD15 AD28 CD44 CD48 CD52 CD73 4K046 AA00 BA01 BA02 BA05 CA01 CC03 CC05 CD07 CE09 EA01 4K063 AA04 BA02 BA03 BA12 CA03 DA05 DA14 DA31 EA05 5F053 AA21 AA50 BB60 DD20 FF04 GG01 RR20

Claims (11)

[Claims] 1. A levitation and melting apparatus for floating and melting a metal or semiconductor material, comprising: a main holding means using a superconducting magnet; an auxiliary holding means for controlling a floating state of the metal or semiconductor material; A levitation and melting device for metal or semiconductor material, comprising: means for heating. 2. A levitation and melting apparatus for floating and melting a metal or semiconductor material, comprising: a main holding means using a superconducting magnet; an auxiliary holding means for controlling a floating state of the metal or semiconductor material; An apparatus for floating and melting a metal or semiconductor material, comprising: means for heating; and means for cooling the metal or semiconductor material. 3. The levitation and melting apparatus according to claim 1, wherein a solenoid coil is used for the superconducting magnet serving as the main holding means. 4. The levitation and melting apparatus according to claim 1, wherein a saddle-shaped coil is used for the superconducting magnet serving as the main holding means. 5. The levitation and melting apparatus according to claim 1, wherein a race track type coil is used for the superconducting magnet serving as the main holding means. 6. The flotation melting apparatus according to claim 4, wherein the main holding means and the auxiliary holding means are inclined with respect to the horizontal axis of the gravitational field. 7. The flotation melting apparatus according to claim 3, wherein the material is supplied from a portion having a high potential of the gravitational field, and the solidified material is taken out from a portion having a low potential. Melting equipment. 8. The levitation melting apparatus according to claim 2, wherein a gas burner is used as a means for heating the metal or semiconductor material, and a gas nozzle is used as a means for cooling the metal or semiconductor material. And a gas melting device wherein the gas burner and the gas nozzle are also used as auxiliary holding means for controlling a floating state. 9. The flotation melting apparatus according to claim 8,
A levitation melting apparatus characterized in that a gas ejected from a gas burner and a gas nozzle forms a vortex. 10. The flotation melting apparatus according to claim 1, further comprising a device for measuring a position of the floating material, wherein the auxiliary holding means is provided based on position information obtained by the device. A flotation melting apparatus characterized by adding a function of adjusting and adjusting a coil current of a main holding means. 11. The flotation and melting device according to claim 1, further comprising a device for removing an insulator on the surface of the material being floated.