JPH06116096A - Method for production metallic single crystal and device therefor - Google Patents

Abstract

PURPOSE:To easily obtain a uniform single crystal by melting a low-m.p. metal in the crucible in a vertical continuous casting device, lowering and cooling the crystal while measuring the temp. of the solid-liq. interface and the load. CONSTITUTION:A low-m.p. metal is placed in the carbon crucible 2 with a nozzle 10 fixed to its opening, heated by a heater 1 and melted to obtain a molten material 4. A thermal diffusion body 5 is arranged in the molten material 4, the temp. of the interface 9 between the crystal 3 and the molten material 4 is adjusted, the crystal 3 is laminated while measuring the load by a load cell 6 connected to the lift 7 and cooled in a water-sealed overflow-type cooling part 8.

Description

Detailed Description of the Invention

[0001]

The present invention relates to bismuth, zinc, lead,
The present invention relates to a method and an apparatus for producing a single crystal of a low melting point metal such as tin.

[0002]

2. Description of the Related Art Conventionally, Bridgman method, VGF (Vertical Gradient Freezing) method and the like have been known as a method for producing a metal single crystal. However, according to these methods, a temperature gradient is difficult to form. Since the heat flow cannot be controlled, the obtained crystal tends to be a polycrystalline body.

On the other hand, as a method for obtaining a metal single crystal and a unidirectionally solidified structure, a continuous casting method capable of controlling heat flow is known. However, according to this continuous casting method, since the nozzle portion is cooled by using the water cooling jacket, the solidification interface is located considerably above the die port,
There has been a problem that it is difficult to obtain a single crystal of metal and a unidirectionally solidified structure that expands during solidification because the extraction load becomes large.

In the above continuous casting method, the solidification interface can be controlled by directly cooling the ingot or the dummy bar by the shower method. However, according to this method, there is a problem of uneven contact with water, Since it is difficult to uniformly cool the lump or the dummy bar, it is difficult to obtain a uniform single crystal. Further, in the above continuous casting method, the solidification interface can be controlled by heating the mold, but this method has a problem that the apparatus becomes more complicated and larger.

[0005]

As described above, according to the conventional method for producing a metal single crystal, a uniform single crystal cannot be obtained particularly when producing a low melting point metal single crystal.

Therefore, the present invention solves the above-mentioned problems of the prior art and can easily obtain a uniform single crystal even with a low melting point metal such as bismuth, zinc, lead or tin. It is an object of the present invention to provide a manufacturing method and a manufacturing apparatus for.

[0007]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the inventors of the present invention have arranged a heat diffuser in the molten metal to form a contact surface between the tip surface of the crystal and the molten metal. The inventors have found that the above problems can be solved by adjusting the temperature of the solid-liquid interface and cooling the crystal body by a submersion type overflow type cooling unit, and arrived at the present invention.

That is, according to the present invention, there is provided a crucible having a heating means for holding the melt of the crystalline material in the periphery, an opening is provided at the bottom, and a nozzle is attached to the opening.
In the nozzle, there is provided a pulling-down means for taking out a columnar crystal body which causes the crystal to precipitate and grow on the front end surface in contact with the molten crystal material, and a cooling unit for cooling the taken-out crystal body. A method for producing a metal single crystal using a vertical continuous casting apparatus, wherein a low melting point metal which is a crystal material in a crucible in the apparatus, particularly one metal selected from the group consisting of bismuth, zinc, lead and tin. Melt and adjust the temperature of the solid-liquid interface, which is the contact surface between the tip of the crystal and the melt, by arranging a heat diffuser in this melt, and measuring the pull-down load with a load meter And a cooling method of a submersion type overflow type cooling the metal single crystal; and a process for holding a melt of the crystal material around the metal single crystal. A crucible having a means, an opening is provided at the bottom, and a nozzle is attached to this opening, and a columnar crystal body for growing crystals on the tip surface of the nozzle that comes into contact with the molten crystal material in the nozzle. A vertical type continuous casting apparatus having a pulling-down means for taking out to, and a cooling unit for cooling the taken out crystal body,
The crystalline material melt in the crucible and the nozzle has a heat spreader arranged by being inserted from the upper part of the crucible, a submersion type overflow type cooling unit is provided below the nozzle, and an elevating table for pulling down the crystal body. The present invention provides an apparatus for producing a metal single crystal, characterized in that a load meter for measuring the pull-down load of the crystal is connected.

[0009]

[Function] Generally, in the case of growing a metal single crystal using a template, in order to prevent nucleus growth from the interface between the template and the molten metal,
It is known that it is desirable to make the solidification interface convex. Therefore, in the present invention, the solidification interface has a convex shape.

In particular, a low-melting-point metal such as bismuth that expands during solidification may cause a large load unless the solidification point is brought near the draw-out port of the nozzle and damage the crucible, and is extremely prone to breakout. It will have to be cast in the state.

Therefore, according to the method of the present invention, the tip surface of the seed or the crystal (crystal) already deposited thereon,
A heat diffuser is placed close to the solid-liquid interface, which is the contact surface with the molten crystal material, and the temperature of the interface is adjusted to control the position of the solidification interface and prevent crucible damage and breakout. is doing.

Further, in the method of the present invention, the crystal body pulled down from the nozzle is cooled by a submersion type overflow type cooling unit capable of cooling uniformly from a fixed direction. As described above, by uniformly cooling the pulled-down crystal in a certain direction, a uniform single crystal can be obtained.

The submerged overflow type cooling unit in the present invention is made of brass and has a cylindrical shape having a cavity through which the dummy bar and the ingot can pass. The submerged overflow type cooling unit will be described in more detail with reference to FIG.

First, the cooling water enters from the water inlets provided in two directions (arrow 11 in the figure), and the dummy bar 3 and the cooling unit 8 are supplied.
When the space between the dummy bar 3 and the cooling unit 8 becomes full, the cooling water flows along the edge of the cooling unit 8 and comes out (arrow 12 in the figure). In this way, the cooling water between the dummy bar 3 and the cooling unit 8 is always replaced, and in fact the dummy bar is completely submerged in this cooling water, so that the dummy bar is cooled uniformly from a certain direction. . By mounting the tank for supplying the cooling water above the cooling unit and keeping the liquid level in the tank constant, the cooling water can be constantly supplied to the cooling unit by the water pressure.

Further, in the present invention, by connecting an elevating table for pulling down the crystal and a load meter and measuring the pulling down load of the crystal, the crucible is prevented from being broken or breakout is prevented.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited by the following examples.

[0017]

Example 1 As an example of the present invention, a method for producing a bismuth single crystal using the apparatus for producing a metal single crystal shown in FIG. 1 will be described.

The apparatus for producing a metal single crystal used in this embodiment is provided with an opening at the bottom and a carbon crucible 2 having a nozzle 10 attached to the opening, and is provided around the crucible 2. The heater 1, which is a heating facility for holding the molten metal 4 inside the crucible 2, and the crucible 2 and the nozzle 10 are arranged in the molten metal, and the tip surface of the dummy bar 3 inside the nozzle 10 and the contact surface of the molten crystalline material 4 The protective tube 5 made of alumina (10φ x 500 L unit mm) that serves as a heat diffuser for adjusting the temperature of the dummy bar 3, the lifting table 7 for pulling down the dummy bar 3, and the lifting table 7 are connected to the dummy bar 3 by the lifting table 7. Which comprises a load cell 6 for measuring the pulling down load of the nozzle and a submersible overflow type cooling unit 8 installed below the nozzle 10 for cooling the dummy bar 3. A.

First, about 2 kg of bismuth, which is a crystalline material, was placed in the carbon crucible 2, the crucible 2 was heated by the heater 1, and the bismuth in the crucible 2 was heated and melted. Next, as shown in FIG. 1, a protective tube 5 was placed in the molten bismuth 4, and when the temperature of the molten metal 4 stabilized at 300 to 330 ° C., the lifting table 7 was pulled down at a speed of 3 to 8 mm / h. The solidification interface 9 at this time has a convex shape. Further, in lowering the dummy bar 3 by the lifting table 7, the load cell 6 connected to the lifting table 7 was used to measure the lifting load to prevent damage to the crucible 2 and breakout. Under the above conditions, pull down about 120mm,
A bismuth single crystal with a length of 50 mm was obtained.

After the bismuth is heated and melted, but before the pulling-down is started, as shown in FIG.
Was measured and the temperature of the molten metal was measured when the protective tube 5 was not arranged, and the results are shown in Table 1.
The molten metal temperature in Table 1 is at a position 25 mm away from the opening at the bottom of the crucible in the vertical direction, and the value in parentheses is the difference from the central temperature.

[0021]

[Table 1]

As can be seen from Table 1, by arranging the protective tube in the molten metal, it became possible to keep the temperature in the center of the furnace lower than the temperature in the vicinity of the inner wall of the crucible.

[0023]

Example 2 Using the apparatus for producing a metal single crystal used in Example 1, about 2 kg of zinc, lead and tin were separately put into a crucible, and the molten metal temperature was zinc 440 to 470 ° C. and lead 350 to 380.
℃, tin 250 ~ 280 ℃ controlled to be constant, 3 ~ 8mm /
When the elevating table was pulled down at a speed of h to grow a crystal, a uniform single crystal of each of the above metals could be obtained as in Example 1.

[0024]

COMPARATIVE EXAMPLE 1 As a cooling unit for cooling the dummy bar, the same apparatus as in Example 1 was used except that a conventional shower type was used instead of the submersion type overflow type. When a single crystal was manufactured in the same manner, it was not possible to stably obtain an ingot due to breakout or the like.

Further, when a single crystal was manufactured in the same manner as described above except that the pulling down was performed while preventing breakout, only an ingot of about 5 crystals could be obtained.

[0026]

[Comparative Example 2] A bismuth single crystal growth test was conducted using a three-zone VGF apparatus. First, about 2 kg of bismuth was put into a carbon crucible and melted, and the temperature gradient in the melt was adjusted to 0.5-1 ° C / cm in the vertical direction, and crystals were grown at a pulling rate of 5 mm / h. It was possible to obtain only the polycrystalline body of.

In order to make the temperature gradient a little larger than the above, an insulating material was put between the heaters, but no particular change was observed.

[0028]

As a result of the development of the present invention, it has become possible to easily manufacture a uniform single crystal of a low melting point metal, which has hitherto been difficult to be made into a single crystal.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for producing a metal single crystal according to the present invention.

FIG. 2 is an enlarged perspective view of the vicinity of a cooling unit in the apparatus for producing a metal single crystal of the present invention.

[Explanation of symbols]

 1 Heater 2 Carbon crucible 3 Dummy bar 4 Molten metal 5 Protective tube 6 Load cell 7 Elevator 8 Cooling unit 9 Solidification Part 10 ... Nozzle 11 ... Water entry 12 ... Water exit

Claims (3)

[Claims] 1. A crucible having a heating means for holding a melt of a crystalline material in the periphery thereof, an opening being provided at the bottom, and a nozzle being attached to the opening, and a crucible contacting the melt of the crystalline material in the nozzle. A metal using a vertical continuous casting device having a pulling-down means for taking out a columnar crystal body that causes the crystal to grow by precipitation on the tip surface, and a cooling unit for cooling the taken-out crystal body. A method for producing a single crystal, in which a low melting point metal which is a crystal material is melted in a crucible in the apparatus, and a heat diffuser is arranged in the melt so that a contact surface between the tip surface of the crystal and the melt is formed. Adjusting the temperature of a certain solid-liquid interface, and pulling down the crystal while measuring the pulling load with a load cell,
A method for producing a metal single crystal, which comprises cooling this with a submersion type overflow type cooling unit. 2. The method for producing a metal single crystal according to claim 1, wherein the low melting point metal which is the crystal material is one selected from the group consisting of bismuth, zinc, lead and tin. 3. A crucible having a heating means for holding the melt of the crystal material in the periphery, an opening being provided at the bottom, and a nozzle being attached to the opening, and a crucible contacting with the melt of the crystal material in the nozzle. A vertical continuous casting apparatus comprising a pulling-down means for taking out a columnar crystal body which causes the crystals to grow by precipitation on the tip surface, and a cooling unit for cooling the taken-out crystal body, The crystalline material melt in the crucible and the nozzle has a heat spreader arranged by being inserted from the upper part of the crucible, a submersion type overflow type cooling unit is provided below the nozzle, and an elevating table for pulling down the crystal body. An apparatus for producing a metal single crystal, comprising a load meter connected to measure a pull-down load of the crystal body.