JP3318012B2 - Method and apparatus for producing metal single crystal - Google Patents

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, as a method for producing a metal single crystal, the Bridgman method, VGF (vertical gradient freezing) method, and the like have been known. However, according to these methods, it is difficult to form a temperature gradient. Since the flow of heat cannot be controlled, there has been a problem that the obtained crystals are likely to be polycrystalline.

On the other hand, as a method for obtaining a metal single crystal and a directionally solidified structure, a continuous casting method capable of controlling a heat flow is known. However, according to this continuous casting method, since the nozzle portion is cooled using a water cooling jacket, the solidification interface is located considerably above the die opening,
The draw load becomes large, and there is a problem that it is difficult to obtain a metal single crystal and a unidirectional solidified structure that expands during solidification.

In the continuous casting method described above, the solidification interface can be controlled by directly cooling the ingot or the dummy bar by a shower method. Since it is difficult to cool the mass or the dummy bar uniformly, there is a problem that it is difficult to obtain a uniform single crystal. In the continuous casting method, the solidification interface can be controlled by heating the mold. However, according to this method, there is 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 a single crystal of a low melting point metal is produced.

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, and tin. It is an object of the present invention to provide a manufacturing method and a manufacturing apparatus.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, a heat diffusion body is arranged in a molten metal to form a contact surface between a tip surface of a crystal and the molten metal. The present inventors have found that the above-mentioned problems can be solved by adjusting the temperature of the solid-liquid interface and cooling the crystal by a submerged overflow type cooling section, and have reached the present invention.

That is, according to the present invention, there is provided a crucible having a heating means for holding a melt of a crystal material around the opening, a bottom provided with an opening, and a nozzle attached to the opening.
In the nozzle, there is provided a pulling-down means for taking out a columnar crystal which causes a crystal to precipitate and grow on the tip end surface in contact with the crystal material melt, and a cooling unit for cooling the taken-out crystal. A method for producing a metal single crystal using a vertical continuous casting apparatus, wherein one kind of metal selected from the group consisting of a low melting point metal, particularly bismuth, zinc, lead and tin, which is a crystal material in a crucible in the apparatus. Is melted, the temperature of the solid-liquid interface, which is the contact surface between the tip surface of the crystal and the melt, is adjusted by disposing a heat spreader in the melt, and the crystal is measured while measuring the pull-down load with a load meter. And cooling it by a submerged overflow type cooling section; and a method for holding a melt of a crystal material around the metal single crystal. Means, a crucible provided with an opening at the bottom, and a nozzle attached to the opening, and a columnar crystal which grows and grows crystals on the tip surface in contact with the crystal material melt in the nozzle. A vertical continuous casting apparatus having a pulling-down means for taking out and a cooling unit for cooling the taken-out crystal,
In the crystal material melt in the crucible and the nozzle, there is a heat diffuser arranged by being inserted from above the crucible, and a submerged overflow type cooling unit is provided below the nozzle, and the elevating table for pulling down the crystal is provided. And a load cell for measuring a pull-down load of the crystal body is provided.

[0009]

In general, when growing a metal single crystal using a mold, in order to prevent nucleus growth from the interface between the mold 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 is made convex.

[0010] Particularly, a low melting point metal such as bismuth which expands at the time of solidification, if the solidification point is not brought near the outlet of the nozzle, the load may be increased and the crucible may be damaged, and extremely breakout may easily occur. It must be cast in a state.

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

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

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

First, the cooling water enters through two water inlets (arrows 11 in the figure), and the dummy bar 3 and the cooling unit 8 are provided.
When the space between the dummy bar 3 and the cooling unit 8 is full, the cooling water flows along the edge of the cooling unit 8 and flows out (arrow 12 in the figure). As described above, the cooling water between the dummy bar 3 and the cooling unit 8 is constantly replaced, and the dummy bar is completely submerged in the cooling water, so that the dummy bar is uniformly cooled 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 supplied to the cooling unit at a constant pressure.

Further, in the present invention, the lifting table for pulling down the crystal and the load cell are connected to measure the pulling load of the crystal to prevent breakage and breakout of the crucible.

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]

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

The apparatus for manufacturing a metal single crystal used in the present embodiment has an opening at the bottom, a carbon crucible 2 having a nozzle 10 attached to the opening, and a crucible 2 provided around the crucible 2. A heater 1, a crucible 2, which is a heating facility for holding the molten metal 4 in the nozzle 2, and a contact surface between the tip surface of the dummy bar 3 in the nozzle 10 and the molten metal 4 in the nozzle 10 A protective tube 5 made of alumina (10φ × 500 L unit mm) serving as a heat spreader for adjusting the temperature of the dummy bar 3, an elevator 7 for pulling down the dummy bar 3, and a dummy bar 3 connected to the elevator 7 A load cell 6 for measuring the pulling down force of the water, and a submerged 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 crystal material, was placed in a carbon crucible 2, the crucible 2 was heated by a heater 1, and the bismuth in the crucible 2 was heated and melted. Then, as shown in FIG. 1, the protective tube 5 was placed in the bismuth molten metal 4, and when the temperature of the molten metal 4 was stabilized at 300 to 330 ° C., the elevator 7 was lowered at a speed of 3 to 8 mm / h. At this time, the shape of the solidification interface 9 is convex. Further, when the dummy bar 3 was lowered by the lift 7, damage to the crucible 2 and breakout were prevented by measuring the pull-down load by the load meter 6 connected to the lift 7. Reduce it by about 120mm under the above conditions,
A single crystal of bismuth having a length of 50 mm was obtained.

After the bismuth is heated and melted, and before the lowering is started, as shown in FIG.
And the temperature of the molten metal when the protective tube 5 was not arranged was measured, and the results are shown in Table 1.
The temperature of the molten metal in Table 1 is obtained at a position 25 mm vertically away from the opening at the bottom of the crucible.

[0021]

[Table 1]

As can be seen from Table 1, by arranging the protective tube in the molten metal, the temperature in the center of the furnace can be kept lower than the temperature near the inner wall of the crucible.

[0023]

Example 2 Using the apparatus for manufacturing a metal single crystal used in Example 1, zinc, lead, and tin were each separately placed in a crucible in an amount of about 2 kg, and the melt temperature was set to 440 to 470 ° C. for zinc and 350 to 380 for lead.
℃, tin 250-280 ℃ controlled to be constant, 3-8mm /
When the crystal was grown by lowering the elevating table at the speed h, a uniform single crystal of each of the above metals could be obtained in the same manner as in Example 1.

[0024]

Comparative Example 1 The same apparatus as in Example 1 was used except that a cooling unit for cooling the dummy bar was replaced with a conventional shower type instead of a submerged overflow type. When a single crystal was produced in the same manner, an ingot could not be obtained stably due to breakout or the like.

When a single crystal was produced in the same manner as described above except that the lowering 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 performed using a three-zone VGF apparatus. First, about 2 kg of bismuth was put into a carbon crucible and melted. The temperature gradient in the melt was set to 0.5 to 1 ° C./cm in the vertical direction, and crystals were grown at a pulling rate of 5 mm / h. Could only be obtained.

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

[0028]

According to the development of the present invention, it has become possible to easily produce a uniform single crystal of a low-melting-point metal, which has conventionally been difficult to crystallize.

[Brief description of the drawings]

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

FIG. 2 is an enlarged perspective view of the vicinity of a cooling unit in the apparatus for manufacturing 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 Lifting table 8 Cooling unit 9 Solidification Part 10 ‥‥‥ Nozzle 11 ‥‥‥ Inlet 12 ‥‥‥ Outlet

Continuation of front page (56) References JP-A-61-296940 (JP, A) JP-A-62-248541 (JP, A) JP-A-62-292242 (JP, A) JP-A-3-180256 (JP) JP-A-4-107227 (JP, A) JP-A-4-280891 (JP, A) JP-A-5-123830 (JP, A) JP-A-5-31424 (JP, A) Field surveyed (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 B22D 11/00-11/22 C22C 1/02

Claims (3)

(57) [Claims] 1. A crucible having a heating means for holding a melt of a crystal material around the periphery thereof, an opening provided in a bottom portion, and a nozzle attached to the opening, wherein the crucible is in contact with the melt of the crystal material in the nozzle. Metal using a vertical continuous casting apparatus having a pulling-down means for taking out columnar crystals for growing crystals on the front end face, and a cooling unit for cooling the taken-out crystals. A method for producing a single crystal, comprising dissolving a low-melting-point metal as a crystal material in a crucible in the above-described apparatus, and disposing a heat diffuser in the molten metal so that a contact surface between the tip surface of the crystal and the molten metal is formed Adjust the temperature of a certain solid-liquid interface, and lower the crystal while measuring the lowering load with a load meter,
This is cooled by a submerged overflow type cooling section, wherein the metal single crystal is produced. 2. The method for producing a metal single crystal according to claim 1, wherein the low melting point metal as 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 a melt of a crystal material around the bottom, an opening provided in a bottom portion, and a nozzle attached to the opening, wherein the crucible contacts the melt of the crystal material in the nozzle. A vertical continuous casting apparatus having a pulling-down means for taking out a columnar crystal body that causes a crystal to precipitate and grow on the tip face to be drawn, and a cooling unit for cooling the taken out crystal body, In the crystal material melt in the crucible and the nozzle, there is a heat diffuser arranged by being inserted from above the crucible, and a submerged overflow type cooling unit is provided below the nozzle, and the elevating table for pulling down the crystal is provided. And a load cell for measuring a pulling-down load of the crystal body.