JP2022039255A - Manufacturing method of thin metallic wire made of aluminum or aluminum alloy - Google Patents

Abstract

To provide a manufacturing method of thin metallic wire made of aluminum or an aluminum alloy, of which at least a part has a single crystal structure.SOLUTION: The present invention relates to a manufacturing method of thin metallic wire made of aluminum or an aluminum alloy, of which at least a part has a single crystal structure. The manufacturing method includes a step (S1) for installing a mask having an open hole for forming thin metallic wire, on the surface of molten metal of aluminum or an aluminum alloy held in a molten metal holding furnace, a step (S2) for increasing pressure in the molten metal and linearly pressing out the molten metal through the open hole of the mask into a space above the mask in the molten metal holding furnace, and a step (S3) for annealing the molten metal linearly pressed out in the space in the molten metal holding furnace.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a thin metal wire made of aluminum or an aluminum alloy having at least a part having a single crystal structure.

In applications such as automobiles, thin metal wires are used as materials for motors, wire harnesses, and the like. As a thin metal wire, a lightweight aluminum (alloy) thin wire is being studied. In the present specification, aluminum (alloy) is a general term for aluminum and aluminum alloys.
Patent Document 1 discloses a thin aluminum alloy wire suitable for use in a wire harness or the like (claim 1, paragraph 0014, etc.).

Japanese Unexamined Patent Publication No. 2016-041854

Conventionally, a method for producing a single crystal is known for semiconductors such as silicon and silicon-containing compounds, but a method for producing a single crystal structure is not known for aluminum (alloy).
In Test Examples 1 and 2 of Patent Document 1, a molten aluminum alloy is prepared and continuously cast and rolled to obtain a wire rod (continuously cast and rolled material), and the wire rod is homogenized and cold-drawn. Was carried out to obtain a wire drawing material, and the wire drawing material was subjected to a solution treatment to obtain a solid molten wire material, and the solid molten wire material was subjected to an aging treatment to produce an aluminum alloy fine wire.
The aluminum (alloy) thin wire obtained by the conventional manufacturing method as described above has a polycrystalline structure. For example, a non-uniform polycrystalline structure containing coarse crystal grains of more than 100 μm or about 300 μm (Patent Document 1 paragraph 0012), or a polycrystalline structure having a maximum crystal grain size of 50 μm or less (Patent Document 1). It has claim 1).
With the electrification, higher performance, and higher functionality of automobiles and the like, it is preferable to establish a method for manufacturing an aluminum (alloy) thin wire having a single crystal structure that is more efficient than a polycrystalline structure.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a thin metal wire made of aluminum or an aluminum alloy having at least a part having a single crystal structure.

The method for manufacturing a thin metal wire of the present invention is:
A method for producing a thin metal wire made of aluminum or an aluminum alloy having at least a part of it having a single crystal structure.
A step (S1) of providing a mask having a through hole for forming a fine metal wire on the surface of a molten metal made of aluminum or an aluminum alloy held in a molten metal holding furnace.
A step (S2) of increasing the pressure in the molten metal and linearly extruding the molten metal from the through hole into the space above the mask in the molten metal holding furnace.
It has a step (S3) of slowly cooling the molten metal extruded linearly in the space portion.

According to the present invention, by slowly cooling the molten metal linearly extruded into the space above the mask in the molten metal holding furnace as it is in the molten metal holding furnace, at least a part of aluminum having a single crystal structure or It is possible to manufacture a thin metal wire made of an aluminum alloy.
According to the present invention, it is possible to produce a thin metal wire made of aluminum or an aluminum alloy having at least a part having a single crystal structure at low cost by a simple method using an existing molten metal holding furnace, which is preferable.

The mask preferably has the through holes formed in the oxide-containing layer formed on the surface of the molten metal.
By forming a mask on the surface of a molten metal made of aluminum or an aluminum alloy by using an oxide-containing layer naturally or by degassing treatment, the mask can be easily prepared at low cost, which is preferable.

In the step (S1), the degassing treatment for supplying bubbles of the inert gas into the molten metal is performed, and the oxide-containing layer having the through holes formed by the passage of the bubbles is formed on the surface of the molten metal. It is preferable to form it.
In this method, the step (S1) can be easily carried out at low cost by using a known degassing device and an inert gas, and the cleaning of the molten metal by the degassing treatment and the step (S1) are carried out at the same time. Can be preferred.

In the step (S2), it is preferable to supply bubbles of the inert gas into the molten metal and increase the pressure in the molten metal by supplying the bubbles.
In this method, the step (S2) can be easily carried out at low cost, which is preferable.
The bubbles of the inert gas can be supplied by the same method as the known degassing treatment. In this method, the step (S2) can be easily carried out at low cost by using a known degassing device and an inert gas, and the cleaning of the molten metal by the degassing treatment and the step (S2) are carried out at the same time. Can be and is preferred.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing a thin metal wire made of aluminum or an aluminum alloy having at least a part having a single crystal structure.

It is a flowchart of the manufacturing method of the metal thin wire made of aluminum or an aluminum alloy of this invention. It is a schematic cross-sectional view which shows the process (S1). It is a schematic cross-sectional view which shows the process (S2). It is a schematic sectional drawing which shows the process (S1) which used the degassing apparatus. It is a schematic sectional drawing which shows the process (S1) which used the degassing apparatus. It is a schematic sectional drawing which shows the process (S1) which used the degassing apparatus. It is a schematic sectional drawing which shows the process (S2) which used the degassing apparatus. It is a schematic sectional drawing which shows the process (S2) which used the degassing apparatus. It is a schematic sectional drawing which shows the process (S3) which used the degassing apparatus. It is a photograph of an example of a structure composed of a mask made of an oxide-containing layer having through holes and a plurality of aluminum alloy fine wires formed on the mask obtained in Example 1. It is a photograph of the aluminum alloy thin wire of the sample 1 to 3 obtained in Example 1. 3 is an SEM cross-sectional photograph of thin aluminum alloy wires of Samples 1 to 3. It is an IPF map of each cross section shown in FIG. 12A. It is an example of the SEM cross-sectional photograph of the upper end portion of the mask and the root portion of the aluminum alloy thin wire formed on the mask in the structure of FIG. 10. It is an IPF map of the cross section shown in FIG. 13A.

The method for manufacturing a thin metal wire of the present invention is:
A method for producing a thin metal wire made of aluminum or an aluminum alloy having at least a part of it having a single crystal structure.
A step (S1) of providing a mask having a through hole for forming a fine metal wire on the surface of a molten metal made of aluminum or an aluminum alloy held in a molten metal holding furnace.
A step (S2) of increasing the pressure in the molten metal and linearly extruding the molten metal from the through hole into the space above the mask in the molten metal holding furnace.
It has a step (S3) of slowly cooling the molten metal extruded linearly in the space portion.
FIG. 1 shows a flowchart.

2 and 3 are schematic cross-sectional views showing a method for manufacturing a thin metal wire made of aluminum or an aluminum alloy of the present invention.
As shown in FIG. 2, in the step (S1), through holes for forming fine metal wires are formed on the surface of the molten metal 21 made of aluminum or an aluminum alloy which may contain impurities, which is held in the molten metal holding furnace 11. A mask 30 having 32 is provided. In the figure, reference numeral 12 is a space above the mask 30 in the molten metal holding furnace.
As shown in FIG. 3, in the step (S2), the pressure in the molten metal 21 held in the molten metal holding furnace 11 is increased, and the through hole 32 of the mask 30 is above the mask 30 in the molten metal holding furnace 11. The molten metal 21 is linearly extruded into the space portion 12. In this step, the position of the mask 30 is lower than that at the time of step (S1). In the figure, reference numeral 22 is a molten metal extruded linearly.
In the step (S3), the state shown in FIG. 3 is maintained, and the molten metal 22 extruded linearly is slowly cooled in the space portion 12 above the mask 30 in the molten metal holding furnace 11.

According to the present invention, the molten metal linearly extruded into the space 12 above the mask 30 in the molten metal holding furnace 11 is slowly cooled in the molten metal holding furnace 11 as it is, so that at least a part thereof is a single crystal. It is possible to manufacture a thin metal wire made of aluminum or an aluminum alloy having a structure.
According to the present invention, it is possible to produce a thin metal wire made of aluminum or an aluminum alloy having at least a part having a single crystal structure at low cost by a simple method using an existing molten metal holding furnace, which is preferable.

In the present invention, aluminum (also referred to as pure aluminum) or an aluminum alloy which may contain impurities is used as the material of the thin metal wire. Aluminum alloys tend to be more excellent in impact resistance, bending characteristics, heat resistance, etc. than pure aluminum, and are preferable. The composition of the aluminum alloy is not particularly limited, and for example, Si is contained in an amount of 8.5 to 10.0% by mass, Mg is contained in an amount of 0.15 to 0.30% by mass, and Cu, Fe, Zn, Mn, and Ti are contained. , Ni, Sn, and Cr may optionally contain at least one metal element selected from the group consisting of Al and unavoidable impurities.
The temperature of the molten metal 21 made of aluminum or an aluminum alloy is not particularly limited, and is preferably about 650 to 760 ° C, more preferably about 650 to 680 ° C.

(Step (S1))
The mask 30 used in the step (S1) is not particularly limited as long as it has a through hole for forming a fine metal wire. For example, a plate-shaped member made of a material having heat resistance to the temperature of the molten metal 21 having through holes formed by a known method can be mentioned.
As the mask 30, it is preferable that the through hole 32 is formed in the oxide-containing layer formed on the surface of the molten metal 21.
By forming the mask 30 on the surface of the molten metal 21 made of aluminum or an aluminum alloy by using an oxide-containing layer naturally or by degassing treatment, the mask 30 can be easily prepared at low cost. ,preferable.

For example, as shown in FIGS. 4 to 6, the molten metal 21 is degassed to supply bubbles 52 of the inert gas into the molten metal 21, and the surface of the molten metal 21 has a through hole 32 formed by the passage of the bubbles 52. The oxide-containing layer 31 can be formed. The inert gas is not particularly limited, and examples thereof include argon gas and nitrogen gas.
In this method, the step (S1) can be easily carried out at low cost by using a known degassing device and an inert gas, and the cleaning of the molten metal by the degassing treatment and the step (S1) are carried out at the same time. Can be preferred.

As the degassing device, a rotary degassing device is preferable. The rotary degassing device ejects fine bubbles 52 of the inert gas from the tip of the rotor that rotates at high speed and disperses them in the molten metal 21 to release hydrogen gas, oxides, and the like contained in the molten metal 21. It is a device that removes impurities. The bubbles 52 of the inert gas are supplied from the rotor of the rotary degassing device to the lower part of the molten metal 21, rise toward the surface of the molten metal 21, and escape to the space portion 12.

Since the cells 52 of the inert gas have a low hydrogen partial pressure, the hydrogen gas in the molten metal 21 moves into the bubbles 52 and floats together with the bubbles 52, so that the hydrogen gas in the molten metal 21 is removed. This removal of hydrogen gas is called "degassing".
Impurities such as oxides float together with the bubbles 52 of the inert gas to form the oxide-containing layer 31. The oxide-containing layer 31 is a layer containing an oxide and other impurities. As the bubbles 52 pass through the oxide-containing layer 31, a through hole 32 is formed in the oxide-containing layer 31.

The degassing treatment time is not particularly limited as long as it is the time for forming the oxide-containing layer 31 having a sufficient thickness as the mask 30. The degassing treatment time is preferably, for example, about 54 hours.

4 to 6 show an oxide-containing layer 31 formed by a degassing treatment using a rotary degassing device, and bubbles pass through the oxide-containing layer 31 to form the oxide-containing layer 31. It is a schematic cross-sectional view which shows the appearance that the through hole 32 is formed in. In the figure, reference numeral 51 is a rotor 51 of the rotary degassing device. FIG. 6 is a partially enlarged view.

(Step (S2))
In the step (S2), as a method of increasing the pressure in the molten metal 21, a method of pressing down the mask 30 from above to pressurize the molten metal 21 and a method of supplying bubbles into the molten metal 21 to increase the pressure in the molten metal 21. The method and the like can be mentioned. The pressure applied to the molten metal 21 is not particularly limited as long as the molten metal 21 can be linearly pushed out into the space 12 from the through hole 32 of the mask 30. The pressure applied to the molten metal 21 is preferably, for example, about 700 to 1000 Pa.

It is preferable to supply bubbles 52 of the inert gas into the molten metal 21 and increase the pressure in the molten metal 21 by supplying the bubbles 52. In this method, the step (S2) can be easily carried out at low cost, which is preferable.
The bubbles of the inert gas can be supplied by the same method as in the known degassing treatment, as in the step (S1). In this method, the step (S2) can be easily carried out at low cost by using a known degassing device and an inert gas, and the cleaning of the molten metal 21 by the degassing treatment and the step (S2) can be performed at the same time. It can be carried out and is preferable.

In FIGS. 7 and 8, an inert gas bubble 52 is supplied into the molten metal 21 by using a rotary degassing device, and the pressure in the molten metal 21 is increased by supplying the bubbles 52 to increase the pressure in the molten metal 21 to increase the pressure in the molten metal 21. It is a schematic cross-sectional view which shows the state of pushing out the molten metal 21 linearly into a space part 12. These figures are partially enlarged views corresponding to FIG. 6, and the same components as those in FIG. 6 are designated by the same reference numerals.

Note that FIG. 8 shows that the air bubbles 52 that have entered the through hole 32 push out the molten metal 21 in the through hole 32 in a linear manner, but the molten metal 21 pushed by the air bubbles 52 is the through hole. The molten metal 21 in 32 may be extruded linearly. That is, the bubble 52 can directly or indirectly push out the molten metal 21 in the through hole 32 in a linear manner. It is considered that the molten metal 21 in the through hole 32 is linearly pushed upward by the pressure increase in the molten metal 21 and the ascending force of the bubbles 52 due to the supply of the bubbles 52.

(Step (S3))
In the step (S3), the state shown in FIG. 8 is maintained, and the molten metal 22 extruded linearly is slowly cooled in the space portion 12 above the mask 30 in the molten metal holding furnace 11. In this way, as shown in FIG. 9, a thin metal wire 23 made of aluminum or an aluminum alloy having at least a part having a single crystal structure is obtained. FIG. 9 is a partially enlarged view corresponding to FIGS. 6 to 8.

The temperature of the space 12 in the molten metal holding furnace 11 is, for example, about 300 to 600 ° C, preferably about 400 to 500 ° C.
By slowly cooling the space 12 in the molten metal holding furnace 11 within the above temperature range, aluminum or an aluminum alloy can be single-crystallized, and at least a part thereof is made of aluminum or an aluminum alloy having a single crystal structure. The thin metal wire 23 can be manufactured.
The time for holding the molten metal 22 linearly extruded in the space 12 and slowly cooling it (also referred to as the slow cooling time) is the time until the molten metal 22 extruded linearly is sufficiently solidified. It is selected according to the temperature in the space portion 12. The slow cooling time is preferably about 12 to 18 hours, for example.
When the oxide-containing layer 31 is formed by the degassing treatment in the step (S1), the slow cooling time referred to here is the time required to form the oxide-containing layer 31 having a sufficient thickness by the degassing treatment. This is the time after (for example, 54 hours) has elapsed. For example, it takes about 66 to 72 hours from the start of the degassing device to the end of the step (S3).

As described above, according to the present invention, it is possible to provide a method for producing a thin metal wire made of aluminum or an aluminum alloy having at least a part having a single crystal structure.
According to the production method of the present invention, it is possible to produce a fine metal wire having a single crystal structure at least partially and having a wire diameter of, for example, about 20 μm to 3 mm.

Examples of the present invention will be described.
[Example 1]
Aluminum alloy molten metal (Si: 8.5 to 10.0% by mass, Mg: 0.15 to 0.30% by mass, Cu: less than 0.2% by mass, Fe) held in the molten metal holding furnace at about 650 ° C. : Less than 0.3% by mass, Zn: Less than 0.1% by mass, Mn: Less than 0.5% by mass, Ti: Less than 0.2% by mass, Ni: Less than 0.1% by mass, Sn: 0.1% by mass %, Cr: less than 0.1% by mass, balance: Al), bubbles of nitrogen gas were supplied using a known rotary degassing device. By this degassing treatment, hydrogen gas in the molten metal was removed, impurities such as oxides floated together with bubbles, and an oxide-containing layer was formed on the surface of the molten metal. By passing the bubbles through the oxide-containing layer, through holes were formed in the oxide-containing layer and a mask was formed (step (S1)). It took 54 hours from the start of the degassing device until the oxide-containing layer having a sufficient thickness was formed.

Further, when the supply of the bubbles using the rotary degassing device was continued, the molten metal was linearly extruded from the through hole of the mask into the space above the mask in the molten metal holding furnace (step (S2). )). The pressure applied to the molten metal by the supply of bubbles was about 700 to 1000 Pa. It is considered that the molten metal in the through hole was pushed out linearly upward due to the pressure increase in the molten metal due to the supply of bubbles and the rising force of the bubbles.
The molten metal extruded linearly was slowly cooled in the space (about 450 ° C.) for about 12 to 18 hours (step (S3)). The slow cooling time referred to here is the time after the time required for forming the oxide-containing layer having a sufficient thickness by degassing has elapsed. It took 66 to 72 hours from the start of the degassing device to the end of the step (S3).

FIG. 10 shows a photograph of an example of a structure composed of a mask (30) made of an oxide-containing layer having through holes and a plurality of aluminum alloy thin wires (23) formed on the mask (30) obtained by the above method. show.

A total of three thin aluminum alloy wires were cut from the tip side of the structure shown in FIG. 10 (Samples 1 to 3). These photographs are shown in FIG. Each thin aluminum alloy wire (Samples 1 to 3) shown in FIG. 11 was cut at an arbitrary point and cross-sectionally observed. In FIG. 11, the cutting position is indicated by a white dashed line, and the observation direction is indicated by a white arrow.
FIG. 12A shows a cross-sectional photograph of each sample with a scanning electron microscope (SEM). FIG. 12B shows an IPF (Inverse Pole Figure) map of each cross section shown in FIG. 12A. As shown in FIGS. 12A and 12B, Samples 1 to 3 were thin aluminum alloy wires having a single crystal structure and a wire diameter of about 100 to 200 μm.

In the structure shown in FIG. 10, the upper end portion of the mask and the root portion of the thin aluminum alloy wire were cut and the cross section was observed. In FIG. 10, the cutting position is indicated by a white dashed line, and the observation direction is indicated by a white arrow. FIG. 13A shows a cross-sectional photograph of a scanning electron microscope (SEM). FIG. 13B shows an IPF (Inverse Pole Figure) map of the cross section shown in FIG. 13A. As shown in FIGS. 13A and 13B, the root of the thin aluminum alloy wire close to the mask had a polycrystalline structure, but elongated grains having a radial size of about 400 μm and a linear size of about 2000 μm were observed. It had a polycrystalline structure close to that of a single crystal structure.

According to the production method of the present invention, it was confirmed that at least a part of the aluminum alloy fine wire having a single crystal structure can be produced. It was also confirmed that an aluminum alloy fine wire having a single crystal structure can be produced except for the root portion near the mask.

The present invention is not limited to the above-described embodiments and examples, and the design can be appropriately changed as long as the gist of the present invention is not deviated.

11 Molten holding furnace 12 Spatial part 21 Molten 22 Molten metal extruded in a linear shape 23 Fine metal wire made of aluminum or aluminum alloy 30 Mask 31 Oxide-containing layer 32 Through hole 51 Rotor 52 of degassing device

Claims (4)

A method for producing a thin metal wire made of aluminum or an aluminum alloy having at least a part of it having a single crystal structure.
A step (S1) of providing a mask having a through hole for forming a fine metal wire on the surface of a molten metal made of aluminum or an aluminum alloy held in a molten metal holding furnace.
A step (S2) of increasing the pressure in the molten metal and linearly extruding the molten metal from the through hole into the space above the mask in the molten metal holding furnace.
A method for producing a thin metal wire, which comprises a step (S3) of slowly cooling the molten metal extruded linearly in the space. The method for producing a thin metal wire according to claim 1, wherein the mask has the through holes formed in the oxide-containing layer formed on the surface of the molten metal. In the step (S1), the degassing treatment for supplying bubbles of the inert gas into the molten metal is performed, and the oxide-containing layer having the through holes formed by the passage of the bubbles is formed on the surface of the molten metal. The method for producing a thin metal wire according to claim 2, which is formed. The production of the thin metal wire according to any one of claims 1 to 3, wherein in the step (S2), bubbles of the inert gas are supplied into the molten metal, and the pressure in the molten metal is increased by supplying the bubbles. Method.

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