JP2002086249A - Method for producing amorphous alloy strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an amorphous strip excellent in the surface property and the shape of the end parts. SOLUTION: This method for producing the amorphous alloy strip is cast under conditions of <35 m/sec to circumferential speed of a cooling roll, from melting point of the base alloy +50 deg.C to this melting point +25 deg.C to the temperature of the molten metal and <=200 μm to the distance between the tip end of a nozzle and the cooling roll, in the injecting state of gas consisting essentially of CO2 gas so that the main axis of the injecting direction substantially directs the cooling roll at the backward part of a paddle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an amorphous ribbon excellent in surface properties and end shape.

[0002]

2. Description of the Related Art As a production method for producing an amorphous ribbon, a liquid quenching method is widely known. As the liquid quenching method, there are a single roll method, a twin roll method, a centrifugal method, and the like, but from the viewpoint of productivity and ease of maintenance,
The single roll method in which molten metal is supplied onto one cooling roll rotating at a high speed and rapidly solidified to obtain a ribbon is excellent. Conventionally, when an amorphous ribbon is produced by a single roll method, a depression called an air pocket is formed on the roll contact surface side of the ribbon. This is because when the entrained gas generated by the rotation of the cooling roll is caught in the boundary layer between the pool (hereinafter referred to as a paddle) and the cooling roll, it expands inside the paddle before solidifying. It is said that there is.

As a method for suppressing the generation of the air pocket, a method of manufacturing in a vacuum or He atmosphere, or a method of flowing He, heated CO, or CO ₂ gas from the rear (upstream side) of the paddle is used. Manufacturing methods have been proposed. Above all, from the viewpoint of manufacturing cost and safety, a method of flowing CO ₂ gas from the rear of the paddle is considered to be excellent, and various proposals have been made. For example,
Japanese Patent Laid-Open No. 6-292950 proposes a method of flowing a CO ₂ gas along a carbon blade. In this method, since the gas layer is prevented from being mixed between the cooling roll and the paddle, the heat transfer resistance between the cooling roll and the molten metal can be reduced.
Even when a relatively thick plate having a plate thickness of 35 to 100 μm is manufactured at m / sec, it is excellent in that it is hardly embrittled. Japanese Patent Application Laid-Open No. Hei 9-268354 also proposes a method for producing a ribbon having a thickness of 15 to 25 μm in an atmosphere having a roll peripheral speed of 35 m / sec or more and a CO ₂ concentration of 50% or more. This proposal is excellent in that the generation of air pockets is suppressed and the surface roughness of the ribbon on the roll contact surface side is reduced.

[0004]

SUMMARY OF THE INVENTION₂
When producing an amorphous ribbon while flowing gas,
It can be manufactured under various conditions by changing the
Built. As a result, CO ₂By introducing gas, thin ribbon
Surface morphology on the tool contact surface side can be improved.
On the other hand, on the free solidification side of the ribbon, CO₂Does not use gas
The unevenness is larger than in the case, and at the end of the ribbon
It turns out that there is a problem that the shape is distorted like a saw
Was.

[0005] If the shape and shape of the surface of the ribbon are not good, when the ribbon is used as a magnetic core by winding it in a toroidal shape or by punching and laminating, the space factor (apparent sectional area) of the magnetic core is reduced. Of the ribbon.)
When the space factor decreases, when a magnetic core having the same inner and outer diameters is manufactured, the total magnetic flux and the inductance also decrease. Therefore, it is necessary to increase the magnetic core and increase the number of windings. This poses problems in terms of downsizing of equipment and cost. Further, for example, a ribbon is continuously wound around a shaft to form a magnetic core. In many cases, the winding is performed while applying a plate or the like to an end of the ribbon to keep the product height constant. At this time, if the end of the ribbon is distorted in a saw-tooth shape, the ribbon sticks to the above-mentioned plate or the like, making it difficult to manufacture a magnetic core.

According to the present invention, a ribbon having an excellent free solidified surface shape and an excellent end shape can be produced without impairing the effect of improving the surface morphology of the ribbon on the roll contact surface side by the CO ₂ gas. Is to provide a way.

[0007]

Means for Solving the Problems The present inventors mainly studied the surface morphology on the free solidification surface side of the ribbon and the problem of the shape of the end portion, and examined the flow of CO ₂ gas and the peripheral speed of the cooling roll. The present invention was found to be able to be improved by optimizing the molten metal temperature and the distance between the molten metal nozzle and the cooling roll, and reached the present invention.

That is, according to the present invention, the peripheral speed of the cooling roll is less than 35 m / sec in a state where the gas mainly composed of CO ₂ gas is ejected such that the main axis in the ejection direction is substantially directed to the cooling roll behind the paddle. , The temperature of the molten metal to the melting point of the mother alloy +
This is a method for producing an amorphous alloy ribbon, wherein casting is performed under the conditions of 50 to melting point + 250 ° C. and the distance between the nozzle tip and the cooling roll is 200 μm or less. Further, the preferable range of the peripheral speed of the cooling roll in the above-mentioned manufacturing method is 20
３０30 m / sec. In addition, in consideration of magnetic characteristic deterioration due to eddy current loss when the ribbon is formed into a magnetic core, the thickness of the ribbon is preferably small.
Even if it is less than m, it is effective in improving the surface morphology and end shape of the ribbon. If the thickness is less than 8 μm, defects are likely to occur in the ribbon due to external factors such as vibration of the roll.
The plate thickness is preferably 8 to 19 μm.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, an important feature of the present invention is that a gas mainly composed of CO ₂ gas is jetted such that the main axis in the jetting direction is substantially directed to a cooling roll behind the paddle, and The peripheral speed of the cooling roll is less than 35 m / sec, the temperature of the molten metal is +50 to + 250 ° C. of the melting point of the mother alloy, and the distance between the tip of the nozzle for ejecting the molten metal and the cooling roll is 200 μm.
m or less.

[0010] The jetting of the main axis of the gas mainly composed of CO ₂ gas so as to be directed substantially toward the cooling roll behind the paddle is performed when the free solidified surface is directly blown to the nozzle tip or the paddle. This is because the skin becomes pear-skin, and a larger air pocket is generated on the roll contact surface side than when no gas is flown, and the surface morphology of the ribbon is deteriorated rather than when no CO ₂ gas is flown. When the main axis of the gas is directed from the front (downstream side) of the paddle to the cooling roll or paddle, the surface configuration on the roll contact surface side is almost the same as when no gas is flown, but the surface configuration on the free solidification surface side Is more degraded than when no CO ₂ gas is flown, so it is not preferable to blow out the gas from the front of the paddle.

Further, the peripheral speed of the cooling roll is set to 35 m / sec.
The reason for the lower limit is that at a peripheral speed higher than this, the surface morphology or end shape of the ribbon becomes poor. Particularly, the deterioration of the shape of the end portion was more remarkably observed when the peripheral speed of the cooling roll was 35 m / sec or more than when the CO ₂ gas was not supplied.

Generally, as the roll rotates, the pressure at which the gas entrained on the roll surface collides with the paddle is 1 /
It is expressed by 2 × gas density × roll peripheral speed ² . Since the pressure of gas collision is proportional to the density of the gas, it is considered that CO ₂ gas having a higher density than air tends to disturb the shape of the paddle at the time of collision. Therefore, in roll casting using CO ₂ gas around the paddle, it is important to lower the roll peripheral speed as compared with normal roll casting performed in air.

[0013] The lower limit of the temperature of the molten metal is calculated as the melting point of the master alloy + 50
The reason why the temperature is set to 0 ° C. is that if the melting point is lower than + 50 ° C., oxides of Si and Al easily adhere to the inside of the molten metal jet nozzle during the production of the ribbon. If oxides or the like adhere to the nozzle, there arises a problem that the ribbon is scratched or the nozzle is blocked.

The upper limit of the temperature of the molten metal is calculated as the melting point of the master alloy + 250
The reason why the temperature is set to ° C. is that if the temperature is too high, the generation of air pockets generated on the roll contact surface side cannot be sufficiently suppressed, and the surface roughness increases. CO ₂
One of the reasons air reduces gas pockets is that CO
₂ has a larger specific heat than air, and thus has a smaller expansion coefficient than air even when it is caught in the paddle. But,
If the temperature of the molten metal is too high, the cooling rate becomes slow, and conversely, the expansion inside the paddle cannot be sufficiently suppressed, and the surface roughness is considered to be large.

The reason why the distance between the nozzle for ejecting the molten metal and the cooling roll is set to 200 μm or less is that if it exceeds 200 μm, the shape of the end of the ribbon is disturbed or the surface morphology on the free solidified surface side deteriorates. . This phenomenon was more remarkable when flowing CO ₂ gas than when not flowing.

In the case of casting a thin ribbon, it is usual to carry out casting at a higher roll peripheral speed than in the case of a thick ribbon. It is better to reduce the peripheral speed of the cooling roll as much as possible. According to the study of the present inventors, if the molten metal temperature or the like is controlled within the range described in claim 1, even if the peripheral speed is less than 35 m / sec and the thickness is 19 μm or less, the surface morphology and the shape of the end portion are good. It was confirmed that a thin ribbon could be obtained. When producing a thin plate material by slowing the peripheral speed, mainly reduce the melt nozzle slit size or the distance between the melt nozzle and the cooling roll,
From the viewpoint of easy control, a preferable range is 20 to 30 m /.
sec. More preferably, it is 27 to 30 m / sec.

[0017]

(Example 1) 4Si-10B-4C in atom% previously melted in the crucible shown in FIG. 1 and the remainder substantially F
An ingot having a composition of e was charged and melted by high-frequency induction heating. This was jetted onto a cooling roll made of a Cu-Be alloy and rapidly solidified to produce an amorphous ribbon having a width of 27 mm and a thickness of 19 µm.

The casting was performed under the following conditions. Gas introduction position: The gas nozzle is installed behind the molten metal jet nozzle with the main axis in the gas jetting direction facing the cooling roll (see FIG. 2). Cooling roll peripheral speed: 27 m / sec Melt temperature: 1270 ° C. (melting point of mother alloy: 1100 ° C.) Distance between tip of molten metal jetting nozzle and cooling roll: 120 μm Gas flow rate: 30 L / min L in FIG. The shape of the outlet of the gas nozzle was 30 mm in the width direction of the roll and 1 mm in the rotation direction. As shown in FIG. 1, the recovery of the ribbon was performed by blowing a high-pressure gas in a direction opposite to the rotation direction of the cooling roll, and forcibly peeling the strip onto a reel or the like.

As a comparison, a ribbon was produced in the same manner with the main axis in the gas ejection direction directed toward the nozzle tip (see FIG. 3) and the paddle (see FIG. 4). In addition, a ribbon was manufactured without flowing gas.

The average roughness Ra of the free contact surface side and the roll contact surface side of the ribbon was measured based on JIS B0601 for the ribbon produced under the above four types of manufacturing conditions. Table 1 shows the results. As is clear from the table, in the present invention in which the main axis in the gas ejection direction is directed to the cooling roll surface, Ra is very small on both the free solidified surface and the roll contact surface, and is excellent. On the other hand, when the gas ejection direction is directed to the nozzle tip and the paddle, it can be seen that the roughness is worse than when the gas is not flown. Further, the space factor after lamination in a toroidal shape was determined according to ASTM A900.
Table 1 also shows the results of measurement based on -91.
Also in this result, when the gas ejection direction is directed to the chill roll, it is greatly improved compared to the case where no gas is flowed, but on the other hand, when the ejection direction is directed to the paddle and the nozzle tip, it becomes worse. ing.

[0021]

[Table 1]

(Example 2) In a crucible shown in FIG. 1, 1.3Fe-3.7Mn-2.5Mo in atomic% was previously melted.
An ingot having a composition of -15Si-9B and the balance substantially consisting of Co was charged and melted by high-frequency induction heating. This is C
An amorphous ribbon having a width of 40 mm and a thickness of 16 μm was produced by squirting onto a cooling roll made of a u-Be alloy and rapidly solidifying it.

The casting was performed under the following conditions. Gas introduction position: The gas nozzle is installed behind the molten metal jet nozzle with the main axis in the gas jetting direction facing the cooling roll (see FIG. 2). Cooling roll peripheral speed: 30 m / sec Melt temperature: 1250 ° C. (melting point of the master alloy: 1050 ° C.) Distance between the tip of the molten metal jet nozzle and the cooling roll: 160 μm Gas flow rate: 40 L / min Note that L in FIG. The shape of the outlet of the gas nozzle was 50 mm in the width direction of the roll and 1.5 mm in the rotation direction. The method of recovering the ribbon was the same as the method described in Example 1.

For comparison, the peripheral speed of the cooling roll was set to 40 m /
The production of a ribbon was performed in sec. However, the slit size of the molten metal jet nozzle was increased so that the plate thickness was almost the same as that described above. In addition, in the above two types of manufacturing processes, a ribbon was manufactured without flowing gas.

The average roughness Ra of the free solidified surface and the roll contact surface side of the ribbon was measured based on JIS B0601 for the ribbon produced under the above four types of manufacturing conditions. Table 2 shows the results. Casting at a peripheral speed of 40 m / sec both when the gas was flowed and when the gas was not flowed, the surface roughness was large, but the surface roughness on the roll contact surface side was particularly affected by the peripheral speed when the CO ₂ gas was flowed. It turns out that it is easy to receive. Also,
FIGS. 5 and 6 show the results of observing the shapes of the ends of the two types of ribbons manufactured by flowing a gas with a scanning electron microscope. As shown in the figure, when the peripheral speed is set to 40 m / sec, compared to the end shape of the ribbon manufactured at the peripheral speed of 30 m / sec,
It can be seen that the shape of the end is largely disturbed. In addition, when the gas is not supplied, such disturbance of the end shape is not recognized.

[0026]

[Table 2]

Example 3 1 Cu-2.5Nb-13.5Si- at atomic% previously melted in the crucible shown in FIG.
7B, an ingot consisting of substantially Fe and having a composition capable of expressing nanocrystals by heat treatment after casting was charged and melted by high-frequency induction heating. This is jetted onto a cooling roll made of a Cu-Be alloy, rapidly solidified, and has a width of 35 mm and a thickness of 1 mm.
An 8.5 μm amorphous ribbon was produced.

The casting was performed under the following conditions. Gas introduction position: The gas nozzle is installed behind the molten metal jet nozzle with the main axis in the gas jetting direction facing the cooling roll (see FIG. 2). Cooling roll peripheral speed: 30 m / sec Molten metal temperature: 1230 ° C., 1300 ° C., 1390 ° C. (melting point of mother alloy: 1150 ° C.) Distance between tip of molten metal jet nozzle and cooling roll: 150 μm Gas flow rate: 32 L / min In FIG. L was 15 mm, and the shape of the outlet of the gas nozzle was 45 mm in the roll width direction and 2 mm in the rotation direction. Recovery of the manufactured ribbon was the same as in the method described in Example 1.

For comparison, the heating temperature of the master alloy was set to 1130
C. and 1430.degree. C., and a ribbon was produced in the same manner.
However, when the heating temperature of the mother alloy was set to 1130 ° C., the nozzle was blocked in a few seconds after the start of the production, so that the ribbon could not be collected.

Using the four types of thin ribbons collected above, JI
Based on SB0601, the average roughness Ra on the roll contact surface side of the ribbon was measured. Table 3 shows the results. From the table, all three types of ribbons of the present invention have Ra of 0.3 μm or less, but the Ra of the ribbon of the comparative example prepared by heating the mother alloy to 1430 ° C. to be 0.48 μm is about 1 μm. .5 times the roughness.

[0031]

[Table 3]

Example 4 In the crucible shown in FIG. 1, 1Cu-3Nb-15.5Si-6.
5B, an ingot composed of substantially the remainder of Fe and capable of expressing nanocrystals by heat treatment after casting was charged and melted by high-frequency induction heating. This is jetted onto a cooling roll made of a Cu-Be alloy, rapidly solidified, and has a width of 20 mm and a thickness of 1 mm.
A 5 μm amorphous ribbon for a nanocrystalline soft magnetic material was produced.

The casting was performed under the following conditions. Gas introduction position: The gas nozzle is installed behind the molten metal jet nozzle with the main axis in the gas jetting direction facing the cooling roll (see FIG. 2). Cooling roll peripheral speed: 25 m / sec Melt temperature: 1350 ° C. (melting point of mother alloy: 1135 ° C.) Distance between tip of molten metal jet nozzle and cooling roll: 120 μm Gas flow rate: 40 L / min Note that L in FIG. The shape of the outlet of the gas nozzle was 30 mm in the width direction of the roll and 1 mm in the rotation direction. Recovery of the manufactured ribbon was the same as in the method described in Example 1.

As a comparative example, the distance between the cooling roll and the tip of the molten metal jet nozzle was 250 μm. At this time, the slit size of the molten metal ejection nozzle was reduced so that the plate thickness became substantially the same as the above-mentioned value. In addition, under the above two types of manufacturing conditions, a ribbon was manufactured even when the gas flow rate was set to 0.

Regarding the above four types of ribbons, JIS B0
Table 4 shows the results obtained by measuring the average roughness Ra of the free solidified surface of the ribbon and the roll contact surface based on 601. It is clear from the table that the surface roughness is smaller when the distance between the melt nozzle and the cooling roll is smaller than 200 μm.
Focusing on the surface roughness on the free solidified surface side, when the distance between the nozzle and the roll is 120 μm, the surface roughness is improved by the CO ₂ gas. On the other hand, when the distance between the nozzle and the roll is 250 μm, the distance is larger than when the CO ₂ gas is not flown. When the CO ₂ gas is used, the distance between the nozzle and the roll is more remarkable due to the surface roughness. You can see the effect.

FIG. 2 shows a photograph of the appearance of the free solidified surface side. Streaks are observed in the width direction at intervals of about 3 mm in the longitudinal direction. The thickness of this streak part is 5
７7 μm thinner. This pattern is no. As can be seen from the ribbon No. 4, the difference in the thickness between the streak portion and the periphery was 4 μm or less. For this reason, it is considered that the surface roughness was increased by flowing the gas. Furthermore, the shape of the end of the ribbon was observed with a scanning electron microscope. Saw-like disturbance as shown in FIG. The saw-like turbulence at the end of the ribbon, which is seen on the free solidified surface side, is caused by the present invention example and comparative example No. Not seen in 3 and 4.

Next, the ribbons manufactured under the above four conditions are wound in a toroidal shape, and the outer diameter is 19 mm and the inner diameter is 15 mm.
Was manufactured. These are placed in a non-reactive atmosphere at 520
℃, the average grain size of the crystal grains constituting the ribbon is 10
A nanocrystalline structure of 0 nm or less was obtained. The magnetic core manufactured in this manner is wound with a primary wire 10 times and a secondary wire 10 times.
The maximum magnetic permeability μm at Hz was measured. The results are shown in Table 4. The highest magnetic permeability is obtained in the magnetic core using the ribbon manufactured by the manufacturing method of the present invention having the smallest Ra on both the free solidified surface and the roll contact surface.

[0038]

[Table 4]

[0039]

According to the present invention, not only the conditions for jetting CO ₂ gas but also other manufacturing conditions, such as the peripheral speed of the cooling roll, are optimized, so that the amorphous material having a good surface morphology and good end shape can be obtained. The ribbon can be manufactured, and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an apparatus for performing a manufacturing method of the present invention.

FIG. 2 is a schematic view showing an example of a gas nozzle for performing the manufacturing method of the present invention.

FIG. 3 is a schematic diagram illustrating an example of a gas nozzle in a comparative example.

FIG. 4 is a schematic diagram illustrating an example of a gas nozzle in a comparative example.

FIG. 5 is a scanning electron micrograph of an end portion on a roll contact surface side of an as-cast ribbon manufactured by the manufacturing method of the present invention.

FIG. 6 is a scanning electron micrograph of an end portion on a roll contact surface side of a comparative example in a state where a thin ribbon is cast.

FIG. 7 is a photomicrograph of the appearance of a free-solidified surface of a comparative example as-cast ribbon.

FIG. 8 is a scanning electron micrograph of a roll contact surface side end portion of a comparative example in a state where a thin ribbon is cast.

[Explanation of symbols]

1. Crucible, 2. High frequency coil, 3. Mother alloy; 4. 4. Molten jet nozzle 5. chill roll, Amorphous ribbon, 7. 7. Stripping gas nozzle 8. gas nozzle (example of the present invention); Paddle; 10. Gas nozzle (comparative example) Gas nozzle (comparative example)

Claims (3)

[Claims] 1. A cooling roll having a peripheral speed of 35 m / sec in a state in which a gas mainly composed of a CO ₂ gas is jetted such that a main axis in a jetting direction is substantially directed to a cooling roll behind a paddle.
c, the temperature of the molten metal is set to the melting point of the mother alloy + 50 to the melting point + 25.
A method for producing an amorphous alloy ribbon, comprising casting at 0 ° C. and a distance between a nozzle tip and a cooling roll of 200 μm or less. 2. A cooling roll having a peripheral speed of 20 to 30 m / sec.
The method for producing an amorphous alloy ribbon according to claim 1, wherein c is used. 3. The method for producing an amorphous alloy ribbon according to claim 1, wherein an amorphous alloy ribbon having a thickness of 8 to 19 μm is produced.