KR100900142B1 - Method for producing Functional Alloy Strips by the Rapidly Solidification Process - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip manufacturing apparatus for various functional alloy materials (magnetic materials, hydrogen storage alloys, anode materials for secondary batteries, etc.), and in particular, melts an alloy material of a desired composition in the outer circumference of a cooling roll rotating at high speed. Unlike the conventional manufacturing method of cooling by instantaneous contacting and copying by cooling, the molten alloy is brought into contact with one side of the upper surface of the vertical cooling roll that rotates at a relatively low speed, cooled, and separated and removed in the form of an alloy strip using a scraper. Characterized in that.

Description

Method for producing Functional Alloy Strips by the Rapidly Solidification Process

1 is a front view of a cooling roll and its main parts in the present invention;

Figure 2 is a perspective view of the cooling roll, the alloy strip and the scraper of the present invention

Figure 3 is a front view of the tundish and nozzle in the present invention

Figure 4 in the present invention, the strip shape of the prepared Sm-Co-Fe-Cu-Zr-based magnetic alloy.

5 is a strip thickness change of the Sm-Co-Fe-Cu-Zr-based magnet alloy prepared according to the cooling roll rotation speed in the present invention.

Figure 6 is a microstructure of the Sm-Co-Fe-Cu-Zr-based magnetic alloy strip prepared by the present invention by optical microscope observation.

[Explanation of symbols on the main parts of the drawings]

3: melting crucible 5: tundish

6: high frequency induction furnace 7: cooling roll

8: alloy ribbon (or strip) 9: cooling roll hollow drive shaft

9a: cold roll support bearing 9b: cold roll drive pulley

11: scraper 11a: tip of scraper
12: refrigerant (water, air, liquid nitrogen, etc.) 15: scraper support shaft
19, 20: vacuum valve 25: drive device
30: refrigerant supply pipe

In general, the rapid solidification process for manufacturing powders or strips (or ribbons) for various functional alloy materials (magnetic materials, hydrogen storage alloys, anode materials for secondary batteries, etc.) is performed by gas spraying and single roll method (including twin roll method). It is divided into two ways. In particular, in the latter single roll method, when producing the master alloy strips (or ribbons) of the various functional alloy materials described above, the cooling rolls are melted in a high frequency induction furnace (or arc furnace) in a vacuum or inert atmosphere and rotated at high speed. Manufactured by instantaneous contact with outer circumference. However, the thickness of the master alloy strip (or ribbon) for magnets produced in this way is about 0.2 to 0.5 mm, but due to the difference in cooling rate between the two surfaces (cold roll contact surface and non-contact surface) and the center, It has been known that coarsening and micro segregation occur to deteriorate the magnetic properties of the entire magnetic alloy. In fact, such a phenomenon is known to generate about 10% of the total alloy ribbon (or strip) even in the mass production process. Practical technology for improving this problem According to a technique known as Japanese Patent Application Laid-Open No. Hei 11-238612, first, an alloy ribbon (or strip) manufactured by rapid solidification is first pulverized and improper particles (magnetically) It is proposed that the magnetic properties can be improved by removing powder particles having low properties. In addition, in the case of the techniques known in Japanese Patent Techniques (Japanese Patent Laid-Open Nos. 11-209804 and 11-297519), if the conventional centrifugal casting method is applied for the preparation of a mother alloy for rare earth permanent magnets, the microstructure control and the process of the magnetic alloy, etc. Although it has been reported that there is an advantage, the actual microstructure due to the cooling rate may vary greatly depending on the thickness of the alloy solidified inside the cylinder, and the process of separating and recovering the solidified alloy from the mold and coarse grinding Increased production costs can rise further.

In addition, according to the US patent technology (US 6790296) by H.Kanekiyo et al. As a means to improve the problem, in order to maintain the contact time of the melt on the outer periphery of the rapid cooling roll from the vertical direction of the cooling roll to the rotation direction A method of contacting the molten metal from the rear (11 o'clock clockwise) is proposed. However, this technique seems to increase the cooling time of the alloy ribbon (or strip) by slightly increasing the contact time of the molten metal to the cooling roll compared to the conventional single roll or twin roll method, but the contact time of the molten metal is actually the cooling roll rotational speed. As a result, the cooling effect due to the increase in contact time may not be very large.

The present invention is a means for solving the problems of the conventional rapid solidification technique and apparatus described above, not the outer circumference of the horizontal cooling roll rotating at high speed, but the outer side of the vertical cooling roll disk rotating at a relatively low speed (1000 rpm or less) The molten alloy is brought into contact with the molten alloy for a long time and stable cooling (relative to about 3/4 of the center of the disc), and then removed in the form of a master alloy strip (or ribbon) using a separately installed scraper.

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Such a cooling device of the present invention, the contact time of the molten metal is increased compared to the conventional single roll method made by contacting the outer circumference, the cooling rate is increased, the segregation is less, so that the microstructure of the master alloy more homogeneous, in particular the magnet In the case of alloys, the unidirectional solidification property is improved, and since the production of the mother alloy strip (or ribbon) of 0.5 mm or more is possible, it may contribute to the improvement of magnetic properties and productivity.

1 is a front view schematically showing main components such as the vacuum chamber 1, the cooling roll 3, the tundish 5, the scraper 11 and the like of the quenching apparatus. The vacuum chamber 1 is basically a permanent magnet alloy containing rare earth elements that are easily oxidized, or when the functional alloy material (hydrogen storage alloy, secondary battery negative electrode material, etc.) to manufacture the oxidation of these alloy materials In order to prevent it, it should be connected to a vacuum device that can be replaced with an inert gas (Ar, He and N _2, etc.) to be hermetically manufactured. In addition, a cooling roll drive device 25, an alloy melting high frequency induction furnace 6, And a vertical cooling roll hollow drive shaft connected to the cooling water supply device. In particular, the cooling roll (7) inside the cooling roll 7 to circulate a suitable refrigerant (water, air, liquid nitrogen, etc.) 12 from the outside to avoid the temperature rise of the upper surface of the cooling roll due to the cooling effect or continuous operation. The cooling roll drive shaft 9 connected to the lower portion is formed by having a hollow shaft, and the inner diameter of the hollow shaft is provided with a refrigerant supply pipe 30 capable of supplying the refrigerant 12 therein, and further, the refrigerant supply pipe. Between the outer diameter of the 30 and the hollow inner diameter of the cooling roll drive shaft 9 is made by being designed so that the supplied refrigerant is easily discharged out.

FIG. 2 is a perspective view illustrating a principle of operating in the present invention composed of a cooling roll 7, a tundish 5, a nozzle 10, a scraper 11, and the like that rotate vertically. The material of the upper plate of the cooling roll 7 is preferably made of Cu, Cu alloy (Cu-Be alloy, etc.) and the like, which have high thermal conductivity and can withstand thermal shock. The circumferential size of the cooling roll directly affects process variables such as the operating capacity of the target alloy or the cooling rate according to the rotational speed of the cooling roll, and the microstructure of the master alloy strip (or ribbon) 8 to be manufactured. (kg / day) and the like are preferably designed.

In the present invention, the position of the tundish 5 and the nozzle 10 required to supply the molten alloy 4 to one side of the upper part of the cooling roll 7 disc is important for the cooling effect. For example, when operating the said cooling roll 5 by rotating clockwise, when the position of the said tundish 5 and the nozzle 10 is installed in the outer periphery of the 8-10 o'clock direction, a scraper ( The position of 11) is preferably provided so as to be in the clockwise range of 5 to 7 o'clock. In addition, the scraper 11 is used to remove the alloy ribbon (or strip) 8 rapidly cooled and solidified from the upper part of the cooling roll, and a high-speed tool steel (or cemented carbide) 11a that can withstand high temperatures at its distal end. It is preferable to attach partially. The scraper 11 is installed to be fixed so as not to rotate in the circumferential direction of the cooling roll 7 from the support shaft 14, but the scraper tip portion 11a does not come into contact with the upper surface of the cooling roll. This is accomplished by installing the alloy ribbon (or strip) 8 so that the screw 13a or the like can be effectively removed. In particular, the scraper support shaft 14 is preferably manufactured using a sliding bearing excellent in the sliding action for smooth up and down operation of the scraper.

3 shows a perspective view of the outer shape and the inside of the tundish 5 and the nozzle 10 for supplying a molten alloy to be operated on one surface of the upper part of the cooling roll 7 according to the present invention. In particular, the inner diameter size of the nozzle 10 should be appropriately designed in consideration of the circumferential size of the cooling roll 7 and the amount of alloying operation, and the inside of the nozzle is made rectangular rather than cylindrical so that the molten metal is formed outside the cooling roll ( It is desirable to be as flat as possible to contact the upper surface (3/4 outer side of the disc diameter), and the separation distance between the lower end of the nozzle 10 and the upper surface of the cooling roll 7 is installed so as not to fall too far.

4 and 5 in the present invention, the circumferential size of the cooling roll 7 is made of Ø300mm, the dropping position of the molten metal fell Ø270mm outside the center of the cold roll (7), the rotational speed Sm-Co-Fe-Cu-Zr based rare earth permanent alloy strip made of 100 to 700rpm by changing the appearance and the thickness of the mother alloy strip produced by varying the rotational speed of the cooling roll (7) It is a change. As the rotation speed of the cooling roll increases, the thickness of the strip decreases and the microstructure of the master alloy strip changes.

The quenching apparatus according to the present invention is a primary means for pulverizing various rare earth permanent magnet alloys containing rare earth elements which are active metals, and various functional alloy materials (such as hydrogen storage materials and negative electrode materials for secondary batteries). In contrast to the conventional method of rapid solidification, which rotates at a high speed, the molten metal is rapidly solidified by contacting the upper surface of the vertical cooling roll disc, which rotates at a relatively low speed, thereby miniaturizing the solidification structure of the functional alloy material, reducing segregation and unidirectional solidification characteristics. The improvement etc. can expect not only the improvement of the characteristic of a product, but also the improvement of product productivity, a reduction of equipment cost, etc ..

Claims (2)

The refrigerant (water, air, liquid nitrogen, etc.) is filled so that the molten metal (4) is in contact with the outer side of the upper plate of the vertical cooling roll (7) that is rotated at a relatively low speed and filled to circulate, so that the molten metal is turned to supply a certain amount A disher 11 is installed to fix the dish 5 and the nozzle 10 and removes and recovers the rapidly solidified master alloy strip (or ribbon) 8 from the top of the rotating cooling roll 7 disc. Functional alloy strip manufacturing apparatus characterized in that using). The scraper (11) according to claim 1, wherein the scraper (11) is centered on the support shaft (14) of the scraper (11) to remove the rapidly cooled solidified alloy ribbon (or strip) (8) from the top of the cooling roll (7). In order to move up and down without rotating in the opposite direction to the cooling roll rotation direction, but using the spring (15) and the adjustment screw (13a) so as not to contact the upper plate of the cooling roll (7) by the alloy ribbon ( Or strips (8) so as to effectively remove the functional alloy strip manufacturing apparatus, characterized in that by using a high-speed tool steel (or cemented carbide) (11a) partially attached to the front end of the scraper (11).

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