JPS6096701A - Preparation of rare earth element-co type thin plate magnet - Google Patents

Abstract

PURPOSE:To prepare a rare earth element-Co type thin plate magnet free from heat strain in a mass production system, by alternately stacking lumpy plates each obtained by applying compression molding to a rare earth element-Co alloy powder in a magnetic field and slightly larger heat resistant metal plates and sintering the whole before cooling. CONSTITUTION:An alloy powder containing a rare earth metal such as Sm and Co is molded into a thin plate form under pressure in a magnetic field to prepare a lumpy plate 1. This lumpy plate 1 and a heat resistant metal plate 2 made of stainless steel having a size protruded from the lumpy plate are alternately stacked while a mold platen 4 is placed on the resulting laminate 3 which is, in turn, sintered while inert gas is injected from gas blow-out orifices 5 provided to the mold platen 4. In this case, the heat resistant metal plate 2 functions as a heat disspating plate. After sintering, the sintered one is cooled at a cooling speed of about 2 deg.C/sec. By this method, a rare earth metal-Co type thin plate magnet excellent in magnetic characteristics can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing a thin plate magnet based on rare earth cobalt, and more specifically, to a method for producing a thin plate magnet based on rare earth cobalt by sintering an alloy powder made of rare earth and cobalt.

[Background technology]

Magnets made of rare earth elements and cobalt are evaluated as high-performance magnets with high saturation magnetization and high coercive force, and based on this performance, they contribute to smaller walls and lighter weight, and are specifically incorporated into speakers and motors. There is.

The general manufacturing method for this magnet is to crush and pulverize an alloy containing rare earth elements and cobalt, press-form it in a magnetic field, then sinter at a high temperature of 1100°C to 1220°C and rapidly cool it.
A method of heating at around 800°C for 1 to 2 hours and slow cooling is adopted.

In order to mass-produce thin plate magnets using this method, they are pressure-formed into columnar bodies and then sliced. However, the cutting associated with slicing becomes a loss, which is reflected in the cost, making it economical. lacking in sex. Furthermore, in order to improve the magnetic properties, it is necessary to quench the columnar body obtained by pressure molding, for example by spraying with inert gas, but the quenching is difficult to be done evenly and thermal distortion occurs.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides a method for producing rare earth root thin plate magnets that are suitable for mass production and free from thermal distortion.

[Disclosure of the invention]

That is, this invention involves pressure forming alloy powder consisting of rare earth elements and cobalt into a thin plate in a magnetic field to obtain a block plate, and then sintering the block plate by alternately stacking heat-resistant metal plates protruding from the block plate. The present invention provides a method for manufacturing a rare earth cobalt thin plate magnet characterized by cooling.

This invention will be explained in detail below.

As the magnet material of the present invention, an alloy powder containing arboreal metal and cobalt is used. Samarium, cerium, etc. are used as rare earth metals. This alloy powder is pressure-molded 7 into a thin plate shape in a magnetic field to produce a block plate. A vertical magnetic field press is used to apply the a field parallel to the pressing direction. The strength of the magnetic field needs to be 10 KOe or more to achieve sufficient orientation.

Next, the obtained block plate is sintered. This sintering is carried out in an inert gas atmosphere by alternately stacking block plates and large heat-resistant metal plates 2 protruding from the block plates 1, as shown in the figure. The heat-resistant metal plate 2 may be made of a high melting point metal such as tantalum or molybdenum, or stainless steel such as 5US304. A mold plate 4 is placed on top of a laminate 3 made by alternately stacking block plates 1 and heat-resistant metal plates 2 as shown in the figure, and an inert gas is supplied from a gas outlet 5 provided in the mold plate 4. , is sintered while being ejected. In this case, the heat-resistant metal plate 2 functions as a heat sink. If the heat-resistant metal plate 2 becomes thick, there is a risk that the sintered body of the block plate 1 will stick when sintered, so a thin plate is preferable. For example, a thickness of about 11111 mm is appropriate, and up to 20 block plates 1 of the laminate B are suitable.

After sintering, cooling is performed. In rare earth cobalt magnets, the cooling rate has a large effect on the magnetic properties.

That is, the faster the cooling rate, the larger the coercive force can be obtained. A cooling rate of 2 v seconds is preferred, and below 1 degree s seconds the coercive force decreases rapidly. This cooling is performed as shown in the figure (by blowing out inert gas from the gas outlet 5. At this time, the heat-resistant gold ingot plate 2 acts as a heat sink for the sintered body. The heat-resistant metal plate 2 is larger than the sintered body If it is too large, it becomes difficult for gas to flow near the sintered body, reducing the cooling effect.It is preferable that the ratio of the heat-resistant metal plate 2 to the surface area of the sintered body is approximately 1:2. The speed will be 1.5 times faster.

Examples of this invention will be given below.

Example 1 0 Sample gold composition Sm (Co Q, 75 CuQ, l (3FeQ, Q4
Mn0.04) 6.8 This alloy powder is 1QKOeid
A block plate was obtained by pressure molding in the field, and a disk with a diameter of 20 mm and a thickness of 1 m was obtained. A 5US604 stainless steel plate with a diameter of 28 g, a thickness of 1 H was used as a heat-resistant metal plate, and a total of 20 pieces of the above-mentioned block plate were alternately stacked to form a multilayer body and sintered at 1210° C. for 1 hour. Then spray nitrogen gas 5! It was cooled down to 500°C at a rate of seconds and aged at 800°C for 1 hour. The magnetic properties of the resulting magnet were as follows.

Br=7800(G) 1Hc=76QQ(Oe)(B
H) m a x = 15.2 (MG Oe) When a heat-resistant full-chest plate with the same diameter of 20 m as the block plate was manufactured under the same conditions as above, the cooling rate was 3.5 ψ seconds, and the magnetic properties were as follows. It became so. The relationship between cooling rate l and coercive force is shown in FIG.

Br=7100(G) IHC=5900(θC)(B
H) max=12.2 (MGOe) Example 2 Q sample gold composition Sm (CoO, 73CuO, 14FeO, I ZrO,
03) 6.7 This alloy powder was molded in a 1QK (Je) magnetic field to produce a block plate with a diameter of 20 layers and a thickness of 1. As a heat-resistant metal plate, a heat-resistant metal plate made of molybdenum with a diameter of 301 mm and a thickness of 1 layer was used. Alternately stack this and the block board for a total of 20 sheets.
Sintering was carried out at 210° C. for 1 hour. Then, nitrogen gas was blown under the same conditions as in Example 1. The cooling rate during this time is 5
．． Cooled down to 500°C for 3°7 seconds and then cooled to 800°C.
Aging treatment was performed for 1 hour. The magnetic properties are shown below.

"r" 7900 (G) IHc near 500 (L) e) (
BH) max = 15.6 (MGOe) [Effect of the invention] In order to mass produce rare earth cobalt thin plate magnets, cutting from a columnar body results in a waste of material equivalent to a cutting margin of 0.5M to 1 turn. Not only can material loss be prevented, but also multiple sintering and cooling processes can be performed simultaneously, similar to slicing. Also, the occurrence of warpage, which was a problem when sintering thin objects, can be prevented by the dynamic weight received from the heat-resistant metal plate.

In the present invention, the heat-resistant metal plate used as the holding plate also serves as a heat sink, improving cooling efficiency, and thus improving magnetic properties. The amount of gas blown out can be reduced compared to conventional methods to obtain the same cooling rate. Furthermore, the difference in temperature between the surface and the inside can be made smaller than when cooling a columnar body.

[Brief explanation of drawings]

The figure is a sectional view showing the sintering and cooling steps according to an embodiment of the present invention. 1......Lump 2...Heat-resistant metal plate 6...Laminated body 4...Mold plate 5・・・・・・・・・Gas outlet procedural amendment document July 10, 1980 Director General of the Special WL Agency Mr. Kou, Indication of the case 11 Total 058 years Patent application No. 206504 Seal 1, Name of invention Rare earth Koba Manufacturing method for JLt5 series thin plate magnets 3, relationship with Hanyu, the person who does the Nell i correction Patent applicant address 1048 Kadoma, Kadoma City, Osaka Name (5)
83) Matsushita Electric Works Co., Ltd. Representative: Iku Kobayashi 4, Agent Address: 1048 Oaza Kadoma, Kadoma City, Osaka Prefecture Page 2 of the Specification, No. 1, where the Detailed Description of the Invention column is amended as follows:
At the end of the third line, insert "On the other hand, if a thin plate is formed in advance and then sintered, warping will occur during shrinkage." In line 16 of the same page, ``and no thermal distortion'' has been corrected to ``and no warping or thermal distortion.'' On page 3, line 14, "as shown" is corrected to "as shown in FIG. 1." In the second and third lines of page 4, ``Narikurayaki--It is blessed....It works as a hot plate.'' is corrected to ``It can be done.'' The explanation of the drawing in the column of a brief description of the drawing is ``Figure 1 is a schematic diagram for explaining the process related to this invention, and Figure 2 is a graph for explaining the relationship between coercive force and cooling rate. Yes,” he corrected. Correct the drawing as shown in the attached drawing. Above Figure 1 5 Figure 2

Claims (1)

[Claims] (1) An alloy powder consisting of rare earth and cobalt is pressure-formed into a thin plate in a magnetic field to obtain a block plate, and the block plate is alternately stacked with heat-resistant metal plates protruding from the block plate, sintered, and then cooled. A method for producing rare earth cobalt thin plate magnets.