JPH01111303A - Manufacture of rare earth magnet - Google Patents

Abstract

PURPOSE:To industrially manufacture a sintered material integral with a metal material in which an adhering step is omitted by pressure molding crude magnetic alloy powder in a magnetic field, sintering it by discharging, and simultaneously baking to integrate the molding with a metal material, such as a yoke material or the like. CONSTITUTION:A metal material, such as a yoke material 6 or the like is charged in a die 1 formed of a cemented carbide or the like, magnetized in a magnetic field generated by a magnetic field generating coil 4 while compressing it by a hydraulic press 8 by upper and lower punches 2, 3 or only an upper punch 2 for charging a predetermined amount of magnetic powder thereon, and sintered and molded by discharging by simultaneously applying a DC current from a power supply 7. A rare earth sintered magnet sintered integrally with the material 6 is obtained by this operation. Thus, it can be utilized immediately as a component without requirement of steps of working and adhering to be industrially manufactured.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing a permanent magnet sintered body containing rare earth elements, and more specifically, it relates to a method for producing a permanent magnet sintered body containing rare earth elements, and more specifically, A method of sintering a magnet of the system (here R represents one or more rare earth elements) under pressure in a magnetic field, and at the same time producing an integral molded product of this sintered body and a metal material such as a yoke material. It is related to.

(Prior Art) (Problems to be Solved by the Invention) Conventionally, when producing a rare earth magnet sintered body, the following steps were usually carried out.

1) Production of bulk or granular alloys by melting raw materials This melting is carried out by high frequency melting, arc melting, electron beam melting, etc. in vacuum or an inert atmosphere.

2) The lump or granular alloy obtained in the pre-process of pulverization of the alloy is ball milled,
It is crushed by a vibrating mill or other mechanical method until the particle size is 1 to 10 microns, or even ultrafine in some cases.

3) Molding process in a magnetic field The fine powder alloy obtained in the pre-process is molded in a magnetic field of several KOe or more. This molding can be performed by using an organic or inorganic binder in addition to pressure molding, and
Both can be combined. Although this organic or inorganic binder is quickly removed, the molded product of this process may be used as a final product without removing the binder.

This step aligns the axis of easy magnetization of the fine alloy powder in the direction of the magnetic field.

4) Densification step by compression The molded product obtained in the previous step is compressed under pressure using an isotropic hydraulic press or a quasi-isotropic press to increase its density.

Prior to this step, the binder and other substances used in the previous step are removed.

5) Sintering and solution treatment step The high-density compact obtained in the previous step is sintered in a vacuum or in an inert atmosphere.

This sintering condition is, for example, 25wt%3m-15wt%CL
In the case of a Sm-cu-co magnet made of J-60 wt% Co, the temperature was 1200'C for 2 hours.

6) Heat treatment is performed to impart desired magnetic properties to the sintered body obtained in the pre-step of iJl yellow heat treatment step.

The rare earth magnet sintered body thus obtained is further polished and
It was processed into a desired shape by cutting, etc., and then bonded to other metal materials and used for various purposes such as motors.

In order to simplify these many steps, a proposal has already been made in Japanese Patent Publication No. 56-27564 to replace the magnetic forming, compression and sintering steps with a single magnetic field pressing and discharge sintering step. The invention particularly relates to the third magnetic field forming step, the fourth densification step, and the sintering step of a part of the fifth step among the above steps, and its purpose is to combine these steps into a single process. The purpose is to simplify the process by replacing it with a magnetic field-directed pressure discharge sintering process, and to provide a permanent magnet alloy with high density and high performance that could not be obtained with the conventional process.

Further, to specifically explain the method of the invention, a suitably pulverized raw material alloy having a desired composition is pressed in a magnetic field of at least 1040e or more using an axle press, a hydrostatic press, a quasi-hydrostatic press, etc. A high-density compact is formed by discharge sintering in a compression molded state, that is, while pressurized in the above magnetic field, and then subjected to solution treatment and aging treatment to obtain a permanent magnet alloy having the desired magnetic properties. It is.

In the method of the invention, in order to effectively carry out the above-mentioned strong fi1m work, at least one of the punches of these presses is made of a highly magnetically permeable conductive material, and an excitation coil is wound around it. A press is used which is energized and excited to generate a strong magnetic field as necessary. However, this method includes the steps of forming in a magnetic field and further solution aging treatment after sintering, and has drawbacks such as the need for post-processing of the sintered body. Therefore, it is difficult to expect a significant improvement in the process as a whole compared to the conventional method.

As is well known, rare earth magnet sintered bodies are extremely brittle and easily chipped, making normal machining difficult.They can only be simply polished and cut, and when used in actual motors etc. In addition to having a suitable shape, they must be fixed and attached using adhesives, etc., and in this case, there are many cases where parts are missing due to cracks, chips, etc.

In view of the above-mentioned situation, the present inventors have conducted intensive studies on an industrial method for producing rare earth magnets using the electric discharge bond method. If the in-situ pressure molding discharge sintering process is adopted, it will be possible to integrally bake and mold the metal materials such as yokes at the same time in the sintering process, which will greatly benefit the production of rare earth magnet compacts. This discovery led to the present invention.

That is, the object of the present invention is to perform magnetic discharge sintering to produce a molded body integrally sintered with a metal material! This provides a method for building A.

(Means for Solving the Problems) The present invention solves the three major problems that were considered to be difficult points in sintering rare earth magnets: ■ Significant simplification of the manufacturing process ■ Elimination of post-processing steps ■ Integral molding with other metal materials It can provide a means to solve many major problems all at once. That is, according to the present invention, it is possible to industrially produce an integrated sintered body with a metal material by omitting the bonding process.That is, the gist of the present invention is to provide a method for manufacturing a permanent magnet sintered body containing rare earth elements. This is a method in which a desired adjusted raw material magnetic alloy powder is press-molded in a magnetic field, discharge-sintered under the pressure, and at the same time, the compact is integrated with a metal material such as a yoke material.

The types of rare earth magnets that can be applied to the implementation of the present invention include all magnets containing rare earth elements, including 1-5 series and 2-17 series R-Co rare earth magnets (
RCo5. R2C01□) and R-Fe-B rare earth magnets can be advantageously produced.

Further, since the molding is performed under pressure of several tons to several tens of tons/crA, a product with good dimensional accuracy can be obtained, and post-processing and bonding steps are not required, and an integrally molded product with the yoke can be obtained in one step.

Although its performance depends on the type of rare earth magnet and sintering conditions, a high-performance sintered magnet with a maximum energy product of 10 MGOe or more, usually 15 MGOe or more can be obtained.

An example of an embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

First, the required raw material is melted in the melting process shown in Figure 1 (■) to form an ingot (■). Melting is usually carried out using high-frequency heating in a vacuum or in an inert gas atmosphere such as argon. The ingot (①) is sent as it is or after being simply crushed and sent to the solution treatment step (②).

After treatment at around 1200'C for several hours in an inert gas atmosphere, an aging treatment operation depending on the ingot composition is performed as necessary.

These operations are carried out in vacuum or in an inert gas using an electrically heated sintering furnace as in (2). The obtained heat-treated ingot is then coarsely crushed using a stamp mill or the like in an inert scum atmosphere, and then finely crushed using a ball mill, vibration mill, or the like.

2/17 When manufacturing R-Co rare earth magnets, depending on the alloy component composition, for example, Sm-Co-Cu-F, -M
In the case of n-based, 3m-Co-Cu-Fe-Ti, etc., the solution treatment step in the sintering furnace can be omitted by controlling the operating conditions and cooling conditions of the melting step. . ■Appropriate particle size.

The magnetic powder whose particle shape has been adjusted is sent to the final magnetic discharge sintering step (2), which is the characteristic step of the present invention. Figure 2 shows an outline of the equipment in (2).

In Fig. 2, a metal material such as a yoke material is charged into a die 1 made of cemented carbide, etc., and a required amount of magnetic powder is charged onto the die 1 using upper and lower punches 2.3 or only the upper punch. While being pressurized and compressed by the press 8, it is magnetized in the magnetic field generated by the magnetic field generating coil 4, and at the same time, a direct current is applied by the power source 7 to carry out discharge sintering. Through this operation, a rare earth magnet sintered body integrally sintered with the yoke material is obtained. The pressure applied at this time needs to be 1 ton/ctir or more, and usually 5 tons or more is used. The current density ranges from several amperes/crA to several thousand amperes/-
degree is used. When carrying out the present invention, various methods such as applying electric current are possible, and a discharge sintering method for general metals is applicable.

For example, a method of superimposing direct current, alternating current, or high frequency components can be applied.

In the discharge sintering operation according to the present invention, unlike conventional sintering operations at high temperatures, the degree of orientation of the particles does not progress during sintering, so the stronger the applied magnetic field, the more the orientation of the particles increases. , the magnetic performance of the obtained compact is also improved.
It is desirable to apply a strong magnetic field. In the present invention, a pulsed magnetic field is normally used, and a magnetic field of 20 KOe or more is desired. Furthermore, the process of the present invention may be carried out by applying a low static magnetic field used for forming in a magnetic field when making a normal sintered magnet before the discharge operation. Further, at this time, the orientation of the raw material magnetic powder can be improved by applying appropriate vibrations.

Of course, the higher the pressure applied, the higher the density of the sintered body, and therefore the higher the magnetic performance.

The sintered body ■ obtained in this way has good precision and is usually 15
μ or less, and no post-processing is required.

This method can be used as a component without any adhesive operation, which is much more advantageous than conventional methods.

In carrying out the present invention, R-Fe-B with a low Curie point
When producing R-Co type rare earth magnets, it is necessary to perform a discharge sintering operation at a slightly lower temperature than that of R-Co type magnets.
It is possible to obtain a sintered body with high performance similar to the -Co type.

(Example) The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

Example 1 Sm 26.5% by weight, Fe6.7% by weight, C
L112.0% by weight, Mn1.5% by weight, balance CO
An alloy consisting of was obtained by vacuum melting. This alloy was solution-treated at 1200°C for 1 hour in an Ar gas atmosphere, then pulverized by a known pulverization method, and placed on a lower punch with a diameter of 20 m and a thickness of 1.
A # iron plate was charged into a mold, and 100OA/c was applied while applying a pressure of 10 tons/crA in a magnetic field of 30KOe.
A DC current of i was applied for 5 minutes, and a diameter of 20# and a thickness of 0 was
．． An integrally molded product with a 5# sintered body was obtained.

The dimensional accuracy of the integrally molded product is ±5μ in the radial direction and ±15μ in the thickness direction.
The torque resistance of the seizing surface of the iron plate and sintered body is 12Kg・
It was more than cm. The maximum energy product of the obtained sintered body was 15 MGOe.

Example 2 The alloy powder obtained in the same manner as in Example 1 was filled into a mold with an iron plate with a diameter of 50 m and a thickness of 1 M arranged on the lower punch,
A direct current of 1000 A/CIi was passed for 5 minutes while applying a pressure of 15 tons/crA in a magnetic field of 60 KOe to obtain an integral molded product with a diameter of 50 m and a thickness of 1#11 sintered body baked onto an iron plate. Dimensional accuracy is ±3μ in the radial direction and ±3μ in the thickness direction.
10μ, and the torque resistance of the seizing surfaces of the iron plate and the sintered body was 12 kg·cm or more. Moreover, its maximum energy product was 18 MGOe.

Example 3 An alloy having a composition of 33% by weight of Nd, 81.3% by weight, and the balance of Fe was obtained by vacuum melting. This was treated in the same manner as in Example 1, and the resulting alloy fine powder was placed in a mold with a diameter of 30#211.
．． It was packed on an iron plate with a thickness of 11M1 and heated at 1000 A/d while applying a pressure of 15 tons/d in a magnetic field of 60 KOe.
A DC current of 7 was passed for 2 minutes, and a diameter of 30 m and a thickness of 1 was applied to the iron plate.
An integrally molded product in which a sintered body of m was baked was obtained. The dimensional accuracy was ±5μ in the radial direction and ±15μ in the thickness direction, and the torque resistance of the seizing surfaces of the iron plate and the sintered body was 15Kg·m or more.

The maximum energy product of the obtained sintered body was 25 MGOe.

(Effects of the Invention) According to the present invention, a sintered body in which the yoke material and the sintering are integrated can be manufactured all at once by the magnetic field-directed pressure molding discharge sintering process, and post-processing, adhesion, etc. processes are not required. Since it can be used immediately as a component without having to do so, its industrial value is enormous.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing the manufacturing process of the present invention. FIG. 2 is a conceptual diagram of an apparatus used in the discharge sintering process. Applicant: Steel Chemical Industry Co., Ltd. (and 1 other person) Representative: Yuji Masuda Figure 1

Claims (1)

[Claims] When producing a permanent magnet sintered body containing rare earth elements, raw magnetic alloy powder is pressure-formed in a magnetic field and discharge sintered under the pressure, and at the same time the molded body is baked and integrated with a metal material such as a yoke material. A method for manufacturing a rare earth magnet, characterized by: