JPS63155603A - Manufacture of bond magnet - Google Patents

Abstract

PURPOSE:To obtain a bond magnet which has high saturation magnetization and residual magnetic flux density by mixing a fatty acid with rare earth magnet powder, by treating the mixture after forming it in a magnetic field and then by curing and solidifying it by impregnating it with a bond agent. CONSTITUTION:A fatty acid of weight of 6 weight % or less of magnet powder is mixed as a forming assistant with the 2-17 system rare earth magnet powder of coercive force 6 kOe or less before an aging treatment. After the mixture is formed in a magnetic field, the obtained compact is subjected to aging. Then, the compact is impregnated with a bonding agent and is cured. Then, the friction among the magnet powder is reduced, the orientation is improved and the magnet powder is densely packed. This enables obtaining a bond magnet which has high saturation magnetization and residual magnetic flux density.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for manufacturing a bonded magnet in which magnet powder is bonded using a resin binder, and more specifically, it relates to a method for producing a bonded magnet in which magnetic powder is bonded using a resin binder. 2-17 in low coercive force state before treatment
The present invention relates to a method for manufacturing a bonded magnet, in which the bonded magnet is mixed with a rare earth magnet powder, molded in a magnetic field, and then subjected to an aging treatment, impregnated with a binder, and solidified.

[Prior Art] Bonded magnets in which rare earth magnet powder is composited with a binder are conventionally known. As the binder, in addition to thermoplastic or thermosetting resins, metals, alloys, or glass-based inorganic substances are used. and compression,
It is manufactured by various molding methods such as injection, extrusion, and rolling, but compression molding is generally used to produce a high energy product.

Such rare earth bonded magnets have advantages such as high magnetic properties, excellent mass production, easy dimensional accuracy, and a large degree of freedom in shape, and are rapidly being used in a variety of applications in recent years.

In the conventional manufacturing method of rare earth bonded magnets, for example, as shown in FIG. 2, in the compression molding method, an alloy as a raw material is first crushed, molded and sintered, and then subjected to an aging treatment as it is.

After pulverizing the powder, the aged powder is kneaded with a binder, formed in a magnetic field, and the binder contained therein is generally cured.

[Problems to be Solved by the Invention] In order to sufficiently orient the magnetic powder when molding is performed in a magnetic field, the strength of the applied magnetic field must be 4 to 5 times the coercive force of the raw material, the magnetic powder. It is said that more than that is necessary. For this reason, in the prior art, for example, in the case of Sm2Co+7 bonded magnets, a strong magnetic field of 40 to 50 kOe or more must be applied during molding.

However, the strength of the magnetic field obtained with the currently widely used magnetic press equipment cannot satisfy the above values (generally, the magnetic field that can be applied on the production line is about 15 kOe).
In actual magnetic field forming, raw material powder cannot be oriented sufficiently.

In order to solve such problems, the present inventors proposed a method in which magnet powder having a coercive force of 6 kOe or less before being subjected to aging treatment is first formed in a magnetic field, and then subjected to aging treatment. This method has the advantage of being able to easily produce bonded magnets with high properties because the magnet powder can be sufficiently oriented with a low magnetic field during molding. However, even if such a manufacturing method is adopted, its (BH)max (maximum energy product) remains at about half the value compared to a fired crystal. In order to further improve this magnetic property, it is necessary to further improve the filling rate of the magnet powder and the degree of orientation.

Therefore, a method of adding a molding aid before molding to make it easier to mold and then molding in a magnetic field can be considered, but in the method proposed by the present inventors, the magnetic powder is made to have a high coercive force after being molded in a magnetic field. Therefore, aging treatment must be carried out at a high temperature of about 400 to 1000° C., and it has been found that depending on the type of molding aid used, the (BH)max may be lowered. This is because the squareness of the hysteresis loop deteriorates depending on its type.

The purpose of the present invention is to eliminate the drawbacks of the prior art as described above, and to perform molding in a magnetic field using magnet powder with a coercive force of 6 kOe or less before aging treatment, as previously proposed by the present inventors. Later, the aging treatment method was further developed to improve the filling rate, increase the degree of orientation, and use a forming aid that did not deteriorate the squareness, making it possible to further improve the magnetic properties. An object of the present invention is to provide a method for manufacturing a bonded magnet.

[Means for Solving the Problems] The present invention, which can achieve the above objects, uses 2-17 rare earth magnet powder with a coercive force of 6 kOe or less before aging treatment as a forming aid. This is a method for manufacturing a bonded magnet in which fatty acids are mixed, molded in a magnetic field, aged, then impregnated with a binder, cured, and solidified.

The raw material 2-17 rare earth magnet powder is Rz T
M I 7 (However, R is Sm or Ce containing Y.

The main component is one or more rare earth elements such as Pr and Nd, and TM is one or more transition metal elements such as Fe, Co, and Ni. Such raw materials are usually produced by grinding an alloy with a predetermined composition;
It is obtained by molding into a certain shape, sintering it, and, if necessary, subjecting it to solution treatment under predetermined conditions.

In 2-17 rare earth magnets, precipitation hardening occurs due to aging treatment and a high coercive force appears. The present invention effectively utilizes this phenomenon.

As shown in FIG. 1, in the present invention, the raw material sintered body as described above is first pulverized. The magnet powder thus obtained has not been subjected to aging treatment and has a low coercive force of 6 kOe or less. The reason for using such low coercive force magnet powder is the result of various experiments conducted by the present inventors on the relationship between the coercive force of magnet powder before magnetic field forming and the magnetic properties of bonded magnets after aging. , if a bonded magnet is manufactured using magnet powder with a coercive force of 6 kOe or less, the method of the present invention has much better magnetic properties, especially B
This is due to the discovery that r and (B H)max become good.

Then, a fatty acid is used as a molding aid, and the fatty acid is mixed with the magnetic powder. Fatty acids have carboxyl groups (-COO
H) is an organic compound R-Cool in which R has a chain hydrocarbon group.

Typical examples include caproic acid, lauric acid, myristic acid, stearic acid, oleic acid, and linoleic acid. The reason why the amount of forming aid is 6% by weight or less of the magnet powder is that in order to obtain a bonded magnet exhibiting high magnetic properties, here high 13r and high (BH) max, the magnet powder in the magnet is This is because the larger the proportion occupied by , the more preferable it is.

Incidentally, if the amount exceeds 6% by weight, the magnetic properties will be lower than when no molding aid is used.

Next, this mixture is molded in a magnetic field and subjected to an aging treatment while maintaining the molded shape to develop a high coercive force.

After that, it is impregnated with a thermosetting synthetic resin such as epoxy resin, phenol resin, or acrylic resin, and then cured.

[Function] In the present invention, by mixing a molding aid before molding, it fills the gaps between the magnet powders and also serves as a lubricant.

This reduces friction between the magnet powders, improves orientation, and makes it possible to densely pack the magnet powders.

In addition, since fatty acids are used as molding aids, even if the magnet powder is aged at high temperatures at the same time, they will be smoothly heated and scattered and will not have any adverse effect on the magnetic properties of the resulting product.

Furthermore, in the present invention, since magnetic field compaction is performed using magnet powder in a low coercive force state before aging treatment, sufficient orientation can be achieved even using a magnetic field press device that is generally used on a production line, and high Magnetic properties can be generated.

Note that the effects of the present invention will be even greater if magnetic powder whose particle size has been adjusted is used.

[Example] S m (Co o, 68F e o, zo
Cuo, +.

Z r o, oz) The alloy in a low coercive force state indicated by q, q is crushed with a show crusher to an average particle size of 200 μm.
Magnet powder was obtained. Next, 2% by weight of fatty acid was added as a molding aid to this magnetic powder, mixed, and compression molded at 3 ton/am'' in a magnetic field of 15 kOe.

Next, the molded body was subjected to an aging treatment at 800° C. for 1 hour to increase the coercive force. Then impregnated with epoxy resin 1
A bonded magnet was obtained by performing a curing treatment at 20° C. for 2 hours.

Here, oleic acid and linoleic acid were used as molding aids.

Further, as comparative examples, bonded magnets were manufactured using the same procedure in cases where an epoxy resin was used as a molding aid and in cases where no molding aid was used.

Furthermore, as a conventional example, 1 at 800℃ for an alloy with the same composition.
After aging to increase the coercive force, it is crushed with a show crusher to give an average particle size of 200 μm, and after kneading with epoxy resin, it is crushed to 3 tons/cm in a 15 kOe magnetic field.
A bonded magnet was produced by compression molding and curing at 120°C for 2 hours.

Table 1 shows the results of measuring the magnetic properties and density of each of these samples.

(The following is a blank space) Table 1 As can be seen from the comparative examples in Table 1, when an epoxy resin is mixed as a molding aid, the magnetic properties are rather lower than when no molding aid is added. In other words, although the density can be increased by using a molding aid, it does not necessarily improve the magnetic properties (BH) max.

If the method of the present invention is applied to these, it is possible to produce magnetic properties that are far superior not only to the conventional method but also to those of the comparative example.

[Effects of the Invention] The present invention comprises molding magnet powder that undergoes precipitation hardening through aging treatment in a magnetic field in a low coercive force state before precipitation hardening, as described above;
This method then hardens the magnetic powder by precipitation while retaining its shape, and produces a high coercive force.It uses a molding aid, making it possible to highly fill and highly orient the magnetic powder, and also uses fatty acids as a molding aid. Therefore, even if the molding aid is aged at high temperatures after molding, it will not have a negative effect on the squareness, and has the excellent effect of making it possible to manufacture bonded magnets with high saturation magnetization and residual magnetic flux density. arise.

[Brief explanation of the drawing]

FIG. 1 is a process explanatory diagram showing an example of the manufacturing process of a bonded magnet according to the method of the present invention, and FIG. 2 is a process explanatory diagram showing an example of the conventional technique. Patent applicant: Fuji Electrochemical Co., Ltd. Representative: Minoru Shigeru Figure 1: Figure 2: Akira

Claims (1)

[Claims] 1. 2-1 with coercive force of 6 kOe or less before aging treatment
7 series rare earth magnet powder is mixed with 6% by weight or less of fatty acid of the magnet powder as a molding aid, and after molding in a magnetic field, the obtained molded body is aged, and then impregnated with a binder and cured. A method for manufacturing a bonded magnet, characterized by: