JPH02276208A - Permanent magnet - Google Patents

Abstract

PURPOSE:To improve the fluidity and the orientational property when a molding operation is conducted by a method wherein the rare-earth metal containing at least a kind of Nd and Pr, iron, boron and zirconium is formed into a specific thickness using a method of quenching in liquid. CONSTITUTION:The title permanent magnet of 100mum in thickness is formed by an alloy consisting of rare-earth metal (of a rare-earth element containing Y, at least a kind selected from Nd and Pr is included), iron, boron, zirconium and other impurities which is inevitable for the manufacture of the permanent magnet using a liquid quenching method. Also, a part of iron may be replaced with the transition metal group such as cobalt, copper and the like. Moreover, the above-mentioned magnet is pulverized into 100mum or smaller, and it is molded after mixing with resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a permanent magnet whose basic components are rare earth metals, iron, boron, and zirconium.

[Conventional technology]

Conventionally, the following rare earth-iron-boron resin bonded magnets have been devised.

(1) A quenched ribbon with a thickness of about 30 μm is made using a quenched ribbon manufacturing device used to produce an amorphous alloy, the ribbon is crushed, mixed with resin, and then molded into a magnet.

(References 1 and 2) (2) The quenched ribbon used in the method (1) above is subjected to mechanical orientation treatment by a two-step hot press method, the resulting compacted body is crushed, and after mixing with resin, A magnet formed in a magnetic field.

(Reference 2, Reference 3) Reference 1: JP-A-59-211549
Publication document 2: R, W, Lee: Appl, Phys
.

Let t, Vo 1.46 (8) 15 April
l 1985 p790 Document 3: Unexamined Japanese Patent Publication 1986-
No. 100402 Next, details of the above conventional method will be explained.

In the method (1), first, a quenched ribbon is produced at an optimal rotation speed of a quenched ribbon manufacturing apparatus. The obtained quenched ribbon with a thickness of about 30 μm is a collection of crystals with a grain size of 1 μm or less, is brittle and easily cracked, and the crystal grains are distributed in the same direction. Therefore, magnetic anisotropy is not obtained and the direction is isotropic.

However, IEEE TRANSACTIONSON
MAGNETICS VoloMAG-23, No.
5 SEPTEMBER1987p3605-360
As described in No. 6, a quenched ribbon in which columnar crystals are grown has an easy magnetization direction, and it is not impossible to produce a magnetically oriented quenched ribbon.

The above-mentioned quenched ribbon is pulverized, mixed with a resin, and then molded to obtain a resin-bonded magnet.

In method (2), the quenched ribbon is placed in a heat-resistant press mold in an inert atmosphere and compressed when it reaches a predetermined temperature. The pressure and temperature conditions at this time are 725±25℃, 1
．． Approximately 4 tons/c- is suitable. At this stage, the axis of easy magnetization of the magnet is generally equidirectional, although it is slightly oriented in the pressing direction. The second hot press is performed in a mold with a large area. Generally 700℃
, 0.7 ton/c- for several minutes. When the processing rate of the magnet reaches 50%, the axis of easy magnetization is oriented parallel to the pressing direction, and the magnet becomes anisotropic. The compacted body obtained above is crushed, mixed with a resin, and then molded in a magnetic field to produce an anisotropic resin-bonded magnet.

In addition, the crystal grains in the quenched ribbon before pressing should be made smaller than the grain size at which they exhibit their maximum coercive force, and the grains may coarsen during the subsequent hot pressing, resulting in the optimum grain size. Make sure that it becomes .

[Problem to be solved by the invention]

Although rare earth-iron-boron resin bonded magnets can be manufactured using the prior art described above, these manufacturing methods have the following drawbacks.

In method (1), the quenched ribbon used as the material for the resin-bonded magnet has a thickness of about 30 μm, and when it is crushed, the powder becomes scaly.

When scaly powder is used in injection molding, extrusion molding, etc., the fluidity of the compound decreases, productivity is poor, and it becomes difficult to manufacture products with complex shapes or thin walls. In order to compensate for these problems, it is possible to increase the mixing ratio of the resin, but this results in a decrease in magnet performance.

In method (2), hot pressing is performed in two stages, so it cannot be denied that it will be very inefficient when considering actual mass production. Such a manufacturing method with poor productivity increases costs and makes it impossible to take advantage of the advantages of rare earth-iron-boron magnets, which are made of relatively cheap raw materials.

The present invention solves the above-mentioned problems of the conventional technology by producing magnetic powder from a quenched ribbon with a thickness of 100 μm or more, improving fluidity and orientation during molding, and achieving high performance and low cost rare earth powder. The present invention provides an iron-boron resin bonded magnet.

[Means to solve the problem]

The permanent magnet of the present invention is manufactured by a liquid quenching method from an alloy consisting of a rare earth metal (including at least one of rare earth elements including Y, Nd, and Pr), iron, boron, zirconium, and other impurities that are unavoidable in manufacturing. and the thickness is 100μ
m or more. Further, a part of the above-mentioned iron may be replaced with a transition metal group such as cobalt and copper.

Furthermore, the magnet is pulverized to 100 μm or less, mixed with a resin, and then molded.

[For production]

The thin ribbon magnets conventionally used as raw materials for rare earth-iron-boron resin mixed magnets have a thickness of about 30 μm, and the reason for this will be explained below.

The properties of the quenched ribbon produced by the liquid quenching method vary greatly depending on the quenching speed during production, that is, the circumferential speed of the roll. At the optimum quenching rate that provides a high coercive force, the quenched ribbon is in a superimposed state of a fine crystalline phase and an amorphous phase, and this amorphous phase becomes a pinning site and a high coercive force is obtained.

On the other hand, the quenched ribbon that has been superquenched is in an amorphous or nearly amorphous state, so it hardly has any coercive force and cannot be used as a permanent magnet material as it is.

In addition, in a quenched ribbon that is insufficiently quenched, the crystal grains become coarser and only a small coercive force can be obtained.

As mentioned above, the quenching rate at which the quenched ribbon has a high coercive force is within a limited range, and the thickness of the quenched ribbon depends on the quenching rate, so it has not been used as a material for resin-bonded magnets until now. The thickness was about 30 μm.

In the present invention, by adding zirconium, coarsening of crystal grains is suppressed, and the quenching rate at which high coercive force is obtained is lowered, so that high coercive force can be obtained even in a quenched ribbon with a thickness of 100 μm or more.

By pulverizing the quenched ribbon having a thickness of 100 μm or more to 100 μm or less, a non-scaly magnetic powder can be obtained. When the above-mentioned powder is used as a material for resin-bonded magnets, the fluidity of the compound during molding improves, and it becomes easier to manufacture products with complex shapes and thin walls.

Furthermore, by controlling the quenching rate and using an oriented quenched ribbon in which columnar crystals are grown, an anisotropic resin-bonded magnet can be produced without going through a complicated process such as two-step hot pressing. In this case as well, if the quenched ribbon having the above shape is crushed to a size of 100 μm or less and used, the fluidity is similarly improved and the orientation during molding in a magnetic field is also good, resulting in a high-performance magnet.

Hereinafter, preferred compositions of the permanent magnet according to the present invention will be explained.

Rare earth metals include YSLa and Ce5Pr.

Nd, Sm5EuSGd, Tb5Dy% HO, ErS
'rm, yb, and Lu are listed as candidates, and among these, P'' and Nd exhibit particularly high magnetic properties, so Nd s
One type including at least one type of P r or a combination of two or more types is used. Therefore, in practical terms, Nd
, Pr, Pr-Nd5Ce-Pr-Nd, etc. are used. Furthermore, adding a small amount of heavy rare earth elements DY and Tb is effective in improving the coercive force.

Zirconium can be substituted for rare earth metals, and a high energy product can be obtained even with a low rare earth composition, so reducing the amount of rare earth metals can be expected to reduce costs and improve corrosion resistance.

Moreover, the Curie temperature can be increased by substituting a part of iron with cobalt.

〔Example〕

Next, examples of the present invention will be shown.

(Example 1) First, N d was melted in an argon gas atmosphere using a high-frequency melting furnace.
An ingot having a composition of 1oF e aoB5 Z r 5 was produced. Next, the ingot was sealed in a quartz test tube in an argon gas atmosphere, and the molten ingot was melted by induction heating and injected onto a copper roll having a diameter of 20 cm rotating at high speed to obtain a quenched ribbon.

Further, as a comparative example, a quenched ribbon was similarly produced with Nd+ and Fe5oBs compositions.

Table 1 shows the roll peripheral speed and the coercive force (iHe) of the quenched ribbon.
, indicates the thickness.

Table 1 As is clear from Table 1, compared to the comparative example, in the present invention, the quenching speed at which the maximum coercive force is obtained is shifted to the lower speed side, and even a quenched ribbon with a thickness of 100 μm or more has a high coercive force. It has been obtained.

(Example 2) Next, among the quenched ribbons of the present invention and the comparative example produced in Example 1, the one with the highest coercive force was 100%
It was ground to micrometers or less. At this time, the quenched ribbon that showed the highest coercive force in the present invention was produced at a roll circumferential speed of 5.2 m/s and had a thickness of 100 to 120 μm, and in the comparative example, the coercive force was 15.
It has a thickness of 30 to 40 μm and was produced at 7 m/s.

These two types of powder were mixed with 40% by volume of polyamide resin, and the viscosity was measured at 240°C. The viscosity of the compound of the present invention is 2.12X10' poise, which has good fluidity compared to the viscosity of the compound of the comparative example, which is 2.74X10' poise.

(Example 3) From the ingot of the present invention produced in Example 1, an anisotropic quenched ribbon in which columnar crystals grew at a roll circumferential speed of 3.1 m/s was produced. The thickness of this quenched ribbon was 130 to 150 μm. This quenched ribbon was pulverized to 100 μm or less to obtain magnetic powder, mixed with 15% by volume of epoxy resin,
Compression molding was performed in an applied magnetic field of KOe.

Further, as a comparative example, the same quenched ribbon was crushed to a size of 150 to 250 μm to obtain a scale-like magnetic powder, and a resin-mixed magnet was produced in the same manner.

The above two types of magnets were measured in the easy magnetization direction and the difficult magnetization direction, and the results are shown in Table 2.

〔Effect of the invention〕

As described above, according to the present invention, a thickness of 100 mm is produced by a liquid quenching method from an alloy made of rare earth metals, iron, boron, zirconium, and other impurities unavoidable in manufacturing.
When a thin strip magnet of 1 μm or more is crushed to 100 μm or less and used as a material for a resin-bonded magnet, the fluidity of the compound increases, making it possible to manufacture magnets with complex shapes and thin walls.

Further, by using the above-mentioned powder produced from a magnetically oriented quenched ribbon, it is possible to produce a high-performance resin-bonded magnet.

Applicant Seiko Epson Corporation Representative Patent Attorney Kisabe Suzuki (and one other person) The magnet has better orientation and higher performance than the comparative magnet using scaly powder. There is.

Claims (3)

[Claims] (1) A rare earth metal containing at least one of Nd and Pr;
A permanent magnet having a thickness of 100 μm or more and manufactured from an alloy consisting of iron, boron, zirconium, and other impurities unavoidable in manufacturing by a liquid quenching method. (2) The permanent magnet according to claim 1, wherein a part of the iron is replaced with a transitional metal such as cobalt or copper. (3) A permanent magnet obtained by pulverizing the ribbon magnet according to claims 1 and 2 to 100 μm or less, mixing it with a resin, and then molding it.