JPS60224722A - Manufacture of anisotropic composite magnet - Google Patents

Abstract

PURPOSE:To manufacture an anisotropic composite magnet having high magnet characteristics by specifying the average particle size of powder of an R2T17 type magnet alloy so as to improve the orienting property of the grains of a magnet when the powder is mixed with a binder, hardened and formed in a magnetic field. CONSTITUTION:An R2T17 type magnet alloy (R is Y and a rare earth element and T is a transition metal) is crushed, and the resulting powder is mixed with a polymer, hardened and formed in a magnetic field to manufacture a polymer-alloy composite magnet. In this method, the magnet alloy is crushed so as to regulate the average particle size of the resulting powder to <=90% of the average grain size of the grains of the magnet alloy. The orienting property of the manufactured magnet is improved to increase the anisotropy and to provide high magnet characteristics.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a polymer composite magnet.

In particular, it relates to a manufacturing method using rare earth cobalt magnet powder.

[Prior art]

Polymer composite magnets are made by dispersing magnetic powder in polymer resin, and have various characteristics not found in cast magnets, sintered magnets, etc., such as elasticity and ease of processing. It is used in the direction of.

However, since this magnet is made of magnetic powder and non-magnetic resin, it has a disadvantage in that its magnetic properties are lower than that of sintered magnets and the like. Therefore, by making the powder anisotropic by orienting it in a magnetic field.

We are trying to achieve high magnetic properties.

The present invention aims to improve the magnetic properties of a polymer composite magnet using a rare earth magnet of the R2T17 system, which is characterized by high Br among rare earth cobalt magnets with excellent magnetic properties.
This was achieved through the manufacturing method.

Conventional R2T17-based rare earth magnet composite magnets are manufactured by melting raw materials, aging an alloy ingot, and then pulverizing it, mixing the powder with polymer resin, and molding it. . In this case, there is a general tendency to increase the mixing ratio of the magnet powder to the resin and increase the particle size of the powder in order to improve the magnetic properties. Since magnetic alloys are mainly composed of expensive metals, the magnets become expensive along with their magnetic properties. Furthermore, there is a manufacturing upper limit for the mixing ratio of polymer resin and powder, for example, up to about 90 inches for combs and up to about 93 inches for nylon. Therefore, the magnetic properties of conventional magnets of this type have reached a plateau. However, in spite of this, there is a strong desire to improve the characteristics of this type of magnet.

[Purpose of the invention]

Therefore, an object of the present invention is to obtain an anisotropic composite magnet with improved magnetic properties regardless of the mixing ratio of magnet alloy powder.

[Structure of the invention]

In order to achieve the above object, the present invention improves the orientation of magnet particles by reducing the diameter of crushed magnet alloy powder, contrary to the conventional method.

That is, according to the present invention, an R2T17 magnet alloy is pulverized to form a powder, the obtained powder is mixed with a polymer resin,
In the method of manufacturing a polymer composite magnet by hardening and molding in a magnetic field, the step of pulverizing to form a powder is such that the average particle size of the obtained powder is the R2T, the average grain of the crystal grains in the 7-series magnet alloy. There is obtained a method for manufacturing an anisotropic composite magnet characterized by a step of crushing the magnet until it has a diameter of 90 inches or less.

〔Effect of the invention〕

The anisotropic composite magnet obtained by the method of the present invention is as follows.

By improving the orientation of the magnet particles, it becomes highly anisotropic and provides excellent magnetic properties without increasing the price.

It is very useful industrially.

〔Example〕

Sm is 25 wL%, Fe is 15.5 wL%, C
u is 9wt%.

The raw materials were adjusted so that Zr was 1.5 wt% and the balance was Co, and the ingots were bath-dissolved by high-frequency heating in an argon atmosphere to produce two types of ingots with average crystal grain sizes of 50 μm and 30 μm at the end of the heat treatment. I got it. However, the two types of crystal grain sizes were obtained by changing the cooling rate of the molten metal.

Next, the ingot thus obtained was subjected to solution treatment at 1180°C for 2 hours and then held at 800°C for 1 hour.

It was cooled to 300°C at a rate of 1°C per minute. The heat-treated ingots were each ground in a ball mill to obtain ingots having an average particle size of 7 to 60 μm. Each of these magnet powders is kneaded with 8 wt% of nylon 12 (trade name), and then injection molded at high temperature in a magnetic field of 15 KOe to produce a polymer composite magnet.

The crystal grain size is measured using an electron microscope or a metallurgical microscope, and the powder particle size is measured using a gas permeation method.

The figure shows the magnetic properties of the polymer composite magnet obtained as described above, such as energy product (B) (), residual magnetic flux distribution ax degree Br, and coercive force xHc, sHC, compared with conventional ones. It is. A solid line connecting circles indicates a case where the average crystal grain size of the ingot is 50 μm, and a broken line connecting triangle marks indicates a case where the average crystal grain size of the ingot is 30 μm. As you can easily see from the figure, if the crystal grain size is 50 μm, and the powder grain size is 40 μm, Br and (BH)
The powder particle size has been improved by 2.
Similarly, if it is 5 μm or less, Br.

(BH) is getting larger. Other properties are less pronounced than the above two.

Summarizing the above characteristics, it can be seen that the magnetic characteristics are significantly improved when the average particle size of the magnetic powder is set to 90% or less of the average crystal grain size of the ingot. This effect can be obtained because if the average particle size of the powder is made smaller than the average crystal grain size and the powder is made into a single grain of magnet, the magnet powder becomes smaller when mixed with polymer resin and molded in a magnetic field. This is because the magnetic orientation of the particles becomes much easier to align than in the past.

Note that the lower limit of the effective particle size is not particularly indicated.

This does not mean that there is no lower limit, and although it can be estimated from the figure that the effective particle size spans a range equivalent to 5 μm or less, in terms of crushing efficiency, the average particle size should be considerably lower than several μm. This is because doing so does not make much sense from an industrial standpoint.

The above describes only the Sm-Co-Fe-Cu-Zr alloy, but the present invention essentially involves grinding an isotropic polycrystalline magnet and making the magnet powder particles anisotropic. This is about polymer composite magnets.

Only R2Tj7 magnets (, SmCo5 magnets and Ba
It can be easily inferred that the present invention can also be applied to the case where a ferrite magnet, typified by a 0.6Fe203 + SrO'6Fe205 magnet, is used as magnet powder.

[Brief explanation of drawings]

The figure shows the magnetic properties of the rare earth cobalt composite magnet in the second embodiment of the present invention in terms of the relationship between the average particle size of the ingot and the average particle size of the crushed ingot. , D', 9' Agent (7127) ButtFl! l, Yosuke Goto ・1,・
・；−、：：、'、−' Figure 10-1 Shikiki no Hirayuki Kobokizui diameter W/JJrL crushed average grain iron (μ hire)

Claims (1)

[Claims] 1, R2T1. A system magnetic alloy (herein, R represents yttrium and rare earth elements, T represents a transition metal) is pulverized to form a powder, the resulting powder is mixed with a polymer resin, and is hardened and molded in a magnetic field to form a polymer. In the method for manufacturing a composite magnet, the step of pulverizing to produce powder includes pulverizing until the average particle size of the obtained powder is 90% or less of the average particle size of the crystal grains in the R2T17-based magnet alloy. 1. A method for manufacturing an anisotropic composite magnet, which is characterized by a process of: