JPH10199717A - Anisotropic magnet and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow simple and low-cost manufacture by performing plastic working with a super quenched ribbon or powder to obtain a mass or powder with magnetic anisotropy. SOLUTION: A magnet alloy composition is rare earth-iron-boron system, with composition range represented as Rx Fe100-x-y-z Coy Bz (R is rare earth element containing Y, X=12.5-16, Y=0-10, Z=4.8-6.5). A supper quenched ribbon is plastic-deformed, through such processes as hi-frequency melting < super quenching with rotational roll, filling of a super quenched ribbon into a metal vessel, and hot single-axis compression of the metal vessel, to obtain an anisotropic magnet material. The temperature at that time is 650-900 deg.C. The compression ratio before/after uniaxial compression of the metal vessel h0/h1 (h0 is height of metal vessel before uniaxial compression, h1 is that after uniaxial compression) is 3.3-20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth-iron-boron anisotropic magnet and, more particularly, to a magnet alloy material, a resin-bonded magnet obtained by bonding and magnetizing the same with a resin binder, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Rare earth-iron-boron magnets have high magnetic performance and are therefore often used as motor components for OA equipment, AV equipment, and the like. Rare earth-iron-
Boron-based magnets are roughly classified into three types: sintered magnets, hot-worked magnets, and resin-bonded magnets. Sintered magnets are generally made according to the process described below. First, fine powder is obtained by finely pulverizing a rare earth-iron-boron alloy. Next, a green field is obtained by applying a magnetic field to the fine powder using a magnetic field press and pressing the crystal while aligning the c-axis direction of the crystal in one direction. Since the rare-earth-iron-boron-based material has an easy c-axis, the c-axis can be anisotropically strong in one direction by aligning the c-axis in one direction. Next, a strong anisotropic sintered magnet can be manufactured by increasing the density through a sintering step at a high temperature.

[0003] A hot-worked magnet is also a strong magnet whose c-axis is aligned in one direction and which has been densified through a hot working process such as hot pressing or extrusion. However, in this case, the mechanism for aligning the c-axis is different from that of the sintered magnet. For example, Journal of Material
s Engineering, vol. 11, no. 1,87
Rare earths as described on page 92 (1989).
The iron-boron-based magnet material has a characteristic that, even when the direction of the crystal is random, when plastic working is performed hot, the direction of the crystal is aligned with the direction in which strain is applied. A hot-worked magnet is manufactured by plastically deforming the material so as to have anisotropically strong magnetization in a predetermined direction using this characteristic. This manufacturing method is characterized in that it can be made anisotropic without applying a magnetic field. The former two sintered magnets and hot-worked magnets are characterized by a particularly high energy product, and are often used when a high magnetic flux density is required.

[0004] On the other hand, resin-bonded magnets are characterized by being excellent in shape flexibility and dimensional accuracy because they are manufactured in a process of molding after mixing magnet powder and resin binder. Many of the magnets used in motors for OA equipment and AV equipment require a thin wall and high dimensional accuracy. For these applications, rare-earth-iron-boron-based resin bonded magnets are often used. However, the rare-earth-iron-boron-based magnet powder for bond magnets currently used is a quenched powder of a rotating roll type, and is an isotropic magnet material having random crystal orientation. For this reason, the energy product is lower than that of an anisotropic sintered magnet or a hot-worked magnet in which crystals are aligned in almost one direction. In addition, due to the fact that the volume occupation ratio of the magnetic phase of the resin-bonded magnet is lower than that of the sintered magnet or the hot-worked magnet due to the presence of the binder, the energy product as the magnet is lower than that of the sintered or hot-worked magnet. 20-3
At present, it is only about 0%.

For this reason, many studies have been made to increase the energy product of the bonded magnet, and several techniques for increasing the energy product have been proposed. One example is the Journal of App
led Physics, Vol. 64, No. 10, 5293-
There is a resin-bonded magnet using a pulverized powder of a rare-earth-iron-boron-based hot-worked magnet as disclosed on page 5295 (1988). In this method, first, a rare-earth-iron-boron-based quenched powder is produced by a rotating roll method, and then the quenched powder is densified by a press or the like, and is further plastically deformed at a high temperature to make magnetic anisotropy. It is what makes it happen. In order to make this a bonded magnet, it is necessary to pulverize the anisotropic alloy mass, mix it with a resin binder, and mold it. According to this method, it is possible to obtain an anisotropic bonded magnet having a higher energy product than an isotropic bonded magnet. However, as described above, this method requires complicated steps of high density and plastic working for anisotropy, and further requires a pulverizing step for forming a bonded magnet. As described above, the anisotropic means for increasing the energy product of the bonded magnet requires a complicated process at present and has a problem that the cost is high. Development of an anisotropic process is desired.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rare earth-iron-boron based bonded magnet material having a high energy product and to obtain a rare earth-iron-boron based magnet material having a high energy product. Another object of the present invention is to provide a simple and inexpensive manufacturing method.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that rare earth-iron-
Fill a metal container with a boron-based super-quenched ribbon or powder,
The present inventors have found that a magnet material having high magnetic performance can be produced by a simple process of uniaxially compressing with heat, and the present invention has been completed.

That is, the magnet material of the present invention is a lump or powder obtained by subjecting a super-quenched ribbon or powder to plastic working, and is characterized by having a magnetic anisotropy. It is a system anisotropic magnet material.

The resin-bonded magnet of the present invention is a resin-bonded magnet produced by mixing the above rare earth-iron-boron-based magnet material and a resin binder and then molding.

[0010] The magnet alloy composition of the present invention is basically a rare earth-iron-boron system, and more specifically, the composition formula R _x Fe
_{100-x-y-z Co} y B z ( where a rare earth element R, including the Y, x is 12.5 to 16, y = 0 or 1
0 or less, z = 4.8 or more and 6.5 or less).

Alternatively, the magnet alloy composition of the present invention is a rare earth-iron-boron-T system, and more specifically, the composition formula R _x F
_{e 100-x-y-z} -w Co y B z T w ( wherein, R
Is a rare earth element containing Y, and T is Ga, Si, Al, C, N
one or more selected from i, Cu, Zn, In, Mn, Nb, Ta, and Ti; x = 12.5 to 16; y = 0 to 10; z = 4.8 to 6.5; Less than,
w = 0 or more and 1 or less).

The method for producing a magnetic alloy powder of the present invention is obtained by filling a rare earth-iron-boron-based ultra-quenched ribbon or powder into a metal container and uniaxially compressing the metal container at a temperature of 650 ° C to 900 ° C. This is a method of manufacturing a magnet material to be used. Here, the uniaxial compression means that a force in a direction substantially perpendicular to the two surfaces is applied to two surfaces opposed to each other substantially parallel to each other in a state where other external force is not applied to the object as much as possible. Refers to compressing the distance.

In the above manufacturing method, when the length of the metal container in the direction of uniaxial compression is h and the area of the bottom surface of the metal container on which a compressive force acts is s, h / h It is preferred that s is 0.1 to 5.0. When the length of the metal container in the uniaxial compression direction before uniaxial compression is h0 and the length of the metal container in the uniaxial compression direction after uniaxial compression is h1, the compression ratio before and after uniaxial compression of the metal container is defined as h1. (H0 / h1) is preferably from 3.3 to 20.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a magnet material and a resin-bonded magnet according to the present invention will be described in detail. The magnet alloy composition in the present invention is basically a rare earth-iron-boron system, and specifically needs to be in a composition range represented by the following formula. _{R x Fe 100-x-y} -z Co y B z ( where a rare earth element R, including the Y, x = from 12.5 to 1
6, y = 0 to 10, z = 4.8 to 6.5)

If R is less than 12.5, the workability in the plastic working step is remarkably deteriorated, the degree of anisotropy is small, and the coercive force of the finally obtained magnet is too small to be practical. When R exceeds 16, the magnetization decreases,
As a result, the energy product decreases. The addition of Co has the advantage that the Curie temperature rises and heat resistance improves. However, when y exceeds 10, magnetization decreases, which is not preferable. The B amount is preferably in the range of 4.8 to 6.5. If it is less than 4.8, the coercive force is too low to be practical. If the amount of B exceeds 6.5, plastic working becomes difficult.

It is effective to add a small amount of element T to improve any of the magnetic properties such as coercive force, residual magnetization, and maximum energy product. As T,
Ga, Si, Al, C, Ni, Cu, Zn, In, M
n, Nb, Ta, and Ti. At this time, the effect differs depending on the type of the additive element. For example, Ga, Si, A
1 and the like improve the residual magnetization, and Cu and Zn improve the coercive force. Therefore, these additional elements and their amounts may be selected so as to obtain desired magnetic properties. The magnet alloy composition at this time is preferably in a composition range represented by the following formula. _{R x Fe 100-x-y} -z-w Co y B z T w ( wherein, R is rare earth element including Y, T is Ga, Si,
Al, C, Ni, Cu, Zn, In, Mn, Nb, T
a, one or more selected from Ti, x = 12.
5-16, y = 0-10, z = 4.8-6.5, w = 0
~ 1)

If the amount w of T exceeds 1, the decrease in magnetization is undesirably large. Even if a trace amount of elements such as N, O, F, Mg, P, S, Ca, etc. which are inevitably mixed during the manufacturing process, the influence on the magnetic properties is small.

The anisotropic magnet material of the present invention comprises (1) high-frequency melting, (2) ultra-quenching by a rotating roll, (3) filling a super-quenched ribbon into a metal container, and (4) hot metal container. Can be manufactured through the steps of uniaxial compression. The resin-bonded magnet made of this magnet material can be manufactured through the steps of (5) mixing a resin binder, (6) compression press molding in a magnetic field, or injection molding in a magnetic field, following the above steps. The respective steps will be described below.

(1) High frequency melting A raw material alloy is prepared so as to have a desired composition, and filled into a nozzle made of alumina or quartz having a circular hole at the bottom and then melted by high frequency. A preferable melting temperature range at this time is about 1400 to 1600 ° C. In addition, in order to prevent oxidation of the alloy, it is preferable to use an inert atmosphere such as Ar, He or vacuum during melting.

(2) Ultra-Quenching by Rotating Roll A metal roll of Cu, Fe or the like is rotated, and a molten alloy is injected into the roll to be rapidly cooled and solidified. In the resulting super-quenched ribbon, the Nd ₂ Fe ₁₄ B crystals are isotropic and oriented in random directions. In order to effectively perform the subsequent plastic working, it is desired to appropriately reduce the crystal grain size of the ribbon after ultra-quenching to about 0.1 nm to 1 μm. In order to obtain an appropriate crystal grain size, the range of the peripheral speed of the roll is preferably set to 15 to 35 m / sec.

(3) Filling the super-quenched ribbon into a metal container The super-quenched ribbon is filled into a metal container. The type of metal used for the container is not particularly limited. For example, Fe-based metal materials such as mild steel and stainless steel, Cu, Ni, Al,
Examples include Ti, Cr, Mn, and Co-based metal materials and alloys made of these materials. Since the subsequent uniaxial compression is performed at a temperature of 650 ° C. or higher, low melting point metals such as Zn and In which melt in this temperature range are not suitable as containers. The shape of the metal container is preferably cylindrical or rectangular parallelepiped. At this time, it is preferable that the height / bottom area ratio (h / s) of the metal container is 0.1 to 5.0. If it is less than 0.1, the plastic working of the Nd-Fe-B super-quenched ribbon by uniaxial compression is insufficient, and the anisotropy is not satisfactorily performed. If it exceeds 5.0, buckling of the container tends to occur during uniaxial compression, and effective plastic working cannot be performed. The filling amount of the super-quenched ribbon in the container is 1 to 4 g as a bulk density.
/ Cm ³ is preferable. If it is less than 1 cm ³ , effective plastic working cannot be performed by subsequent uniaxial compression. Also, 4g /
Filling more than cm ³ is time-consuming and impractical. It is effective to vacuum the inside of the container after filling the ultra-quenched ribbon or to fill the container with a gas such as nitrogen or argon to form an inert atmosphere, in order to prevent oxidation of the ribbon.

(4) Hot uniaxial compression The metal container is compressed by hot uniaxial pressing, and the super-quenched ribbon is plastically deformed to obtain an anisotropic magnet material. The temperature at this time needs to be 650 to 900 ° C. If the temperature is lower than 650 ° C., the energy product of the magnet material which cannot be sufficiently anisotropically formed is low. Also, 9
If the temperature exceeds 00 ° C., the coercive force of the material decreases, so that it is not practical. Various methods for heating the container, such as heating with a resistance furnace and high-frequency heating, can be considered. The compression ratio (h0 / h1) before and after uniaxial compression of the metal container is preferably 3.3 to 20. Here, h0 is the height of the metal container before uniaxial compression, and h1 is the height of the metal container after uniaxial compression. If the compression ratio is less than 3.3, the anisotropy is insufficient,
Also, it is difficult to compress beyond 20 due to the performance of an actual device.

The magnet alloy powder of the present invention can be produced by the above steps. In order to produce a bonded magnet using this, subsequently, resin binder mixing and molding in a magnetic field are performed. Hereinafter, these steps will be described.

(5) Resin Binder Mixing The resin binder mixed with the magnetic alloy powder of the present invention is not particularly limited. For example, a thermosetting resin such as an epoxy resin or a phenol resin, or a thermoplastic resin such as a nylon resin. And the like. Epoxy resin is used when performing compression molding. The amount of epoxy for obtaining good magnetic properties is about 1 to 5% by weight based on the magnet powder.
It is also effective to mix a silane-based or Ti-based coupling agent or a lubricant such as a stearate at the same time when mixing the resins.

Nylon resin is used for injection molding or extrusion molding. The amount of nylon for obtaining good magnetic properties is about 4 to 8% by weight based on the magnet powder.
Also in this case, it is effective to add a coupling agent, a lubricant and the like at the time of resin mixing.

(6) Compression molding in magnetic field, injection molding in magnetic field A resin bonded magnet can be obtained by compression molding or injection molding while orienting magnet alloy powder mixed with resin in a magnetic field. In order to sufficiently orient the magnet powder, it is preferable to generate a magnetic field of preferably 8 kOe or more, more preferably 10 kOe or more. In the case of compression molding, a curing treatment of the epoxy resin is performed at a temperature of about 150 ° C. after molding.

[0027]

The present invention will be described in more detail with reference to the following examples.

Example 1 Nd _13.31 Fe _74.98 Co _6.08 B _5.63
Is filled into a quartz nozzle having a circular hole with a diameter of about 0.5 mm at the bottom, heated to about 1500 ° C. and melted, and then the molten metal is rotated at a peripheral speed of 24 m / sec. It was spray-solidified on one roll to obtain a super-quenched ribbon. The ribbon has a thickness of 2 mm, an inner diameter of 20 mm, and a height of 50 m.
m was filled into a cylindrical mild steel container having a capacity of 20 g. After filling, the vessel was evacuated and sealed. Next, the container was placed in a box-type resistance furnace for 1 hour.
After holding for 0 minute and heating to 800 ° C., the container was taken out of the furnace and immediately pressed by a uniaxial press so that the compression ratio became 2.5. After the compression, the mild steel container was cooled to room temperature, and a massive Nd—Fe—B material was separated from the container. The massive Nd-Fe-B material was ground to 300 mm or less, and the obtained powder was solidified with wax while being oriented in a magnetic field of 15 kOe to obtain a sample for measuring magnetic properties. Vibration sample type magnetometer (VS
M), the remanent magnetization (Br) was 12.5 kG and the coercive force (iHc) was 16.
3 kOe, and Br is 1.4 for the hard axis.
kG and iHc were 8.9 kOe. Next, an epoxy resin was mixed with the magnet powder at a ratio of 2% by weight.
The mold filled with the mixture was set in a magnetic field press, and
A compression molded body was obtained by pressing at a pressure of 10 ton / cm2 while applying a magnetic field of 5 kOe while orienting the particles. This molded body was heated at 150 ° C. for 1 hour in an Ar atmosphere to cure the epoxy resin, thereby obtaining a compression-molded resin bonded magnet. As a result of measuring the magnetic properties of the obtained resin-bonded magnet with a BH tracer, Br was 8.9 k.
G, iHc is 16.2 kOe, maximum energy product ((B
H) max) was 17.2 MGOe.

Comparative Example 1 An alloy having the same composition as in Example 1 was prepared in the same manner as in Example 1 to obtain C
The ribbon was obtained by spray-solidifying the molten metal on the u-piece roll. The obtained ribbon was crushed to 300 mm or less, and the magnetic properties were measured in the same manner as in Example 1. As a result, Br was 2.8 kG for the easy axis, 5.8 kOe for iHc, and Br for the hard axis. Is 2.9 kG, iHc
Was 5.8 kOe, which was a material having isotropic and low characteristics.

Example 2 The ultra-quenched ribbon obtained in Example 1 was uniaxially compressed under the conditions shown in Table 1, and the obtained Nd—Fe—B material was used to produce a bonded magnet in the same manner as in Example 1. . Table 1 shows the magnetic properties of the obtained bonded magnet.

[0031]

[Table 1]

Example 3 An ultra-quenched ribbon having the composition shown in Table 2 was produced in the same manner as in Example 1, and the container was filled, uniaxially compressed, and a bonded magnet was produced under exactly the same conditions as in Example 1. Table 2 shows the magnetic properties of the obtained bonded magnet.

[0033]

[Table 2]

[0034]

According to the method of manufacturing an anisotropic magnet according to the present invention, the anisotropic magnet can be made magnetically anisotropic by a simpler process than before. In terms of magnetic characteristics, it is possible to provide a magnet having higher characteristics than before.

Claims (7)

[Claims] 1. A rare earth-iron-boron anisotropic magnet material, which is a lump or powder obtained by subjecting a super-quenched ribbon or powder to plastic working and has magnetic anisotropy. 2. A resin-bonded magnet produced by mixing the rare-earth-iron-boron-based magnet material according to claim 1 and a resin binder, followed by molding. 3. The composition formula R _x Fe _100-xyz Co
_y B _z (where a rare earth element R, including the Y, x is 12.
The rare-earth-iron-boron-based anisotropic magnet alloy powder according to claim 1, having a composition represented by 5 to 16; y = 0 to 10; z = 4.8 to 6.5). 4. The composition formula R _x Fe _100-xyzw
Co _y B _z T _w (provided that the rare earth element R, including a Y, T
Is Ga, Si, Al, C, Ni, Cu, Zn, In, M
one or more selected from n, Nb, Ta, and Ti; x = 12.5 to 16; y = 0 to 10;
2. The rare earth-iron-boron anisotropic magnet alloy powder according to claim 1, having a composition represented by the formula: z = 4.8 to 6.5, w = 0 to 1). 5. A metal container is filled with a rare-earth-iron-boron-based super-quenched ribbon or powder, and the metal container is heated to 650 ° C. to 9 ° C.
2. The method according to claim 1, wherein the material is uniaxially compressed at a temperature of 00.degree. 6. The length of the metal container in the uniaxial compression direction is h.
The h / s of the metal container before compression is 0.1 to 5.0, assuming that the area of the bottom surface of the metal container on which the compressive force acts is s, and the h / s is 0.1 to 5.0. Production method. 7. The uniaxial compression before and after uniaxial compression of the metal container before uniaxial compression is defined as h0, and the length of the metal container after uniaxial compression in the uniaxial compression direction is defined as h1. The method according to claim 5, wherein the compression ratio (h0 / h1) is 3.3 to 20.