JPH10189320A - Anisotropic magnet alloy powder, and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rare earth-iron-boron anisotropic magnet alloy powder of high energy product by a method wherein in a flaky powder manufactured by a single roller type quenching magnetization of the flake is made larger in the thickness direction than in the longitudinal direction. SOLUTION: A material alloy is prepared so as to be, in composition, 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), or, Rx Fe100-x-y-z-w Coy Bz Tw (R is rare earth element containing Y, T is one or more kinds selected among Ga, Si, Al, C, Ni, Cu, Zn, In, Mn, Nb, Ta, Ti, x=12.5-16, y=0-10, z=4.8-6.5, w=0-1), and then filled in a nozzle of alumina or quartz provided with a circular hole at its bottom, for high-frequency melting. Then with such single rollers as Cu, Fe, etc., rotated, a molten alloy is jetted to the roller for rapid cooling for solidification, then quenched to be solidified, and the quenched and solidified ribbon is continuously plastic ally processed to give magnet powder.

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 powder of a magnet alloy and a resin-bonded magnet obtained by binding and magnetizing the powder with a resin binder.

[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 manufactured 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. The rare-earth-iron-boron-based magnet material has a characteristic that, even when the direction of the crystal is random, if plastic working is performed hot, the direction of the crystal is aligned with the direction in which strain is applied. At this time, it is considered that the temperature of the plastic working is preferably in the range of 500 to 900 ° C. in order to align the direction of the crystal in one direction. 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 it magnetically anisotropic. 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, and a manufacturing apparatus therefor.

[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-
By a simple process of continuously performing quenching and solidification by injecting a molten boron-based alloy onto one roll and plastic working of a rare earth-iron-boron ribbon generated by the solidification, it is possible to produce magnet powder with high magnetic performance. The present invention has been completed.

[0008] That is, the magnet powder of the present invention is a flaky powder produced by a one-roll quenching method, characterized in that the magnetization in the thickness direction is larger than the longitudinal direction of the flake, and is rare earth-iron-boron. Anisotropic magnet alloy powder.

The resin bonded magnet of the present invention is a resin bonded magnet manufactured by mixing the above rare earth-iron-boron anisotropic magnet alloy powder 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).

A resin-bonded magnet according to the present invention is characterized in that the rare earth-iron-boron anisotropic magnet alloy powder according to any one of claims 1 to 3 is bonded by a resin binder.

In the first method for producing a magnetic alloy powder according to the present invention, a rare earth-iron-boron alloy melt is sprayed onto a single roll and quenched and solidified, and the manufactured ribbon is heated during cooling after quenched and solidified to form a plastic. It is characterized by processing.

According to a second method for producing a magnetic alloy powder of the present invention, a rare earth-iron-boron alloy melt is sprayed onto a single roll and quenched and solidified, and the produced ribbon is heated during cooling after quenched and solidified to form a plastic. It is characterized by processing.

A second method for producing a magnetic alloy powder according to the present invention is characterized in that the plastic working method in the first or second production method is roll rolling.

Further, a fourth method for producing a magnetic alloy powder according to the present invention is characterized in that, in the first to third production methods, the temperature of the plastic working is 500 ° C. or more and 900 ° C. or less.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a magnet alloy powder and a resin-bonded magnet of the present invention will be described in detail.
The magnet alloy composition in the present invention is basically a rare earth-iron-
It is a boron-based material, and specifically needs to be in a composition range represented by the following composition 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 the R amount x 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 x exceeds 16, the magnetization decreases, and 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. B amount z is 4.8 to 6.5.
Is preferably within the range. If it is less than 4.8, the coercive force is too low to be practical. If z 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 composition 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 addition 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 powder of the present invention can be produced through the steps of (1) high frequency melting, (2) quenching with a single roll, and (3) plastic working. The resin-bonded magnet made of this powder can be manufactured through the steps of (4) resin binder mixing, (5) compression press molding in a magnetic field, or injection molding in a magnetic field, following the above steps. It is also effective to provide a quenching ribbon heating step between steps (2) and (3). 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 charged 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) Rapid Cooling by Rotating Rolls A metal piece roll of Cu, Fe or the like is rotated, and a molten alloy is sprayed onto the rolls to be rapidly cooled and solidified.
In the resulting quenched ribbon, the Nd ₂ Fe ₁₄ B crystal is isotropic and oriented in a random direction. In order to effectively perform the subsequent plastic working, it is desired to appropriately reduce the crystal grain size of the ribbon after 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) Plastic working It is a feature of the present invention to continuously perform plastic working on a rapidly solidified ribbon. The term “continuous plastic working” as used herein means to apply plastic working to a rapidly solidified ribbon immediately, in other words, before the ribbon is cooled to around room temperature. For a few seconds after the molten metal comes into contact with the roll and solidifies, the ribbon is expected to maintain a high temperature state of about 500 to 900 ° C. By subjecting the ribbon to plastic working in such a high temperature state, the c-axis of the crystal is aligned in one direction, and the material after plastic working is expected to be anisotropic, in which the magnetization in the direction in which the c-axis is aligned increases. . The manufacturing method of the magnet alloy of the present invention,
With this aim, plastic working is performed within seconds after quenching and solidification. Roll rolling, uniaxial compression press, and the like can be considered as a method of the plastic working. Among them, in consideration of promptly performing plastic working after rapid cooling, roll rolling is considered to be particularly effective in terms of the structure of the apparatus. FIG. 1 shows an example of an apparatus for continuously performing single roll quenching and roll rolling. When plastic working by roll rolling is performed, plastic deformation occurs in the direction in which the thickness of the ribbon decreases, so that the magnetization in the thickness direction of the ribbon increases after rolling, and the magnetization in the longitudinal direction decreases. In order to further increase the degree of anisotropy, it is also effective to heat the ribbon to slightly increase the ribbon temperature immediately before plastic working.
When performing ribbon heating, the ribbon in flight in the air must be heated in a short period of time after quenching and solidification, so that heating by a laser beam, infrared heating, high-frequency heating, or the like is effective.

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

(4) Mixing of resin binder 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 when performing 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.

(5) Compression molding in a magnetic field, injection molding in a magnetic field A resin bonded magnet can be obtained by compression molding or injection molding while orienting a magnet alloy powder mixed with a 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.

[0029]

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

Example 1 Nd _13.36 Fe _74.93 Co _6.09 B _5.62
Is filled in a quartz nozzle having a circular hole with a diameter of about 0.5 mm at the bottom and made into a molten state at about 1500 ° C. by high-frequency heating, and then the molten metal is rotated at a peripheral speed of 22 m / sec. It was spray-solidified on one roll. The alloy ribbon produced by solidification was blown in the same direction as the rotation of the roll.
A double roll was placed in front of the roll, and the flying alloy ribbon was rolled to a working rate of about 60%. FIG. 1 is an explanatory diagram of the manufacturing method up to this point. As a result of measuring the magnetic properties in the thickness direction and the longitudinal direction of the alloy flake obtained after the rolling using a vibrating sample magnetometer (VSM), the residual magnetization (Br) was 12.1 in the thickness direction.
4 kG, coercive force (iHc) is 15.3 kOe,
In the longitudinal direction, Br was 1.6 kG and iHc was 8.6 kOe. Next, the grain size of the alloy flakes after the rolling was adjusted to about 100 to 300 mm by mortar pulverization, and then the epoxy resin was mixed at a ratio of 2% by weight to the magnet powder. The mold filled with the mixture was set in a magnetic field press, and pressed at a pressure of 10 ton / cm ² while applying a magnetic field of 15 kOe to orient the particles to obtain a compression-molded body. 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 8.8 kG, iHc was 15.2 kOe, and the maximum energy product ((BH) max) was 16.8 MGOe, so that a high-performance bonded magnet could be manufactured.

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. However, in Comparative Example 1, the rolling process in Example 1 was not performed. As a result of measuring the magnetic properties in the thickness direction and the longitudinal direction of the obtained ribbon in the same manner as in Example 1,
In the thickness direction, Br is 7.8 kG, iHc is 1
In the longitudinal direction, Br was 7.9 kG and iHc was 15.9 kOe. From this result, it can be seen that when the rolling process is not performed, the material exhibits magnetically isotropic properties. Next, a resin-bonded magnet was manufactured in the same manner as in Example 1 using the ribbon obtained in Comparative Example 1, and as a result, Br was 5.9 kG, iHc was 15.7 kOe,
(BH) max was 8.5 MGOe, and only low characteristics were obtained.

Example 2 An alloy flake having the composition shown in Table 1 was produced in the same manner as in Example 1, and then a resin-bonded magnet was produced in the same manner as in Example 1. Table 1 shows the magnetic characteristics of the obtained resin-bonded magnet.

[0033]

[Table 1]

Example 3 In the manufacturing method described in Example 1, a laser beam irradiation device was installed so that the ribbon after quenching and solidification could be heated. Nd _13.43 Fe _74.97 Co _6.01 B
An alloy having a composition of _5.59 was melted in the same manner as in Example 1, and the melt was injected and solidified on a Cu piece roll rotated at a peripheral speed of 22 m / sec. Further, the solidified alloy ribbon was heated to about 800 ° C. by irradiating a laser beam. Immediately thereafter, the alloy ribbon was rolled by a double roll so as to have a working ratio of about 60%. As a result of measuring the magnetic properties in the thickness direction and the longitudinal direction of the flakes after rolling using VSM, Br was 13.5 kG in the thickness direction.
iHc was 15.1 kOe, and in the longitudinal direction, Br was 1.1 kG and iHc was 8.0 kOe. Next, the grain size of the flakes after rolling was reduced to 100 by mortar pulverization.
After adjusting to about 150 mm, a resin bonded magnet was obtained in the same manner as in Example 1. The magnetic properties of the obtained resin-bonded magnet are as follows: Br is 9.1 kG, iHc is 14.9 kO.
e, (BH) max was 18.9 MGOe.

[0035]

According to the method for producing anisotropic magnet powder according to the present invention, the ribbon is made magnetically anisotropic at the same time as the production. Since anisotropic magnet powder is produced, and the anisotropic magnet powder according to the present invention is magnetically anisotropic in advance, it is possible to omit anisotropic steps such as plastic working after molding. The anisotropic magnet can be manufactured in substantially the same process as that of the isotropic magnet. By using the present invention, it is possible to inexpensively manufacture a high-performance magnet having excellent magnetic properties.

[Brief description of the drawings]

FIG. 1 is a basic explanatory diagram of an apparatus for producing an anisotropic magnet alloy powder of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnet powder manufacturing apparatus 2 Molten vessel 3 High frequency heating coil 4 Alloy melt 5 Rapid cooling single roll 6 Rapidly cooled ribbon 7 Rolling roll 8 Plastically processed alloy powder 9 Laser beam irradiation apparatus 9a Laser beam

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01F 1/053 H01F 1/04 H

Claims (8)

[Claims] 1. A rare-earth-iron-boron-based anisotropic magnet alloy powder, which is a flaky powder produced by a single-roll quenching method and has a larger magnetization in a thickness direction than in a longitudinal direction of the flake. . 2. A composition formula of 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). 3. 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). 4. The rare earth-iron according to claim 1, wherein:
A resin-bonded magnet, wherein boron-based anisotropic magnet alloy powder is bound by a resin binder. 5. The magnet alloy powder according to claim 1, wherein the rare-earth-iron-boron alloy melt is sprayed onto one roll to be rapidly cooled and solidified, and the produced ribbon is subjected to plastic working during cooling after the rapid cooling and solidification. Manufacturing method. 6. The method according to claim 5, wherein the rare-earth-iron-boron alloy melt is sprayed onto one roll and rapidly cooled and solidified, and the manufactured ribbon is heated during cooling after the rapid cooling and solidified to perform plastic working. Method of producing magnet alloy powder. 7. The method for producing a magnet alloy powder according to claim 5, wherein the plastic working method is roll rolling. 8. The method for producing a magnetic alloy powder according to claim 5, wherein the temperature of the plastic working is 500 ° C. or more and 90 ° or more.
A method for producing a magnet alloy powder, wherein the temperature is 0 ° C. or lower.