JPH0498803A - Manufacture of rare-earth alloy magnet powder - Google Patents

Abstract

PURPOSE:To make it possible to manufacture rare-earth alloy magnet powder for highly efficient anisotropic resin bonding at low cost by a method wherein rare-earth alloy magnet raw material powder only is annealed at 400 to l000 deg.C in a vacuum atmosphere of 1X10<-3> to 1X10<-5>Torr, a suitable thin oxide film is formed on the surface of the powder, and the powder is annealed at 500 to 1200 deg.C in a non-oxidizing atmosphere. CONSTITUTION:It is important to select and control the degree of vacuum atmosphere in which the first stage of annealing is conducted on raw material powder, and it is necessary to control the degree of vacuum at 1X10<-3> to 1X10<-5>Torr, desirably in the range of 1X10<-3> to 1X10<-4>Torr. The temperature of annealing, which is smaller than the influence of an atmosphere, is to be conducted at 100 to 400 deg.C, and the temperature range of 600 to 900 deg.C is desirable in order to obtain the magnet powder having high magnetic characteristics (iHc and OS). Then the above-mentioned raw material powder is thoroughly mixed with high melting point powder and the mixture is dispersed. There is calcium oxide (CaO) and the like, for example, as the high melting point powder, and the ratio of its adding quantity is 0.3 to 2 : 1 (raw material powder : high melting point powder) or thereabout.

Description

[Detailed Description of the Invention] [Industrial Application Field 1] The present invention relates to the production of rare earth alloy resin bonded magnets.
The present invention relates to a method for inexpensively manufacturing rare earth element-iron (Fe)-boron (B) alloy, especially neodymium (Nd)-Fe-B alloy magnet powder, which is ideal for resin-bonded magnets that particularly require high magnetic properties.

[Conventional technology 1 High magnetic properties [coercive force 1iHc], strength of magnetization (σ, )
A variety of magnet powders are used as materials for permanent magnets having the following characteristics. Typical magnet powders include ferrite-based and rare earth element-cobalt-based magnet powders.

Recently, the R-Fe-B system is being developed as a new high-performance permanent magnet magnetic powder that has a significantly superior maximum energy product (BHI wax) using inexpensive rare earth elements and iron.

There are the following two methods for manufacturing this R-Fe-B alloy magnet powder.

(1) As disclosed in JP-A-59-46008, etc., melting-ingot-pulverization (2) JP-A-59-64739, JP-A-60-LO(1)
402 and JP-A-60-189902, ultra-rapid solidification (solid material, e.g. ribbon-like) - grinding or ultra-rapid solidification - heat treatment - grinding.

Resin bonded magnets are generally manufactured by mixing magnet powder and a resin as a binder, kneading, extrusion molding, compression molding, or injection molding.

When a resin-bonded magnet is manufactured by the method described above using Nd-Fe-B alloy magnet powder obtained by the ultra-rapid solidification method, the resulting resin-bonded magnet is isotropic, so its magnetic properties are is not at a satisfactory level. Anisotropic resin bond &
! Although it is possible to make one stone, it requires expensive manufacturing equipment, making it impossible to obtain a cheap magnet. In addition, Nd-F obtained by crushing the ingot under the same conditions as before
Magnet powder manufactured using magnet raw material powder such as e-B alloy has low magnetic properties, particularly iHc, and is therefore not suitable for resin bonded magnets.

This is thought to be because the rare earth alloy magnet powder manufactured under the same conditions as conventional ones deteriorates in magnetic properties, particularly in 1tlc, due to alteration of the powder surface and residue inside the powder.

As one way to solve this problem, a method of annealing at a high temperature after pulverization has been proposed, but annealing at a temperature suitable for obtaining desirable magnetic properties causes sintering of the raw material powder, so re-pulverization is necessary. This caused the problem of degrading the magnetic properties.

As a means to solve this problem, the inventor has proposed
The method shown in No. 94397 and Japanese Patent Application No. 1I8451 was proposed.

According to this method, iHc is recovered and improved, but there is a problem that Os, which is another important magnetic property, is not necessarily sufficient.

The present invention was made in order to solve the above-mentioned problems in a magnet powder manufacturing method that uses pulverized ingots as magnet raw material powder in order to manufacture rare earth alloy magnet powder for fat-bonded magnets. Anisotropic...The object of the present invention is to provide a method for manufacturing at low cost a rare heptad-based amorphous amorphous powder for use in resin bonding.

[Means for Solving the Problems 1] In order to solve the above problems, magnetic powder obtained by the manufacturing method shown in Japanese Patent Application No. 1-94397 and Japanese Patent Application No. 1-318451 was studied, and the present invention was developed. It's arrived.

In other words, only the rare earth alloy magnet raw material powder is I
By annealing at 400 to 1.000°C in a vacuum atmosphere of O-3-I Then, the raw material powder was mixed with high melting point powder and heated to 500-1,
By annealing at 200℃, the interaction between the raw material powder and the high melting point powder is appropriately controlled to prevent sintering of the powder, and the powder surface is modified to improve magnetic properties such as iHc and 03. The gist of the present invention is a method for producing #-based alloy magnet powder, which is characterized in that the present invention is described in detail below.

First, in the case of ingot crushing, by a well-known method,
A rare-type alloy ingot whose components are adjusted in a predetermined ratio is obtained. In the case of ultra-secondary solidification or rapid solidification, rare earth alloy ribbons and the like are obtained by well-known methods.

Regarding the component system and composition of the rare earth alloy, Nd
-Fe -B system, praseodymium (Prl -F
e-B series or other rare earth elements may be used in place of these Nd and Pr.

In addition, other additive elements include cobalt (Go), aluminum (At), zirconium (Zr), and silicon (Si) for the purpose of improving the magnetic properties of the alloy magnet powder.
, niobium (Nb), etc. may be added. The material may be a two-element rare earth alloy such as samarium fsml-Go type or Fe-R type. In short, there are no particular limitations as long as the component system and composition can be used for this type of use. (The given ingot or ribbon, etc. is crushed by a well-known crushing method, i.e., a crusher, stamp mill, ball mill, etc.)
Grind in a non-oxidizing atmosphere, preferably with an average particle size of 10 μm
The following powder is obtained. An average grain size of 40 μm or less is sufficient; if the grains are made too fine, they will be oxidized too much during the first annealing, making it impossible to obtain the desired properties. Further, the pulverization method may be a dry method or a wet method.

The reason for grinding in a non-oxidizing atmosphere is that rare earth alloys are extremely easily oxidized, and oxidation proceeds quickly even when left in the air at room temperature. This is to strictly control oxidation only in the next step of annealing. In the first stage annealing, control to generate a moderately resistant oxide film on the magnet raw material powder has a great influence on the effects of the present invention. For that,
It is important to select and manage the degree of vacuum in the atmosphere.
~IX1O-5Torr, preferably lXl0-"
It is necessary to manage the temperature within the range of ~1×10 −3 to 1×10 −5 Torr. Although the influence of the atmosphere is smaller, the annealing temperature is 400~1,00℃, and the high magnetic fi'
60 to obtain magnetic powder of l1Hc, o,)
A temperature of 0 to 900°C is desirable. As the annealing temperature increases, both the iHc and Of magnetic properties of the resulting magnet powder improve; Therefore, the above-mentioned temperature range is preferable.

If fusion or sintering occurs in a part of the magnet raw material powder, it is re-pulverized to an average particle size of about 10μ■. This re-grinding exposes a new, unoxidized surface of a portion of the magnet raw powder.

Next, the magnet raw material powder is thoroughly mixed with a high melting point powder,
disperse. As a powder with a high melting point, at least 1.8
It is preferable to have a high melting point of 00℃ or higher, and that does not oxidize (or sinter) when annealed at a temperature of 1.200℃ or lower. For example, calcium oxide (Ca01), zirconium oxide (ZrOz), magnesia ( oxide powder such as legal, alumina (AlaOil, titanium oxide (T10□), dysprosium oxide (Dyz03),
Examples include powders of rare earth oxides such as neodymium oxide (Naioil), powders of nitrides such as boron nitride, and the like.

The average particle size of these powders may be sufficient as long as the particle size is sufficient to disperse the raw material powder. In addition, as for addition, it is sufficient that it completely prevents sintering of the raw material powder, and the volume ratio is 0.3 to 2.
:1 (raw material powder: powder with high melting point) may be used, for example, 1:1.0.5:1. After the mixed powder is sufficiently degassed in vacuum, it is annealed in a non-oxidizing atmosphere.

Taking the case of using Nd-Fe-B thread magnet raw material powder as an example, the main purpose of the main annealing is to improve the magnetic properties by thinning the Nd rich layer formed on the surface of the magnet raw material powder. At this time, it is necessary to prevent the mixed powder from fusion and sintering, and to avoid re-grinding. Annealing is 500 to 1.
Perform at 200°C. When the annealing temperature is lower than 500℃, Nd
The Illization of the rich layer is insufficient, the interaction between the magnet raw material powder and the powder having a high melting point is also insufficient, and annealing takes time and is less effective. When the temperature exceeds 1,200°C, it approaches the melting point of the main phase of the crystal of the magnet raw material powder (because
This is not preferable because it adversely affects magnetic properties. Examples of the non-oxidizing atmosphere include an inert gas atmosphere. The mixed powder obtained in this way is hardly sintered, so there is no need for pulverization after annealing, and there is little fusion between the raw material powder and the powder with a high melting point, and separation is possible using conventional separation methods, ie ultrasonic waves. The combination of separation and magnetic sorting allows easy separation, and
Since the effect of modifying the surface of the magnet raw powder can be obtained, a magnet powder with high magnetic properties fiHc and oct can be obtained.

[Effect]

According to the invention, l x 10-3 to l x 10-3
In a vacuum atmosphere of ~1 x 10-5 Torr, 40
Only the rare earth alloy magnet raw material powder is annealed at a temperature of 0-1.000°C, and then the magnet raw material powder and high melting point powder are sufficiently mixed and dispersed, and then heated in a non-oxidizing atmosphere such as argon gas. By annealing at a temperature of 500 to 1,200°C, it has become possible to simultaneously improve both the magnetic properties of the magnet powder, including the coercive force and magnetization strength. Although the mechanism of this effect is not clear, the inventor infers as follows.

Taking as an example the case of manufacturing Nd-Fe-B based magnet powder, in the first stage annealing, Nd+5Fet aB
A part of the Nd rich layer formed and layered on the surface of the magnet raw material powder with a composition of is removed.

In the subsequent annealing, the high melting point powder that was sufficiently mixed and dispersed with the magnet raw material powder was difficult to fuse and no oxide film was present on the surface of the magnet raw material powder where an oxide film existed. If a part of the magnet is re-pulverized after pre-annealing, it will discontinuously separate and fuse to a part of the new surface created by re-pulverizing the magnet raw material powder, and the fused area will become smaller. Therefore, sintering of the powders together becomes extremely small, and re-grinding becomes unnecessary. In addition, since the Nd rich layer formed on the surface of the magnet raw material powder and covering it becomes thinner, the M1'R characteristics such as coercive force and magnetization strength of the obtained magnet powder as a whole are improved. .

[Example] A cast ingot of an alloy having a composition of Nd+5FeyyBs was pulverized in an Ar gas atmosphere to obtain powder with a grain size of 45 μm or less. Transfer raw material powder in vacuum (I [+-3 Torr)
The sample was annealed at three temperatures of 700°C, 800°C and 880°C for 1 hour, cooled, and ground again to 45 μm in an Ar gas atmosphere. The obtained re-pulverized powder was mixed with DygOs as a sintering inhibitor with an average particle size of 1μ so that the volume ratio was 1.1, and the mixed powder was mixed in an Ar gas atmosphere with a
It was annealed at ℃ for 1 hour. After cooling, the mixed powder was separated in ethyl alcohol in an ultrasonic cleaning unit with a capacity of 300 W for 10 minutes, and then subjected to magnetic separation to obtain magnetic powder. This separation procedure was repeated six times.

After drying the magnet powder after Dy*Ox removal and separation in an Ar gas atmosphere, the magnetic properties of the magnet powder were measured using a VSM, and the results are shown in Table 1.

As a comparative example, Table 1 shows the measurement results obtained when manufacturing was performed under the same conditions except for the first stage annealing using only the raw material powder and the subsequent re-pulverization.

Table 1 This magnet powder was mixed with epoxy resin, molded under a pressure of about 5t/crn in a magnetic field (15), and hardened with #M resin to give an Oe of 7 (B old wax).
A bonded magnet of 10 MGOe was obtained.

[Effect of the invention J] As detailed above, the magnetic powder obtained by the ingot crushing method according to the conventional technology either cannot obtain a high coercive force, or even if a high coercive force is obtained, a high magnetization strength can be obtained. I couldn't. According to the present invention, it has become possible to produce inexpensive magnet powder with high magnetic properties (coercive force and magnetization strength) without using expensive equipment.

Therefore, it has become possible to manufacture a high-performance rare earth alloy anisotropic resin bonded magnet.

Claims (5)

[Claims] 1. Rare earth alloy magnet raw material powder only 1×10^-^3
4 in a vacuum atmosphere of ~1×10^-^5 Torr
A rare earth alloy magnet characterized by annealing at 00 to 1,000°C, and then annealing the raw material powder mixed with high melting point powder at 500 to 1,200°C in a non-oxidizing atmosphere. Method of manufacturing powder. 2. 2. The method of claim 1, wherein said high melting point powder is selected from high melting point oxides and high melting point nitrides. 3. 3. The method of claim 2, wherein the high melting point oxide is selected from calcium oxide, zirconium oxide, magnesia, alumina, titanium oxide, and rare earth oxides. 4. 4. The method of claim 3, wherein said rare earth oxide is selected from dysprosium oxide or neodymium oxide. 5. 3. The method of claim 2, wherein the high melting point nitride is boron nitride.