JPH0278204A - High-polymer composite-type rare-earth magnet and its manufacture - Google Patents

Abstract

PURPOSE:To obtain an anisotropic magnet of a high characteristic by making use of a manufacturing process of a rare-earth-based sintered magnet by a method wherein the magnet is constituted of the following: a specific rare-earth magnet powder; a ferrite powder; a high-polymer resin binder. CONSTITUTION:Ab R2T14B-based (where R is rare-earth elements containing Y and T is a transition metal) sintered substance which is composed mainly of Nd, Fe and B is pulverized; a magnet powder whose particle diameter is 25mum or lower is separated and removed. A powder, of a high magnet characteristic, whose particle diameter is 25mum or higher is mixed with a ferrite powder of the same amount as the powder of 25mum or lower. A mixed powder is formed, in addition, a high-polymer resin binder is added; they are molded; a magnet is formed; thereby, it is possible to manufacture a high-performance anisotropic high-polymer composite-type rare-earth magnet by making use of a manufacturing process of a rare-earth-based sintered magnet.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is particularly applicable to Nd-Fe-B polymer composite magnets, typically rubber magnets and plastic magnets.
Rare earth metals (R) and transition metals (represented by system permanent magnets)
The present invention relates to the improvement of a polymer composite rare earth magnet using R2T14B rare earth magnet powder containing T) and boron (B) as main components.

[Prior Art] A polymer composite magnet is one in which magnet powder is dispersed in a polymer resin, or one in which magnet powder is bound with a polymer resin. This magnet has various characteristics not found in cast magnets, sintered magnets, etc., such as elasticity and ease of processing, and is used in a variety of fields. however,
Since it is made of magnet powder and non-magnetic resin, it has the drawback of having lower magnetic properties than sintered magnets and the like.

Therefore, efforts are being made to achieve high magnetic properties by making the powder anisotropic, such as by orienting the powder in a magnetic field.

Various types of magnetic powder have been used to disperse and bind, but in the present invention, R2T, which is represented by the Nd-Fe-B system, which currently exhibits the highest magnetic properties, has been used.
Uses l4B magnet powder.

Conventional polymer composite magnets using rare earth magnet powder are manufactured by heat-treating and crushing an alloy ingot obtained by melting raw materials, mixing the powder with polymer resin, and molding it in a magnetic field. Ta. The magnet alloy powder used here was desirably composed of fine single-crystal particles in order to improve crystal orientation in a magnetic field.

[Problem to be solved by the invention] However, R, which is represented by Nd-Fe-B magnets,
In T,, B-based alloys, the coercive force (IHc) decreases due to mechanical stress during pulverization, so Hc is significantly decreased in fine regions where the powder is composed of single crystal grains. Therefore, in a manufacturing method using a molten ingot as a starting material, even if a sintered magnet with high IHc is crushed and used as magnet powder, the result is a polymer composite magnet that exhibits extremely poor magnetic properties. Moreover, in the method of manufacturing a polymer composite magnet by heat-treating an ingot and then pulverizing it to produce a polymer composite magnet, the magnet exhibits extremely poor magnetic properties that are worthless.

On the other hand, R-
As a method for producing a T-B magnetic alloy, a liquid quenching method has been known in which a molten alloy is injected onto a rotating roll or the like, and then super-quenched to obtain a magnetic alloy. however,
Anisotropy could not be achieved with the powder obtained by this manufacturing method. Subsequently, it was found that a magnetic powder capable of being anisotropic was obtained by hot plastic working this liquid quenched alloy. This method requires high temperature and high pressure, making the equipment expensive and large-scale.
Concerns remain regarding the stabilization of properties in manufacturing conditions,
It is still difficult to obtain powder with small variations in properties through mass production, and it is difficult to say that it is industrially useful.

The technical problem of the present invention is to provide a high-performance anisotropic polymer composite magnet by utilizing the normally practiced manufacturing process of R/T-B based sintered magnets.

Therefore, this is an industrially very useful method for producing a polymer composite magnet.

[Means to solve the problem] According to the invention, the particle size is greater than 25 μm.

R2T14B system whose main components are Nd, Fe, and B (here, R represents a rare earth element containing Y, and T represents a transition metal).
A polymer composite rare earth magnet is obtained, which is characterized by being composed of rare earth magnet powder, ferrite powder, and a polymer resin binder.

According to the present invention, R2T containing Nd, Fe, and B as main components
14B series (here, R represents a rare earth element containing Y, T represents a transition metal) sintered body, a separation step of separating and removing powder of 25 μm or less, and a particle size obtained in the separation step. A mixing step of mixing a powder larger than 25 μm with the same amount of ferrite powder as the powder of 25 μm or less to obtain a mixed powder, and a molding step of mixing a polymer resin binder with the mixed powder and molding the mixed powder. A method for manufacturing a polymer composite rare earth magnet is obtained.

-Here, in the present invention, the polymer resin binder that can be used includes epoxy resin and polyethylene resin, but is not limited to these.

The present invention involves pulverizing an alloy ingot obtained by melting, sintering the resulting powder compact by compacting it in a magnetic field to obtain a sintered body with a high degree of crystal orientation, and then After crushing the
By using 21-ordered powder that contains ferrite magnet powder in the particle range of 25 μm or less in the sintered powder, an R-T-B polymer composite magnet with high magnetic properties is realized. It is something to do.

The improvement in the magnetic properties of the present invention is related to the improvement in IHc, Br, and squareness of the demagnetization curve of the sintered powder by heat treatment, and this effect is due to the fact that the forming powder has a plurality of oriented crystal grains. This is deeply due to the fact that it is composed of However, the improvement in magnetic properties due to heat treatment of this powder tends to decrease as the powder particle size becomes smaller.

As a result of various experiments conducted by the present inventors, it has been found that it is clearly difficult for particles of 30 μm or less in the sintered powder to be recovered from damage caused by crushing, even by heat treatment. This 25μm
It has been discovered that in the following range, by containing ferrite magnet powder with a relatively small particle size, an R-T-B polymer composite magnet with high magnetic properties and improved packing density can be obtained. .

The reason why the ferrite magnet powder is specified to be contained in the particle size range of 25 μm or less in the sintered powder is that the effect becomes significant when the particle size is 25 μm or less.

Examples will be described below.

Example 1 Using Nd with a purity of 97 wt.% (the remainder being other rare earth elements mainly consisting of Ce and Pr), DY with a purity of 99 νt.% or more, ferroboron (B purity about 20 wt.%), and electrolytic iron. , (N d O,9・DyO,l) is 34, OvL・
%, B is 1. An ingot having a composition of Ovt.% and balance Fe was melted by high frequency heating in an argon atmosphere.

Next, this ingot was coarsely ground, and then finely ground to an average particle size of 2 μm using a ball mill.

This alloy powder was mixed in a magnetic field of about 20 KOe at a rate of 1 ton/
The molded body was molded into a rectangular parallelepiped shape at a pressure of
A sintered body was obtained by holding for a period of time. This sintered body is 7.55gr
/c+s', and the average crystal grain size was about 5 μm. A part of this was aged at 600°C for 2 hours and the magnetic properties were determined by n1, and the result was B r 12.8KG, ,H
It was about c20KOe, (BH)max, and 39MφG·Oe.

The sintered body that was not subjected to aging treatment was coarsely ground to a particle size of 300 μm or less, and then the powder was held at 600° C. in vacuum for 1 hour and in Ar for 4 hours and heat treated.

On the other hand, a-Fe20B, 5rCOi powder was mixed with Sr0.5.
9Fe20. After weighing so that
Ferrite powder was obtained. Next, this powder was pickled with boiled hydrochloric acid to remove unreacted components and isolate Sr ferrite crystal grains. After pickling, the Sr ferrite was
The crystal grain size is approximately 2μI, and the magnetic properties of oriented powder are 4π!
S was approximately 4.7KG and 1Hc was approximately 4.5KOe.

Next, the above-mentioned (Nd0.9 ・DyO,l)・F e
・The fine particles in the B-based heat-treated coarse powder are 20 μm or less, 3
When the Sr ferrite powder was separated and removed in the range of 0 μm or less and 40 μm or less and the corresponding amount was supplemented with the above-mentioned Sr ferrite powder, it was about 3 νt・% for 20 μm or less, about 6 wt・% for 30 μm or less, and about 10 vt・% for 40 μm or less. % ferrite amount.

Next, 35 vt.% of polyethylene was mixed into these mixed powders, and then injection molded into a mold at about 100° C. while applying a magnetic field of 20 KOe to obtain a polymer composite magnet. The magnetic properties were determined by applying a magnetic field of about 30 KOe to 71-1, and the results are shown in FIG.

25μm or less (NdO,9・D yO,l )・
The magnetic properties of the polymer composite magnet are clearly improved by replacing the Fe/B-based sintered body powder with S ferrite magnet powder.

For reference, the above-mentioned aging treated (NdO, 9.D
yO, l) - Even if it was laid on a Fe-B based sintered body, it was coarsely pulverized to an amount of 300μ or less, mixed with polyethylene and injection molded to produce a polymer composite magnet, and the magnetic properties were B.
r5.4 KG, +Hc3.5KOe, (BH
) 5ax4.5M-G φOe.

Example 2 Conducted using cerium dididium, ferroboron, electrolytic cobalt, electrolytic iron, and aluminum consisting of 5 vt・% Ce, 15 wt・% Pr, and the balance Nd (however, other rare earth elements were included as Nd). In the same manner as in Example 1, the rare earth element R was 32 wt.%.

R with 7wt% Co, 1vt% Ag, and the balance Fe.
-A T-B series ingot was obtained.

Next, using this ingot, pulverization, compaction in a magnetic field, and sintering at 1040°C were performed in the same manner as in Example 1.

The sintered body obtained here has a density of approximately 7.55gr/cv
3, and consisted of crystals with an average particle size of about 6.5 μm. When a part of this sintered body was aged at 600℃ for 2 hours, Br12.2KG, 1Hc11.5KOe,
(BH) wax, 33.5 M eG Oe.

The sintered body that was not subjected to aging treatment was coarsely ground to a particle size of 500 μm or less, and then fine particles were separated and removed in the ranges of 20 μm or less, 30 μl or less, and 40 μl or less. Accordingly, Alff1 was about 3wt#1%, about 7vt·%, and about 13wtφ%, respectively, based on the total amount of powder.

On the other hand, a-Fe20. and B a CO3 powder to BaO・
After weighing to give 5,7 Fe203, mixing, firing, and pickling were performed in the same manner as in Example 1 to obtain M-type Ba ferrite powder. This Ba ferrite had a crystal grain size of about 2.5 μm, and the magnetic properties of the oriented powder were 4πIs about 4.6 K G and +Hc about 3.7 KOe.

Next, the R-T-B based sintered body powder from which the fine particles have been removed is added with the above-mentioned B
a Ferrite powder was supplemented and mixed. After mixing 25 vol/% of epoxy resin with this mixed powder, approximately 20K
It was molded into a disk shape at a molding pressure of 5 ton/c12 in a magnetic field of Oe. This molded body was held at 100° C. for 2 hours to be cured, thereby forming a polymer composite magnet. Figure 2 shows the measurement results of the magnetic properties. By replacing the R-T-B based sintered body powder with a diameter of 25 μm or more with Ba ferrite magnet powder,
The magnetic properties of polymer composite magnets are clearly improved.

For reference, the above-mentioned aging-treated R-T・B-based packed body was also coarsely ground into particles of 500 μm or less, mixed with resin, molded in a magnetic field, and hardened in the same manner to form a polymer composite magnet. After that, the magnetic characteristics were determined by JP1, and it was found that Br was about 5.4K.
G, IHc approximately 2.5KOe.

(BH) wax was approximately 3.5 M-Oe.

As shown in the above examples, R2T with anisotropy
,, 2 in the molding powder made by crushing the B-based sintered alloy
By containing ferrite magnet powder in the particle size range of 5 μm or less, a polymer composite magnet with significantly improved magnetic properties can be realized.

In the above embodiments, the Nd-Dy-Fe-B system is used.

Ce-Pr-Nd-Fe-Co-AN-B system.

Although only the Nd-Fe-B system has been described, a portion of Nd may be replaced by Y and other rare earth elements such as Gd and Tb.

Even if a part of Fe is replaced with HO, etc., a part of Fe is replaced with another transition metal such as Mn, Cr, Ni, etc., or a part of B is replaced with another semimetal such as St, C, etc., the magnetic alloy can be improved. The composition of N
R2T, which has d-Fe-B as a main component, and is a magnet compound system represented by the NdzFezB system,
If 4B contributes to magnetism, it can be easily inferred that the effects of the present invention can be fully expected.

In addition, in the present invention, only epoxy resin and polyethylene have been described as polymer resins, but any material (e.g., other high Those skilled in the art will easily understand that not only molecular resins, rubbers, etc., but also metals are within the scope of the present invention.

In addition, regarding the manufacturing method of polymer composite magnetization shown in this example, there is an impregnation type in which a molded body is impregnated with resin, a compression molding type in which powder and resin are mixed and then compression molded, and a molding type in which powder and resin are mixed and then compression molded. Although I have only mentioned injection molds for injection molding,
Those skilled in the art can easily imagine that other molding methods such as extrusion molding, roll molding, etc. can also be applied.

In addition, in this example, only Sr ferrite and Ba ferrite having an M-type crystal structure were described as ferrite magnet powder to replace the RTB-based sintered body powder, but for example, S' and Ba ferrite were described. Even if it is a compound-containing ferrite or a W-type ferrite, as long as the ferrite powder has magnetic properties of H, even if it is a crushed powder of a ferrite sintered body, it falls within the scope of the present invention. It is something that can be done.

[Effects of the Invention] According to the present invention, most of the powder for polymer magnets can be manufactured using a manufacturing process for sintered magnets that have high characteristics, can be processed in large quantities, and exhibit magnetic characteristics with little variation. , which is very useful industrially.

According to the present invention, it is possible to provide a powder that can be applied to a wide range of manufacturing methods for polymer composite magnets, such as impregnation molding, compression molding, and injection molding. It is industrially very useful because a molded magnet can be realized.

[Brief explanation of the drawing]

FIG. 1 shows that (NdO,9・Dy
O, l) ・M type S in Fe-B based sintered magnet powder
Powder particle size and polymer 73 replaced with r ferrite magnet powder
2 is a diagram showing the relationship with the magnetic properties of the composite magnet. FIG. 2 shows (Ce-P"・Nd)・
M-type Ba in Fe-co-AI/B-based sintered magnet powder
FIG. 3 is a diagram showing the relationship between the particle size of a powder substituted for ferrite magnet powder and the magnetic properties of a polymer composite magnet. Figure 1: Replaced powder particle size (, um) Figure 2: Replaced powder particle size (, um)

Claims (2)

[Claims] 1. Rare earth magnet powder, ferrite powder, A polymer composite rare earth magnet characterized by comprising a molecular resin binder. 2. R_2T_1_4B whose main components are Nd, Fe, and B
(Here, R represents a rare earth element containing Y, and T represents a transition metal.) A separation step of pulverizing the sintered body and separating and removing powder of 25 μm or less, and a particle size of 25 μm obtained in the separation step. It is characterized by having a mixing step of mixing a larger powder with the same amount of ferrite powder as the powder of 25 μm or less to obtain a mixed powder, and a molding step of mixing a polymer resin binder with the mixed powder and molding it. A method for manufacturing a polymer composite rare earth magnet.