JPH02301A - Permanent magnet - Google Patents

Abstract

PURPOSE:To obtain stable magnetic characteristics by heat-treating and hardening alloy composed of rare earth metal and transition metal in a lumpy state. CONSTITUTION:Alloy composed of 23.8% Sm, 6.5% Cu, 15.6% Fe, 3.2% Zr and Co of the residual part is melted in a high frequency melting furnace, and cast in a metal mold. This alloy ingot in a lumpy state is subjected to solid solution treatment in argon gas. By using a ball mill, this alloy is subjected to wet grinding in polytrifluorochloroethylene atmosphere and fine powder is obtained. Liquid type epoxy resin is added to the fine powder type particles and both are incorporated. The incorporated fine powder type particles are subjected to pressure molding in a magnetic field press shown by figure. The incorporated fine powder type particles are inserted between an upper punch 3 and a lower punch 4, oil pressure is applied to press pedestals 7, 8 in an impressed magnetic field, and pressure molding is performed. After pressure is applied uniaxially by a separately installed oil press, the object is pulled out from the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a permanent magnet comprising a rare earth permanent magnet alloy and a binder.

Conventional methods for manufacturing Re T M It type permanent magnets include, for example, general formula Sm (Cobal Cub, 12Fe
d, 2 ZrO, 02) The intermetallic compound represented by 7.0 is ground and the particle size is adjusted to 2 μm to 10 μm,
A method is used in which this powder is molded into a desired shape in a magnetic field and then sintered. In the sintering method, the magnetic properties of the magnet are (BH)
A very high performance of max 22 to 30 MGOe has been obtained. However, it is said that the amount of rare earth elements (R) in Re TM+ type alloys has a large effect on magnetic properties.

In other words, as a condition for obtaining desired magnetic properties, R(TM)Z
The range of 2 is known to be a very narrow range.For example, in the case of R=Sm, Ce, Pr, Y, it is approximately ±0.
5! A displacement of I11% means that 2 changes by 1, so at least ±0. However, because rare earth elements are active and their vapor pressure is high, their composition fluctuates greatly during the magnetization process, making it impossible to stably maintain the desired magnetic performance. evaporation, oxidation, sintering, and solution heat treatment in the powdering process (
(hereinafter referred to as SST), aging treatment'' (hereinafter referred to as AGE)
evaporation and oxidation of the R element due to
It had the disadvantage of being prone to cracking. On the other hand, permanent magnet materials made by finely pulverizing RTMs gold alloys, such as SmCo5 alloys and bonding them with resin, are also known, but the maximum magnetic energy product is 5 to 1.
It is low at 0MGOe.

Furthermore, a great deal of process technology control is required to prevent oxidation, which is the most decisive factor in the magnetic performance of RsTM I7 type permanent magnets. Sintered magnets made using the powder method have a sintering temperature of 1150°C.
Sintering is carried out at ~1200° C. in an inert atmosphere or in a reducing gas, but the powder surface has the disadvantage that it tends to be oxidized by very small amounts of air or oxygen.

The present invention improves the drawbacks of the conventional methods described above, and aims to provide a manufacturing method that can easily obtain a predetermined composition while suppressing fluctuations due to oxidation and evaporation of rare earth elements. The present invention will be explained in detail below in accordance with the steps.

The magnetic alloy in the present invention includes Y, Sm, Pry
20% to 28% of rare earth metals such as Ce, La, etc.
weight%), Cu (copper) 3 to 15%, Fe (iron) 5 to 35%* Zr, Hf* Ti, N
It is an alloy consisting of 1 to 5% of one or more of beCr, V, Mn, and the remainder Co.

First, an alloy having the above composition is melted at high frequency in argon gas and cast into an ingot. In this case, the H-type structural material is a mold, and by controlling the cooling rate and exposing columnar crystals, 4πIs (saturation magnetization) and iHe
(coercive force) can be increased. Furthermore, the alloy ingot was heated at 1100°C to 12°C in a non-oxidizing atmosphere such as argon gas.
Heat treatment is performed at 20° C. for 1 to 24 hours, and then cooled to room temperature. The cooling rate at this time is 10 to 100℃
/min, a large coercive force can be obtained.
Next, the magnetic alloy cooled to room temperature is heated to 500 to 850°C and magnetically hardened by aging treatment. Since the above two types of heat treatments are performed on the magnetic alloy ingot as it is, that is, in the form of a block, there is an advantage that fluctuations in the alloy composition can be extremely reduced. That is, the surface area of the magnetic alloy can be made very small compared to its volume since the heat treatment is performed while the ingot remains in the form of a block. As a result, it naturally has the advantage of significantly reducing surface oxidation of the magnetic alloy. The first heat-treated ingot is thought to be magnetically hardened by solution treatment to create a homogeneous phase, followed by aging to promote precipitation hardening.
Coarsely grind using a crusher top mill, etc. The particle size at this time was 130 mesh, which was a fairly coarse powder.

The coarse powder is finely pulverized using a mechanical device such as a ball mill or a shoot mill. Crush it to the extent that it will not be damaged. The particle size of the powder is desirably pulverized to 3 μm to 85 μm. If the particle size is less than 3 μm, the fine structure is destroyed, so the saturation magnetization and coercive force are likely to decrease, so it is set to 3 μm or more. Moreover, if it exceeds 85μ, there is a problem that coercive force and saturation magnetization decrease. In addition, the powder filling rate and orientation in a magnetic field tend to decrease.Therefore, it is preferable to use magnetic powder particles with an average particle size of 10 to 15 μm and a distribution of 3 μm to 50 μm. After adding and mixing an organic binder and a metal binder with a melting point of 400°C or less, it is filled into a mold made of non-magnetic material, and a magnetic field of 12 to 30 kg is applied to magnetically orient the particles. A permanent magnet is produced by compacting into a desired shape by pressure molding at a pressure of ton/cm- and firing. Here, the organic binder may be either thermosetting or thermoplastic, preferably epoxy resin, EVA resin, phenol resin, polyester resin, etc., and the amount thereof is 0.5% (I
i amount ratio) to 10%.

A more preferable amount of the organic binder is 1% to 5%, and in this case, the filling rate of the magnetic powder in pressure molding is 6.
0% or more, and a density p of 5.0 or more can be obtained.

Also, metal binders include am, Pb, In,
Low melting point metals such as Bi, Ca, and Tl, and alloys thereof, having M and P (melting points) of approximately 400° C. or lower are used. The effect of the metal binder can improve the mechanical strength, toughness, magnetic properties, and temperature characteristics of permanent magnets.

Next, preferred alloy compositions in the method for producing permanent magnet materials of the present invention are as follows.

One or more types of 3m, Y, Pr, Ce...22%
~25% Cu...4%~10% Fe...10%~35% Co...Remaining one or more of Zr, Hf, Ti, Nb, Ta, and V...0%~ 5% In the present invention, the reason why the amount of rare earth metal added is limited to the above composition is that if it is 20% or less, Ra TMI? This is because the Fe-Co phase shifts from the W crystal and the coercive force decreases. When it exceeds 28%, the RTMs phase increases, the 4πIS decreases to 5000 G or less, and the maximum energy product becomes 4.5. This is because the following is true. Rare earth metals are 1
Similar effects can be obtained not only by species but also by combining two or more species.

This is because if Cu (copper) is less than 3%, no increase in coercive force is observed, and if it exceeds 15%, 4πIs decreases.

One or two of Zr, Nb, Hf, Ti, Cr, V, Mn
If it is more than 5% and less than 1%, there is no effect of improving coercive force, and if it exceeds 5%, 4πIs decreases. Furthermore, if iron is less than 5%, 4πIs cannot be increased, and if it exceeds 35%, the coercive force decreases.

Next, examples of the present invention will be described.

(Example 1) An alloy IKg consisting of the following composition was melted in a high frequency melting furnace,
The sample composition of the zero alloy cast into the mold is as follows.

3m: 23.8%, Cu: 6.5%,
Fe: 15.6%, Zr: 3. 2%, C
o: Remainder The magnetic alloy ingot obtained here is 80%
The above was a columnar crystal. The analytical values of this alloy were as follows.

Next, 100 g of each ingot of the alloy in the form of a lump was subjected to solution treatment in argon gas. The cooling rate was approximately 00°C/min. The alloy was then cooled to room temperature and heated to 800°C in argon gas in a separate heat treatment furnace.
It was heated for 8 hours, subjected to aging treatment, and cooled at 1-00°C/min. Almost no oxidation was observed on the alloy surface after heat treatment.

Next, this alloy was wet-milled in a Daiflon using a ball mill to obtain particles with an average particle size of 15 μm and 3 μm to 50 μm.
rllj3) of the distribution of 1 again. Two m % of a liquid epoxy resin having a viscosity of 2000 CPS was added to the fine powder particles and mixed in a mortar. The ball milled powder was dried in vacuum at room temperature.

The fine powder particles mixed with the epoxy resin were pressure molded in a magnetic field press as shown in FIG.

1 is an excitation coil, 2 is a pole piece made of pure iron, and a magnetic field of 15 KG is generated between them. 5 is Stellite, which is a non-magnetic material, and 3 and 4 are upper and lower punches made of the same material. 3,
Between 4 and 4, 8 g of the powder mixed with the epoxy resin was charged, and hydraulic pressure was applied from 7 and 8 in an applied magnetic field of 15 kg to perform pressure molding. The pressurizing force at this time was 2 ton/cm". While molding was performed in the zero-order magnetic field, the mold was molded using a separate hydraulic press with 5 ton/cm" applied in the -axial direction, and then extracted from the mold. . The sample shape at this time was the prismatic sample shown in FIG. Subsequently, the shape and dimensions of the molded body baked in an oven at 150°C for 1 hour were a==8m/m, b=
14 m/m, h = 8.0 n/m, and the arrow direction is the direction of anisotropy. According to the method of the present invention, as shown in Tables 1 to 5, as a resin bonded magnet, a very high magnetic performance was achieved.

No. 6 is a comparative example, in which the ingot is finely pulverized and the particle size is 5 to 5.
The average particle size was 15 μm and the average particle size was 7 μm, and magnetic field molding was performed in the same manner as the method of the present invention. The pressing force of the magnetic field molding was 1 ton/am', and a temporary molded body (green body) having the same shape as shown in FIG. 2 was obtained. Table 1, No. 6, shows the characteristics of the sintered permanent magnet of the comparative example.

(Example 2) Heat treated under the conditions of Example 1-NO, 4 = 10 lots,
A permanent magnet was formed. Subsequently, it was heated and baked in an oven at 150°C for 1 hour, and after cooling to room temperature, the measured magnetic field strength was 25KO.
Magnetic performance was investigated using a self-recording magnetometer. Moreover, as Comparative Example 1, SmG.

1 alloy powder having an average particle size of 5 μm was mixed with 2% by weight of epoxy resin. Similarly, n=5 pieces were molded in a magnetic field,
After firing (150°C x 1 hour), magnetic measurements were performed. In addition, as Comparative Example 2, it was manufactured under the same conditions as No. 6 in Table 1,
Ten lots of sintered and heat-treated specimens were investigated. Second
The above results are summarized in the table.

Table 2 The magnetic performance of the resin-bonded magnets of the present invention is SmCo5
Higher than that of alloy, slightly lower than that of sintering method, but
It was found that the variation in magnetic performance was extremely small. The reason for this is thought to be that, in the method of the present invention, problems related to the composition such as oxidation and evaporation of am can be prevented as much as possible since the alloy ingot is heat treated as it is. In other words, since the sintering method uses a green body (temporary molded body), gas is adsorbed inside it, and since the powder is molded, the surface area is large, and during sintering, oxygen gas in Ar gas, nitrogen gas, etc. It was found that this was due to the variation in performance.

(Example 3) A permanent magnet was manufactured by an impregnation method using magnetic powder under the same manufacturing conditions as shown in Example Table 1, No. 002. First, the particle size of the magnetic powder was set to an average particle size of 15 μm, and 0.3% by weight of oleic acid was added to 25 g and mixed in a mortar.

This mixed powder was processed into Table 1 N by the magnetic field forming apparatus shown in Fig. 1.
Pressure molding was performed under the same conditions as 002 to obtain a prismatic block (molded body). The molded article was immersed in 200 cc of a one-component epoxy resin liquid with a viscosity of 1000 PS, and left at room temperature for 2 hours to effect impregnation. Subsequently, the molded body was taken out from the binder epoxy liquid, washed with ethyl alcohol, and then baked and solidified in an oven at 150° C. for 1 hour. The BH curve of the sample was measured using a self-recording magnetometer. The results are shown in Figure 3, where 1 is 3mC of Comparative Example 1.
The B-H curve obtained when a block formed with o5 alloy powder was similarly impregnated is shown.

Further, 2 shows a typical -H curve of the mass-produced SmCo5 sintered magnet of Comparative Example 2.

As can be seen from Table 3, the method of the present invention has much higher magnetic properties than the conventionally known SmCo5 alloy resin-bonded magnet, and has the same magnetic properties as the 3mCo5 magnet made by the sintering method. was gotten.

(Example 4) Fine powder 2 obtained under the same heat treatment conditions as No. 003 in Table 1
0g was prepared. Mj of solder powder (average particle size 2 μm) consisting of a composition ratio of PB and 3N of 1:1 is added to this magnetic powder.
The mixture was mixed for 1 hour in a glow box with nitrogen gas flowing out.

Next, the magnetic field forming apparatus shown in FIG. 1 was used to form Table 1.

Pressure molding in a magnetic field was performed in the same way as sample No. 3. The final molding pressure at this time was 7 ton/cm'', but the molded product could be pulled out from the mold without any problems.Next, it was heated in an Ar gas atmosphere at a temperature of 325°C for 1 hour. The characteristics of the permanent magnet obtained by the method of the present invention cooled to room temperature are described below.

It was found that the magnetic properties of this example could be further improved compared to the permanent magnet produced by the method of the present invention shown in Table 1, No. 003. Furthermore, the permanent magnet material of this example was found to be highly resistant to impact, chipping, cracking, etc. Magnet molded body 1m high
No abnormalities were observed even when the product was dropped onto a concrete floor from a height of Furthermore, since the method of the present invention uses rare earth metals and cobalt, which have high raw material costs, the raw material yield greatly affects the cost.The method of the present invention can directly mold the product shape using a mold, so the yield is over 90%. Met. On the other hand, the conventional sintered magnet has a yield of 10% to 30% and has the drawback of high cost.

The present invention improves the magnetic properties of the R2TM+v type permanent magnet alloy by resin bonding or metal binder method, and reduces the variation in mass production.
1. The permanent magnet material of the present invention, which will bring great benefits to the industry, can be used in precision equipment such as coreless motors, stepping motors, electromagnetic buzzers, speakers, stepping motors for watches, and cartridges. We believe that if used in this device, it will have a revolutionary effect on the production of low-cost, high-performance products, that is, high cost performance. As described above, the method of the present invention is industrially very useful.

FIG. 1 is a schematic cross-sectional view of the magnetic field forming apparatus used in this example.

1...Exciting coil 2...Pole piece 3...Mold upper punch (non-magnetic stellite) 4...
Lower punch of mold (〃) 5... 〃(〃) 6... Magnetic powder 7... Press pedestal (upper part) 8... 〃 (lower part) Figure 2 shows the block formed in the magnetic field in this example. Schematic diagram.

FIG. 3 is a diagram showing a B-H curve of a permanent magnet material obtained in Example 3 of the method of the present invention.

that's all Applicant: Seiko Epson Corporation Agent: Patent attorney Kisanbe Suzuki (1 person)

[Brief explanation of the drawing]

Procedural amendment (voluntary) 2. Name of the invention Permanent magnet 3゜Relationship with the case Patent applicant: 163 2-4-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Hisashi Nakamura, Representative Director of Seiko Epson Corporation 4. Agent contact information e348-8531 Extensions 300-302 5゜Specification subject to amendment (full text amendment) Figure 2 Figure 3 Procedural amendment form

Claims (1)

[Claims] In a permanent magnet made of a mixed molded product of a rare earth permanent magnet alloy composed of one or more rare earth metals (including Y) and one or more transition metals and a binder, the alloy is obtained by melting and casting. A permanent magnet characterized by being made of an alloy made by magnetically hardening an ingot that has been heat-treated in its lump form.