JPH02268404A - Magnetic powder and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magnetic powder and a method for producing the same.

[Prior Art] Conventionally, rare earth-iron-boron (hereinafter abbreviated as R-Fe-B) based magnetic materials for permanent magnets have been developed or mass-produced using the following manufacturing method.

(1) Powder obtained by heat-treating and pulverizing a quenched thin flake with a thickness of about 10 to 30 μm produced using a quenched ribbon manufacturing device used to produce an amorphous alloy, and a resin-bonded magnet using the powder, (References (2) ) A magnetically anisotropic compacted magnet obtained by subjecting the rapidly cooled flakes obtained in (1) to mechanical orientation treatment using a two-step hot pressing method;
(Reference document 1) (3) Anisotropic sintered magnet created by powder metallurgy and sintering method, (Reference document 2) (4
) A magnetically anisotropic cast alloy magnet obtained by hot working an alloy ingot at a temperature of 500°C or higher to refine the crystal grains and orient the crystal axes in a specific direction; (Reference 3) (Reference 1: R, W
, LeeHAppl, Phys, Lett.

vol, 46(8), 15 April 1985.
p790. ) (Reference 2: H, Sagawa,
S., Fujimura, N.

Togawa, H. Yamamoto and Y.
Hatsuura; J, Appl.

Phys, Vol, 55(8),! 5 March
1984. p2083) (Reference 3: Japanese Unexamined Patent Publication No. 1983
2-278803) [Problem M to be solved by the invention] Of the above-mentioned conventional techniques, the quenched flake of (1) has a sufficiently high coercive force (8 to 16 kOe or more) for practical use.
However, as mentioned above, since it is magnetically isotropic, the problem is that the obtained magnetic properties (eg, energy product) are low.

To improve the magnetic properties of isotropic magnets, it is sufficient to use magnetically anisotropic magnetic powder, which can be achieved by grinding a magnetically anisotropic bulk material, for example in the Sm-Co system. A magnetically anisotropic magnetic powder should be obtained. However, with the R-Fe-B system, although a high coercive force can be obtained in the bulk state, when it is crushed to obtain powder to create a resin-bonded magnet, the coercive force drops significantly to the point where it is not practical. , Therefore, (2
) is the only Nd-Fe material in practical use because the reduction in coercive force due to crushing is relatively small.
-B-based anisotropic magnetic powder. However, (3), (
4) has the problem that when the particle size is used for magnetic powder for resin-bonded magnets, the coercive force is less than 1 kOe, making it completely impractical.

Furthermore, in (2), the coercive force decreases as the powder is crushed, although the degree is small, and in the powder state of several to several hundred micrometers, there is a large decrease in the squareness of the demagnetization curve as well as a decrease in the coercive force. The problem is that this not only causes a decrease in magnetic properties but also a large decrease in thermal stability.

The present invention is intended to solve these problems, and its purpose is to provide a high-performance magnetic powder and a method for producing the same.

[Means for Solving the Problems] The magnetic powder and the method for producing the same of the present invention involve creating a magnetically anisotropic compacted body, shaping it into a thin plate with a thickness of 1 mm or less, and coating the surface with a rare earth metal. It is characterized in that it is coated with at least one rare earth element including Y using a sputtering method or a vapor deposition method, heat-treated at a temperature of 250° C. or higher, and then pulverized.

In addition, the compacted body can be produced by: a) creating a quenched flake from the alloy using a quenched ribbon manufacturing device, mechanically orienting the flake using a two-step hot pressing method, and making it magnetically anisotropic; compacted body.

b) After melting and casting the alloy, the alloy ingot is
Using the so-called powder metallurgy method, pulverization, molding in a magnetic field,
A sintered magnet that has been made magnetically anisotropic through processes such as sintering and heat treatment.

C) After melting and casting the alloy, this alloy ingot is
It is characterized by being a cast alloy that has been made magnetically anisotropic by making the crystal grains finer and orienting the crystal axes in a specific direction by hot working at a temperature of 00° C. or higher.

In the present invention, a magnetically anisotropic consolidated body is made into a thin plate with a thickness of 1 mm or less, and the surface is coated with a rare earth metal using a sputtering method or a vapor deposition method, thereby eliminating surface distortion caused by processing. Since the coercive force can be relaxed, the reduced coercive force can be recovered. In addition, by heat-treating at a temperature of 250°C or higher after coating,
The effect can be further increased.

In addition, it is sufficient that the subsequent pulverization is mild, and the deterioration of the properties due to this is slight if any.

However, if the thin plate is thicker than 1 m111, the subsequent crushing will be burdensome and the magnetic properties will deteriorate to some extent, so the thickness of the thin plate is preferably 1 mm or less.

By the way, in Reference 4, a thin plate sliced from a sintered body is coated with a rare earth element by RF sputtering.
In the present invention, by converting this into powder, it has become possible to obtain magnetic powder that can be used for resin-bonded magnets for the first time.

(Reference 4: H, Sagawa and S, formerly Rosawa; J.

Mater, Res, Vol, 3. 1 19
88. p45) Rare earth metals as coating elements include Y, La, Ce,
Pr, Nd, Pm.

Sm, Eu, Gd, Tb, Dy,
Ho, Er.

It may be one or more of the rare earth elements Tm, Yb, and Lu.

Furthermore, Nd-Fe-B is well known as a rare earth magnet whose basic composition is composed of rare earth metals, iron, and boron. Sufficient magnetic performance can be obtained even with Nd), which is advantageous in terms of supply and price. Furthermore, D
By adding a heavy rare earth element such as y or Tb in a small amount, the coercive force iHc can be increased, and a substantial improvement in temperature characteristics can be achieved.

Furthermore, by replacing a portion of Fe with Co, the Curie temperature can be improved. Since Zr replaces rare earth metals, practical magnetic properties can be obtained with a low rare earth composition, which not only reduces costs, but also greatly improves corrosion resistance, which has been a problem. Substitution with other transition metal groups also improves magnetic performance, corrosion resistance, etc.

[Examples] Hereinafter, the present invention will be described in detail based on Examples.

(Example-1) In Example-1, a consolidated body produced by the manufacturing method of a) above will be described.

Melt and melt in an argon gas atmosphere using a high frequency melting furnace to obtain a composition of N d iFe@2.7B 4.1.
The obtained ingot was cast into a quenched ribbon using a quenched ribbon manufacturing apparatus in an argon gas atmosphere using a copper roll having a diameter of 20 mm. This quenched flake was lightly broken, placed in a mold, and heated to 700 to 800 ml in an argon atmosphere.
Hot compression molding was carried out at a temperature of °C for a short time and at a pressure of 20 kg/mm2.

The compacted body obtained had a density of approximately 100%.

This compacted body was heated again at 700 to 800 in an argon atmosphere.
℃ temperature and a pressure of 10 kg/aIm2 in a direction perpendicular to the initial compression direction.

(That is, die-up setting was performed.) The magnetic properties of the obtained bulk magnet were: 1Hc=14.2 [kOel Br=12.3 [kG] (BH)max=37.9 [MGOel .

The bulk magnet obtained here was pulverized and sieved into powder particle sizes as shown in Table 1, and the iHc of the powder of each particle size was measured. This is taken as a comparative example.

In addition, we made the bulk magnet into a thin plate with a thickness of 0.15 mm,
After coating the surface with terbium (Tb) by RF sputtering, the sample was heat-treated at 600°C for 10 minutes, and the iHc was similarly measured after crushing and sieving. This is the present invention.

The results are shown in Table 1.

As is clear from Table 1, in the comparative example, as the particle size of the powder becomes finer, the coercive force decreases, whereas in the present invention, there is almost no decrease in coercive force. I understand.

(Example 2) In Example 2, a compacted body produced by the manufacturing method b) above will be described.

Melt and cast in an argon gas atmosphere using a high-frequency melting furnace so that the composition of the Nd+5FevvB pot is obtained, and grind it using a stamp mill/ball mill to obtain an average particle size of 3 to 5.
A μm magnetic powder was obtained. This magnetic powder is filled into a mold,
Magnetic field orientation with 15 kOe magnetic field, 15-20 kg/
Compression molding was performed at a molding pressure of ma+2, sintering was performed at an optimal temperature of 1000 to 1250°C in an argon gas atmosphere, and heat treatment was performed as necessary at an optimal temperature of 400 to 1250°C.

The magnetic properties of the obtained sintered magnet are as follows: 1Hc=16.7 [kOel Br=12.8 [kG] (BH)wax=38.4 [MGOel.

The sintered magnet obtained here was used in the same manner as in the present invention of Example-1, but instead of sputtering Tb, dysprosium (
Using a method of vapor-depositing Dy), the prepared powder was mixed and kneaded with an epoxy resin, pressure-molded in a magnetic field, and then cured to produce a resin-bonded magnet. Magnetic measurements were performed on this in the anisotropic direction (easy magnetization direction) and the direction perpendicular thereto (difficult magnetization direction).

The results are shown in Table 2.

Table 2 As is clear from Table 2, the value of Br is significantly different between the easy magnetization direction and the difficult magnetization direction, indicating that a resin-bonded magnet with a large degree of anisotropy has been obtained, and the maximum energy A high value was also obtained for the product.

(Example 3) In Example 3, a compacted body produced by the manufacturing method of C) above will be described.

The ingot was melted and cast in an argon gas atmosphere using a high frequency melting furnace so that it had the composition P r ITF e ts, sB sCu +, s, and the obtained ingot was heated to 80% heat at 1000°C in an argon gas atmosphere. Apply intermittent press,
Heat treatment was performed at 1000° C. for 24 hours in an argon gas atmosphere. The magnetic properties of the obtained bulk magnet were: 1Hc=13.2 [kOel Br=12.6 [kG] (BH)max=36.2 [MGOel].

The bulk magnet obtained here was made into a thin plate with the thickness shown in Table 3, and a resin-bonded magnet was created using the method of sputtering Pr in the same manner as in Examples 1 and 2, and magnetic measurement was carried out. I did this.

As can be seen from Table 3, there is no problem if the thickness of the thin plate before coating is 1 m or less, and even if it is more than that, only some deterioration of the magnetic properties is observed.

(Example 4) Injection molding and extrusion molding were performed using the powders of Examples 1, 2, and 3 and using nylon 12 as a binder.

The results are shown in Table 4, and it is clear that there were no problems under any conditions, and the present invention does not depend on the method of manufacturing the resin-bonded magnet.

As described above in the examples, the present invention has the following features: - The type of magnet to be used and the thickness of the thin plate - The type of rare earth metal to be coated - The coating method - The method for manufacturing the resin-bonded magnet It is clear that there is no dependence.

[Effects of the Invention] As described above, according to the present invention, a magnetically anisotropic compacted body is created, this is formed into a thin plate having a thickness of 1+a+m or less, and a rare earth metal is applied to the surface of the compact by sputtering. Alternatively, by applying a coating using a vapor deposition method, heat-treating it at a temperature of 250°C or higher, and then pulverizing it, it has a high coercive force even in a powder state, so it can be quenched isotropically using the conventional quenching method. Since anisotropic powder with much higher performance than thin flakes can be obtained, it not only improves magnetic properties but also has great effects in terms of applications, such as simplifying the process and reducing costs. .

that's all

Claims (5)

[Claims] (1) Create a magnetically anisotropic compacted body and make it 1mm thick.
A thin plate with the following thickness is coated with a rare earth metal (at least one rare earth element including Y) using a sputtering method or vapor deposition method, and then heat treated at a temperature of 250°C or higher. A magnetic powder obtained by grinding. (2) Create a magnetically anisotropic compacted body and make it 1mm thick.
Form into a thin plate with the following thickness, coat the surface with rare earth metal using sputtering or vapor deposition, and heat at 250°C.
A method for producing magnetic powder, which comprises pulverizing the powder after heat treatment at a temperature above. (3) The above-mentioned magnetically anisotropic consolidated body is produced by quenching an alloy consisting of rare earths, iron, boron, and impurities that are unavoidable in manufacturing, using a quenching ribbon production device, and then processing this thin flake in two stages. 2. The magnetic powder according to claim 1, which is a compacted body that has been subjected to mechanical orientation treatment using a hot pressing method to make it magnetically anisotropic. (4) After the magnetically anisotropic compact body melts and casts an alloy consisting of rare earths, iron, boron, and impurities unavoidable in manufacturing, the alloy ingot is pulverized using a so-called powder metallurgy method. 2. The magnetic powder according to claim 1, which is a sintered magnet that has been made magnetically anisotropic through steps such as forming in a magnetic field, sintering, and heat treatment. (5) After the magnetically anisotropic compact body melts and casts an alloy consisting of rare earth elements, iron, boron, copper, and impurities unavoidable in manufacturing, the alloy ingot is hot-processed at a temperature of 500°C or higher. 2. The magnetic powder according to claim 1, which is a cast alloy made magnetically anisotropic by refining the crystal grains and orienting the crystal axes in a specific direction.