JPH0786015A - Permanent magnet having sufficient mechanical strength and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To increase the mechanical strength by a method wherein rare earth- iron-boron alloy powder and rare earth-based alloy powder in a specific composition are wet-mixed with one another to be sintered later. CONSTITUTION:The title permanent magnet is mainly composed of 8-40atm% of R (R represents at least one kind out of rare earth elements including Y) 50-85atm% of Fe, 2-30atm% of B and not exceeding 0.15wt.% of O. This rare earth iron-boron alloy particles are wet-crushed to produce a slurry. Next, rare earth-based alloy powder is directly mixed with the slurry leaving the dried up state thereof intact further wet-molded in a magnetic field for sintering step later. Through these procedures, the oxygen concentration in the magnet is lowered for enhancing the mechanical characteristics in the grain boundry as well as the mechanical strength of the magnet. Furthermore, the wettability in the sintered step can be enhanced due to the decrease in the oxygen amount on the particle surface to make the surface of magnetic particles smooth thereby enhancing the magnetic characteristics thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet having high mechanical strength and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, neodymium-iron-boron (Nd-F)
The e-B) and samarium-cobalt (Sm-Co) sintered magnets have been put to practical use as magnets having high magnetic characteristics (BH _MAX ). In recent years, permanent magnets have come to be used in turbochargers and energy recovery devices that have a high-speed rotating motor / generator installed in an engine. In such an energy recovery device and a turbocharger, the permanent magnet is attached to a shaft that rotates at high speed, and therefore, a permanent magnet having a large mechanical strength such as tensile strength has been required.

Further, JP-A-63-93841 discloses a rare earth permanent magnet alloy. The rare earth permanent magnet alloy has a weight percentage of 20 to 35% R (at least one or more rare earth elements including Y) and 0.5 to 1.
5% B and the balance M (Fe or a mixture of Fe and Co)
An alloy consisting of 35 to 80% R (same as above),
Remainder X (Fe or Fe and S, Al, Ti, V, Co, Z
Mixture of at least one of r, Nb and Mo)
And an alloy obtained by quenching a melt composed of 99.
It is composed of a ratio of 9: 0.1 to 80:20. The rare earth permanent magnet alloy improves magnetic properties by combining two kinds of powders and a wet type, reduces the amount of rare earth metal used, and lowers the cost.

Further, Japanese Laid-Open Patent Publication No. 3-1504 discloses a method of manufacturing a permanent magnet. The permanent magnet manufacturing method is intended to improve the magnetic properties by improving the orientation of the powder by a wet method.

Further, Japanese Patent Laid-Open No. 64-10602 discloses a method for manufacturing an Al-based rare earth magnet.
The Al-based rare earth magnet is manufactured by using Al powder or Al powder.
The alloy powder is used as a binder, and the rare earth magnet powder is added to the Al powder or the Al alloy powder in a volume ratio of 10 to 80.
% Of the mixture was preformed by cold pressing in a magnetic field, then hot pressed to form a solidified molded body, and then magnetized.

[0006]

However, in the conventional permanent magnet, the process using the dry press is mainly used, and the effort is focused only on the improvement of the magnetic characteristics. Currently, there is no permanent magnet with high strength.

Further, none of the rare earth permanent magnet alloys, the permanent magnet manufacturing method and the Al-based rare earth magnet manufacturing method disclosed in the above publications have the purpose of increasing mechanical strength.

Therefore, an object of the present invention is to solve the above-mentioned problems, and in an Nd-based rare earth magnet alloy having excellent magnetic properties, a rare earth base alloy powder is used as a binder, and wet grinding and wet pressing are performed. By dispersing the rare earth-Fe-B based alloy phase in the rare earth-based alloy phase by
A permanent magnet having high mechanical strength and improved mechanical properties, which prevents deterioration of mechanical strength due to an oxide phase, improves wettability with magnet powder, improves magnetic properties, and a manufacturing method thereof Is to provide.

[0009]

In order to achieve the above object, the present invention is configured as follows. That is,
According to the present invention, the rare earth-iron-boron alloy powder and the rare earth-based alloy powder are mixed and sintered at 8 to 40 at.
m% of R (R is at least 1 of rare earth elements including Y)
Seed), 50 to 85 atm% Fe, 2 to 30 atm% B and 0.15 wt% or less O as main components, and a permanent magnet having high mechanical strength.

In the permanent magnet having high mechanical strength, the rare earth-based alloy powder is an alloy powder produced by the atomizing method.

Further, in this permanent magnet having high mechanical strength, the rare earth-iron-boron alloy powder is prepared by pulverizing by a ball mill by a wet method.

Further, in this permanent magnet having high mechanical strength, when the rare earth-iron-boron alloy powder is pulverized by a wet method, hexane having a water content of 0.1% or less is pulverized.

Alternatively, according to the present invention, the rare earth-iron-boron alloy powder is wet-milled by a ball mill to prepare a slurry, and the rare earth-based alloy powder is directly added and mixed without drying the slurry, and the state The present invention relates to a method for producing a permanent magnet having high mechanical strength, which is characterized in that it is formed by wet-molding in a magnetic field to prepare a molded body, and sintering the molded body.

[0014]

The permanent magnet having a high mechanical strength and the method for manufacturing the same according to the present invention are configured as described above, and operate as follows. That is, the present invention is 8 to 40 atm%
R (R is at least 1 of the rare earth elements including Y)
Seeds), 50 to 85 atm% Fe, 2 to 30 atm% B and 0.15 wt% or less O as main components, and rare earth-
The iron-boron alloy powder is wet-milled and the slurry produced by wet pulverization is directly added and mixed with the rare earth-based alloy powder without drying,
In that state, since it was wet-molded and sintered in a magnetic field, the concentration of oxygen in the magnet can be lowered, the mechanical properties of the grain boundaries are improved, and the mechanical strength of the magnet is improved. Further, since the amount of oxygen on the surface of the magnet powder is reduced, the wettability during sintering is improved, the surface of the magnet powder is made smooth, and the magnetic characteristics are improved.

[0015]

EXAMPLES Examples of permanent magnets having high mechanical strength and a method for producing the same according to the present invention will be described below. The permanent magnet with high mechanical strength according to the present invention is a mixture of rare earth-iron-boron alloy powder and rare earth-based alloy powder and sintered, and contains 8 to 40 atm% of R (where R includes Y). At least one of rare earth elements), 50 to 85 at
m% Fe, 2-30 atm% B and 0.15 atm
% Or less of O as a main component. In this permanent magnet, the rare earth-based alloy powder is an alloy powder produced by an atomizing method. The rare earth-iron-boron alloy powder was pulverized by a ball mill by a wet method. When the rare earth-iron-boron alloy powder is pulverized by a wet method, hexane having a water content of 0.1% or less is pulverized.

In this method for producing a permanent magnet having high mechanical strength, a rare earth-iron-boron alloy powder is wet-milled by a ball mill to prepare a slurry, and the rare earth-based alloy powder is directly added without drying the slurry. Then, the mixture is mixed, and in that state, it is wet-molded in a magnetic field to prepare a molded body, and the molded body is sintered.

In this method of manufacturing a permanent magnet having high mechanical strength, first, neodymium-iron-boron (Nd-Fe) is used.
In order to produce a —B) -based alloy powder, electric field iron having a purity of 99.9% or more, ferroboron alloy, N having a purity of 99.7% or more
d and Co were weighed so as to have the composition shown in Table 1, and A1, A
Alloy powders of Nd-Fe-B based alloy compositions of 2, A3, A4 and A5 were prepared.

[Table 1]

In Table 1, the composition of each element is atomic%.
(Atm%), and these atm% are indicated by the numbers described as subscripts for each element. That is, the sample A1 has Nd: 11.7, Fe: 82.4, and B: 5.
It is 9 (atm%). Sample A2 has Nd: 11.7,
Fe: 75.0, Co: 7.4 and B: 5.9 (atm
%). Sample A3 is Nd: 12.7, Fe: 8
1.4 and B: 5.9 (atm%). Sample A4
Are Nd: 12.7, Fe: 74.0, Co: 7.4 and B: 5.9 (atm%). Further, the sample A5 is
Nd: 11.7, Fe: 82.4 and B: 5.9 (at
m%).

A neodymium-iron-boron alloy having a composition of elements A1, A2, A3, A4 and A5 is argon A.
An alloy was prepared by melting in a r atmosphere by high frequency or arc. Next, the prepared alloy is subjected to 2
Annealed in vacuum for 0 hours. Next, it was pulverized to 250 mesh by a stamp mill and finely pulverized by a ball mill by a wet method until it became about 3 to 4 μm. Hexane having a water content of 0.1% or less was used for fine pulverization.

On the other hand, in order to produce a rare earth-based alloy powder,
Depending on the atomizer, B1, B2, B3 shown in Table 2
Alloy powders of B4 and B5 were produced. The particle size of these alloy powders was 3 to 10 μm.

[Table 2]

Table 2 shows the composition of the rare earth-based alloy powder. The composition of each element in the rare earth-based alloy powder is shown in atomic% (atm%).
m% is indicated by a number described as a subscript for each element.
That is, the sample B1 is Nd: 50, Dy (dysprosium): 39, and Fe: 11 (atm%). Sample B
2 is Nd: 50, Dy: 39, Fe: 8 and Al: 3
(Atm%). Sample B3 has Nd: 50, Dy:
30, Y: 8, Fe: 10 and Zr: 2 (atm%). Sample B4 is Nd: 51, Dy: 35, Fe: 1
2 and Cu: 2 (atm%). Sample B5 is N
d: 51, Dy: 36, Fe: 11 and Zn: 2 (at
m%).

Samples A1, A2, A3 of rare earth, that is, neodymium-iron-boron alloy powder produced as described above.
Samples B1, B2, B3, B4, B5 were combined with each other in the combinations shown in Table 3 without drying the slurry prepared by pulverizing A4 and A5 by a ball mill.
Of rare earth-based alloy powder of 20 to the total weight of the powder
wt% was added and mixed, these mixed slurries were wet-molded in a magnetic field to prepare molded bodies, and these molded bodies were immediately sintered and heat-treated.

[Table 3]

The combinations shown in Table 3 are A1 and B1, A
1 and B1, A1 and B1, A2 and B2, A3 and B3, A4
And B4 and A5 and B5. The mixing ratio is 80% for the neodymium-iron-boron alloy powder and 20% for the rare earth-based alloy powder. Also, molding in a magnetic field
A molded body was produced by molding in a magnetic field of 12 kOe at a pressure of 1.5 ton / cm ² . 1000 of these molded bodies
Sintering was performed at ˜1100 ° C. in an argon atmosphere for 1 to 4 hours, and heat treatment was performed at 600 ° C. for 2 hours.

The mechanical strength of the permanent magnet manufactured as described above was measured by a 4-point bending strength test, and the measurement results are shown in Table 3. The magnetic characteristics of these permanent magnets were measured by a vibrating sample magnetometer, and the magnetic characteristics are shown in Table 3.
Shown in.

As shown in Table 3, the mixed sample M1 of the samples A1 and B1 has a four-point bending strength: 30.5 kg / mm ² ,
The magnetic property BH _{MAX was} 20.4 MGOe and the oxygen concentration in the magnet was 0.30 wt%. The mixed sample M2 of the samples A1 and B1 has a four-point bending strength: 36.2 kg / mm ² ,
The magnetic property BH _{MAX was} 26.7 MGOe and the oxygen concentration in the magnet was 0.20 wt%. The mixed sample M3 of the samples A1 and B1 has a four-point bending strength of 41.7 kg / mm ² ,
The magnetic property BH _{MAX was} 32.9 MGOe and the oxygen concentration in the magnet was 0.15 wt%. For samples A2 and B2,
4-point bending strength: 43.2 kg / mm ² , magnetic property BH
_MAX : 32.5 MGOe and oxygen concentration in magnet: 0.1
It was 2 wt%. For samples A3 and B3, 4-point bending strength: 44.8 kg / mm ² , magnetic property BH _MAX : 3
Oxygen concentration in 3.5 MGOe and magnet: 0.13 wt%. For samples A4 and B4, 4-point bending strength: 47.4
kg / mm ² , magnetic characteristic BH _MAX : 34.6MGOe
And oxygen concentration in the magnet: 0.10 wt%. Sample A
5 and B5, 4-point bending strength: 46.9 kg / mm ² ,
The magnetic property BH _{MAX was} 34.8 MGOe and the oxygen concentration in the magnet was 0.10 wt%.

From the above, it was found that the permanent magnet produced by this method for producing a permanent magnet having high mechanical strength has high magnetic properties and high mechanical strength.

Further, in order to compare the permanent magnets according to the present invention, when the rare earth-iron-boron alloy powder is pulverized by a wet method, sample A1, which is pulverized by using ethanol containing 0.2% of water content, Using A2, A3, A4 and A5, A1 and B1, A2 and B2, A3 and B3, A4 and B
4, 5 types of combinations of A5 and B5 were mixed in the same manner as above, molded, sintered and heat-treated to produce a comparative permanent magnet. The mechanical strength of these comparative permanent magnets is
It measured by the 4-point bending strength test similarly to the above, and a measurement result is shown in Table 4. Further, the magnetic characteristics of these permanent magnets were measured by a vibrating sample type magnetometer as in the above, and the magnetic characteristics are shown in Table 4.

[Table 4]

As shown in Table 4, the samples A1 and B1 are 4
Point bending strength: 22.3 kg / mm ² , magnetic property BH
_MAX : 12.1MGOe and oxygen concentration in magnet: 0.6
It was 7 wt%. For samples A2 and B2, 4-point bending strength: 23.1 kg / mm ² , magnetic property BH _MAX : 1
The oxygen concentration in 5.3 MGOe and the magnet was 0.62 wt%. For samples A3 and B3, 4-point bending strength: 21.9
kg / mm ^2, magnetic properties BH _{MA X:} 18.2MGOe
And oxygen concentration in the magnet: 0.65 wt%. Sample A
4 and B4, 4-point bending strength: 23.2 kg / mm ² ,
The magnetic property BH _{MAX was} 19.4 MGOe and the oxygen concentration in the magnet was 0.60 wt%. For samples A5 and B5,
4-point bending strength: 24.8 kg / mm ² , magnetic property BH
_MAX : 19.7 MGOe and oxygen concentration in magnet: 0.6
It was 6 wt%.

It has been found that the comparative permanent magnets using ethanol for grinding increase the amount of oxygen in the magnets and reduce the mechanical properties, ie mechanical strength and magnetic properties.

[0030]

The permanent magnet having a high mechanical strength and the method for manufacturing the same according to the present invention are configured as described above, and have the following effects. That is, the permanent magnet having a high mechanical strength according to the present invention is 8 to 40 atm% of R (R is a rare earth element containing Y) when the rare earth-iron-boron alloy powder and the rare earth base alloy powder are mixed and sintered. At least one), 50 to 85 atm% Fe, 2
Since B of ˜30 atm% and O of 0.15 wt% or less are the main components, the oxygen concentration in the permanent magnet is low and the mechanical strength due to the oxide phase can be prevented from lowering. It is possible to improve the sex.

Further, in the Nd-based rare earth magnet alloy according to the present invention, the magnet is obtained by wet-milling rare-earth-iron-boron alloy powder and forming a mixed slurry of rare-earth-iron-boron alloy powder and rare-earth-based alloy powder by wet-pressing. The concentration of oxygen in the inside can be lowered, the mechanical properties of the grain boundaries can be taught, and the mechanical strength of the magnet can be improved. Moreover, since the oxygen concentration on the surface of the magnet powder is reduced, the wettability during sintering is improved, the surface of the magnet powder is smoothed, and the magnetic characteristics are improved.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01F 1/053

Claims (5)

[Claims] 1. When mixing rare earth-iron-boron alloy powder and rare earth-based alloy powder and sintering, 8 to 40a
tm% R (R is at least one of rare earth elements including Y), 50 to 85 atm% Fe, 2 to 30 atm%
Of B and 0.15 wt% or less of O as a main component. 2. The permanent magnet having high mechanical strength according to claim 1, wherein the rare earth-based alloy powder is an alloy powder produced by an atomizing method. 3. The permanent magnet with high mechanical strength according to claim 1, wherein the rare earth-iron-boron alloy powder is prepared by pulverizing with a ball mill by a wet method. 4. The mechanical strength according to claim 3, wherein when the rare earth-iron-boron alloy powder is pulverized by a wet method, hexane having a water content of 0.1% or less is pulverized. Big permanent magnet. 5. A rare earth-iron-boron alloy powder is wet-milled by a ball mill to prepare a slurry, and the rare earth-based alloy powder is directly added and mixed without drying the slurry, and the magnetic field is wet in that state. A method for producing a permanent magnet having high mechanical strength, which is characterized in that it is produced by molding in a medium to produce a compact, and sintering the compact.