JP2003229306A - Rare earth-iron hollow thick film magnet manufacturing method and magnet motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thickness region of 50 to 160 which is difficult to process by a sintered magnet or a bonded magnet by powder metallurgy.
Provided is a method for manufacturing a rare earth-iron-based hollow thick film magnet having a thickness of 0 μm, and a magnet motor using the same. SOLUTION: A quenched flake of an R-TM-BM-based molten alloy or a buret thereof is formed by a pair of electrodes having a concave portion at at least one end face center portion with a thickness of 50 having an uncompressed portion corresponding to the concave portion. In the compression molding step of forming a compressed portion of about 1600 μm, the compressed portion is heated to a temperature equal to or higher than the crystallization temperature of the magnetic phase R ₂ TM ₁₄ B by energization between the electrodes to form an alloy magnet, The compressed part is mechanically removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a rare earth-iron thick film magnet, and a small and high performance magnet motor used as a driving source in microrobots, medical care, space development and the like.

[0002]

2. Description of the Related Art Rare earth-iron-based magnets are known as high-performance magnets, and various methods for forming thin-film magnets thereof have been proposed, such as JP-A-5-21865 and JP-A-6-151226. ing. However, all of them were generally formed by a sputtering method. To prepare a rare earth-iron thin film magnet by the sputtering method, the substrate should be 4
It is necessary to heat to 50 ° C or higher, and the film forming rate is 0.1 to
It is limited to 4 μm / hr. In particular, the magnetic phase R ₂ Fe ₁₄
In the rare earth-iron thin film magnet having B, the film thickness is limited to less than 5 μm in order to suppress the decrease in coercive force due to oxidation. Further, in the case of a multilayer rare earth-iron based thin film magnet having a thickness of 0.01 to 300 μm in which the thicknesses of the soft magnetic layer and the hard magnetic layer are strictly controlled at the nm level, the magnet production is further complicated and the economical efficiency becomes poor. Therefore, in Japanese Patent Laid-Open No. 11-288812,
A film is formed by a sputtering method without heating the substrate,
Also disclosed is a R ₂ Fe ₁₄ B rare earth-iron based thin film magnet that is heat treated after film formation. However, even in this method, the film forming rate is 4 μm / hr or less, and the film thickness is more than 10 μm.
There was a problem of being limited to m or less.

On the other hand, there is a strong demand for miniaturization of electromagnetic motors and electromagnetic actuators. The key to downsizing motors and actuators is to reduce the number of components and simplify assembly. For this reason, the movers of small motors and actuators are rare earth-based by powder metallurgy.
It is common to use a rare earth-iron bond magnet in which a ferrous sintered magnet, a quenched thin piece, and the like are hardened in a specific shape with a resin. Due to the positional relationship between the magnet and the armature winding, this type of small motor has an axial gap type in which the magnet and the armature winding have a gap in the axial direction, and the magnet and the armature winding have a gap in the radial direction. A radial void type has been proposed.

However, in the case of a motor or actuator (in this case, an axial gap type) having a diameter of 5 mm and a height of 1 mm as shown in FIG. The iron-based magnet also needs to be manufactured to a thickness of 500 μm or less. FIG. 1 shows an axial air gap type motor. The substrate 1 has a bearing 2 in the center, and a plurality of armature windings 3 are fixed so as to surround the bearing 2. The frame 4 has a rotary shaft 5 supported by a bearing 2, and has a hollow rare earth-iron magnet 6 on its lower surface.
Is fixed.

As a magnet for this type of small motor, a method of using a rare earth-iron-based sintered magnet ground and processed can be considered. However, the rare earth-iron-based sintered magnet is R ₂ Fe ₁₄
The crystal grain size of B is generally as large as 6 to 9 μm, and the R-rich phase exists in the crystal grain boundary, so that the magnetic performance of the surface layer from the surface to a depth of several 10 μm deteriorates during grinding.
Further, since the material is brittle and poor in workability, the working limit considering the yield is estimated to be about 500 μm in thickness. Furthermore, in order to mount the rotating shaft 5, the rare earth-iron-based magnet 6 needs to have a hollow shape. However, there is no description about it in the conventional literature on rare earth-iron thin film magnets. Therefore, in the rare earth-iron based thin film magnet, considering not only the magnet thickness but also the hollow magnet shape,
It can be said that it is difficult to adapt the shape to motor and actuator applications as shown in.

In the R ₂ Fe ₁₄ B rare earth-iron based bonded magnet, the crystal grain size of R ₂ Fe ₁₄ B is relatively small at 20 to 100 nm, but the coercive force of the quenched thin flakes is adjusted when it is adjusted to 50 μm or less. Dependence on particle size tends to increase. Therefore, if the magnet is made thinner, the squareness (Hk
/ Hci) and the residual magnetism Jr due to the decrease in magnet density
Inevitably lowers. Japanese Unexamined Patent Publication No. 6-244045 discloses a method for manufacturing a hollow thin plate magnet, in which a pressurizing and heating molding die is not provided with a die member corresponding to the hollow portion, but a non-pressurizing portion is provided instead. It is disclosed that a molded product having a non-pressurized dense portion and a pressurized dense portion is manufactured, and then the easily processable non-pressurized dense portion is mechanically removed to obtain a desired hollow shape. However, since the magnet powder is a so-called metal bonded magnet in which a metal solder or the like is used as a non-magnet powder, there is a drawback that the residual magnetization Jr is lowered.

As described above, in the millimeter-sized motor and actuator, the rare earth-iron based sintered magnet by the conventional powder metallurgical method or the rare earth-iron based bonded magnet obtained by hardening the quenched thin piece with the resin or the metal solder is adopted. However, the original magnetic performance of the rare earth magnet could not be fully utilized as a motor or an actuator. Further, in order to produce a rare earth-iron based thin film magnet by the sputtering method, it is generally necessary to heat the substrate to 450 ° C. or higher, and the film forming rate is limited to 0.1 to 4 μm / hr. Particularly, in the rare earth-iron thin film magnet having R ₂ Fe ₁₄ B as the main phase, the film thickness is 5 in order to suppress the decrease in coercive force due to oxidation.
Limited to less than μm. Further, the thickness of the soft magnetic layer and the hard magnetic layer is 0.01 to 300 μm, which is strictly controlled at the nm level.
The multi-layered rare earth-iron thin film magnet of m has drawbacks such that the magnet production is more complicated and the economical efficiency is poor, which has been a cause of hindering the spread of millimeter-sized motors and actuators. When the electromagnetic motor and actuator are miniaturized, according to the scaling rule, the electromagnetic force is "L ³ ".
Since (L is the physique), for example, when the mover size (magnet) becomes 1/10, the electromagnetic force decreases to 1/1000. Therefore, if the rare earth-iron thin film magnet having a film thickness of less than 5 μm is used as a movable element as it is, there is a problem that an electromagnetic force corresponding to a load in actual use cannot be obtained.

[0008]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a rare earth-iron-based hollow thick film magnet suitable for millimeter size motors and actuators. Another object of the present invention is to provide a method for economically producing a hollow thick film magnet without impairing the performance of the rare earth-iron magnet.

[0009]

The present invention provides an R-TM-B
-M system (wherein R is at least one element selected from the group consisting of Nd and Pr, 13 to 20 atomic%, TM
Is a transition metal element Fe or a part of Fe substituted with Co, B is 5 to 20 atomic%, M is at least one element selected from the group consisting of Ga and Cu, and 0.2 to 3.
0 atomic%, balance TM, including unavoidable impurities)
A quenching thin piece of the molten alloy is formed by a pair of electrodes having a concave portion at the center of at least one end face, and a non-compressed portion corresponding to the concave portion and a thickness surrounding the non-compressed portion are 50 to 1600.
A compression molding step of forming a compressed portion of μm, in which the compressed portion is heated to a temperature equal to or higher than the crystallization temperature of the magnetic phase R ₂ TM ₁₄ B by passing an electric current between the electrodes during the step. And a method of manufacturing a rare earth-iron-based hollow thick film magnet, which includes a step of forming a magnetic field and a step of mechanically removing the non-compressed portion.

In the present invention, the R-TM-BM system (where R is 13 to 20 atomic% of at least one element selected from the group consisting of Nd and Pr, and TM is the transition metal element Fe or Part of Fe replaced by Co, B is 5 to 20 atom%, M is at least one element selected from the group consisting of Ga and Cu, and 0.2 to 3.0 atom%.
Quenched thin piece of molten alloy which is the balance TM and contains inevitable impurities, and R-TM-B system (where R is at least one element selected from the group consisting of Nd and Pr).
1.5 atomic% or less, TM is a transition metal element Fe or Fe
In which a part of Co is replaced by Co, B is 5 to 20 atomic% and the balance is TM, and contains unavoidable impurities.) A step of preparing a mixture with a quenched thin piece of a molten alloy, at least one of the above mixture. Of a pair of electrodes having a concave portion at the center of the end face thereof, forming a non-compressed portion corresponding to the concave portion and a compressed portion having a thickness of 50 to 1600 μm surrounding the non-compressed portion. To the magnetic phase R ₂ TM ₁₄ B and α by energizing between the electrodes.
Rare earth-iron, which has a step of heating above the crystallization temperature of Fe / R ₂ TM ₁₄ B to form an alloy magnet having a mixed phase of both magnetic phases, and a step of mechanically removing the incompressible portion Provided is a method for manufacturing a hollow-type thick film magnet.

Furthermore, the present invention provides an R-TM-BM system (wherein R is 13 to 20 atomic% of at least one element selected from the group consisting of Nd and Pr, and TM is a transition metal element Fe or A part of Fe replaced by Co,
B is 5 to 20 atom%, M is at least one element selected from the group consisting of Ga and Cu, 0.2 to 3.0 atom%, and the balance is TM, and contains inevitable impurities.) A billet having a relative density of 85% or more made of a quenched thin piece is formed by a pair of electrodes having a recess at the center of at least one end face, and has a thickness of 50 to 1600 μm surrounding the incompressible part corresponding to the incompressible part and the recess. A compression molding step of forming a compression portion, wherein the compression portion is heated to a temperature equal to or higher than the crystallization temperature of the magnetic phase R ₂ TM ₁₄ B by passing an electric current between the electrodes during this step, and And a method of manufacturing a rare earth-iron-based hollow thick film magnet, which includes a step of forming an anisotropic alloy magnet in which the c-axis of the magnetic phase is oriented, and a step of mechanically removing the non-compressed portion.

The present invention provides a rare earth-iron based hollow thick film magnet obtained by the above method. Further, the present invention relates to an axial air gap type magnet motor including a mover having the magnet and a rotating shaft, and a stator facing the mover via a gap. The present invention also relates to a magnet motor including a plate-shaped mover and a plate-shaped stator having the rare earth-iron-based hollow thick film magnet.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides an R-TM-B via a pair of electrodes having a recess at the center of at least one end face.
-M system (R = Pr, Nd, TM = Fe, Co, M = G
a, Cu) A quenching thin piece of molten alloy or its billet has a thickness of 50 to 1600 μm by pressure heating by direct energization.
m of rare earth-iron-based hollow thick film magnet.
R-TM-B-M system and R-TM-B used in the present invention
System alloy magnets are already known, and the thin pieces obtained by quenching a molten metal of this type of alloy are described in JP-A-59-64739 and JP-A-59-211549. Are well known as those obtained by

A quenching thin piece of this type is R-TM-B.
-(M) type molten alloy in which crystals have already been precipitated by the quenching condition (speed), completely amorphous alloy, or intermediate thereof (crystallized portion and amorphous portion) And can be quantified as crystallinity by X-ray diffraction). R-TM-B
-A thin piece containing an amorphous material obtained by rapidly cooling a (M) -based molten alloy is
The viscosity becomes 1013 poise or less and the plastic deformability is exhibited only after heating to the crystallization temperature (about 595 ° C.) or higher. That is, in the present invention, the quenched thin piece is subjected to plastic working (plastic deformation diffusion) under the condition that crystallization and crystal grain growth proceed simultaneously. This makes it possible to obtain a thick film magnet having a high density and an effective magnetic phase. According to the present invention, a rare earth-iron-based hollow thick film magnet having a true density close to that of a true density can be obtained without using a resin or a metal solder.

The size of the crystal grains of the magnet obtained by the present invention is closely related to the magnetic characteristics such as the coercive force of the magnet and the temperature coefficient of the coercive force, and grain growth deteriorates the magnetic characteristics.
Therefore, as will be described later, when plastic-working an alloy flakes containing an amorphous material at a temperature equal to or higher than the crystallization temperature, it is preferable to carry out under the constraint of suppressing crystal grain growth. Generally several tens of seconds
It is preferable to finish the processing as follows. As a heating / pressurizing means in the present invention, a method of heating by Joule heat by directly energizing a thin piece or a bullet is
It is suitable for such processing in an extremely short time.

In the present invention, it is preferable that the heating during the compression step is performed by pulse current by applying a DC voltage and Joule heat by direct energization. By applying a DC voltage and passing a pulse current, the surface of the flakes can be etched to make the contact portions of the flakes uniform. The electrode for compressing the thin piece or the billet preferably has an electric resistance-volume specific heat ratio of 10 ^-2 (Ωcm ⁴ · deg / cal) or less. The pressure applied during the compression process is 250 kg.
It is preferably f / cm ² or more. Furthermore, it is preferable that the compression step is performed under a reduced pressure of 1 Torr or less.

By satisfying the above conditions, a high density thick film magnet having a coercive force Hci of 1100 kA / m or more, less irreversible demagnetization and a relative density of 95% or more can be obtained. Such a thick film magnet has a residual magnetization Jr of 0.8.
It becomes T or more. On the other hand, in the anisotropic thick film magnet, the residual magnetization Jr of the compressed portion can be 1.1 T or more.

The film formation of the alloy magnet according to the present invention is carried out by plastic deformation of the quenched thin piece or its billet, and the film formation rate of sputtering or laser ablation is 4 to 50 μm.
Compared with m / hr, it is possible to form a film with a desired thickness in several tens to one hundred and several tens of seconds. In the R-TM-BM system alloy, R
Is particularly preferably Nd or Pr, and part of Nd or Pr may be replaced with Dy. When R is less than 13.0 atomic%, sufficient plastic deformability and coercive force Hci are not developed, and when it exceeds 20 atomic%, the saturation magnetization Js is decreased due to the decrease of Fe component, and as a result, the residual magnetization Jr is decreased. To do.
Therefore, R is particularly preferably 13.0 to 14.0.
It is atomic%. If B is less than 5 atomic%, the coercive force Hci is lowered, and if it exceeds 20 atomic%, the residual magnetization Jr is lowered. M
Is Ga and / or Cu, and if it is less than 0.2 atomic%, the plastic deformability is not improved, and it becomes difficult to form a film having a thickness of 100 μm or less. On the other hand, if it exceeds 3.0 atom%, the residual magnetization Jr decreases with the decrease of the saturation magnetization Js.

The present invention is based on the R-TM-BM system (however,
R is at least one element selected from the group consisting of Nd and Pr and 13 to 20 atomic%, and TM is a transition metal element F.
One in which e or Fe is partially replaced by Co, B is 5 to 2
0 atomic%, M is at least one element selected from the group consisting of Ga and Cu, and is 0.2 to 3.0 atomic%, and the balance T
A melt-quenched thin piece of molten alloy (M, including unavoidable impurities) is compression-formed with heating by energizing between the electrodes with a pair of electrodes having a recess in the central portion of at least one end face to a thickness of 50- 1600 μm R ₂ TM ₁₄ B
An alloy magnet is formed, and a non-compressed portion corresponding to the recess of the electrode is mechanically removed to manufacture a rare earth-iron-based hollow thick film magnet. The present invention is based on the material for compression molding described above, in which R-TM-
B-based (where R is at least one element selected from the group consisting of Nd and Pr, 11.5 atomic% or less, TM
Those obtained by replacing part of the transition metal element Fe or Fe with Co, B is 5 to 20 atomic%, and the balance TM, by mixing the quenched foil of unavoidable containing impurities) molten alloy, R ₂ obtaining a TM ₁₄ B, a thick film magnet comprising a mixed phase of αFe / R ₂ TM ₁₄ B showing the higher than this residual magnetization Jr.

The magnets obtained by these methods are isotropic magnets. According to the present invention, a billet having a relative density of 85% or more, which is made of a quenched thin piece of an R-TM-B-M type molten alloy, is subjected to plastic working to obtain a magnetic phase R ₂ TM in the thickness direction.
An anisotropic alloy magnet with ₁₄ B c-axis oriented is obtained. For details of the principle of obtaining this anisotropic magnet, see the paper “Synthesis of Anisotropic Nd-Fe-B Based Magnets” by the present inventor.
by Direct Joule Heating ”IEEE.Trans.Magn., Vol.36,
No. 5, pp3365 (2000), it is quoted here.

Next, the R-TM-BM system (R = P
r, Nd, TM = Fe, Co, M = Ga, Cu) A quenched thin piece of a molten alloy, or a plastic deformation by pressure heating by direct current application to its billet, which is a rare earth-iron thick film with a thickness of 50 to 1600 μm. Direct current pressure heating as means for forming a magnet film will be described.

FIG. 2 shows the structure of the main part of the direct current pressure heating device 10. Reference numeral 30 represents a vacuum chamber equipped with a water cooling mechanism. This vacuum chamber 30 has an inner diameter of 300 mm and a depth of 400 mm, and a pair of plunger rods 13 and 23 made of stainless steel SUS-304 having a water cooling mechanism and having an outer diameter of 80 mm face each other inside. The upper plunger rod 13 is a stationary plate 1 via an electric insulating plate 12.
It is fixed at 1. Meanwhile, lower plunger rod 2
Reference numeral 3 is connected to a movable rod 22 made of an electrically insulating material of the hydraulic cylinder 21.

In the hydraulic cylinder 21, the oil feed passage 27 is connected to the pressurizing system 26 (maximum pressing force of 2 tons), and the pressurizing stroke of the movable rod 22 is 70 mm. The upper and lower plunger rods are connected to a heating power supply. The heating power source is a DC pulse power source 38 (voltage 0 to 30 V, pulse voltage application time 1 to 500 msec, operation setting time to 90 s).
ec) and DC power supply 39 (voltage 0 to 30 V, current to 500
0 A, energization time to 999 sec), and a mechanism for switching the connection from the DC pulse power supply to the DC power supply by a changeover switch 40 operated by a timer. The vacuum system 31 is an oil rotary pump (RP: pumping speed 310 l / mi
n) and mechanical booster pump (MBP: pumping speed 150 l / min) are used together, the ultimate vacuum is 10 ^-4 Torr.
r.

Punches 15 and 25 made of tungsten carbide are attached to the tips of the plunger rods 13 and 23 via graphite pieces 14 and 24, and the punches 15 and 25 are made in a ceramic die 16.
The sample set between and is compression molded. The electric pressurizing and heating device 10 includes a thermocouple 32 for detecting the temperature of the compressed portion and a thermometer 3 for displaying the detected temperature.
3, a vacuum gauge 34 and the like are provided.

Production of a hollow thick film magnet from a quenched alloy thin piece or a billet thereof can be carried out as follows. First, as shown in FIG. 3, in a ceramic die 41, an alloy quenching thin piece or a billet thereof is sandwiched between an electrode 42 having a recess 44 and an electrode 43 having a recess 45 at the center of the end face, Punches 15 and 25
Set between and. Then, as described below, compression molding including heating by energizing between both electrodes is performed. FIG. 3 shows a state after compression molding. The quenched thin piece or billet of the alloy becomes the non-compressed portion 52 corresponding to the concave portion of the electrode and the compressed portion 51 surrounding it by the compression molding accompanied by heating. If this is taken out of the die and the non-compressed part is mechanically removed, as shown in FIG.
A thick film magnet 50 having 3 is obtained.

The electrode 42, 43 and the die 41 sandwiching the alloy quenching flakes or billets thereof as described above are used in the device 1
After being set to 0, the pressure in the vacuum chamber is reduced to 1 Torr or less and 250 to 300 kgf / cm ² between the electrodes.
Apply the compression pressure of. Next, a direct current pulse voltage (300 A / cm ² ) is applied after applying a DC pulse voltage between both electrodes. The electrode ignores heat dissipation to the outside of the system, 1 (W) = 0.2
Considering 389 (cal / sec), the temperature rising rate dT / dt (° C./sec) due to energization is 0.2389 ΔI ²
(Ρ / SC). Where ΔI is the current density (A / c
m ² ), ρ is electrical resistivity (Ωcm), C is specific heat (cal /
° C · g), S is specific gravity (C × S is volume specific heat). That is, the rate of temperature rise dT / dt (° C./sec) is proportional to the square of the current density and the electrical specific resistance ρ, inversely proportional to the volume specific heat, and independent of the interelectrode distance. For example, TiN / Si ₃ N ₄
Ρ / SC of the electrode at room temperature is about 10 ^-4 (Ωcm ⁴ · de
g / cal), if the current density ΔI is 300 and 400 A / cm ² , then 9 and 16 ° C. /
High-speed heating with a heating time of sec is possible.

Therefore, the chamber pressure was reduced to 1 Torr or less, and TiN / Si ₃ N ₄ (ρ / SC = 10 ⁻⁴ Ωcm ⁴ ·
deg / cal) R-TM-B- sandwiched between electrodes
250 to 30 pieces of M-type alloy quenched flakes or their billets
Current density ΔI = 20 while compressing at 0 kgf / cm ^2.
Pulse energization of 0 A / cm ² , 0.5 sec on-0.5 sec off is performed for 30 sec. After that, the current density ΔI =
Direct energization of 300 or 400 A / cm ² is performed for 70 or 40 seconds. Then, it cools to room temperature. The coercive force Hci of the thick film magnet obtained as described above after the 4MA / m pulse magnetization was approximately 1100 kA / m or more. As described above, increasing the heating rate suppressed the coarsening of the crystal grain size and was effective in increasing the coercive force. Further, the density of the obtained thick film magnet is about 7.65 g / cm ^3, which is close to the true density.

[0028]

EXAMPLES Specific examples will be described below. 1. Optimization of Nd-Fe-Co-B alloy The composition is Nd: x atomic%, B: 6 atomic%, (Fe_0.8Co
_0.2): The balance (however, x = 12 to 15) alloy, and
And Nd: 13.5 at%, B: 6 at%, (Fe _1-yC
o_y): The balance (however, y = 0.1 to 0.3) of the alloy
Fig. 2 shows 30 mg of each thin slice obtained by quenching each molten metal.
Direct current pressure heating device of 3.4mm (0.090mm)
8 cm²) Was prepared. However, in Figure 3
Instead of the electrodes 42 and 43 having the recesses 44 and 45,
Do not have a recess, so that it matches the diameter of the billet to be obtained
The designed die and compression punch were used. Also, pressure 2
50-300kg / cm², Current density 300A / cm²,
The maximum ultimate temperature of the electrode was 700 to 730 ° C. Next,
Pressure of the manufactured billet is 600kgf / cm²,Current density
300-400A / cm²Maximum electrode temperature reached 700
A cylindrical magnet having a diameter of 5 mm was prepared at ˜780 ° C. Obtained porcelain
The stone has a thickness of 200 μm and a density of 7.6 when x = 13.0 or more.
0 to 7.65 g / cm³It was a uniform thick film. Was
However, the ratio of the electrical specific resistance and the volume specific heat of the electrodes used is 10^-2
(Ωcm^Four-Deg / cal).

FIGS. 5 and 6 are characteristic diagrams showing the magnetic characteristics as a function of x or y after the above cylindrical magnet is magnetized by 4 MA / m pulse in the thickness direction. x or Nd
The amount strongly affects the magnetic properties as well as the thick film forming ability.
When x = 12, which is close to the stoichiometric composition of R ₂ Fe ₁₄ B,
It was not possible to fabricate a thick film magnet due to its large plastic deformation resistance and brittleness. On the other hand, when x = 15, it became difficult to release from the electrode, and the maximum energy product (BH) max and the residual magnetization Jr also decreased. x = 13.0 to 14.0 ((B
H) max was 200 to 220 kJ / m ³ . However, Hci is 906 to 1030 kA / m and billet has 7
It fell to 4-75%. On the other hand, y, that is, the amount of Co has little effect. Therefore, the optimum Nd amount of the thick film magnet due to the plastic deformation in the direct current pressure heating was 13.0 to 14.0 atomic%.

The composition is Pr: 9 atom%, Fe: 73 atom%, Co: 9 atom%, B: 7 atom%, V: 1 atom%, N.
b: 1 atomic%, R ₂ Fe ₁₄ B (R = Nd, P
When R is smaller than the stoichiometric composition of r) and the crystal grain size is small, for example, 40 nm, αFe phase and R ₂ F ₂
As a nanocomposite magnet with e ₁₄ B phase, due to the remanence enhancement effect, for example, R ₂ Fe ₁₄ B composed of Nd: 13.5 at%, Fe: 79 at%, Co: 15 at%, B: 6 at%. A remanent magnetization Jr higher than that of a single-phase magnet is obtained. Actual composition is Pr: 9 atomic%, Fe:
The residual magnetization Jr of the alloy magnet flakes of 73 at%, Co: 9 at%, B: 7 at%, V: 1 at%, and Nb: 1 at% was 950 mT, and the composition was Nd: 13.5 at%. F
e: 79 at%, Co: 15 at%, B: 6 at%, which is about 18% higher than 800 mT of the alloy magnet flakes.

In the thick film magnet according to the present invention, the residual magnetization J
In order to improve r, nanocomposite magnet quenched flakes having an αFe phase and an R ₂ Fe ₁₄ B phase may be mixed in a range that does not significantly impair the coercive force Hci. For example, the composition is Nd: 13.5 at%, Fe: 79 at%, Co: 1
The composition of 20% of the alloy of 5 at% and B: 6 at% is Pr:
9 atom%, Fe: 73 atom%, Co: 9 atom%, B: 7
When a quenched thin piece of an alloy of atomic%, V: 1 atomic% and Nb: 1 atomic% is obtained, the remanent magnetization Jr of the obtained thick film magnet is 83.
It can be improved by several% from 0 mT to 860 mT.

2. Optimization of Electrode Material In FIG. 7, the composition is Nd: 13.6 at%, Pr: 0.15 at%, Fe: 77.5 at%, Co: 3 at%, B:
30 mg of quenching flakes of 5.8 atomic% molten alloy had a diameter of 3.
Use a cylindrical billet of 4 mm with a pressure of 300-40
0 kgf / cm ² , current density 300 to 400 A / cm
² is a characteristic diagram showing the relationship between electrode material, energization time, and magnetic characteristics when a thick film magnet having a diameter of 5 mm and a thickness of 200 μm is used in FIG. However, the maximum voltage applied between the electrodes is 30V.
The electrode material is represented by the ratio ρ / SC of the electrical specific resistance and the volume specific heat, and the energization time represents the time required for the process.

Ρ / SC of the electrode is 10 ^-5 (Ωcm ⁴ · deg)
/ Cal) level, the energization time becomes a little longer and the residual magnetization Jr is a little lower at 1020 mT. On the other hand, ρ of the electrode
When / SC exceeds 10 ^-2 (Ωcm ⁴ · deg / cal), it is difficult to control the current under the condition of the maximum voltage of 30 V, and it takes several hundred seconds until the current reaches a predetermined current density. Moreover, since the temperature rising speed after reaching the predetermined current density is high, Hci is lowered due to overheating of the billet. Therefore, ρ / SC of the electrode is 10 ^-2 (Ωcm ⁴ · deg / ca
lci or less, Hci is 1260 to 1360 kA / m,
Jr is 1150 to 1200 mT, which makes it possible to manufacture a thick film magnet in a short time with a relatively high coercive force Hci.

3. Coercive force and irreversible demagnetization Fig. 8 shows the composition of Nd: 14 atomic%, Fe: 73 atomic%, C
The initial irreversible demagnetization factor for the coercive force Hci after 4 MA / m pulse magnetization of thick film magnets with different coercive force Hci made from a quenched thin piece of molten alloy of o: 7 atomic%, B: 6 atomic% or its billet It is a characteristic view to show. However, in the figure, a and b represent the characteristics of a thick film magnet manufactured from a thin piece and a billet, respectively. The initial irreversible demagnetization rate is a value obtained from the rate of change in magnetic flux at room temperature before and after exposure to 120 ° C. air for 1 hour.

From FIG. 8, the initial irreversible demagnetization rate increases as the coercive force Hci decreases. However, Hci is 1100k
The initial irreversible demagnetization rate became smaller when it was more than A / m.
That is, even in the thick film magnet according to the present invention, Nd
_When the crystal grain size of ₂ (Fe, Co) ₁₄ B increases, the shape of the recoil curve of the demagnetization curve gradually shifts from the Pinning type to the Nucleation type. Since both Hci, which is important for thermal stability represented by irreversible demagnetization of thick film magnets, and its temperature coefficient β are both strongly related to the crystal grain size of Nd ₂ (Fe, Co) ₁₄ B, For a thick film magnet having a small miance coefficient, Hci is preferably set to 1100 kA / m or more.

4. Nd-Fe-Co-BM (M = G
a, Cu, Mo, Sn) -based alloy and coercive force R (Nd, Pr) set to 13.0 to 14.0 atomic% R
A thick film magnet can be produced from a quenched thin piece of a —Fe—Co—B based molten alloy or a billet thereof by direct current pressure heating, and its maximum energy product (BH) max is 21.
It reaches 8 to 220 kJ / m ³ . However, R-Fe-C
The coercive force Hci of the o-B type alloy tends to decrease. Therefore, the decrease in thermal stability represented by irreversible demagnetization and the thickness of 200 μm
There is a concern that the following magnets will be compatible with the shape of thinner magnets. Therefore, for the purpose of reducing the plastic deformation resistance (processing temperature for thickening the film), Nd-Fe-Co-BM (M = Ga, Sn,
Mo, Cu) -based molten alloy quenching flakes and their billets were investigated.

A billet having a diameter of 3.4 mm and a relative density of 85 to 90% was used under the conditions of a pressure of 300 to 600 kgf / cm ² and a current density of 300 to 400 kA / m ² and a diameter of 5 mm and a thickness of 200 μm of Nd-Fe-Co-. B-M (M = Ga,
Sn, Mo, Cu) thick film magnet and their 4 MA / m
The magnetic characteristics after pulse magnetization were measured. The results are shown in Table 1. On the other hand, when M = Sn, the desired workability was lowered, and it was necessary to raise the temperature to a high temperature of 850 ° C. or higher when finishing the magnet into the final shape. As a result, the magnet obtained with M = Sn was brittle and had a low coercive force Hci. It is when M is Ga or Cu that the film thickness can be easily increased by the direct current pressure heating. For example, the coercive force Hci of M = Ga system is 1644.
At ˜1679 kA / m, the difference in coercive force Hci due to the difference in crystallinity of the quenched thin pieces was 20 kA / m or less at most. On the other hand, in the system in which Nd was 16.1 atomic%, Hci was 1358 kA / m at most even for an amorphous thin piece.
Therefore, Nd-Fe-Co-B- with M = Ga and Cu
It has been clarified that the M-based alloy is effective for controlling the coercive force level in the direct current pressure heating, which is a key point in manufacturing the thick film magnet according to the present invention.

The crystallinity in Table 1 was measured by X-ray diffraction. The X-ray source was Cu-Kα, 40 kV-30 mA, and 1 / obtained from the diffraction line obtained at a scanning speed of 0.5 deg / min.
The crystallinity was defined as [1 + K (I _a / I _c )]. However, I
_a is an amorphous peak area intensity, _Ib is a crystalline peak area intensity, and K is 1 which is a constant peculiar to the substance.

[0039]

[Table 1]

5. Shape response force and heat stability The shape response force of the plastically deformable magnet when the diameter D of the billet and the thick film magnet was fixed to 3.4 mm or 5.0 mm and only the magnet thickness t was changed was examined. The appearance was visually inspected to see if defects such as cracks and the peripheral portion were uniformly processed into the final shape. In addition, the magnetic property is 4M
A / m pulse was magnetized and measured with a BH tracer. However, the composition of the sample is Nd: 13.5 atomic%, Pr:
0.20 atomic%, Fe: 77.2-Z atomic%, Co:
3.18 atomic%, B: 5.92 atomic%, Ga: z atomic%
A billet was prepared from a quenched thin piece of a molten alloy of (z = 0 to 3.0).

The maximum energy product (BH) max is 220-
It was in the range of 250 kJ / m ³ . However, z = 0.5
At ~ 0, when t / D = 0.02 and t = 100 μm, the shape of the peripheral portion of the thick film magnet became incomplete, and the coercive force Hci also decreased. Further, at t / D = 0.5, a crack was generated in the central portion of the magnet. However, by adjusting the particle size of the flakes with z = 3.0 to 32 μm, t / D = 0.02, t
= 50 μm, (BH) max of 110 to 120 kJ / m ³ thick film magnet can be manufactured. Therefore, there are restrictions on the thickness and the shape of the thick film magnet, and when the shape limit of this experiment with a diameter of 5 mm is represented by t / D and the film thickness, z = 0.
5 to 3.0, 0.01 to 0.32 (50 to 160
It became clear that it was in the range of 0 μmt).

6. The manufacturing composition of the hollow thick film magnet motor is Nd: 13.5 at%, Pr: 0.20 at%,
Fe: 74.2 atomic%, Co: 3.18 atomic%, B:
30 mg of a quenched thin piece of a molten alloy of 5.92 atomic% and Ga: 3.0 atomic% was used in the same manner as in 1 above with a direct current pressure heating device of FIG. 2 to obtain a diameter of 3.4 mm (0.0908 cm ² ) and a relative density of 85. % (Ratio to true density) billet was produced. However, pressure 250 to 300 kg / cm ² , current density 30
The maximum temperature reached by the electrode was 0 A / cm ² and 700 to 730 ° C.

Next, the prepared billet was provided with a pair of hollows shown in FIG. 3 having a ratio of electrical specific resistance to volume specific heat of 10 ⁻² (Ωcm ⁴ · deg / cal) and a hollow hole having a diameter of 1.5 mm at the center of the shaft. Compressing part pressure 300-600kgf / c using electrode
m ² , uncompressed part 0 kgf / cm ² , current density 3 in compressed part
00-400 A / cm ² , maximum temperature reached by electrode 700-
It was pressurized and heated at 750 ° C. to obtain a magnet having a diameter of 5 mm. However, the vacuum chamber was under a reduced pressure of 1 Torr, but the atmosphere was introduced together with the current interruption. The compression portion 51 of the obtained magnet has a thickness of 200 μm and a density of 7.65.
The maximum energy product (BH) max of the compressed portion after the 4 MA / m pulse magnetization was 240 kJ / m ³ at g / cm ³ . However, the billet of the non-compressed portion (roughly dense portion) is raised in both holes of the pair of hollow electrodes as shown by 52 in FIG.
It was oxidized. The non-compressed portion (rough and dense portion) 52 was mechanically brittle and easy to remove, and it was possible to obtain a rare earth-iron-based hollow thick film magnet having hollow holes as shown in FIG.

Next, the thickness is 200 μm and the outer diameter is 5.0 m.
2M for rare earth-iron-based hollow thick film magnets with m, inner diameter 1.5 mm
Two poles were magnetized with a pulsed magnetic field of A / m, the rotating shaft was fixed, and a mover having a diameter of 5 mm and a thickness of 1 mm to be incorporated into the millimeter size motor of FIG. 1 was produced. At the same time, the Nd-Fe-B system sintered magnet was ground to produce a mover having the same structure.
This motor obtains a rotational force by sequentially energizing the three-phase armature windings. A three-phase signal is generated by an oscillation circuit to energize the armature windings, and the speed is changed in synchronization with the frequency change. When the motor is driven (60 to 10,000 rpm), the maximum output of the motor is 18 mW for the motor using the magnet according to the present invention and 8 mW for the motor using the sintered magnet.
Met. As described above, when the thick film multilayer magnet of the present invention is used as a mover, it is possible to increase the output of a millicentimeter size electromagnetic motor or actuator.

[0045]

As described above, according to the present invention, it is a thick film magnet that is formed by plastic deformation instead of the conventional film formation by a physical deposition method such as sputtering or laser ablation. It is possible to obtain a thick film magnet having a high Hci of 1100 kA / m or more and a high (BH) max of 120 to 250 kJ / m ³ grade by anisotropicizing by high speed heat treatment. This high coercive force rare earth thick film magnet can be easily made into a hollow thick film magnet by removing the dense and dense parts formed by non-compression, and it is possible to perform grinding processing of sintered magnets and forming processing with bonded magnets. For example, it is difficult to improve the performance of small motors and actuators that require high-performance magnets in a thickness range of 50 to 1600 μm, reduce the number of parts, and reduce the number of assembly work steps.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the configuration of a small motor.

FIG. 2 is a diagram showing a configuration of a main part of a direct current pressurizing and heating device used in an example of the present invention.

FIG. 3 is a vertical cross-sectional view showing an electrode and a die used for molding a hollow thick film magnet.

FIG. 4 is a vertical cross-sectional view of a hollow thick film magnet excluding a non-compressed portion.

FIG. 5 is a diagram showing a relationship between atomic characteristics of Nd and magnetic characteristics of an Nd—Fe—Co—B system alloy magnet.

FIG. 6 is a diagram showing a relationship between Co atom% and magnetic characteristics of an Nd—Fe—Co—B alloy magnet.

FIG. 7: Electrode material (ratio ρ / S of electrical specific resistance and volume specific heat)
It is a figure which shows the relationship between C) and the characteristic of a thick film magnet.

FIG. 8 is a diagram showing a relationship between a coercive force of a thick film magnet and an irreversible demagnetization rate.

[Explanation of symbols]

41 die 42, 43 electrodes 44, 45 recess 50 thick film magnet 51 Compressor 52 Uncompressed part

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01F 41/02 H01F 1/04 H

Claims (15)

[Claims] 1. R-TM-BM system (where R is Nd
And at least one element selected from the group consisting of Pr and 13 to 20 atomic%, TM is a transition metal element Fe or a part of Fe replaced by Co, B is 5 to 20 atomic%, M is Ga and A quenching thin piece of a molten alloy containing 0.2 to 3.0 atomic% of at least one element selected from the group consisting of Cu and the balance TM and containing inevitable impurities).
A compression molding step of forming a non-compressed portion corresponding to the concave portion and a compressed portion having a thickness of 50 to 1600 μm surrounding the non-compressed portion by a pair of electrodes having a concave portion at the center of at least one end face. A step of heating the compressed portion to a temperature equal to or higher than the crystallization temperature of the magnetic phase R ₂ TM ₁₄ B by applying an electric current between the electrodes during the step to form an alloy magnet,
And a method for manufacturing a rare earth-iron-based hollow thick film magnet, which comprises a step of mechanically removing the non-compressed portion. 2. R-TM-BM system (where R is Nd
And at least one element selected from the group consisting of Pr and 13 to 20 atomic%, TM is a transition metal element Fe or a part of Fe replaced by Co, B is 5 to 20 atomic%, M is Ga and A quenched thin piece of a molten alloy containing 0.2 to 3.0 atomic% of at least one element selected from the group consisting of Cu and the balance TM and containing unavoidable impurities;
R-TM-B system (wherein R is at least one element selected from the group consisting of Nd and Pr and 11.5 atomic%
Hereinafter, TM is a transition metal element Fe or a part of Fe is Co.
, B is 5 to 20 atomic% and the balance is TM, and contains unavoidable impurities.) A step of preparing a mixture with a quenched thin piece of a molten alloy, the mixture being provided on at least one end face central portion. A compression molding step of forming a non-compressed portion corresponding to the concave portion and a compressed portion having a thickness of 50 to 1600 μm surrounding the non-compressed portion by a pair of electrodes having a concave portion, and between the electrodes during the step. By energizing the compressed portion, the compressed portion is magnetic phase R ₂ TM ₁₄ B and αFe / R ₂ T.
A rare earth-iron-based hollow thick film including a step of forming an alloy magnet having a mixed phase of both magnetic phases by heating to a crystallization temperature of M ₁₄ B or higher, and a step of mechanically removing the non-compressed portion. Magnet manufacturing method. 3. R-TM-BM system (where R is Nd
And at least one element selected from the group consisting of Pr and 13 to 20 atomic%, TM is a transition metal element Fe or a part of Fe replaced by Co, B is 5 to 20 atomic%, M is Ga and A billet having a relative density of 85% or more, which is formed from a quenched thin piece of a molten alloy, which is 0.2 to 3.0 atom% with at least one element selected from the group consisting of Cu and the balance is TM and contains unavoidable impurities. A compression molding step of forming a non-compressed portion corresponding to the non-compressed portion and a compressed portion having a thickness of 50 to 1600 μm surrounding the non-compressed portion by a pair of electrodes having a recessed portion in the central portion of at least one end face. During this step, the compressed portion is heated to a temperature equal to or higher than the crystallization temperature of the magnetic phase R ₂ TM ₁₄ B by applying an electric current between the electrodes, and the c-axis of the magnetic phase is oriented in the thickness direction. Isotropic alloy magnet Step of forming, and the rare earth has the step of mechanically removing the non-compressed portion - method of manufacturing the iron-based hollow thick magnet. 4. The method for producing a rare earth-iron-based hollow thick film magnet according to claim 1, 2 or 3, wherein the heating in the compression step is performed by a pulse current by applying a DC voltage and Joule heat by direct energization. 5. The ratio of the electric resistance of the electrode to the volume specific heat is 1
The method for producing a rare earth-iron-based hollow thick film magnet according to claim 1, 2 or 3, which is 0 ^-2 (Ωcm ⁴ · deg / cal) or less. 6. The pressure applied during the compression step is 250 kgf /
cm ² or more, the rare earth element according to claim 1, 2 or 3.
Iron-based hollow thick film magnet manufacturing method. 7. The method of manufacturing a rare earth-iron-based hollow thick film magnet according to claim 1, 2 or 3, wherein the compressing step is performed under a reduced pressure of 1 Torr or less. 8. The method for producing a rare earth-iron-based hollow thick film magnet according to claim 1, 2 or 3, wherein a relative density of a compression portion formed by the compression step is 95% or more. 9. The coercive force Hci of the compression section is 1100 kA.
/ M or more, The method for producing a rare earth-iron-based hollow thick film magnet according to claim 1, 2 or 3. 10. The residual magnetization Jr of the compression part is 0.8 T.
As described above, the maximum energy product (BH) max is 112 kJ / m ³
The method for producing a rare earth-iron-based hollow thick film magnet according to claim 1 or 3 as described above. 11. The residual magnetization Jr of the compressed portion is 1.1 T.
Above, the maximum energy product (BH) max is 240 kJ / m ³
The above is the method for producing a rare earth-iron-based hollow thick film magnet according to claim 2. 12. The method for producing a rare earth-iron-based hollow thick film magnet according to claim 1, 2 or 3, wherein the particle diameter of the quenched flakes is 32 μm or less. 13. A rare earth-iron thick film magnet obtained by the manufacturing method according to claim 1. 14. An axial air gap magnet motor comprising the rare earth-iron hollow thick film magnet according to claim 13, a mover having a rotating shaft, and a stator facing the mover via a gap. 15. A magnet motor comprising a flat plate-shaped mover and a flat plate-shaped stator having the rare earth-iron-based hollow thick film magnet according to claim 13.