TW201532085A - Rare earth permanent magnet and manufacturing method of rare earth permanent magnet - Google Patents

Abstract

The present invention provides a manufacturing method of rare earth permanent magnet and rare earth permanent magnet which does not decrease the magnetic property, and which increases coercive force by Cu and inhibits principal phase decomposition or the precipitation of alpha Fe even the calcination is launched in the hydrogen gas environment. The permanent magnet is produced by forming and pulverizing magnet material without Cu and subjecting the formed article in the hydrogen gas environment at 200 Celsius degree ~ 900 Celsius degree for several hours to dozens of hours and then performing calcination treatment, followed by performing vacuum sintering or pressure sintering to sinter the formed article, further followed by sputtering Cu on the surface of the sintered body.

Description

Method for manufacturing rare earth permanent magnet and rare earth permanent magnet

The invention relates to a method for manufacturing a rare earth permanent magnet and a rare earth permanent magnet.

In recent years, permanent magnet motors used in hybrid electric vehicles, hard disk drives, and the like have been required to be small, lightweight, high in output, and high in efficiency. Further, when the permanent magnet motor is reduced in size, weight, output, and efficiency, the magnetic properties of the permanent magnet embedded in the permanent magnet motor are further improved. Further, as the permanent magnet, there are ferrite magnets, Sm-Co magnets, Nd-Fe-B magnets, and Sm ₂ Fe ₁₇ N _x magnets, and in particular, Nd-Fe- having a high residual magnetic flux density is used. The B-series magnet is used as a permanent magnet for a permanent magnet motor.

However, Nd-based magnets such as Nd-Fe-B have a problem that the heat resistance temperature is low. Therefore, when the Nd-based magnet is used for a permanent magnet motor, if the motor is continuously driven, the residual magnetic flux density of the magnet gradually decreases. Also, irreversible demagnetization occurs. Therefore, as a method of increasing the coercive force of the Nd-based magnet, a trace amount of Cu has been added.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2007-294917 (page 7)

Further, as a cause of deteriorating the magnetic properties of the Nd-based magnet, carbonaceous materials remain in the magnet. Especially in Nd-based magnets, the reactivity of Nd with carbon is very high, so if The carbonaceous material remains in the sintering step until it rises to a high temperature, and carbides are formed. As a result, there is a problem that a void is formed between the main phase of the magnet after sintering and the grain boundary phase due to the formed carbide, and the entire magnet cannot be densely sintered, and the magnetic properties are remarkably lowered. Further, even when voids are not formed, there is a problem that αFe is precipitated in the main phase of the magnet after sintering due to the formed carbide, and the magnet characteristics are largely lowered. Therefore, a technique is considered in which a calcination treatment is performed in a hydrogen atmosphere before the magnet is sintered, whereby the carbonaceous material is thermally decomposed to remove the contained carbon.

However, when the calcination treatment is carried out in a hydrogen atmosphere, it is considered that the following reaction (1) occurs in the rare earth magnet.

Nd ₂ Fe ₁₄ B+2H ₂ →2NdH ₂ +12Fe+Fe ₂ B. . . . (1)

When the reaction of the above (1) is pushed to the right side, the main phase of the rare earth magnet (Nd ₂ Fe ₁₄ B) is decomposed and αFe is precipitated, which causes a decrease in magnet characteristics. Further, it is also considered that one part of the decomposed main phase is recovered by the subsequent sintering treatment, but αFe remains.

In addition, as in the case of the above-described Patent Document 1, it is assumed that Cu is contained in the magnet raw material in advance, and Cu is contained in the magnet at the time of performing the calcination treatment. In this case, there is a problem that the reaction of the above (1) is easily advanced to the right side. Here, FIG. 12 is a permanent magnet produced by pulverizing, molding, and sintering a magnet raw material containing Cu in advance as in Patent Document 1, and by pulverizing, forming, and sintering a magnet raw material containing no Cu. A permanent magnet, which changes the conditions of the calcination process and compares the coercive force.

As shown in FIG. 12, when the calcination treatment is not performed in a hydrogen atmosphere, a large coercive force difference is not generated between the permanent magnet containing Cu and the permanent magnet containing no Cu. However, when the calcination treatment is carried out in a hydrogen atmosphere, the permanent magnet containing Cu has a lower coercive force than the permanent magnet containing no Cu, and if the temperature for the calcination treatment is further increased, the coercive force difference is obtained. Become bigger. That is, in the case where the calcination treatment is performed in a hydrogen atmosphere, the permanent magnet containing Cu easily advances the reaction of the above (1) to the right side, and is decomposed by the main phase as compared with the increase in the coercive force obtained by decarburization. Precipitation of αFe The influence of the reduction of the coercive force is greater, and it is predicted that the coercive force is lowered.

The present invention has been made to eliminate the above-mentioned problems, and an object thereof is to provide a method for producing a rare earth permanent magnet and a rare earth permanent magnet, which can achieve an increase in coercive force obtained by using Cu, and even if When calcination is carried out in a hydrogen atmosphere, decomposition of the main phase or precipitation of αFe can be suppressed without deteriorating the magnetic properties.

In order to achieve the above object, the rare earth permanent magnet of the present invention is characterized by the steps of: pulverizing a magnet raw material into a magnet powder; and forming a shaped body by molding the pulverized magnet powder; a step of calcining the magnet powder before or after forming and before sintering, in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas; sintering is performed by holding the formed body at a firing temperature to obtain a sintered body And a step of sputtering Cu on the surface of the sintered body.

Further, the rare earth permanent magnet of the present invention is characterized in that: by sputtering the sintered body sputtered with Cu, Cu sputtered on the surface of the sintered body is diffused to the sintered body Internal steps.

Further, the rare earth permanent magnet of the present invention is characterized in that heating is performed at a temperature lower than the firing temperature when the sintered body in which Cu is sputtered is heated.

Further, the rare earth permanent magnet of the present invention is characterized in that in the step of sputtering Cu on the surface of the sintered body, after sputtering of Nd on the surface of the sintered body, Cu is sputtered on the surface of the sintered body.

Further, the rare earth permanent magnet of the present invention is characterized in that Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co are added to the pulverized magnet powder. Bi, Zn, Mg or Nb and an organometallic compound which does not contain an oxygen atom and a nitrogen atom, and the above organometallic compound is adhered to the surface of the particle of the magnet powder, and the above-mentioned magnet powder is adhered to the surface of the particle by the above organometallic compound. to make Formed into a shaped body.

Further, the rare earth permanent magnet of the present invention is characterized in that the central metal is Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb. Metal complex, or diisobutylaluminum hydride.

Further, the rare earth permanent magnet of the present invention is characterized in that in the step of molding the magnet powder into a molded body, a mixture in which the magnet powder and the binder are mixed is produced, and the mixture is formed into a sheet shape to be produced. A green sheet of the above shaped body.

Further, the method for producing a rare earth permanent magnet of the present invention is characterized by comprising the steps of: pulverizing a magnet raw material into a magnet powder; forming a shaped body by molding the pulverized magnet powder; before or after forming And a step of calcining the magnet powder in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas before sintering; and performing the sintering by maintaining the molded body at a firing temperature to obtain a sintered body; The step of sputtering Cu on the surface of the sintered body.

Further, the method for producing a rare earth permanent magnet according to the present invention is characterized in that Cu is sputtered on the surface of the sintered body by heating the sintered body in which Cu is sputtered, and is diffused inside the sintered body. A step of.

Moreover, the method for producing a rare earth permanent magnet according to the present invention is characterized in that heating is performed at a temperature lower than the firing temperature when the sintered body in which Cu is sputtered is heated.

Further, in the method for producing a rare earth permanent magnet according to the present invention, in the step of sputtering Cu on the surface of the sintered body, after sputtering Nd on the surface of the sintered body, Cu is sputtered on the surface of the sintered body. .

Further, the method for producing a rare earth permanent magnet of the present invention is characterized in that Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga are added to the pulverized magnet powder. , Co, Bi, Zn, Mg or Nb and does not contain an organometallic compound of an oxygen atom and a nitrogen atom, and the above organic gold is adhered to the surface of the particle of the magnet powder. It is a compound and forms a molded body by molding the above-described magnet powder to which the above-described organometallic compound adheres.

Further, the method for producing a rare earth permanent magnet according to the present invention is characterized in that the organometallic compound-based central metal is Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, A metal complex of Bi, Zn, Mg or Nb, or diisobutylaluminum hydride.

Further, in the method for producing a rare earth permanent magnet according to the present invention, in the step of molding the magnet powder into a molded body, a mixture in which the magnet powder and the binder are mixed is produced, and the mixture is formed into a sheet shape. A green sheet as the above molded body was produced.

According to the rare earth permanent magnet of the present invention having the above-described configuration, the coercive force obtained by Cu can be improved, and even in the case of calcination in a hydrogen atmosphere, decomposition of the main phase or precipitation of αFe can be suppressed. Prevent deterioration of magnetic properties. Further, in the case of calcining the powdery magnet particles, the surface area of the magnet to be calcined can be expanded as compared with the case of calcining the magnet particles after molding. That is, the amount of carbon in the calcined body can be more surely reduced.

Further, according to the rare earth permanent magnet of the present invention, since the sintered body sputtered with Cu is heated, the Cu sputtered on the surface of the sintered body is diffused inside the sintered body, so that it is not included in the magnet raw material. Cu, so that the Cu which is sputtered after sintering is appropriately biased against the grain boundary. In other words, the effect of improving the coercive force can be obtained by using Cu without preliminarily including Cu in the magnet raw material.

Further, according to the rare earth permanent magnet of the present invention, when the sintered body sputtered with Cu is heated at a temperature lower than the firing temperature, the sputtered Cu is diffused inside the sintered body. In the step, grain growth of the magnet particles can be prevented.

Further, according to the rare earth permanent magnet of the present invention, after sputtering of Nd on the surface of the sintered body, Cu is sputtered on the surface of the sintered body, so that the sputtered Cu can be diffused inside the sintered body at a lower temperature. step.

Further, according to the rare earth permanent magnet of the present invention, Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn contained in the organometallic compound can be used. Mg or Nb is efficiently biased against the grain boundaries of the magnet. As a result, the magnetic properties of the permanent magnet can be improved. Further, the addition amount of Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb can be set to be smaller than the previous one, so The reduction of the residual magnetic flux density is suppressed.

Further, according to the rare earth permanent magnet of the present invention, the central metal is Cu, Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb. The metal complex or the diisobutylaluminum hydride is used as the organometallic compound, so that the thermal decomposition of the organometallic compound can be easily performed in the subsequent heating step, and the metal contained in the organometallic compound can be appropriately biased. Rely on the grain boundary. Further, the amount of carbon remaining in the magnet can be reduced by thermal decomposition. As a result, voids are not formed between the main phase of the magnet after sintering and the grain boundary phase, and the entire magnet can be densely sintered to prevent a decrease in coercive force. Further, a large amount of αFe is not precipitated in the main phase of the magnet after sintering, and the magnet characteristics are not greatly lowered.

Further, according to the rare earth permanent magnet of the present invention, the magnet obtained by sintering the green sheet formed by mixing the magnet powder and the binder constitutes a permanent magnet, so that shrinkage due to sintering becomes uniform without sintering. After the deformation such as warping or depression, and the pressure unevenness in the case of no pressurization, the correction processing after the previous sintering is not required, and the manufacturing steps can be simplified. Thereby, the permanent magnet can be formed with higher dimensional accuracy.

Further, according to the method for producing a rare earth permanent magnet of the present invention, the coercive force obtained by Cu can be improved, and the decomposition of the main phase or the precipitation of αFe can be suppressed even when the calcination is performed in a hydrogen atmosphere. To prevent deterioration of magnetic properties. Also, for powder When the magnet particles are calcined, the surface area of the magnet to be calcined can be expanded as compared with the case where the magnet particles after the forming are calcined. That is, the amount of carbon in the calcined body can be more surely reduced.

Further, according to the method for producing a rare earth permanent magnet of the present invention, since the sintered body sputtered with Cu is heated, Cu deposited on the surface of the sintered body is diffused inside the sintered body, so that it is not necessary to be in advance of the magnet. Cu is contained in the raw material, and Cu which is sputtered after sintering is appropriately biased against the grain boundary. In other words, the effect of improving the coercive force can be obtained by using Cu without preliminarily including Cu in the magnet raw material.

Moreover, according to the method for producing a rare earth permanent magnet of the present invention, when the sintered body sputtered with Cu is heated, the temperature is lowered at a temperature lower than the firing temperature, so that the sputtered Cu is diffused to the sintered body. In the step of the inside of the body, grain growth of the magnet particles can be prevented from occurring.

Further, according to the method for producing a rare earth permanent magnet of the present invention, after sputtering of Nd on the surface of the sintered body, Cu is sputtered on the surface of the sintered body, so that the sputtered Cu can be diffused to the sintered body at a lower temperature. Internal steps.

Further, according to the method for producing a rare earth permanent magnet of the present invention, Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi contained in the organometallic compound can be used. Zn, Mg or Nb is efficiently biased against the grain boundaries of the magnet. As a result, the magnetic properties of the permanent magnet can be improved. Further, the addition amount of Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb can be set to be smaller than the previous one, so The reduction of the residual magnetic flux density is suppressed.

Further, according to the method for producing a rare earth permanent magnet of the present invention, the central metal is Cu, Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, a metal complex of Mg or Nb or diisobutylaluminum hydride as an organometallic compound, so that thermal decomposition of the organometallic compound can be easily performed in the subsequent heating step, and the metal contained in the organometallic compound can be obtained. Properly biased against the grain boundary. Also, The amount of carbon remaining in the magnet is reduced by thermal decomposition. As a result, voids are not formed between the main phase of the magnet after sintering and the grain boundary phase, and the entire magnet can be densely sintered to prevent a decrease in coercive force. Further, a large amount of αFe is not precipitated in the main phase of the magnet after sintering, and the magnet characteristics are not greatly lowered.

Further, according to the method for producing a rare earth permanent magnet of the present invention, the magnet obtained by sintering the green sheet formed by mixing the magnet powder and the binder constitutes a permanent magnet, so that shrinkage due to sintering becomes uniform without Deformation such as warpage or depression after sintering is generated, and the pressure is not uniform when there is no pressurization, so that the correction processing after the previous sintering is not required, and the manufacturing steps can be simplified. Thereby, the permanent magnet can be formed with higher dimensional accuracy.

1‧‧‧ permanent magnet

2‧‧‧Nd crystal particles

3‧‧‧Metal bias

4‧‧‧Includes grains such as Cu

10‧‧‧ coarsely crushed magnet powder

11‧‧‧Bead mill

12‧‧‧Complex

13‧‧‧Support substrate

14‧‧‧Life

15‧‧‧Mold

16‧‧‧ Block

17‧‧‧ Block

18‧‧‧ slit

19‧‧‧ cavity

20‧‧‧ supply port

21‧‧‧Spray outlet

22‧‧‧Application roller

25‧‧‧ Solenoid

26‧‧‧heating plate

27‧‧‧ arrow

30‧‧‧Magnetic field application device

31‧‧‧ coil department

32‧‧‧ coil part

33‧‧‧Magnetic pole pieces

34‧‧‧Magnetic pole pieces

35‧‧‧film

37‧‧‧ heating device

38‧‧‧Table components

39‧‧‧ hollow

40‧‧‧Formed body

41‧‧‧Sintering mould

42‧‧‧vacuum chamber

43‧‧‧Upper punch

44‧‧‧lower punch

45‧‧‧Upper punch electrode

46‧‧‧ Lower punch electrode

50‧‧‧Sintered body

51‧‧‧Nd film

52‧‧‧Cu film

d‧‧‧The thickness of the metal bias layer

Particle size of D‧‧‧Nd crystal particles (Fig. 2)

D‧‧‧The gap between the mold and the supporting substrate (Fig. 6)

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a general view showing a permanent magnet of the present invention.

Fig. 2 is a schematic enlarged view showing the vicinity of a grain boundary of the permanent magnet of the present invention.

Fig. 3 is a schematic enlarged view showing the vicinity of a grain boundary of the permanent magnet of the present invention.

Fig. 4 is an explanatory view showing a manufacturing step of the permanent magnet of the present invention.

Fig. 5 is an explanatory view showing a manufacturing step of the permanent magnet of the present invention.

Fig. 6 is an explanatory view showing a forming step of a green sheet, in particular, a green sheet in the manufacturing process of the permanent magnet of the present invention.

Fig. 7 is an explanatory view showing a heating step and a magnetic field alignment step of a green sheet in the manufacturing process of the permanent magnet of the present invention.

Fig. 8 is a view showing an example in which a magnetic field is aligned in the vertical direction in the plane of the green sheet.

Fig. 9 is a view for explaining a heating device using a heat medium (polyoxygenated oil).

Fig. 10 is a schematic view showing a step of pressure sintering of a green sheet in the manufacturing process of the permanent magnet of the present invention.

Fig. 11 is a view showing various measurement results of the respective magnets of the examples and the comparative examples.

Fig. 12 is a diagram for explaining problems of the prior art.

Hereinafter, the method for producing the rare earth permanent magnet and the rare earth permanent magnet of the present invention will be described in detail with reference to the following embodiment.

[Composition of permanent magnets]

First, the configuration of the permanent magnet 1 of the present invention will be described. Figure 1 is a general view showing a permanent magnet 1 of the present invention. Further, the permanent magnet 1 shown in Fig. 1 has a fan shape, and the shape of the permanent magnet 1 changes depending on the punched shape.

The permanent magnet 1 of the present invention is an anisotropic magnet of the Nd-Fe-B system. Further, Cu, Al, Dy (镝), Tb (鋱), Nb (铌), V (vanadium), Mo (molybdenum), Zr (zirconium), Ta (钽) for improving the magnetic properties of the permanent magnet 1 ), Ti (titanium) or W (tungsten) is biased against the interface (grain boundary) of each of the crystal particles forming the permanent magnet 1. Further, the content of each component is set to Nd: 25 to 37 wt%, Cu, Al, Dy, Tb, Nb, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg Either (including at least Cu; hereinafter referred to as Cu or the like): 0.01 to 5 wt%, B: 0.8 to 2 wt%, and Fe (electrolytic iron): 60 to 75 wt%. Further, in order to improve the magnetic properties, a small amount of other elements such as Si may be contained.

Specifically, the permanent magnet 1 of the present invention generates a layer 3 containing Cu or the like by the surface portion (outer shell) of the crystal grains constituting the Nd crystal particles (main phase) 2 of the permanent magnet 1 as shown in FIG. 2 (hereinafter) It is referred to as a metal bias layer 3), and Cu or the like is biased against the grain boundary of the Nd crystal particles 2. Fig. 2 is an enlarged view of the Nd crystal particles 2 constituting the permanent magnet 1. Furthermore, the metal bias layer 3 is preferably non-magnetic.

Here, in the present invention, in particular, in order to produce the metal bias layer 3 containing Cu, Cu is sputtered on the surface of the sintered body as described below. Specifically, the sintered body is attached to a sputtering apparatus, and after sputtering of Cu on the surface of the sintered body, the sintered body to be sputtered is heated. As a result, the sputtered Cu diffuses and penetrates into the inside of the sintered body to form the metal offset layer 3 shown in FIG. Moreover, especially if Sputtering Nd before sputtering Cu, Cu can be made lower than Cu monomer. The state of the Nd-Cu alloy having a melting point (melting point of 459 ° C) is diffused and infiltrated, so that Cu can be more easily diffused and diffused into the inside of the sintered body.

In addition, in order to produce a metal offset layer 3 containing a metal element other than Cu (hereinafter referred to as Dy or the like), an organometallic compound containing Dy or the like is added to the magnet powder before molding the pulverized magnet powder. in. Specifically, when the magnet powder to which the organometallic compound containing Dy or the like is added is sintered, Dy or the like which is uniformly adhered to the surface of the particles of the Nd crystal particles 2 is diffused and diffused into the Nd by wet dispersion. The crystal growth region of the crystal particles 2 is replaced and replaced to form the metal offset layer 3 shown in FIG. Further, the Nd crystal particles 2 include, for example, an Nd ₂ Fe ₁₄ B intermetallic compound, and the metal bias layer 3 includes, for example, an Nd—Cu intermetallic compound, an Nd—Fe—Cu intermetallic compound, an NbFeB intermetallic compound, (Dy _x Nd). _1-x ) ₂ Fe ₁₄ B intermetallic compound or the like. Further, in addition to the metal bias layer 3, for example, Nd-rich may be formed in the grain boundaries.

Further, in the present invention, in particular, an organometallic compound containing Dy or the like and Nd and containing no oxygen atom and nitrogen atom, more specifically, a metal complex of Dy or the like or Nd or a hydrogenated dihydric compound is contained as follows. Butyl aluminum (DIBAL) is added to the organic solvent and mixed in the magnet powder in a wet state. Thereby, an organometallic compound containing Dy or the like or Nd can be dispersed in an organic solvent, and an organometallic compound containing Dy or the like or Nd can be uniformly adhered to the surface of the particles of the Nd crystal particles 2.

Here, as the above metal complex, it is particularly preferred to use a metal alkyl complex in which a ligand is an alkyl group. Particularly preferred is a cyclopentadienyl group, a methyl group, a benzyl group, an isobutyl group, a phenyl group, an octyl group, an ethylcyclopentadienyl group, an isopropylcyclopentadienyl group, a tetramethylcyclopentadiene. a metal or pentamethylcyclopentadienyl metal complex, or an acetylene metal complex. Examples of such a metal complex include tris(ethylcyclopentadienyl)ruthenium (III), tris(isopropylcyclopentadienyl)ruthenium (III), and bis(cyclopentadienyl). Magnesium (II), bis(cyclopentadienyl)dibenzyl ruthenium (IV), bis(pentamethyldicyclopentadienyl) ruthenium (V), bis(cyclopentadienyl) dimethyl Titanium (IV), bis(cyclopentadienyl)dimethylzirconium (IV), dihydro(cyclopentadienyl)zirconium dihydride (IV), tris(tetramethylcyclopentadienyl) ruthenium (III), trioctyl aluminum (III), diphenyl zinc (II), triphenyl ruthenium (III), tert-butyl alkyne Silver (I), (2,4,6-trimethylphenyl)silver (I), tricyclopentadienyl gallium (III). Further, in the present invention, in particular, in order to improve the magnetic properties of the permanent magnet 1, Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb acts as the central metal of the metal complex.

In addition, when the molded body of the magnet powder to which the organometallic compound is added is fired under appropriate firing conditions, diffusion or penetration (solid solution) of Dy or the like into the Nd crystal particles 2 can be prevented. Therefore, in the present invention, even if Dy or the like is added, Dy or the like can be biased only to the grain boundary after sintering. As a result, as a whole of the crystal grains (that is, as a whole of the sintered magnet), the core Nd ₂ Fe ₁₄ B intermetallic compound phase accounts for a large volume ratio. Thereby, the decrease in the residual magnetic flux density of the magnet (the magnetic flux density when the intensity of the external magnetic field is 0) can be suppressed.

Moreover, it is considered that if each of the Nd crystal particles 2 after sintering is in a dense state, exchange interaction occurs between the respective Nd crystal particles 2. As a result, when a magnetic field is applied from the outside, magnetization reversal of each crystal particle is likely to occur, and even if the crystal particles after sintering are temporarily set to a single magnetic domain structure, the coercive force is also lowered. However, in the present invention, the exchange interaction between the Nd crystal particles 2 is cut by the non-magnetic metal biasing layer 3 applied to the surface of the Nd crystal particles 2, even when a magnetic field is applied from the outside. It is also possible to prevent magnetization reversal of each crystal particle.

Further, in the present invention, since the metal offset layer 3 is formed of a layer containing at least Cu, it also functions as a method of uniformly dispersing the Nd-rich phase in the permanent magnet 1 after sintering to increase the coercive force.

Further, when the metal bias layer 3 is composed of a layer containing V, Mo, Zr, Ta, Ti, W or Nb as a high melting point metal, the metal layer 3 applied to the surface of the Nd crystal particle 2 is When the permanent magnet 1 is sintered, it also functions as a method of suppressing so-called grain growth in which the average particle diameter of the Nd crystal particles 2 is increased.

On the other hand, when the metal bias layer 3 is composed of a layer including Dy or Tb having a high magnetic anisotropy, the method of suppressing the generation of the antimagnetic region and improving the coercive force (preventing the magnetization reversal) is also exerted. Features.

Further, when the metal offset layer 3 is made of a layer containing, in particular, Al, it functions as a method of uniformly dispersing the Nd-rich phase in the permanent magnet 1 after sintering and increasing the coercive force.

Further, in the case where the metal bias layer 3 is composed of a layer containing other Ag, Ga, Co, Bi, Zn or Mg, it is also expected to improve the permanent magnet by the grain boundary control or the increase in the coercive force of the grain growth suppression. The effect of magnetic properties.

Moreover, when the structure of the organometallic compound containing Nd is added, the Nd-rich phase can be uniformly dispersed in the permanent magnet 1 after sintering. Further, even if the rare earth element is combined with oxygen or carbon during the production process, the rare earth element is sufficient with respect to the stoichiometric composition, and generation of αFe in the permanent magnet 1 after sintering can be suppressed.

Further, the particle diameter D of the Nd crystal particles 2 is preferably 0.2 μm to 1.2 μm, preferably about 0.3 μm. Further, when the thickness d of the metal bias layer 3 is about 2 nm, the effect of using the metal offset layer 3 (suppressing grain growth, cutting exchange interaction, and increasing coercive force) can be obtained. However, when the thickness d of the metal bias layer 3 is excessively large, the content ratio of the nonmagnetic nonmagnetic component is not increased, and thus the residual magnetic flux density is lowered.

In addition, as a structure in which Cu or the like is biased against the grain boundary of the Nd crystal particles 2, as shown in FIG. 3, the grain 4 containing Cu or the like may be dispersed in the grain boundary of the Nd crystal particles 2. Even in the configuration shown in Fig. 3, the same effect (suppression of grain growth, cutting exchange interaction, improvement of coercive force, etc.) can be obtained. Further, regarding the manner in which Cu or the like is biased against the grain boundary of the Nd crystal particles 2, for example, SEM (Scanning Electron Microscope), FIB (Focused Ion Beam), and SEM can be used. The system, TEM (Transmission Electron Microscopy), and three-dimensional atom probe method were used for confirmation.

Further, the metal offset layer 3 need not be only a Cu compound, an Al compound, a Dy compound, a Tb compound, a Nb compound, a V compound, a Mo compound, a Zr compound, a Ta compound, a Ti compound, an Ag compound, a Ga compound, a Co compound, or the like. A layer composed of a Bi compound, a Zn compound, a Mg compound or a W compound (hereinafter referred to as a compound such as Cu) may be a layer containing a mixture of a compound such as Cu and a Nd compound. In this case, a layer containing a mixture of a compound such as Cu and a Nd compound is formed. As a result, liquid phase sintering at the time of sintering of the Nd magnet powder can be promoted.

Here, the permanent magnet 1 is a film-shaped permanent magnet having a thickness of, for example, 0.05 mm to 10 mm (for example, 1 mm). The permanent magnet 1 is produced by sintering a molded body formed by powder molding or a molded body (green body) obtained by mixing a mixture of a magnet powder and a binder as described below. Further, the green body is produced by molding a mixture (slurry or composite) in which a mixture of a magnet powder and a binder is mixed into a specific shape (for example, a sheet shape, a block shape, a final product shape, etc.) as follows. Further, the mixture may be temporarily molded into a shape other than the shape of the final product, and then subjected to punching, cutting, deformation processing, or the like, thereby forming a shape of the final product. Further, in particular, when the mixture is formed into a sheet shape and then processed into a final product shape, productivity can be improved by production in a continuous step, and the precision of molding can be improved. When the mixture is formed into a sheet shape, a film member having a film thickness of, for example, 0.05 mm to 10 mm (for example, 1 mm) is formed. Further, even in the case of forming a sheet shape, a large permanent magnet 1 can be produced by laminating a plurality of sheets.

Further, in the present invention, in particular, when the permanent magnet 1 is produced by sintering the green body, the binder mixed in the magnet powder may be a resin, a long-chain hydrocarbon, a fatty acid ester or a mixture thereof. .

Further, in the case where a resin is used as the binder, it is preferred to use a polymer having no oxygen atom and having depolymerization property in the structure. Further, as described below, in order to reuse the residue of the mixture produced by molding the mixture of the magnet powder and the binder into the shape of the final product A thermoplastic resin is used for the magnetic field alignment in order to soften the formed mixture by heating it. Specifically, a polymer containing one or two or more polymers or copolymers selected from the monomers represented by the following formula (1) is suitable.

(wherein R ₁ and R ₂ represent a hydrogen atom, a lower alkyl group, a phenyl group or a vinyl group)

Examples of the polymer satisfying the above conditions include polyisobutylene (PIB) which is a polymer of isobutylene, polyisoprene (isoprene rubber, IR) which is a polymer of isoprene, and 1, Polybutadiene (butadiene rubber, BR) of 3-butadiene polymer, polystyrene as polymer of styrene, styrene-isoprene as copolymer of styrene and isoprene Diene block copolymer (SIS), butyl rubber (IIR) as a copolymer of isobutylene and isoprene, styrene-butadiene block copolymer as a copolymer of styrene and butadiene ( SBS), 2-methyl-1-pentene polymer resin as a polymer of 2-methyl-1-pentene, 2-methyl-1- as a polymer of 2-methyl-1-butene Butylene polymer resin, α-methylstyrene polymer resin as a polymer of α-methylstyrene, and the like. Further, in order to impart flexibility to the α-methylstyrene polymer resin, it is preferred to add a low molecular weight polyisobutylene. Further, the resin used as the binder may be a polymer or a copolymer (for example, polybutyl methacrylate or polymethyl methacrylate) containing a small amount of a monomer containing an oxygen atom. Further, a monomer which does not belong to the above formula (1) may be partially copolymerized. Even in this case, the object of the invention can be achieved.

Further, as the resin used in the binder, in order to appropriately perform magnetic field alignment, it is preferred to use a thermoplastic resin which is softened at 250 ° C or lower, more specifically, glass. A glass transition point or a thermoplastic resin having a melting point of 250 ° C or less.

On the other hand, in the case where a long-chain hydrocarbon is used as the binder, a long-chain saturated hydrocarbon (long-chain alkane) which is solid at room temperature and liquid at room temperature or higher is preferable. Specifically, it is preferred to use a long-chain saturated hydrocarbon having a carbon number of 18 or more. Further, when the mixture of the magnet powder and the binder is subjected to magnetic field alignment as described below, the mixture is heated in a state where the mixture is heated at a temperature higher than the melting point of the long-chain hydrocarbon to soften the magnetic field.

Further, when a fatty acid ester is used as the binder, it is also preferred to use methyl stearate or methyl behenate which is solid at room temperature and liquid at room temperature or higher. Further, when the mixture of the magnet powder and the binder is subjected to magnetic field alignment as described below, the magnetic field alignment is performed in a state where the mixture is heated and softened at a temperature equal to or higher than the melting point of the fatty acid ester.

By using a binder satisfying the above conditions as a binder mixed in the magnet powder, the amount of carbon and the amount of oxygen contained in the magnet can be reduced. Specifically, the amount of carbon remaining in the magnet after sintering is 2,000 ppm or less, more preferably 1,000 ppm or less. Moreover, the amount of oxygen remaining in the magnet after sintering is 5,000 ppm or less, more preferably 2,000 ppm or less.

Further, in order to increase the thickness precision of the molded body when molding the slurry or the composite which is heated and melted, the amount of the binder added is an amount which appropriately fills the space between the magnet particles. For example, the ratio of the binder to the total amount of the magnet powder and the binder is from 1 wt% to 40 wt%, more preferably from 2 wt% to 30 wt%, still more preferably from 3 wt% to 20 wt%.

[Method of manufacturing permanent magnet]

Next, a method of manufacturing the permanent magnet 1 of the present invention will be described with reference to FIGS. 4 and 5. 4 and 5 are explanatory views showing the manufacturing steps of the permanent magnet 1 of the present embodiment.

First, an ingot containing a specific fraction of Nd-Fe-B (for example, Nd: 32.7 wt%, Fe (electrolytic iron): 65.96 wt%, B: 1.34 wt%) is produced. Thereafter, the ingot is roughly pulverized to a size of about 200 μm by a masher, a crusher or the like. Or, melt the ingot Thin, strips are produced by strip casting, and coarsely pulverized by hydrogen crushing. Thereby, the coarsely pulverized magnet powder 10 is obtained.

Then, the coarsely pulverized magnet powder 10 is finely pulverized by a wet method using a bead mill 11 or a dry method using a jet mill. For example, in the fine pulverization using the wet method using the bead mill 11, the coarsely pulverized magnet powder 10 is finely pulverized into a specific range of particle diameter (for example, 0.1 μm to 5.0 μm) in a solvent, and the magnet powder is dispersed. In the solvent. Further, the type of the solvent to be pulverized is not particularly limited, and examples thereof include alcohols such as isopropyl alcohol, ethanol, and methanol, esters such as ethyl acetate, and lower hydrocarbons such as pentane and hexane, and benzene, toluene, and An aromatic group such as toluene, a ketone, a mixture of the above, and the like. Further, it is preferred to use a solvent which does not contain an oxygen atom in the solvent.

On the other hand, in the fine pulverization using a dry method using a jet mill, (a) an atmosphere containing an inert gas such as nitrogen, argon or helium in an oxygen content of substantially 0%, or (b) In an environment containing an inert gas such as nitrogen gas, argon gas or helium gas having an oxygen content of 0.0001 to 0.5%, the coarsely pulverized magnet powder is finely pulverized by a jet mill to form a particle diameter having a specific range (for example, 0.7). A fine powder having an average particle diameter of μm to 5.0 μm). In addition, when the oxygen concentration is substantially 0%, it is not limited to the case where the oxygen concentration is completely 0%, and it means that oxygen may be contained in an amount which is extremely small in the surface of the fine powder.

Then, an organometallic compound is attached to the surface of the particles of the magnet powder by adding and mixing the organometallic compound to the solvent containing the magnet powder after the wet pulverization. Further, as the molten organometallic compound, it is preferred to use an organometallic compound containing Dy or the like as described above and containing no oxygen atom and nitrogen atom, more specifically, a metal metal of Dy or the like or Nd. (eg, tris(ethylcyclopentadienyl)ruthenium (III), tris(isopropylcyclopentadienyl)ruthenium (III), bis(cyclopentadienyl)magnesium (II), double (cyclopentadienyl) dibenzyl ruthenium (IV), bis(pentamethyldicyclopentadienyl) ruthenium (V), bis(cyclopentadienyl)dimethyltitanium (IV), Bis(cyclopentadienyl)dimethylzirconium (IV), di(cyclopentadienyl)zirconium(IV) dihydride, tris(tetramethylcyclopentadienyl)ruthenium(III), trioctyl Aluminum (III), two Phenyl zinc (II), triphenyl ruthenium (III), tributyl butyl acetylide (I), (2,4,6-trimethylphenyl) silver (I), tricyclopentadienyl gallium ( III) etc.) or DIBAL. Further, the amount of the organometallic compound to be melted is not particularly limited, and the content of Dy or the like with respect to the magnet after sintering is preferably 0.001% by weight to 10% by weight, preferably 0.01% by weight to 5% by weight. Further, the addition of the organometallic compound may be carried out by adding the solvent to the solvent before the pulverization step and simultaneously pulverizing and mixing. Further, in the case of using a dry method using a jet mill, an organometallic compound is adhered to the surface of the particles of the magnet powder by separately adding and mixing the pulverized magnet powder and the organometallic compound to the solvent. Thereafter, the magnet powder contained in the solvent after the wet pulverization is dried by vacuum drying or the like to extract the dried magnet powder.

Then, a magnet powder obtained by attaching an organometallic compound to the surface of the particle is formed into a desired shape. Further, the formation of the magnet powder includes, for example, powder molding in which a mold is formed into a desired shape, or a green mold in which a mixture of the magnet powder and the binder is mixed into a desired shape. Further, the powder molding includes a dry method in which the dried fine powder is filled into the cavity, and a wet method in which the slurry containing the magnet powder is not dried and filled into the cavity. On the other hand, in the green molding, the mixture can be directly formed into the shape of the final product, or the mixture can be temporarily formed into a shape other than the shape of the final product to perform magnetic field alignment, and then subjected to punching, cutting, and deformation processing. Etc., thereby forming the final article shape. In the following examples, the mixture was temporarily formed into a sheet shape (hereinafter referred to as a green sheet) and then processed into a final product shape. Further, in the case of forming the mixture into a sheet shape in particular, for example, it is formed by hot-melt coating in which a composite in which a mixture of a magnet powder and a binder is heated and formed into a sheet shape is formed. Or, a slurry containing a magnet powder, a binder, and an organic solvent is applied to a substrate to form a sheet-like slurry coating or the like.

Hereinafter, the green sheet molding using hot melt coating will be specifically described.

First, a magnet powder is prepared by mixing a magnet powder and a binder. A powdery mixture (composite) of the binder 12 . Here, as the binder, a resin, a long-chain hydrocarbon, a fatty acid ester, a mixture of these, or the like can be used as described above. For example, it is preferred to use a thermoplastic resin containing a polymer having no oxygen atom and having depolymerization in the case of using a resin, and, on the other hand, a solid at room temperature in the case of using a long-chain hydrocarbon. And a long-chain saturated hydrocarbon (long-chain alkane) which is liquid above room temperature. Further, in the case of using a fatty acid ester, methyl stearate or methyl behenate or the like is preferably used. Further, the amount of the binder added is such that the ratio of the binder in the composite 12 added as described above to the total amount of the magnet powder and the binder is from 1% by weight to 40% by weight, more preferably from 2% by weight to 30% by weight. The amount of %, further preferably from 3 wt% to 20 wt%.

Further, in order to increase the degree of alignment in the subsequent magnetic field alignment step, an additive for promoting alignment may be added to the composite 12. As the additive for promoting the alignment, for example, a hydrocarbon-based additive can be used, and it is particularly preferable to use an additive having a polarity (specifically, an acid dissociation constant pKa of less than 41). Further, the amount of the additive to be added depends on the particle diameter of the magnet powder, and the smaller the particle diameter of the magnet powder, the more the amount of addition is required. The specific addition amount is 0.1 parts to 10 parts, more preferably 1 part to 8 parts, per part of the magnet powder. Further, the additive added to the magnet powder adheres to the surface of the magnet particles, and has an effect of assisting the rotation of the magnet particles in the magnetic field alignment treatment described below. As a result, the alignment is easily performed when a magnetic field is applied, and the direction of the easy magnetization axis of the magnet particles can be made to coincide with the same direction (that is, the alignment degree is improved). In particular, when a binder is added to the magnet powder, a binder is present on the surface of the particles, so that the frictional force at the time of alignment is improved, and the alignment property of the particles is lowered, so that the effect of adding an additive becomes more remarkable.

Further, the addition of the binder is carried out in an environment containing an inert gas such as nitrogen, argon or helium. Further, the mixing of the magnet powder and the binder is carried out, for example, by separately charging a magnet powder and a binder into an organic solvent and stirring the mixture with a stirrer. Further, in order to promote kneading, heating and stirring may be performed. Further, the composite 12 is extracted by heating an organic solvent containing a magnet powder and a binder after heating to vaporize the organic solvent. Further, the mixing of the magnet powder and the binder is preferably carried out in an atmosphere containing an inert gas such as nitrogen, argon or helium. Further, in particular, when the magnet powder is pulverized by the wet method, the magnet powder may be extracted from the solvent used for pulverization, and the binder may be added to the solvent and kneaded, and then the solvent may be used. Volatilization gave the following composite 12.

Then, a green sheet is produced by forming the composite 12 into a sheet shape. In particular, in the hot melt coating, the composite 12 is melted and heated in a fluid state by heating the composite 12, and then applied to a support substrate 13 such as a separator. Thereafter, it is solidified by heat dissipation to form a long sheet-like green sheet 14 on the support substrate 13. Further, the temperature at which the composite 12 is heated and melted differs depending on the type or amount of the binder to be used, and is set to 50 to 300 °C. Among them, it must be set to a temperature higher than the melting point of the binder used. Further, in the case of using a slurry coating, the magnet powder and the binder (which may further contain an additive for promoting alignment) are dispersed in a large amount of an organic solvent, and the slurry is applied onto a support substrate 13 such as a separator. . Thereafter, the organic solvent is volatilized by drying to form a long sheet-like green sheet 14 on the support substrate 13.

Here, the coating method of the molten composite 12 is preferably a method in which the layer thickness controllability such as a slit die method or a calender roll method is excellent. In particular, in order to achieve a high thickness precision, it is preferable to use a mold method or a notch wheel coating which is excellent in layer thickness control property (i.e., a layer which can apply a high-precision thickness layer on the surface of a substrate). the way. For example, in the slit die method, the composite 12 which is heated by the gear pump is extruded and inserted into a mold to perform coating. Further, in the calender roll method, a certain amount of the composite 12 is added to the gap between the two heated rolls, and the composite 12 which is thermally melted by the rolls is applied to the support substrate 13 while rotating the rolls. Further, as the support substrate 13, for example, a polyester film treated with polyfluorene oxide is used. Further, it is preferable to sufficiently perform the defoaming treatment so that air bubbles do not remain in the developed layer by using an antifoaming agent or heating vacuum defoaming. Further, it may be configured not to be applied to the support substrate 13, but to be squeezed. The forming or injection molding forms the melted composite 12 into a sheet shape and is extruded onto the support substrate 13, whereby the green sheet 14 is formed on the support substrate 13.

Hereinafter, the step of forming the green sheet 14 by the slit mold method will be described in more detail with reference to Fig. 6 . Fig. 6 is a schematic view showing a step of forming a green sheet 14 by a slit mold method.

As shown in FIG. 6, the mold 15 used in the slit mold method is formed by overlapping the blocks 16, 17 with each other, and the slit 18 and the cavity are formed by the gap between the blocks 16, 17. (liquid storage unit) 19. The cavity 19 communicates with the supply port 20 provided in the block 17. Further, the supply port 20 is connected to a supply system of a coating liquid composed of a gear pump (not shown) or the like, and supplies the measured fluid-like composite 12 to the cavity 19 via the supply port 20 by a metering pump or the like. Further, the fluid-like composite 12 supplied to the cavity 19 is supplied with liquid to the slit 18, and is supplied at a constant amount per unit time and uniformly in the width direction, and is ejected from the slit 21 of the slit 18 in accordance with a predetermined coating width. ejection. On the other hand, the support base material 13 is continuously conveyed at a predetermined speed as the coating roller 22 rotates. As a result, the discharged fluid-like composite 12 is applied to the support substrate 13 with a specific thickness, and then heat-dissipated and solidified, whereby the elongated sheet-like green sheet 14 is formed on the support substrate 13. .

Further, in the step of forming the green sheet 14 by the slit mold method, it is preferable to actually measure the thickness of the sheet of the green sheet 14 after the application, and the gap between the mold 15 and the support substrate 13 based on the measured value. D performs feedback control. Moreover, it is preferable that the fluctuation of the amount of the fluid-like composite 12 supplied to the mold 15 is as small as possible (for example, the variation is suppressed to ±0.1% or less), and the fluctuation of the coating speed is also reduced as much as possible ( For example, the suppression is ±0.1% or less). Thereby, the thickness precision of the green sheet 14 can be further improved. Further, the thickness accuracy of the formed green sheet 14 is set to within ±10%, more preferably within ±3%, and even more preferably within ±1% with respect to the design value (for example, 1 mm). Further, on the other hand, in the calender roll method, by controlling the calendering conditions based on the measured values in the same manner, the transfer film thickness of the composite 12 on the support substrate 13 can be controlled.

Further, the thickness of the green sheet 14 is preferably set to be in the range of 0.05 mm to 20 mm. When the thickness is less than 0.05 mm, it is necessary to laminate a plurality of layers, so that productivity is lowered.

Then, the magnetic field alignment of the green sheet 14 formed on the support substrate 13 by the above-described hot melt coating is performed. Specifically, first, the green sheet 14 is softened by heating the green sheet 14 continuously conveyed together with the support base material 13. Specifically, the viscosity is softened until the green sheet 14 has a viscosity of 1 to 1500 Pa. s, more preferably 1~500Pa. s so far. Thereby, the magnetic field alignment can be appropriately performed.

Further, the temperature and time when the green sheet 14 is heated vary depending on the type or amount of the binder to be used, and is, for example, 100 to 250 ° C for 0.1 to 60 minutes. However, in order to soften the green sheet 14, it is necessary to set the temperature of the glass transition point or the melting point of the binder to be used. Further, as a heating method for heating the green sheet 14, there is, for example, a heating method using a hot plate or a heating method using a heat medium (polyoxygenated oil) as a heat source. Then, a magnetic field is applied to the in-plane direction and the longitudinal direction of the green sheet 14 which is softened by heating, thereby performing magnetic field alignment. The intensity of the applied magnetic field is set to 5000 [Oe] to 150,000 [Oe], preferably 10,000 [Oe] to 120,000 [Oe]. As a result, the C-axis (easy magnetization axis) of the magnet crystal contained in the green sheet 14 is aligned in one direction. Further, as a direction in which the magnetic field is applied, a magnetic field may be applied to the in-plane direction and the width direction of the green sheet 14. Further, it is also possible to adopt a configuration in which a plurality of green sheets 14 are simultaneously aligned with a magnetic field.

Further, when a magnetic field is applied to the green sheet 14, a step of applying a magnetic field simultaneously with the heating step may be employed, and a step of applying a magnetic field may be performed after the heating step and before the green sheet is solidified. Further, it is also possible to adopt a configuration in which the green sheet 14 coated by the hot melt coating is subjected to magnetic field alignment before solidification. In this case, no heating step is required.

Next, the heating step and the magnetic field alignment step of the green sheet 14 will be described in more detail using FIG. Fig. 7 is a schematic view showing a heating step and a magnetic field alignment step of the green sheet 14. Furthermore, in the example shown in FIG. 7, the magnetic alignment step is performed simultaneously with the heating step. Line description.

As shown in Fig. 7, the heating and the magnetic field alignment of the green sheet 14 coated by the slit die method are performed on the long sheet-like green sheet 14 in a state of being continuously conveyed by a roller. That is, the apparatus for performing heating and magnetic field alignment is disposed on the downstream side of the coating device (such as a mold), and is carried out by a step that is continuous with the coating step.

Specifically, on the downstream side of the mold 15 or the application roller 22, the solenoid 25 is placed such that the supported support substrate 13 and the green sheet 14 pass through the inside of the solenoid 25. Further, the heating plate 26 is disposed in the solenoid 25 in the upper and lower sides of the green sheet 14 in pairs. Then, the green sheet 14 is heated by the heating plate 26 disposed in pairs up and down, and an electric current is supplied to the solenoid 25, thereby in the in-plane direction of the long sheet-like green sheet 14 (ie, with the green sheet) The sheet of 14 is parallel to the direction of the surface and a magnetic field is generated in the longitudinal direction. Thereby, the continuous conveyance of the green sheet 14 is softened by heating, and a magnetic field is applied to the in-plane direction of the softened green sheet 14 and the longitudinal direction (the direction of the arrow 27 in Fig. 7), so that the green sheet 14 can be appropriately aligned uniformly. The magnetic field. In particular, by setting the direction in which the magnetic field is applied to the in-plane direction, the surface of the green sheet 14 can be prevented from fluffing.

Further, the heat dissipation and solidification of the green sheet 14 after the magnetic field alignment is preferably carried out in a conveyed state. Thereby, the manufacturing steps can be further streamlined.

In the case where the magnetic field is aligned in the in-plane direction and the width direction of the green sheet 14, a pair of magnetic field coils are disposed on the right and left sides of the conveyed green sheet 14 instead of the solenoid 25. Further, by applying an electric current to each of the field coils, a magnetic field can be generated in the in-plane direction and the width direction of the long sheet-like green sheet 14.

Further, the magnetic field alignment may be set to be perpendicular to the surface of the green sheet 14. In the case where the magnetic field is aligned in the direction perpendicular to the surface of the green sheet 14, it is performed by, for example, a magnetic field applying device using a magnetic pole piece or the like. Specifically, as shown in FIG. 8 , the magnetic field applying device 30 using a magnetic pole piece or the like includes two annular coil portions 31 and 32 that are arranged in parallel so that the central axis is the same axis, and are disposed in the coil portions 31 and 32, respectively. The two substantially cylindrical pole pieces 33 and 34 of the annular hole are arranged at a predetermined interval with respect to the conveyed green sheet 14 Set. Then, by applying a current to the coil portions 31 and 32, a magnetic field is generated in a direction perpendicular to the surface of the green sheet 14, and the magnetic field alignment of the green sheet 14 is performed. Further, when the direction of the magnetic field alignment is set to be perpendicular to the surface of the green sheet 14, it is preferable that the green sheet 14 is also on the opposite side of the laminated support substrate 13 as shown in FIG. The laminated film 35. Thereby, the raising of the surface of the green sheet 14 can be prevented.

Further, instead of the heating method using the heating plate 26, a heating method using a heat medium (polyoxygenated oil) as a heat source may be used. Here, FIG. 9 is a view showing an example of a heating device 37 using a heat medium.

As shown in FIG. 9, the heating device 37 is configured such that a substantially U-shaped cavity 39 is formed inside the flat member 38 which is a heating element, and is heated to a specific temperature (for example, 100 to 300 ° C) in the cavity 39. It is used as a heat medium for the polyoxygen oil cycle. Further, in the solenoid 25, a heating device 37 is disposed in the upper and lower rows of the green sheet 14 in place of the heating plate 26 shown in Fig. 7. Thereby, the continuously conveyed green sheet 14 is softened by the flat member 38 which generates heat by the heat medium. Further, the flat member 38 may be in contact with the green sheet 14, or may be disposed at a predetermined interval. Further, by applying a magnetic field to the in-plane direction and the longitudinal direction (the direction of the arrow 27 in FIG. 7) of the green sheet 14 by the solenoid 25 disposed around the softened green sheet 14, the green sheet 14 can be appropriately aligned. A uniform magnetic field. Further, in the heating device 37 using the heat medium shown in FIG. 9, the heating wire is not provided inside the heating plate 26 as usual, and therefore, even in the case of being placed in a magnetic field, there is no Lorentz force ( Lorentz force) The heating of the green sheet 14 can be appropriately performed by vibrating or cutting the heating wire. Further, when the current is controlled, there is a problem that the heating wire is vibrated due to the ON or OFF of the power source, which causes fatigue fracture. However, by using the heating device 37 using the heat medium as the heat source, the problem can be eliminated. .

Here, in the case where the green sheet 14 is formed by a liquid material having a high fluidity such as a slurry by a conventional slit die method or a doctor blade method without using hot melt molding, if a magnetic field is generated When the gradient is carried into the green sheet 14, the magnet powder contained in the green sheet 14 is pulled. Leading to the side where the magnetic field is strong, there is a difference in the thickness of the green sheet which forms the slurry of the green sheet 14, that is, the thickness of the green sheet 14. On the other hand, when the composite 12 is formed into the green sheet 14 by hot melt forming as in the present invention, the viscosity at room temperature reaches tens of thousands to hundreds of thousands of Pa. s, the concentration of magnetic powder when the magnetic field gradient passes does not occur. Further, by carrying out the transportation and heating in a uniform magnetic field, the viscosity of the adhesive can be lowered, and the same C-axis alignment can be performed only with the torque in the uniform magnetic field.

In the case where the green sheet 14 is formed by a liquid material having a high fluidity such as a slurry containing an organic solvent, such as a conventional slit die method or a doctor blade method, the hot-melt molding is used. When the sheet having a thickness of more than 1 mm is foamed by the vaporization of the organic solvent contained in the slurry or the like during drying, it becomes a problem. Further, when the drying time is increased in order to suppress the foaming, precipitation of the magnet powder occurs, and a variation in the density distribution of the magnet powder with respect to the direction of gravity occurs, which causes the warpage after the firing. Therefore, in the molding of the slurry, in order to substantially regulate the upper limit of the thickness, it is necessary to form the green sheet to a thickness of 1 mm or less, and then laminate the green sheet. However, in this case, the binders are insufficiently fused to each other, and interlayer peeling occurs in the subsequent debonding step (calcining treatment), which becomes a decrease in the alignment of the C-axis (easy magnetization axis), that is, residual magnetic flux. The reason for the decrease in density (Br). On the other hand, when the composite 12 is formed into the green sheet 14 by hot melt forming as in the present invention, since the organic solvent is not contained, even when a sheet having a thickness of more than 1 mm is produced, it can be eliminated. The fear of foaming as described above. Further, since the binder is in a state of being sufficiently fused, there is no possibility that interlayer peeling occurs in the debonding step.

Further, when a magnetic field is applied to the plurality of green sheets 14 at the same time, for example, continuous deposition is carried out in a state in which a plurality of sheets (for example, 6 sheets) of the green sheets 14 are laminated so that the green sheets 14 of the layers are placed on the solenoid 25 It is formed by means of internal passage. Thereby, productivity can be improved.

Thereafter, the green sheet 14 subjected to the magnetic field alignment is punched into a desired product shape (for example, a fan shape as shown in Fig. 1), and the formed body 40 is molded.

Then, by forming the formed body 40 at atmospheric pressure or pressurizing it to above the atmosphere a non-oxidizing environment at a pressure or a pressure lower than atmospheric pressure (for example, 1.0 Pa or 1.0 MPa) (especially in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas in the present invention) at a binder decomposition temperature (in In the case where the additive for promoting the alignment is added, the calcination treatment is carried out for several hours to several tens of hours (for example, 5 hours) at a temperature which satisfies the conditions of the thermal decomposition temperature of the additive. In the case of performing in a hydrogen atmosphere, for example, the supply amount of hydrogen in calcination is set to 5 L/min. By performing the calcination treatment, an organic compound such as a binder can be decomposed into monomers by a depolymerization reaction or the like and scattered and removed. Further, the organometallic compound can be thermally decomposed to leave the metal element in the grain boundary and remove the carbon. That is, so-called decarburization which reduces the amount of carbon in the molded body 40 is performed. In addition, the calcination treatment is carried out under the conditions that the amount of carbon in the molded body 40 is 2,000 ppm or less, more preferably 1,000 ppm or less. Thereby, the entire permanent magnet 1 can be densely sintered by the subsequent sintering treatment without deteriorating the residual magnetic flux density or the coercive force. In the case where the pressurization condition at the time of the calcination treatment is carried out at a pressure higher than atmospheric pressure, it is preferably 15 MPa or less. Further, when the pressurization condition is set to a pressure higher than atmospheric pressure, more specifically 0.2 MPa, the effect of reducing the amount of carbon can be expected in particular.

Further, the binder decomposition temperature is determined based on the analysis results of the binder decomposition product and the decomposition residue. Specifically, a temperature range is selected in which the decomposition product of the binder is collected, no decomposition products other than the monomer are produced, and no side reaction due to the residual binder component is detected in the residue analysis. product. The decomposition temperature of the binder varies depending on the type of the binder, and is set to 200 ° C to 900 ° C, more preferably 400 ° C to 600 ° C (for example, 450 ° C). Further, the thermal decomposition temperature of the organometallic compound is determined depending on the type of the organometallic compound to be added, but the thermal decomposition of the organometallic compound can be basically performed as long as the binder decomposition temperature is obtained. Further, in the case where the magnet powder is mixed with a binder and molded (for example, powder molding), the calcination treatment is carried out at the thermal decomposition temperature of the organometallic compound.

Further, in particular, the case where the magnet raw material is pulverized by wet pulverization in an organic solvent At the time, the calcination treatment is carried out at the thermal decomposition temperature of the organic compound constituting the organic solvent and at the binder decomposition temperature. Thereby, the residual organic solvent can also be removed. The thermal decomposition temperature of the organic compound is determined depending on the type of the organic solvent to be used, but the thermal decomposition of the organic compound can be basically performed as long as it is the decomposition temperature of the above-mentioned binder.

Further, it is preferable that the calcination treatment slows down the temperature increase rate as compared with the case of sintering a normal magnet. Specifically, the temperature increase rate is set to 2 ° C / min or less (for example, 1.5 ° C / min). Therefore, in the case of performing the calcination treatment, the temperature is raised at a specific temperature increase rate of 2 ° C/min or less, and after reaching a preset set temperature (adhesive decomposition temperature), the temperature is maintained at the set temperature for several hours to several tens of hours. Thereby, the calcination treatment is performed. The calcining treatment as described above removes the carbon in the formed body 40 stepwise rather than sharply by slowing down the rate of temperature rise, so that the density of the permanent magnet after sintering can be increased (i.e., reduced in the permanent magnet) Void). In addition, when the temperature increase rate is 2° C./min or less, the density of the permanent magnet after sintering can be made 95% or more, and high magnet characteristics can be expected.

Further, the molded body 40 obtained by calcining by calcination may be further subjected to a dehydrogenation treatment while maintaining the vacuum atmosphere. In the dehydrogenation treatment, NdH ₃ (large activity) in the molded body 40 produced by the calcination treatment is changed stepwise from NdH ₃ (large activity) to NdH ₂ (small activity). The activity of the molded body 40 activated by the calcination treatment is lowered. Thereby, even when the molded body 40 calcined by the calcination treatment is moved to the atmosphere, Nd can be prevented from being combined with oxygen, and the residual magnetic flux density or coercive force is not lowered. Further, an effect of restoring the structure of the magnet crystal from NdH ₂ or the like to the Nd ₂ Fe ₁₄ B structure can be expected.

Then, a sintering treatment for sintering the formed body 40 which has been calcined by calcination is performed. In addition, as the sintering method of the molded body 40, in addition to the usual vacuum sintering, pressure sintering or the like for sintering the molded body 40 in a pressurized state may be used. For example, when sintering is performed by vacuum sintering, the temperature is raised to a firing temperature of about 800 ° C to 1080 ° C at a specific temperature increase rate for about 0.1 to 2 hours. In this period, vacuum firing is performed, and as the degree of vacuum, it is preferably 5 Pa or less, preferably 10 ^-2 Pa or less. Thereafter, the mixture was cooled, and heat treatment was again performed at 300 ° C to 1000 ° C for 2 hours. Then, sintering is performed, and as a result, a molded body of the sintered magnet (hereinafter referred to as sintered body 50) is obtained.

On the other hand, as the pressure sintering, there are, for example, hot press sintering, hot press pressure (HIP) sintering, ultrahigh pressure synthetic sintering, gas pressure sintering, and discharge plasma (SPS) sintering. In order to suppress the grain growth of the magnet particles during sintering and to suppress the warpage caused by the magnet after sintering, it is preferably used for uniaxial pressure sintering in a uniaxial direction and by electric conduction sintering. Sintered SPS is sintered. Further, in the case of sintering by SPS sintering, it is preferred to set the pressurization value to, for example, 0.01 MPa to 100 MPa, and to increase the temperature to 10 ° C/min to 940 ° C in a vacuum atmosphere of several Pa or less, and thereafter to maintain 5 minute. Thereafter, the mixture was cooled, and heat treatment was again performed at 300 ° C to 1000 ° C for 2 hours. Then, sintering is performed, and as a result, the sintered body 50 is obtained.

Hereinafter, the pressure sintering step of the molded body 40 obtained by SPS sintering will be described in more detail with reference to Fig. 10 . Fig. 10 is a schematic view showing a pressure sintering step of the formed body 40 obtained by SPS sintering.

When SPS sintering is performed as shown in FIG. 10, first, the molded body 40 is provided in the graphite sintered mold 41. Further, the calcination treatment may be performed in a state where the molded body 40 is placed on the sintering mold 41. Then, the formed body 40 provided in the sintering mold 41 is held in the vacuum chamber 42, and the upper punch 43 and the lower punch 44, which are also made of graphite, are provided. Then, a low voltage and high current DC pulse voltage/current is applied using the punch electrode 45 connected to the upper portion of the upper punch 43 and the punch electrode 46 connected to the lower portion of the lower punch 44. At the same time, a load is applied to the upper punch 43 and the lower punch 44 from the vertical direction by a pressurizing mechanism (not shown). As a result, the molded body 40 provided in the sintering mold 41 is pressed while being pressed. Further, in order to improve productivity, it is preferred to simultaneously perform SPS sintering on a plurality of (for example, ten) shaped bodies. Further, when a plurality of molded bodies 40 are simultaneously subjected to SPS sintering, a plurality of molded bodies 40 may be disposed in one space, or each molded body 40 may be disposed in a different space. Furthermore, each shaped body 40 is disposed in a different space. In the case of the space, the molded body 40 is pressurized in each space. The upper punch 43 or the lower punch 44 is integrated between the spaces (i.e., an upper punch that is integrated by driving) 43 and the lower punch 44 can be configured to simultaneously press a plurality of molded bodies in each space.

Then, as shown in FIG. 5, the sintered body 50 obtained by sintering the above-described sintering treatment is attached to a sputtering apparatus, and the surface of the sintered body 50 is sputtered by Nd. As a condition of sputtering, for example, it is set to 300 mA for 60 minutes. Further, when the sintered body 50 has a thin plate shape as shown in Fig. 1, Nd is sputtered on both surfaces of the sintered body 50, respectively. As a result, a film 51 of Nd is formed on the surface of the sintered body 50.

Then, the surface of the sintered body 50 subjected to the Nd sputtering described above is further subjected to Cu sputtering. The conditions for sputtering are, for example, 15 minutes at 300 mA. Further, when the sintered body 50 has a thin plate shape as shown in Fig. 1, Cu is sputtered on both faces of the sintered body 50. As a result, a film 51 of Nd and a film 52 of Cu are repeatedly formed on the surface of the sintered body 50.

Then, the sintered body 50 in which the Nd film 51 and the Cu film 52 are respectively formed by sputtering is heated to diffuse Cu sputtered on the surface of the sintered body 50 into the sintered body 50. Diffusion treatment. Furthermore, the diffusion treatment is performed by a temperature in a vacuum environment at a temperature lower than the sintering temperature and higher than the melting point of the intermetallic compound of Cu and Nd (for example, Nd-Cu) (for example, 600 ° C to 800 ° C). The time (for example, 5 hours) is performed by heating. As a result, Cu sputtered on the surface of the sintered body 50 becomes a liquid phase at the stage of the diffusion treatment and penetrates into the grain boundary, so that Cu can be biased against the grain boundary.

Here, the alloy of Cu and Nd has a lower melting point than the monomer metal. Therefore, the diffusion treatment can be performed at a low temperature, and the grain growth is not generated at the stage of the diffusion treatment. Further, even when the amount of addition of Cu is made small (for example, 0.1 wt%), Cu can be appropriately biased against the grain boundary. Further, the diffusion treatment described above is carried out, and as a result, the permanent magnet 1 can be produced.

Moreover, the sintered body 50 after the sintering by the above-described sintering treatment and before or after the above-described diffusion treatment may be further subjected to heat treatment. Further, the heat treatment is carried out by heating the sintered body for a predetermined time (for example, one hour) at a temperature lower than the sintering temperature (460 ° C to 600 ° C) in a vacuum atmosphere.

Here, in the cooling stage after the sintering treatment, Dy or the like contained in the organometallic compound in the sintered body forms a eutectic with Nd. Further, in particular, when Dy or the like contained in the organometallic compound is a specific metal (for example, Al, Ag, or Ga (hereinafter referred to as Al), the melting point of the eutectic is lower than that of the Nd monomer. Therefore, if the heat treatment is performed at a temperature higher than the melting point of the eutectic of Al or the like contained in the organometallic compound after sintering, the eutectic with Al or the like contained in the organometallic compound is used for the low melting point. The Nd-rich phase becomes a liquid phase at the stage of heat treatment and penetrates into the grain boundary, forming a uniform Nd-rich phase at the grain boundary. As a result, the coercive force of the permanent magnet 1 can be increased. Further, since the heat treatment is performed at a low temperature, there is no possibility of grain growth at the stage of heat treatment.

Further, when the heat treatment is performed at a temperature higher than the melting point of the eutectic of Cu or the like contained in the organometallic compound, the alloy containing Al or the like which is in the liquid phase together with the Nd-rich phase can be infiltrated into the grain boundary. . As a result, even when the amount of the organometallic compound added is a small amount (for example, 0.1% by weight), Al or the like contained in the organometallic compound can be appropriately biased to the grain boundary.

[Examples]

Hereinafter, an embodiment of the present invention will be described in comparison with a comparative example.

(Example)

The alloy composition of the neodymium magnet powder of Example 1 was set to Nd/Fe/B = 32.7 / 65.96 / 1.34 in wt%. Further, it was molded into a molded body having a thickness of 3 mm by green sheet molding. Further, the calcination treatment is carried out at 450 ° C in a hydrogen atmosphere in which the molded body is at atmospheric pressure (further, in this embodiment, the atmospheric pressure at the time of manufacture is assumed to be a standard atmospheric pressure (about 0.1 MPa)). It is carried out for 10 hours. Further, after vacuum sintering of the calcined body, Nd sputtering was performed on the upper surface of the sintered body at a current value of 300 mA for 60 minutes, and then sputtering of Cu was performed for 15 minutes at a current value of 300 mA on the upper and lower sides of the sintered body. . Further, the sputtering apparatus was an MSP-30T magnetron sputtering apparatus (manufactured by Shinkuu Device). Further, the amount of Cu contained in the sintered body after sputtering was 0.13 wt%. Further, after sputtering of Cu, the sintered body was kept at 800 ° C for 5 hours in a vacuum atmosphere to carry out diffusion treatment. Thereafter, the sintered body was heat-treated by holding the sintered body in a vacuum atmosphere at 500 ° C for 1 hour. In addition, the other steps are the same as the above [manufacturing method of permanent magnet].

(Comparative example)

It is assumed that the magnet raw material contains 0.1% by weight of Cu in advance, and the magnet raw material containing Cu is pulverized to prepare a neodymium magnet powder. Further, sputtering of Nd or Cu on the sintered body is not performed, and the diffusion treatment may be omitted. Other conditions are the same as in the embodiment.

(Comparative study of magnet characteristics of the examples and comparative examples)

The coercive force [kOe] of each of the permanent magnets of the examples and the comparative examples was measured. A list of measurement results is shown in FIG.

Here, when the coercive force of each of the permanent magnets of the examples and the comparative examples is compared, the amount of Cu added is substantially the same, but the magnet raw material does not contain Cu and the sputtering is biased against the grain boundary. The permanent magnet showed a coercive force higher than that of the permanent magnet of the comparative example. In other words, in the case where the calcination treatment of the molded body is carried out in a hydrogen atmosphere, the permanent magnet of the comparative example is in a state in which Cu is contained in the molded body, and therefore it is predicted that the reaction in the following (2) is easy when the calcination treatment is performed. The state of advancing to the right.

Nd ₂ Fe ₁₄ B+2H ₂ →2NdH ₂ +12Fe+Fe ₂ B. . . . (2)

In addition, when the reaction of the above (2) is pushed to the right side, the main phase of the rare earth magnet (Nd ₂ Fe ₁₄ B) is decomposed and αFe is precipitated, and as a result, the coercive force is considered to be lowered.

On the other hand, in the case where the calcining treatment of the formed body is carried out in a hydrogen atmosphere, since the formed body of the permanent magnet of the example does not contain Cu, it is predicted that the reaction of the above (2) is difficult when the calcination treatment is performed. The state of the right side advancement. As a result, it is considered that in the rare earth permanent magnet of the example, the main phase (Nd ₂ Fe ₁₄ B) of the rare earth magnet is not decomposed, and precipitation of αFe can be suppressed, and a high coercive force is exhibited.

As described above, in the method for producing the permanent magnet 1 and the permanent magnet 1 of the present embodiment, the molded body obtained by pulverizing and molding the magnet raw material containing no Cu in a hydrogen atmosphere at 200 ° C to 900 ° C The calcination treatment is carried out for several hours to several tens of hours. Thereafter, the formed body is sintered by vacuum sintering or pressure sintering, and the permanent magnet 1 is produced by sputtering Cu on the surface of the sintered body. Thereby, the coercive force obtained by Cu can be improved, and even when calcination is performed in a hydrogen atmosphere, decomposition of the main phase or precipitation of αFe can be suppressed, and deterioration of magnetic properties can be prevented.

Further, by heating the sintered body sputtered with Cu, Cu deposited on the surface of the sintered body is diffused inside the sintered body. Therefore, it is possible to cause sputtering after sintering without including Cu in the magnet raw material. Cu is suitably biased against the grain boundaries. In other words, the effect of improving the coercive force can be obtained by using Cu without preliminarily including Cu in the magnet raw material.

Further, when the sintered body in which Cu is sputtered is heated, it is heated at a temperature lower than the firing temperature (for example, 800 ° C), so that in the step of diffusing the sputtered Cu into the inside of the sintered body, It prevents the growth of crystal grains of magnet particles.

Further, after sputtering of Nd on the surface of the sintered body, Cu is sputtered on the surface of the sintered body, so that the sputtering of Cu can be diffused into the inside of the sintered body at a lower temperature.

Further, the pulverized magnet powder is added with Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb and does not contain oxygen atoms and nitrogen. The organometallic compound of the atom uniformly adheres the organometallic compound to the surface of the magnet particle, and forms a magnet powder of the organometallic compound on the surface of the particle to form a molded body. Therefore, Al, Dy, and the like contained in the organometallic compound can be formed. Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb are efficiently biased against the grain boundaries of the magnet. As a result, the magnetic properties of the permanent magnet can be improved. Also, Al, The addition amount of Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb is set to be smaller than the previous one, so that the residual magnetic flux density can be suppressed. reduce.

Further, a metal complex of Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb, or hydrogenated diisobutylene is used. Since the base aluminum is used as the organometallic compound, the thermal decomposition of the organometallic compound can be easily performed in the subsequent heating step, and the metal contained in the organometallic compound can be appropriately biased against the grain boundary. Further, the amount of carbon remaining in the magnet can be reduced by thermal decomposition. As a result, voids are not formed between the main phase of the magnet after sintering and the grain boundary phase, and the entire magnet can be densely sintered to prevent a decrease in coercive force. Further, a large amount of αFe is not precipitated in the main phase of the magnet after sintering, and the magnet characteristics are not greatly lowered.

Further, since the magnet obtained by sintering the green sheet formed by mixing the magnet powder and the binder constitutes a permanent magnet, the shrinkage due to sintering becomes uniform, and deformation such as warpage or depression after sintering does not occur. Further, since the pressure is not uniform when there is no pressurization, it is not necessary to perform the correction processing after the previous sintering, and the manufacturing steps can be simplified. Thereby, the permanent magnet can be formed with higher dimensional accuracy.

It is a matter of course that the present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the spirit and scope of the invention.

For example, the pulverization conditions of the magnet powder, the kneading conditions, the magnetic field alignment step, the calcination conditions, the sintering conditions, the sputtering conditions, the diffusion treatment conditions, the heat treatment conditions, and the like are not limited to the conditions described in the above examples. For example, in the above embodiment, the green sheet is formed by a slit die method, and other methods (for example, a calender roll method, a notch wheel coating method, an extrusion molding, an injection molding, a mold forming, a doctor blade method) may be used. Etc.) Forming a green piece. Further, a slurry in which a magnet powder or a binder is mixed in a solvent may be produced, and then the resulting slurry may be formed into a sheet shape to prepare a green sheet. In this case, a binder other than a thermoplastic resin may also be used. Moreover, as long as the environment during calcination is a non-oxidizing environment, It is carried out in an environment other than a hydrogen atmosphere (for example, a nitrogen atmosphere, a helium atmosphere, or the like, an argon atmosphere, etc.). Further, it is also possible to adopt a configuration in which only sputtering of Cu is performed without performing sputtering of Nd. However, in this case, it is necessary to set the heating temperature at which the sputtered Cu is diffused inside the sintered body to a higher temperature. Moreover, the order of sputtering of Cu and Nd can also be changed.

Further, in the above-described embodiment, the mixture of the magnet powder and the binder is temporarily formed into a sheet shape and then subjected to magnetic field alignment, and may be formed into a shape other than the shape of the sheet, and then magnetic field alignment may be performed. Composition. For example, it may be formed into a block shape. Further, the molded body having a block shape aligned by the magnetic field is further processed into a final product shape.

Further, in the above examples, a resin, a long-chain hydrocarbon or a fatty acid ester is used as the binder, and other materials may be used.

Further, the permanent magnet can be produced by calcining and sintering a molded body formed by molding (for example, powder molding) other than green sheet molding. In this case, the carbonaceous material remaining in the molded body other than the binder (the added organometallic compound or the organic compound remaining by wet pulverization) may be expected to utilize the decarburization effect by calcination. Further, in the above embodiment, after the magnet powder is molded, calcination is carried out in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen gas and an inert gas, and the magnet powder before molding may be calcined to be used as a calcined body. The magnet powder is formed into a molded body, followed by sintering, thereby producing a permanent magnet. According to this configuration, since the powdery magnet particles are calcined, the surface area of the magnet to be calcined can be expanded as compared with the case where the magnet particles after molding are calcined. That is, the amount of carbon in the calcined body can be more surely reduced. In the case where the green body is formed, in order to thermally decompose the binder by the calcination treatment, it is preferred to carry out the calcination treatment after the molding.

Further, in the above embodiment, the heating step and the magnetic field alignment step of the green sheet 14 are simultaneously performed, and the magnetic field alignment step may be performed after the heating step and before the green sheet 14 is solidified. Moreover, before the applied green sheet 14 is solidified (that is, even if the heating step is not performed, the green sheet 14 is also When the magnetic field is aligned in the softened state, the heating step may be omitted.

Further, in the above embodiment, the coating step, the heating step, and the magnetic field aligning step by the slit mold method may be carried out by one successive series of steps, or may be configured not by continuous steps. Further, it may be divided into a first step before the coating step and a second step after the heating step, and each step is carried out. In this case, the green sheet 14 to be applied may be cut to a specific length, and the green sheet 14 in a stationary state may be heated and magnetic field applied to perform magnetic field alignment.

Further, in the above examples, as the organometallic compound added to the magnet powder, tris(ethylcyclopentadienyl)ruthenium (III) or tris(isopropylcyclopentadienyl)phosphonium (III) was used. , bis(cyclopentadienyl)magnesium (II), bis(cyclopentadienyl)dibenzyl ruthenium (IV), trihydrobis(pentamethyldicyclopentadienyl)fluorene (V), Bis(cyclopentadienyl)dimethyltitanium(IV), bis(cyclopentadienyl)dimethylzirconium(IV), di(biscyclopentadienyl)zirconium(IV), tris(tetra) Methylcyclopentadienyl)ruthenium (III), trioctylaluminum (III), diphenylzinc (II), triphenylphosphonium (III), tertiary butylated silver (I), (2) , 4,6-trimethylphenyl)silver (I), tricyclopentadienyl gallium (III), DIBAL, but as long as it contains Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W An organometallic compound which is Ag, Ga, Co, Bi, Zn, Mg or Nb and which does not contain an oxygen atom and a nitrogen atom may be other organometallic compounds. For example, a metal complex other than a metal alkyl complex can also be used. Further, the organometallic compound may be configured to include an element other than the above-described metal element (for example, Si or the like).

Further, in the present invention, an Nd-Fe-B-based magnet is exemplified, and other magnets (for example, lanthanum-cobalt magnet, alnico magnet, ferrite magnet, or the like) may be used. Further, in the alloy composition of the magnet, in the present invention, the Nd component is made more than the metered composition, and may be a metering composition. Further, the present invention can be applied not only to anisotropic magnets but also to isotropic magnets. In this case, the magnetic field alignment step of the green sheet 14 can be omitted.

1‧‧‧ permanent magnet

51‧‧‧Nd film

52‧‧‧Cu film

Claims (14)

A rare earth permanent magnet, which is characterized by the steps of: pulverizing a magnet raw material into a magnet powder; forming a shaped body by shaping the pulverized magnet powder; before or after forming and a step of calcining the magnet powder in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas before sintering; a step of sintering by holding the formed body at a firing temperature to obtain a sintered body; The step of sputtering Cu on the surface of the sintered body. The rare earth permanent magnet of claim 1, which is produced by heating the sintered body sputtered with Cu to diffuse Cu sputtered on the surface of the sintered body to the sintered body. Internal steps. The rare earth permanent magnet of claim 2, wherein when the sintered body in which Cu is sputtered is heated, heating is performed at a temperature lower than the firing temperature. The rare earth permanent magnet of claim 1, wherein in the step of sputtering Cu on the surface of the sintered body, after sputtering Nd on the surface of the sintered body, Cu is sputtered on the surface of the sintered body. The rare earth permanent magnet of claim 1, wherein the powder of the pulverized magnet is added with Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb and an organometallic compound containing no oxygen atom or nitrogen atom, and the organometallic compound is adhered to the surface of the particle of the magnet powder, and the magnet powder is formed by forming the above-mentioned organometallic compound on the surface of the particle. Shaped body. The rare earth permanent magnet of claim 5, wherein the organometallic compound center The metal is a metal complex of Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb, or diisobutylaluminum hydride. The rare earth permanent magnet according to any one of claims 1 to 6, wherein in the step of forming the magnet powder into a shaped body, a mixture in which the magnet powder and the binder are mixed is produced by forming the mixture into a sheet. A green sheet as the above-mentioned molded body was produced in the form of a shape. A method for producing a rare earth permanent magnet, comprising: a step of pulverizing a magnet raw material into a magnet powder; a step of forming a shaped body by molding the pulverized magnet powder; before or after forming and before sintering a step of calcining the magnet powder in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas; performing the step of sintering by maintaining the molded body at a firing temperature to obtain a sintered body; and the sintered body The step of sputtering Cu on the surface. The method for producing a rare earth permanent magnet according to claim 8, comprising: diffusing Cu sputtered on the surface of the sintered body to the inside of the sintered body by heating the sintered body sputtered with Cu step. The method for producing a rare earth permanent magnet according to claim 9, wherein when the sintered body in which Cu is sputtered is heated, heating is performed at a temperature lower than the firing temperature. The method for producing a rare earth permanent magnet according to claim 8, wherein in the step of sputtering Cu on the surface of the sintered body, after sputtering Nd on the surface of the sintered body, Cu is sputtered on the surface of the sintered body. The method for producing a rare earth permanent magnet according to claim 8, wherein the powder of the pulverized magnet is added with Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, Zn, Mg or Nb and an organometallic compound which does not contain an oxygen atom and a nitrogen atom, and the above organometallic compound adheres to the surface of the particle of the magnet powder by adhering the surface of the particle The magnet powder having the above organometallic compound is molded to form a molded body. The method for producing a rare earth permanent magnet according to claim 12, wherein the central metal of the organometallic compound is Al, Dy, Tb, Nd, V, Mo, Zr, Ta, Ti, W, Ag, Ga, Co, Bi, a metal complex of Zn, Mg or Nb, or diisobutylaluminum hydride. The method for producing a rare earth permanent magnet according to any one of claims 8 to 13, wherein in the step of forming the magnet powder into a shaped body, a mixture in which the magnet powder and the binder are mixed is produced by using the mixture The green sheet as the molded body was produced into a sheet shape.