JP2016066675A - Rare earth isotropic bond magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rare earth isotropic bond magnet which enables the easy magnetization with a narrow pitch without sacrificing the productivity by enhancement of a magnetization property of an isotropic bond magnet including Nd-Fe-B based magnetic powder.SOLUTION: A rare earth isotropic bond magnet comprises: anisotropic magnetic powder A including a rare earth element (Sm or at least one element of lanthanoids including Sm and Y), iron and nitrogen as primary components and having a ThZntype crystal structure; and isotropic magnetic powder B including a rare earth element (Nd, Pr, or at least one element of lanthanoids including Y and as its matrix, Nd or Pr), iron and boron as primary components and having a NdFeB type crystal structure. The ratio A/(A+B) of the anisotropic magnetic powder A to the total mass of the kinds of magnetic powder is 10-60%.SELECTED DRAWING: None

Description

  The present invention relates to a rare earth isotropic bonded magnet having excellent magnetization characteristics.

There are various types of permanent magnets. Among them, there are bonded magnets in which magnetic powder is bonded with a resin binder. As the magnetic powder, materials such as Ba ferrite, Sr ferrite, Nd ₂ Fe ₁₄ B, Sm ₂ Fe ₁₇ N ₃ , Sm ₂ (Co, Fe, Cu, Zr) ₁₇ are used. As the resin binder, thermoplastic resins such as polyamide 6, polyamide 12 and polyphenylene sulfide, and thermosetting resins such as epoxy resin, phenol resin and unsaturated polyester resin are used.

  Such a bond magnet is used by forming a mixture of magnetic powder and a resin binder (referred to as a composition or a compound) by a resin molding technique such as injection molding, extrusion molding or compression molding, and magnetizing the mixture.

  Magnetic powders include anisotropic powders that are used by being magnetized in a specific direction of particles, and isotropic powders that can be magnetized in any direction of particles. Similarly, bond magnets have anisotropy and isotropic properties, and anisotropic magnets can be magnetized only in a specific direction of the molded magnet product, but isotropic magnets are magnetized in any direction. Can be used.

  An anisotropic bonded magnet is composed of anisotropic magnetic powder and a resin binder, and there are exceptions. However, an anisotropic bonded magnet is manufactured by applying a magnetic field to a mold during molding to align individual magnetic powders in the magnetic field direction. On the other hand, isotropic bonded magnets are often produced from isotropic powder and a resin binder, but a composition comprising anisotropic powder and resin binder is molded without applying a magnetic field to the mold. Can also be manufactured.

  Among the bonded magnets, those using rare earth magnetic powder have high magnetic properties, and it is expected that the application fields will continue to expand in the future for further miniaturization, weight reduction, and energy saving of small motors that are the main applications. . Here, the anisotropic rare earth bonded magnet has a higher residual magnetic flux density Br than the isotropic magnet made of the same material, and can take full advantage of the intrinsic magnetic properties of the magnetic powder. From the viewpoint of

However, in application to a small motor, a bonded magnet is used as a rotor magnet which is a small-diameter cylindrical shape and is multipolarized in the radial direction, and the magnetization pitch may be several mm to 1 mm or less. Not a few. In manufacturing such a magnet as an anisotropic magnet, there are problems such as the configuration of a magnetic circuit for applying a magnetic field to the mold and the cogging torque of the motor, which are not easy. Therefore, in such an application example, an isotropic magnet is selected even if the intrinsic magnetic properties of the magnetic powder are impaired, and most of them are liquid quenching methods using a compound of Nd ₂ Fe ₁₄ B type crystal structure as a main phase. Isotropic Nd—Fe—B magnetic powder produced by

  Furthermore, when an isotropic magnet is selected, when the magnet is used with a narrow pitch as described above, the pitch of the magnetic yoke for magnetizing is also reduced, and a sufficient magnetizing magnetic field is obtained. In some cases, the magnetic properties of the isotropic Nd—Fe—B based bonded magnet are not sufficiently exhibited.

  As means for solving such a problem of magnetization, JP 2013-157506 A (Patent Document 1) and JP 2014-045044 A (Patent Document 2) provide a heating and cooling mechanism in a magnetizing device, A method is disclosed in which a magnetizing magnetic field is applied in a state where the magnetic material is heated to the Curie temperature or higher, and the magnetic field is continuously applied to cool to a temperature lower than the Curie temperature. On the other hand, Japanese Patent Application Laid-Open No. 2004-134698 (Patent Document 3) discloses a method of magnetizing in a state where a composition is filled in a mold cavity in a molding process at a high temperature.

  However, in the former method, since it is magnetized at a high temperature, it is magnetized in a irreversible demagnetized state, and because the temperature is raised and lowered in the magnetizing device, the takt time of magnetization becomes longer and production is performed. There is a problem of impairing sex. In the latter method, a magnetic circuit for magnetization is provided in the mold, and there is a problem that the structure of the mold becomes complicated when magnetization at a narrow pitch is required.

JP 2013-157506 A JP 2014-045044 A JP 2004-134698 A Japanese Patent Laid-Open No. 05-152116 Japanese Patent Laid-Open No. 06-013212 Japanese Patent Laid-Open No. 06-061023 Japanese Patent Laid-Open No. 06-132107 Japanese Patent Laid-Open No. 06-208913 Japanese Patent Laid-Open No. 08-031626 JP 09-171916 A

  The present invention has been made in consideration of such circumstances, and enhances the magnetization characteristics of the isotropic bonded magnet itself containing the Nd—Fe—B based magnetic powder, thereby reducing the productivity. An object of the present invention is to provide a rare earth isotropic bonded magnet that can be easily magnetized at a narrow pitch.

The inventors of the present invention have made extensive studies in order to solve the above-described problems. As a result, when mixing Nd—Fe—B based magnetic powder with another magnetic powder having good magnetization characteristics, a Th ₂ Zn ₁₇ type crystal structure known as a so-called nucleation type magnetic powder was studied. R-Fe-N-based anisotropic magnetic powder having R (R is a lanthanoid element containing Y), in particular, Sm ₂ Fe ₁₇ N ₃ magnetic powder using Sm as R improves the magnetization. As a result, the present invention has been completed. That is, the present invention provides the following.

(1) A first invention of the present invention is a Th ₂ Zn ₁₇ type comprising, as main constituents, a rare earth element (Sm or any one or more of lanthanoid elements including Sm and Y), iron, and nitrogen. An anisotropic magnetic powder A having the following crystal structure, a rare earth element (Nd, Pr, or any one or more of lanthanoid elements containing Y mainly composed of Nd or Pr), iron, and boron And isotropic magnetic powder B having a Nd ₂ Fe ₁₄ B type crystal structure, the ratio A / (A + B) of the anisotropic magnetic powder A to the total magnetic powder being It is a rare earth isotropic bond magnet characterized by being 10% or more and 60% or less.

  (2) The second invention of the present invention is a rare earth isotropic bonded magnet according to the first invention, wherein the anisotropic magnetic powder A has a 50% particle size of 10 μm or less.

  (3) A third invention of the present invention is the rare earth isotropic bonded magnet according to the first or second invention, wherein the isotropic magnetic powder B has a 50% particle diameter of 30 μm or more.

(4) According to a fourth aspect of the present invention, in any one of the first to third aspects described above, the maximum value of the residual magnetic flux density Br measured in three orthogonal directions (X direction, Y direction, Z direction). And a minimum value (ΔBr) is a rare earth isotropic bonded magnet having a Br value within 5% of the average value (Br _avg ) of Br in the three directions.

  According to the present invention, it is possible to improve the magnetizing characteristics of the magnet itself, and as a result, it is possible to cope with further downsizing of the rotor magnet for a small motor and the narrow magnetizing pitch thereby resulting in productivity. Without loss, its industrial value is enormous.

  Hereinafter, a specific embodiment of the rare earth isotropic bonded magnet according to the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, A various change is possible in the range which does not change the summary of this invention.

The rare earth isotropic bonded magnet according to the present embodiment includes a rare earth element (Sm or one or more of lanthanoid elements including Sm and Y), iron, and nitrogen as main components, and Th _2. Any one of an anisotropic magnetic powder A (first magnetic powder) having a Zn ₁₇ type crystal structure and a rare earth element (Nd, Pr, or a lanthanoid element mainly containing Nd or Pr and containing Y) Seeds or more), iron, and boron as main constituent components, and isotropic magnetic powder B (second magnetic powder) having an Nd ₂ Fe ₁₄ B type crystal structure.

  The rare earth isotropic bonded magnet is mixed so that the ratio of the mass of the anisotropic magnetic powder A to the mass of the total magnetic powder is a specific ratio. Specifically, the ratio A / (A + B) of the anisotropic magnetic powder A to the mass of the total magnetic powder is 10% or more and 60% or less.

  According to such a rare earth isotropic bonded magnet according to the present embodiment, it is possible to improve the magnetization characteristics of the magnet itself, and facilitate magnetization at a narrow pitch without impairing productivity. it can.

<First magnetic powder (anisotropic magnetic powder)>
In the rare earth isotropic bonded magnet according to the present embodiment, the first magnetic powder includes rare earth elements, iron (Fe), and nitrogen (N) as main constituent components, and a Th ₂ Zn ₁₇ type crystal structure. An anisotropic magnetic powder (also referred to as “anisotropic magnetic powder A” as appropriate). Most of the magnetic powder is single crystal particles, and the c-axis of the crystal is the direction of easy magnetization.

The rare earth element constituting the anisotropic magnetic powder is at least one of samarium (Sm) or a lanthanoid element containing Sm and yttrium (Y). Since a typical main phase having a Th ₂ Zn ₁₇ type crystal structure is a nitride compound of Sm ₂ Fe ₁₇ N ₃ , the magnetic powder contains 20% by mass to 25% by mass of all rare earth elements including Sm, N Is 2.9 mass% to 4.0 mass%, and the balance is Fe.

  Further, in order to improve the temperature characteristics and corrosion resistance of the magnetic powder, the proportion of Fe of 20% by mass or less is changed to Co, Ni, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Pd, Zn, B, Al, Ga, C, Si, Ge, Sn can be substituted.

  The particle diameter of the anisotropic magnetic powder is not particularly limited, but the 50% particle diameter is preferably 10 μm or less, more preferably 5 μm or less, and further preferably 3 μm or less. When the 50% particle diameter of the anisotropic magnetic powder exceeds 10 μm, the coercive force and squareness of the magnetic powder may be reduced.

In addition, as a magnetic powder having a rare earth element, iron, and nitrogen as main components and having a Th ₂ Zn ₁₇ type crystal structure, for example, an isotropic property as disclosed in JP-A-11-297518 is disclosed. However, even if the magnetic powder described in that document is used as in the present embodiment, the magnetization characteristics cannot be improved. There must be. As described above, if a magnetic field is not applied to the mold at the time of molding, the bonded magnet using anisotropic rare earth magnetic powder becomes an isotropic bonded magnet. There is almost no use, and in particular, an example of using anisotropic magnetic powder having a Th ₂ Zn ₁₇ type crystal structure as an isotropic bonded magnet with rare earth elements, iron, and nitrogen as main components. Never before.

The method for producing the anisotropic magnetic powder as the first magnetic powder will be described by taking the case where the rare earth element is Sm as an example. The Sm ₂ Fe ₁₇ alloy powder contains nitrogen N such as nitrogen gas or ammonia gas. Heat treatment (nitriding heat treatment) is performed in the temperature range of 350 ° C. to 550 ° C. in an atmosphere, and nitrogen is diffused into the powder to produce Sm ₂ Fe ₁₇ N ₃ powder. The powder can be produced by adjusting the particle size such as pulverization and classification so that the 50% particle size of the powder is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less.

The Sm ₂ Fe ₁₇ alloy powder is prepared by a reduction diffusion method in which a reducing agent such as metallic calcium is added to samarium oxide and iron powder and heat treatment, and an alloy obtained by melting metal samarium and iron. There is a melting method in which a lump is produced and mechanically pulverized. However, the particle size distribution of the Sm ₂ Fe ₁₇ alloy powder produced by the melting method is wide, and the uniformity of the particle size is inferior to that of the reduction diffusion method. Therefore, the magnetic properties of the anisotropic magnetic powder finally obtained are lowered, and the residual magnetic flux density Br of the isotropic bonded magnet mixed with the isotropic R—Fe—B based magnetic powder is greatly reduced. Therefore, the anisotropic magnetic powder constituting the rare earth isotropic bonded magnet according to the present embodiment is manufactured based on Sm ₂ Fe ₁₇ alloy particles produced by the reduction diffusion method. preferable.

<Second magnetic powder (isotropic magnetic powder)>
In the rare earth isotropic bonded magnet according to the present embodiment, the second magnetic powder is mainly composed of rare earth elements, iron, and boron as main components, and an intermetallic compound having an Nd ₂ Fe ₁₄ B type crystal structure. Isotropic magnetic powder (isotropic R—Fe—B based magnetic powder, also referred to as “isotropic magnetic powder B” as appropriate). This isotropic magnetic powder is a polycrystalline powder having a main phase crystal grain size of 100 nm or less, and the c-axis direction of the crystal, which is the easy axis of magnetization, is random in each crystal grain. As such magnetic powder, what is manufactured by the liquid quenching method is known.

  As the rare earth element (R) constituting the isotropic magnetic powder, neodymium (Nd), praseodymium (Pr), or any one or more of lanthanoid elements containing Y such as La and Ce mainly composed of these elements It is. In addition, a main body here means containing Nd or Pr in the ratio over 50 mass%.

  In order to improve the temperature characteristics and corrosion resistance of the magnetic powder, a part of Fe is made of Co, Ni, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Pd, Zn, B, Al, Ga, C, Si, Ge, Sn can be substituted.

In addition, a powder called nanocomposite powder in which αFe or a Fe—B compound phase is generated can be added to the magnetic powder in a phase having an Nd ₂ Fe ₁₄ B type crystal structure.

  The particle diameter of the isotropic magnetic powder is not particularly limited, but the 50% particle diameter is preferably 30 μm or more, and more preferably 40 μm or more. If the 50% particle diameter of the isotropic magnetic powder is less than 30 μm, the coercive force and squareness of the magnetic powder may be reduced. The upper limit of the particle diameter of the isotropic magnetic powder is not particularly limited, but the 50% particle diameter is preferably 100 μm or less from the viewpoint of the surface smoothness of the bonded magnet.

In addition to the production by the liquid quenching method described above, even if it is an R—Fe—B based magnetic powder produced through a hydrogenation / dehydrogenation heat treatment step called the HDDR method, Nd ₂ Fe ₁₄ depending on the production conditions. An isotropic magnetic powder having a B-type crystal structure can be obtained. As the isotropic magnetic powder constituting the rare earth isotropic bonded magnet according to the present embodiment, an isotropic magnetic powder manufactured by such an HDDR method may be used.

  Here, in the isotropic magnetic powder as the second magnetic powder, the crystal grain size is smaller than the single-domain critical grain size of the main phase, so that the initial magnetization curve is close to the pinning type, and a relatively large magnetization magnetic field. Is needed. On the other hand, the anisotropic magnetic powder, which is the first magnetic powder, has a nucleation type coercive force mechanism, and magnetization reversal proceeds due to the domain wall movement in the particles. Such first magnetic powder replaces a part of the second magnetic powder, and a magnetostatic interaction acts between them. It is considered that the magnetism of the magnet is improved.

  However, it is considered that the ratio of the first magnetic powder to the mass of the total magnetic powder becomes important. Specifically, in the present embodiment, in a rare earth isotropic bond magnet including anisotropic magnetic powder A and isotropic magnetic powder B, anisotropic magnetism which is the first magnetic powder with respect to the mass of the total magnetic powder. The mass ratio (A / A + B) of the powder A is 10% or more and 60% or less.

  If the ratio of the first magnetic powder with respect to the mass of the total magnetic powder exceeds 60%, the magnetization will be reduced. The mechanism of this is not clear, but particles with an easy magnetization direction that is not parallel to the direction of the magnetizing magnetic field have a weak magnetic pressure applied to the domain wall, and the ratio of magnetization that the reverse domain buds cannot be sufficiently erased by magnetization. It is estimated that it will increase. On the other hand, if the ratio of the first magnetic powder is less than 10%, the effect of improving the magnetizing characteristics of the magnet cannot be sufficiently obtained.

<Resin binder, additive>
It does not specifically limit as a resin binder which couple | bonds the magnetic powder mentioned above, The thing generally used for manufacture of a bonded magnet can be used. For example, a thermoplastic resin such as polyamide or polyphenylene sulfide, or a thermosetting resin such as epoxy resin, phenol resin, or unsaturated polyester resin can be used.

  Furthermore, additives such as lubricants and resin stabilizers can be used to improve moldability or prevent deterioration of the resin.

  A method for mixing the magnetic powder, the resin binder, and the additive described above is not particularly limited. For example, the anisotropic magnetic powder that is the first magnetic powder and the isotropic magnetic powder that is the second magnetic powder are first mixed using a mixer or blender, and then a resin binder is added. If it is a thermoplastic resin, it can be melt kneaded, and if it is a thermosetting resin, it can be diluted with a solvent and mixed to volatilize and remove the solvent. However, if the kneading or mixing is not uniform and the dispersion state of the first magnetic powder and the second magnetic powder is deteriorated, the degree of improvement in the magnetization characteristics may be lowered. It is preferable to make it.

  As described above, the mixing ratio of the first magnetic powder (anisotropic magnetic powder A) and the second magnetic powder (isotropic magnetic powder B) is anisotropic with respect to the mass of the total magnetic powder. The mass ratio A / (A + B) of the conductive magnetic powder A is set to 10% or more and 60% or less. As described above, if the ratio of the anisotropic magnetic powder A is less than 10% or exceeds 60%, the effect of improving the magnetization characteristics cannot be sufficiently obtained. In particular, when the anisotropic magnetic powder A is used alone, the magnetization characteristics are extremely deteriorated.

<Method for producing rare earth isotropic bonded magnet>
The rare earth isotropic bonded magnet according to the present embodiment can be manufactured by molding by a known molding method such as injection molding, extrusion molding, compression molding, calendar roll molding or the like. Here, in order to be an “isotropic bonded magnet”, it is important to mold in a state where a magnetic field including residual magnetism is not applied to the mold during molding.

Since the anisotropic magnetic powder constituting the rare earth isotropic bonded magnet according to the present embodiment has a high magnetic field orientation during molding, the bonded magnet can be obtained even when a magnetic field of about 0.1 T is applied to the mold. The residual magnetic flux density Br varies depending on the direction of the magnet. When such variation occurs, for example, when a rotor magnet for a small motor is used, the cogging torque increases, and the effect of improving magnetization is reduced. Therefore, in the rare earth isotropic bonded magnet according to the present embodiment, the maximum value and minimum value of Br (Brx, Bry, Brz) measured in any three orthogonal directions (X direction, Y direction, Z direction). The difference (ΔBr) from the value is preferably within 5% with respect to the average value (Br _avg ) of Br in the three directions.

<Conventional bonded magnet>
Here, as a bonded magnet in which an R—Fe—N magnetic powder and an R—Fe—B magnetic powder are mixed, for example, Japanese Patent Laid-Open No. 05-152116 (Patent Document 4) discloses R ₂ T ₁₄ B. Discloses a technique of mixing magnetic alloy powder and R ₂ T ₁₇ N alloy powder (R is a rare earth element including Y, T is at least one of C and transition metals) and magnetic field forming is performed. The bond magnet manufactured by this technique is an anisotropic bond magnet because it is magnetic field-molded, and is different from the rare earth isotropic bond magnet according to the present embodiment. Further, this patent document _4, but R _{2 T 14} B-based alloy powder is to be amorphous, _R 2 _{T 14} B alloy powder in the present embodiment, the crystal grain size of 100nm or less The c-axis of each crystal is in a random direction. Further, according to the description of Patent Document 4, it is described as an anisotropic powder by pulverizing an amorphous ribbon, forming it with a hot press, and then hot-working and pulverizing. Also in this respect, the present embodiment is also described. This is different from the isotropic magnetic powder constituting the rare earth isotropic bonded magnet. Further, the R-Fe-N magnetic powder is assumed to be an R ₂ T ₁₇ N alloy powder, and has a composition with less nitrogen N than R ₂ T ₁₇ N ₃ in the present embodiment. It is. Furthermore, in the production, an ingot produced by high frequency melting or the like is used, which is different from that by the reduction diffusion method.

Japanese Patent Laid-Open No. 06-013212 (Patent Document 5) discloses a rare earth bonded magnet using a mixture of R ₂ Fe ₁₇ N _x magnetic powder and R ₂ Fe ₁₄ B magnetic powder. Yes. However, the R ₂ Fe ₁₇ N _x- based magnetic powder is characterized by being substantially magnetically isotropic, and is an anisotropic material constituting the rare earth isotropic bond magnet according to the present embodiment. Is different from magnetic powder. In addition, examples of the magnetic powder production method include a melt span method, a mechanical alloying method, a hydrogen treatment method, a gas atomization method, and the like, which are different from those by the reduction diffusion method.

  Japanese Patent Laid-Open No. 06-061023 (Patent Document 6) uses a mixture of a magnetic powder having a basic composition of Sm and Fe nitride and a magnetic powder having a basic composition of Nd, Fe and B. A rare earth bonded magnet is disclosed. According to Patent Document 6, since the bonded magnet is manufactured using a compression magnetic field molding machine, the bonded magnet is an anisotropic bonded magnet, which is different from the rare earth isotropic bonded magnet according to the present embodiment. Patent Document 6 describes that the average particle size of magnetic powder composed of Sm and Fe nitride is 10 μm or less because the orientation is disturbed and it is difficult to improve the magnetic properties. Therefore, it is premised on an anisotropic bonded magnet manufactured by orienting magnetic powder by magnetic field shaping.

Japanese Patent Laid-Open No. 06-132107 (Patent Document 7) discloses a composite obtained by uniformly mixing anisotropic magnet powder whose main phase is Nd ₂ Fe ₁₄ B and anisotropic SmFeN magnet powder. A bonded magnet obtained by compression-molding magnet powder together with a binder in a magnetic field is disclosed. In the rare earth isotropic bonded magnet according to the present embodiment, the main phase is composed of magnetic powder made of Nd ₂ Fe ₁₄ B, which is an isotropic magnetic powder and molded without applying a magnetic field. It is an isotropic bonded magnet, which is completely different from the bonded magnet described in Patent Document 7.

Japanese Patent Laid-Open No. 06-208913 (Patent Document 8) discloses an R ₂ Fe ₁₄ B-based magnetic powder and an R ₂ Fe ₁₇ N _X- based magnetic powder (R is one of rare earth elements including Y or A bonded magnet in which two or more are mixed is disclosed. In the technique described in Patent Document 8, R ₂ Fe ₁₄ B-based isotropic magnetic powder is used, but the bonded magnet is an anisotropic bonded magnet that is compression-molded in a magnetic field of 15 kOe. It is different from the rare earth isotropic bonded magnet according to the embodiment. The R ₂ Fe ₁₇ N _X- based magnetic powder described in Patent Document 8 is produced from an ingot melted and cast in a high-frequency melting furnace, and is completely different from that obtained by the reduction diffusion method.

Japanese Patent Application Laid-Open No. 08-031626 (Patent Document 9) discloses a mixed powder of two or more types of magnetic powder having a specific relationship between residual magnetic flux density and coercive force, a bond magnet manufactured therefrom, and the like. ing. In this Patent Document 9, R ₂ TM ₁₇ (NCH) _X- based magnetic powder and R ₂ TM ₁₄ B-based magnetic powder (R is one or more of rare earth elements including Y, TM is mainly Fe and The bonded magnet is an anisotropic bonded magnet that is compression-molded in a magnetic field of 15 kOe, and is a rare earth isotropic bond according to the present embodiment. Different from magnets. The R ₂ TM ₁₇ (NCH) _X- based magnetic powder used in the technique described in Patent Document 9 is produced from an ingot melted and cast in a high-frequency melting furnace, and R ₂ TM ₁₄ B System magnetic powder is anisotropic, and according to the present embodiment using an R ₂ TM ₁₇ N _X system magnetic powder obtained by a reduction diffusion method and an isotropic R ₂ TM ₁₄ B system magnetic powder. It is completely different from rare earth isotropic bonded magnets.

Japanese Patent Application Laid-Open No. 09-171916 (Patent Document 10) discloses a Nd—Fe—B alloy powder containing a hydrogen-treated Nd ₂ Fe ₁₄ B compound as a main phase and a rare earth alloy obtained by a rapid cooling method. A bonded magnet obtained by magnetic field molding of a powder mixed with powder together with a binder is disclosed. However, this bonded magnet is an anisotropic bonded magnet and is different from the rare earth isotropic bonded magnet according to the present embodiment. Further, the Nd—Fe—B alloy powder containing the Nd ₂ Fe ₁₄ B compound subjected to hydrogen treatment as a main phase is an anisotropic magnet powder and is not isotropic. Furthermore, the treated Sm—Fe—N alloy powder is an isotropic powder produced by a rapid cooling method.

  EXAMPLES Hereinafter, although the Example of this invention is shown and this invention is demonstrated more concretely, this invention is not limited to a following example at all.

[Examples 1-6, Conventional Example 1, Comparative Examples 1-2]
A samarium (Sm), iron (Fe), and nitrogen (N) pulverized so as to have a 50% particle diameter d50 of 2.3 μm as main constituents and having a Th ₂ Zn ₁₇ type crystal structure. Anisotropic magnetic powder (trade name: SFN-C, manufactured by Sumitomo Metal Mining Co., Ltd., hereinafter referred to as “anisotropic magnetic powder A”) and neodymium (Nd) pulverized so that the 50% particle diameter d50 is 42 μm. ), Iron (Fe), and boron (B) as main components, and an isotropic magnetic powder having a crystal structure of Nd ₂ Fe ₁₄ B type (trade name: MQP-B, manufactured by Moricope Magnequench, (Hereinafter referred to as “isotropic magnetic powder B”). When each magnetic powder is observed with a transmission electron microscope (TEM), the anisotropic magnetic powder A is a single crystal particle, and the isotropic magnetic powder B has a main phase crystal grain size of 10 nm to 30 nm. confirmed.

  These magnetic powders, polyamide 12 (“resin 1” in Table 1) powder having a weight average molecular weight Mw of 5,300 (GPC, polymethyl methacrylate conversion method), and ethylene bis-stearic acid amide powder (in Table 1) The “additive”) was mixed at the blending ratio shown in Table 1 below, and melt-kneaded at 220 ° C. for 30 minutes in an argon gas atmosphere by a batch kneader. In Table 1 below, the mixing ratio of the anisotropic magnetic powder A to the entire magnetic powder is also shown in mass%.

  Next, the composition recovered after kneading was pulverized to 5 mm or less with a plastic pulverizer, and this was crushed into a cube having a cylinder temperature of 230 ° C., a mold temperature of 110 ° C., and a side of 10 mm using a 50 t magnetic field injection molding machine. Injection molded. Since no magnetic field is applied to the mold, the obtained injection-molded product is an isotropic magnet.

The obtained cubic injection-molded magnet is magnetized with a pulse magnetizer having a peak magnetic field of 4T, with the injection direction being the Z direction and the directions orthogonal to the Z direction being the X and Y directions. Then, measurement was performed with a BH curve tracer having a maximum magnetic field of 2.4 T. Br in the X, Y, and Z directions were Brx, Bry, and Brz, respectively, and the ratio of the difference between the maximum value and the minimum value to the average value was ΔBr / Br _avg (%). The measurement results are shown in Table 2 below.

  The injection-molded magnet was magnetized with a peak magnetic field of 1.5T and 4T, respectively, and the total magnetic flux was measured by a drawing method using a digital magnetometer. The total magnetic flux when magnetized at a peak magnetic field of 1.5T is Φ1.5, the total magnetic flux when magnetized at 4T, which is completely magnetized, is Φ4, and the ratio Φ1.5 / Φ4 (%) is calculated. The magnetism was evaluated. The results on the magnetization are also shown in Table 2. Note that the closer this ratio is to 100%, the better the magnetization.

[Examples 7 to 12, Conventional Example 2, Comparative Examples 3 to 4]
As the resin binder, only polyphenylene sulfide (PPS, “resin 2” in Table 1) powder having a weight average molecular weight Mw of 65,000 (ultra-high temperature GPC, standard polystyrene conversion method) is used, and the kneader kneading temperature is 300 ° C. Isotropic injection-molded magnets were obtained in the same manner as in Example 1 except that the mixture was melt-kneaded and after the kneading, injection molding was performed at a cylinder temperature of 300 ° C and a mold temperature of 130 ° C. Table 1 below shows the blending conditions, and Table 2 below shows the measurement results for Brx, Bry, Brz, ΔBr / Br _avg , and Φ1.5 / Φ4.

[Examples 13 to 18, Conventional Example 3, Comparative Examples 5 to 6]
The mixed powder of magnetic powder A and magnetic powder B used in Example 1 (Examples and Comparative Examples), or a single powder of only magnetic powder A (conventional example), bisphenol A type epoxy resin (table) 1) “Resin 3” in 1) and dicyandiamide (“Resin 4” in Table 1), which is a curing agent, are diluted 10 times with acetone, and acetone is stirred at 30 ° C. under reduced pressure while stirring with a mixer. Volatilized. Table 1 below shows their formulation.

The obtained composition was crushed, supplied into a press mold, and compression-molded in a magnetic field at a surface pressure of 490 MPa. This molded body was heat-treated in vacuum at 180 ° C. for 1 hour to cure the epoxy resin, and a cube having a side of 10 mm was obtained. Brx, Bry, Brz, ΔBr / Br _avg , Φ1.5 / Φ4, in the same manner as in Example 1, with the pressing direction of the obtained cubic compression-molded magnet as the Z direction and the directions orthogonal thereto as the X and Y directions Was measured. The measurement results are shown in Table 2 below.

[Example 19]
An isotropic injection-molded magnet was produced in the same manner as in Example 1 except that the blending ratio of the magnetic powder A and the magnetic powder B was as shown in Table 1 below. Table 2 below shows the measurement results of Brx, Bry, Brz, ΔBr / Br _avg , and Φ1.5 / Φ4.

[Example 20]
An isotropic injection-molded magnet was produced in the same manner as in Example 7 except that the blending ratio of magnetic powder A and magnetic powder B was as shown in Table 1 below. Table 2 below shows the measurement results of Brx, Bry, Brz, ΔBr / Br _avg , and Φ1.5 / Φ4.

[Example 21]
An isotropic injection molded magnet was produced in the same manner as in Example 13 except that the blending ratio of the magnetic powder A and the magnetic powder B was as shown in Table 1 below. Table 2 below shows the measurement results of Brx, Bry, Brz, ΔBr / Br _avg , and Φ1.5 / Φ4.

The magnets obtained in Examples 1 to 6 are isotropic injection molded magnets using polyamide 12 as a resin binder, and Φ1.5 / Φ4 is 88% to 91%, and has high magnetization characteristics. Indicated. Since the magnet shown in Conventional Example 1 with only isotropic magnetic powder was 82%, and the amount of anisotropic magnetic powder mixed was more than 60%, it was 84% or less. It can be seen that the magnetizing characteristics of the magnets obtained in Examples 1 to 6 are high. Further, ΔBr / Br _avg was an isotropic magnet within 5%.

The magnets obtained in Examples 7 to 12 are isotropic injection-molded magnets using polyphenylene sulfide as a resin binder, and Φ1.5 / Φ4 is 86% to 94%, which is highly magnetized. The characteristics are shown. The magnet shown in Conventional Example 2 with only isotropic magnetic powder was 80%, and the magnet content exceeding 60% was 85.5% or less. It can be seen that the magnetizing characteristics of the magnets obtained in Examples 7 to 12 are high. Further, ΔBr / Br _avg was an isotropic magnet within 5%.

The magnets obtained in Examples 13 to 18 are isotropic compression-molded magnets using an epoxy resin as a resin binder, and Φ1.5 / Φ4 is 86% to 94.5%, which is high. The magnetization characteristics are shown. Since the magnet shown in Conventional Example 3 containing only isotropic magnetic powder was 86%, and the amount of mixed anisotropic magnetic powder was more than 60%, it was 83% or less. It can be seen that the magnetizing characteristics of the magnets obtained at 13 to 18 are high. Further, ΔBr / Br _avg was an isotropic magnet within 5%.

The magnet obtained in Example 19 is at a level where the total amount of magnetic powder in Example 3 is increased, and Φ1.5 / Φ4 is 91.3%, which is excellent wear equivalent to the magnet of Example 3. Magnetic properties were obtained. Moreover, the magnet obtained in Example 20 is a level in which the total amount of magnetic powder in Example 9 is increased, and Φ1.5 / Φ4 is 94.2%, which is equivalent to the magnet of Example 9. Magnetization characteristics were obtained. Furthermore, the magnet obtained in Example 21 is a level in which the total amount of magnetic powder in Example 15 is increased, and Φ1.5 / Φ4 is 94.4%, which is equivalent to the magnet of Example 15. Magnetism was obtained.

Claims (4)

An anisotropic magnetic powder A comprising a rare earth element (Sm or any one or more of lanthanoid elements including Sm and Y), iron, and nitrogen as main components and a Th ₂ Zn ₁₇ type crystal structure; ,
Nd ₂ Fe ₁₄ B type crystal comprising, as main constituents, a rare earth element (Nd, Pr, or any one or more of lanthanoid elements including Y mainly composed of Nd or Pr), iron, and boron An isotropic magnetic powder B having a structure,
A rare earth isotropic bonded magnet, wherein a ratio A / (A + B) of the mass of the anisotropic magnetic powder A to the mass of the total magnetic powder is 10% or more and 60% or less.   2. The rare earth isotropic bonded magnet according to claim 1, wherein the anisotropic magnetic powder A has a 50% particle size of 10 μm or less.   3. The rare earth isotropic bonded magnet according to claim 1, wherein a 50% particle diameter of the isotropic magnetic powder B is 30 μm or more. The difference (ΔBr) between the maximum value and the minimum value of the residual magnetic flux density Br measured in three orthogonal directions (X direction, Y direction, Z direction) is the average value (Br _avg ) of Br in the three directions. The rare earth isotropic bond magnet according to any one of claims 1 to 3, wherein the content is within 5%.