JP4238114B2 - Powder for high resistance rare earth magnet and method for producing the same, rare earth magnet and method for producing the same, rotor for motor and motor - Google Patents

Description

  The present invention relates to a novel high resistance rare earth magnet powder having high electrical resistance, a method for producing the same, a rare earth magnet using the powder, a method for producing the same, a motor rotor, and a motor using the same.

  Conventionally, ferrite magnets have been frequently used as magnets used in permanent magnet motors. However, the use of higher performance rare earth magnets has been increasing year by year as rotary electricity has become smaller and higher in performance. Typical rare earth magnets include Sm-Co magnets and Nd-Fe-B magnets, and developments are underway to achieve higher performance and lower costs.

  However, since the rare earth magnet is a metal magnet, its electric resistance is low. For this reason, the eddy current loss when it is incorporated in the motor is increased, resulting in a problem of lowering the motor efficiency. Therefore, various techniques for solving this problem by increasing the electric resistance of the rare earth magnet itself have been proposed.

For example, Patent Document 1 proposes a rare earth magnet having a structure in which a rare earth magnet powder is bound with at least one of SiO ₂ and Al ₂ O ₃ particles.

Japanese Patent Laid-Open No. 10-321427

In Patent Document 1, when at least one of SiO ₂ and Al ₂ O ₃ is present between the rare earth magnet powders, the electric resistance of the rare earth magnet can be increased. However, if SiO ₂ and Al ₂ O ₃ are added individually to the rare earth magnet, the magnet characteristics are greatly deteriorated. This is difficult to apply to medium to large output motors. Furthermore, even if the electric resistance of the rare earth magnet can be increased, on the other hand, the magnetic characteristics are greatly deteriorated.

  An object of the present invention is to provide a high resistance rare earth magnet powder having high electrical resistance and minimizing deterioration in magnet characteristics, a method for producing the same, a rare earth magnet, a method for producing the same, and a rotor for a motor using the rare earth magnet. And providing a motor using the same.

  According to the present invention, for each grain of rare earth magnet powder, a thin film with high heat resistance capable of minimizing deterioration of magnet characteristics is coated thinly and uniformly, and electric resistance is applied on the coated film. This is made in view of the importance of thinly and uniformly coating a large heat-resistant film. That is, to suppress the deterioration of the magnet characteristics of the rare earth magnet, it is necessary to increase the volume fraction of the rare earth magnet powder, but at the same time, it is necessary to obtain a high electric resistance. For this reason, it is essential to form the above-described two kinds of coatings thinly and uniformly on at least a part of each particle surface of the rare earth magnet powder, preferably on the entire surface of each particle. Surface treatment by a wet method using a chemical reaction is effective for forming a thin and uniform film on the surface of each particle. The thickness of each coating is 0.05 to 1.0 μm, preferably 0.05 to 0.5 μm, more preferably 0.05 to 0.3 μm, and the total amount of each coating is 0.5 to 20% by volume, preferably 0.5 to 10 volume with respect to the powder. %, More preferably 0.5 to 5% by volume.

In the present invention, at least a part of the powder surface for rare earth magnets is made of terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu). At least a part of the surface of the rare earth magnet particle coated with a compound containing at least one rare earth oxide (R is a rare earth element) and coated with the compound containing the rare earth oxide , Al ₂ O ₃ , SiO ₂ , It is a powder for a high electric resistance rare earth magnet characterized by being coated with at least one metal compound of silicon nitride, TiO ₂ , ZnO and ZrO ₂ , and after this, using this powder, it is hot formed It is a rare earth magnet characterized by the above.

As described later, the rare earth magnet powder is formed by a solution containing a rare earth oxide-containing compound and a metal compound such as Al ₂ O ₃ in a solution, so that it is uniform on the individual particles of the powder. It is preferable that the entire surface is covered, but a portion that is partially covered is also formed slightly, so that at least a portion is covered. The coating is characterized in that it is partially formed into a film.

  The rare earth oxide and the metal compound have at least one of amorphous and crystalline, and the rare earth magnet powder is partially or entirely coated on the surface, but is mostly amorphous. .

  Rare earth magnet powders generally tend to cause chemical changes such as reaction with metals and organic compounds, surface oxidation, and the like, and deterioration of magnet properties becomes a problem. A surface coating agent capable of maintaining magnet properties even at high temperatures is desired.

The present inventors diligently studied, and the surface of the rare earth magnet powder has high heat resistance, terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb). In order to maintain the magnet characteristics without increasing the volume fraction of the rare earth oxide, which is at least one of lutetium and lutetium (Lu), the formula RL ₃ [R is R of the rare earth oxide, L is a ligand of the _{organic, {CO (CH 3) CHCO} (CH 3)} - _{ions, {CO (C (CH 3} ) 3) CHCO (C (CH 3) 3)} - ions, {CO _{(C 3 F 7) CHCO (} C (CH 3) 3)} - _{ions, {CO (CF 3) CHCO} (CF 3)} - ions either β- _{Jiketonatoion, (O-i-C 3} H 7) ^- ions and _{(O-C 2 H 4 -OCH} 3) - use the solution of ions is an organic group of any of the anions] Be a wet process was found to be effective. This is because almost all of the surface of the rare earth magnet powder can be coated uniformly and preferably with a thin film of preferably 0.1 to 0.3 μm on the entire surface by using wet processing.

Also, without causing deterioration such as oxidation of the surface of the powder for rare earth magnet by the solvent which dissolves the formula RL ₃ using low-boiling alcoholic solvent, produce a rare earth oxide on the surface of the powder for rare earth magnet It became possible to make it. Also, by using one of the same anionic organic groups as described above, which can be decomposed and removed at a low temperature of 500 ° C. or less and in an oxygen-free state, the ligand L is a carbon compound on the surface of the rare earth magnet powder. It became possible to suppress the generation of. The bulk magnet obtained by hot forming using the rare earth magnet powder with the rare earth oxide formed on the surface is thermally stable, and even after heat treatment at 800 ° C, the magnet properties at room temperature are The change was small before and after the heat treatment. It has been found that this surface-treated film made of rare earth oxide is effective in stabilizing the magnetic properties against heat treatment of a magnet compression-molded using rare earth magnet powder.

Furthermore, in order to improve the insulation properties of the rare earth magnet powder surface, Al ₂ O ₃ , SiO ₂ , silicon nitride, TiO ₂ , high insulating and high heat resistance are formed on the rare earth oxide film on the rare earth magnet powder surface. It is important to produce one or more kinds of ZnO and ZrO ₂ as a thin and uniform film. In order to produce these highly insulating heat-resistant metal compounds as a thin and uniform film on the rare earth oxide film on the surface of the rare earth magnet powder, the following insulating film forming method using a wet process is effective. I found it.
(1) In the case of using a metal compound containing at least one of a metal alkoxide and a metal diketonate when generating one or more kinds of metal oxides of Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZnO, ZrO ₂ , Using a solution obtained by dissolving the metal compound in an organic solvent having a boiling point of 150 ° C. or less, mixing the solution with the rare earth magnet powder, and preferably performing a heat treatment in deoxidation at 100 to 600 ° C. It has become possible to produce the above metal oxide on the rare earth oxide film without altering the surface of the magnet powder. In addition, the ligands alkoxide and diketonate can be decomposed and removed at a low temperature of 600 ° C. or lower and in an oxygen-free state, {CO (CH ₃ ) CHCO (CH ₃ )} ^- ion, {CO (C ( _{CH 3) 3) CHCO (C} (CH 3) 3)} - _{ions, {CO (C 3 F 7} ) CHCO (C (CH 3) 3)} - _{ions, {CO (CF 3) CHCO} (CF 3) } ^- either β- Jiketonatoion _{ion, (O-i-C 3} H 7) - _{ion, (O-S-C 4} H 9) - _{ion, (O-n-C 4} H 9) - ions and By using an anionic organic group of any one of (O—C ₂ H ₄ —OCH ₃ ) ⁻ ions, it has become possible to suppress the generation of a carbon compound on the rare earth magnet powder surface as much as possible.
(2) In the case of using a metal compound containing at least one of a metal alkoxide and a metal diketonate when generating one or more kinds of metal oxides of Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZnO, and ZrO ₂ The rare earth magnet is obtained by using a mixed solution of the metal compound in water and a water-soluble organic solvent, mixing the solution with the powder for the rare earth magnet, and preferably performing heat treatment in deoxygenation at 100 to 400 ° C. The above-described metal oxide can be formed on the rare earth oxide film without altering the surface of the powder for use. In order to control the sol-gel reaction between a metal compound and water, it is effective to dilute with an alcohol-based low-boiling solvent, and a rare earth magnet can be used without altering the surface of the rare earth magnet powder with a solution using this diluent. The aforementioned metal oxide can be generated on the powder surface.

  In the control of this sol-gel reaction, it is not preferable to add commonly used acids and basic compounds. That is, since acid and basic compounds corrode rare earth magnet powders, the magnetic properties of magnets using the corroded powders are significantly impaired. On the other hand, diketonate, which is a ligand in a metal compound accompanied by a sol-gel reaction, can be decomposed and removed at a low temperature of 400 ° C. or lower and in an oxygen-free state.

By using any one of the anionic organic groups described in (1) above as the diketonate ligand, it has become possible to suppress the formation of carbon compounds on the rare earth magnet powder surface as much as possible.
(3) When generating a compound containing SiO ₂ ,
_{C n H 2n + 1 O- {} Si (C n H 2n + 1 O) 2 -O} m -C n H 2n + 1
(Where n is an integer of 1 to 2 and m is an integer of 1 to 10), using a mixed solution using a silane compound, water and a water-soluble organic solvent, and mixing the solution with the rare earth magnet powder, Preferably, by performing heat treatment in deoxygenation at 100 to 200 ° C., SiO ₂ can be formed on the rare earth oxide film without altering the surface of the rare earth magnet powder. In order to control the sol-gel reaction between the above-mentioned silane compound and water, it is effective to dilute with an alcohol-based low-boiling solvent, and the rare earth magnet powder surface can be altered by a solution using this diluted solution. As a result, SiO ₂ can be generated on the surface of the rare earth magnet powder. In the control of this sol-gel reaction, addition of commonly used acids and basic compounds is not preferable as described above.

On the other hand, by using C _n H _{2n + 1} O (n is an integer of 1 to 2) as the organic group in the silane compound, the organic group can be removed at a low temperature of 150 ° C. or less and in an oxygen-free state. Generation of carbon compounds on the surface of the magnet powder can be suppressed as much as possible. _{{Si (C n H 2n +} 1 O) 2 -O} may be m repeating a unit of the Si of m 10 or more, but in practice is easy to control the reaction, 1 to 10 of the material easily available good.
(4) When producing silicon nitride, a solution of polysilazane dissolved in a low-polar organic solvent is mixed with a rare earth magnet powder and heat treated in a deoxidized environment at 600 to 800 ° C. It has become possible to form silicon nitride on a rare earth oxide film without altering the surface. As silicon nitride, Si ₃ N ₄ is preferable.

In order to improve the insulation properties of the rare earth magnet powder surface , at least Al ₂ O ₃ , SiO ₂ , silicon nitride, TiO ₂ , ZnO, ZrO ₂ is formed on the rare earth oxide film on the rare earth magnet powder surface. it is to form a kind of metal compound.

Rare earth magnet powder consists of a ferromagnetic main phase and other components. When the rare earth magnet is an Nd—Fe—B based magnet, the main phase is an Nd ₂ Fe ₁₄ B phase. Considering improvement in magnet characteristics, the rare earth magnet powder is preferably an anisotropic rare earth magnet powder prepared by using the HDDR method or hot plastic working. The anisotropic rare earth magnet powder prepared using the HDDR method or hot plastic working becomes an aggregate of a large number of crystal grains as described later. At this time, it is preferable to improve the coercive force if the crystal grains have an average grain size equal to or smaller than the single magnetic domain grain size. Examples of the rare earth magnet powder include Sm—Co based magnets in addition to Nd—Fe—B based magnets. Considering the magnet characteristics of the obtained rare earth magnet and the manufacturing cost, Nd—Fe—B based magnets are preferable. However, the rare earth magnet of the present invention is not limited to the Nd—Fe—B based magnet. In some cases, two or more rare earth magnet powders may be mixed in the rare earth magnet. That is, two or more types of Nd—Fe—B magnets having different composition ratios may be included, and Nd—Fe—B magnets and Sm—Co magnets may be mixed.

  In the present application, the “Nd—Fe—B system magnet” is a concept including a form in which a part of Nd or Fe is substituted with another element. Nd may be substituted with other rare earth elements such as Dy and Tb. Only one of these may be used for substitution, or both may be used. The substitution can be performed by adjusting the amount of the raw material alloy. By such replacement, the coercive force of the Nd—Fe—B magnet can be improved. The amount of Nd to be substituted is preferably 0.01 atom% or more and 50 atom% or less with respect to Nd. If it is less than 0.01 atom%, the effect of substitution may be insufficient. If it exceeds 50 atom%, the residual magnetic flux density may not be maintained at a high level.

  On the other hand, Fe may be substituted with another transition metal such as Co. By such replacement, the Curie temperature (Tc) of the Nd—Fe—B magnet can be increased and the operating temperature range can be expanded. The amount of Fe to be substituted is preferably 0.01 atom% or more and 30 atom% or less with respect to Fe. If it is less than 0.01 atom%, the effect of substitution may be insufficient. If it exceeds 30 atom%, the coercive force may decrease significantly.

The average particle diameter of the rare earth magnet powder in the rare earth magnet is preferably 1 to 500 μm. When the average particle size of the rare earth magnet powder is less than 1 μm, the specific surface area of the magnetic powder is large and the influence of oxidative degradation is great, and there is a concern that the magnet properties of the rare earth magnet using the rare earth magnet powder may deteriorate. On the other hand, if the average particle size of the rare earth magnet powder is larger than 500 μm, the magnet powder is crushed by the pressure during production, and it becomes difficult to obtain sufficient electric resistance. In addition, when an anisotropic magnet is produced using anisotropic rare earth magnet powder as a raw material, the main phase in rare earth magnet powder (Nd ₂ Fe _{14 in} Nd—Fe—B magnets) extends over a size exceeding 500 mm. It is difficult to align the orientation direction of (B phase). The particle size of the rare earth magnet powder is controlled by adjusting the particle size of the rare earth magnet powder that is the raw material of the magnet. The average particle size of the rare earth magnet powder can be calculated from the SEM image.

  The present invention relates to an isotropic magnet manufactured from an isotropic magnet powder, an isotropic magnet in which anisotropic magnet powder is randomly oriented, and an anisotropic magnet in which anisotropic magnet powder is oriented in a certain direction. It is applicable to both. If a magnet having a high energy product is required, an anisotropic magnet using anisotropic magnet powder as a raw material and oriented in a magnetic field is suitable.

The rare earth magnet powder is produced by blending raw materials according to the composition of the rare earth magnet to be produced. When producing an Nd—Fe—B based magnet whose main phase is the Nd ₂ Fe ₁₄ B phase, a predetermined amount of Nd, Fe and B is blended. As the rare earth magnet powder, one produced by a known method may be used, or a commercially available product may be used. Preferably, an anisotropic rare earth magnet powder manufactured using the HDDR method or the UPSET method using hot plastic working is used. Such anisotropic rare earth magnet powder is an aggregate of many crystal grains. The crystal grains constituting the anisotropic rare earth magnet powder are suitable for improving the coercive force when the average particle diameter is not more than the single domain critical particle diameter. Specifically, the average grain size of the crystal grains is preferably 500 nm or less. In the HDDR method, the Nd—Fe—B alloy is hydrogenated to decompose the Nd ₂ Fe ₁₄ B compound as the main phase into three phases of NdH ₃ , α-Fe and Fe ₂ B, and then In this method, Nd ₂ Fe ₁₄ B is generated again by forced dehydrogenation. The UPSET method is a technique in which an Nd—Fe—B alloy produced by an ultra-quenching method is plastically processed hot after pulverization and temporary molding.

The anisotropic rare earth magnet powder after the surface treatment is filled in a mold. The shape of the mold is not particularly limited, and may be determined according to the part to which the magnet is applied. When filling the mold, an appropriate pressure may be applied for temporary molding. The pressure for temporary molding is about 0.5 to ⁵ t / cm ² . In addition, when the rare earth magnet powder to be used is an anisotropic magnet powder, an anisotropic rare earth magnet can be obtained by temporarily forming the rare earth magnet powder while orienting the magnetic field. The orientation magnetic field applied is about 796 to 1592 kA / m (10 to 20 kOe).

The surface-treated anisotropic rare earth magnet powder filled in the mold is molded to obtain a bulk magnet. In addition, the operation | work which hardens the anisotropic rare earth magnet powder after surface treatment by the above-mentioned temporary forming shall not correspond to "forming" in this application. For the molding, a known apparatus usually used for magnet production can be used. Preferably, it is preferable to form by hot forming. When the hot forming method is used, the rare earth magnet powder as a raw material can be sufficiently plastically deformed to obtain a high density rare earth magnet. Although it does not prescribe | regulate especially as a hot forming method, a hot press can be used. The molding pressure is about 1 to 10 t / cm ² . The molding temperature is suitably 600 to 800 ° C. and the pressing time is suitably 5 to 30 minutes. The normal hot forming atmosphere is a vacuum of 10 Pa or less or an inert gas flow.

  When anisotropic magnet powder is used as the raw material magnet powder, it may be magnetically oriented during molding as is well known. By forming the raw magnet powder with the easy magnetization axes aligned, the residual magnetization in the orientation direction can be increased, and the energy product of the magnet can be improved. The orientation magnetic field applied is about 796 to 1592 kA / m (10 to 20 kOe).

  After molding, processing (cutting, polishing, etc.), surface treatment (protection film formation, painting, etc.), magnetization, etc. are performed.

  Various known techniques can be appropriately applied to the processing of the rare earth magnet. That is, processing such as grinding (external grinding, internal grinding, surface grinding, forming grinding), cutting (peripheral cutting, inner peripheral cutting), lapping, and chamfering can be performed. As the processing tool, diamond, GC grindstone, outer / inner peripheral cutting machine, outer / inner peripheral grinder, surface grinder, NC lathe, milling machine, machining center and the like can be used.

  Since rare earth magnets are easily oxidized, a protective film may be provided on the magnet surface. The configuration of the protective film is not particularly limited, and a suitable composition may be selected according to the magnet characteristics and the thickness may be determined so as to obtain a sufficient protective effect. Specific examples of the protective film include a metal film, an inorganic compound film, and an organic compound film. Examples of the metal film include Ti, Ta, Cr, Mo, Ni, etc., and examples of the inorganic compound film include transition metal nitride films such as TiN, FeN, and CrN, and transition metal oxide films such as NiO and FeO. Examples of the organic compound film include a resin film made of epoxy resin, phenol resin, polyurethane, polyester, or the like. The thickness of the protective film is preferably about 0.01 to 10 μm when the protective film is made of a metal film or an inorganic film, and about 1 to 10 μm when the protective film is made of an organic compound. preferable.

Magnetization can be performed by a static magnetic field or a pulsed magnetic field. A standard for obtaining a magnetization state close to saturation is a magnetization magnetic field strength of at least twice the spontaneous coercive force, preferably about four times.
A concentrated-winding surface magnet type motor to which the high resistance rare earth magnet of the present invention with improved insulation on the surface of the magnetic powder for rare earth magnets of the present invention is applied will be described. The rare earth magnet of the present invention has a high electric resistance and also has excellent magnet characteristics. For this reason, if the motor manufactured using the rare earth magnet of the present invention is used, the continuous output of the motor can be easily increased, and it can be said that it is suitable as a medium to high output motor. In addition, since the motor using the rare earth magnet of the present invention has excellent magnet characteristics, the product can be reduced in size and weight. For example, when applied to automotive parts, fuel efficiency can be improved as the vehicle body becomes lighter. Furthermore, it is particularly effective as a drive motor for electric vehicles and hybrid electric vehicles. Drive motors can be installed in places where it was difficult to secure space so far, and it will play a major role in the generalization of electric vehicles and hybrid vehicles.

In the present invention, a rare earth oxide having poor reactivity with a rare earth element is formed on the surface of a magnetic powder for a rare earth magnet, so that it has excellent magnet characteristics even under severe manufacturing conditions such as hot forming, One or more types of Al ₂ O ₃ , SiO ₂ , silicon nitride, TiO ₂ , ZnO, and ZrO ₂ exist between the magnetic particles for rare earth magnets having oxides, and the amorphous or / and crystalline Al ₂ O ₃ , SiO ₂ , silicon nitride, TiO ₂ , ZnO, ZrO ₂ One or more kinds of metal compounds exist, and the presence of these metal compounds has a structure in which the magnetic powders for rare earth magnets are connected. A rare earth magnet having high strength is obtained.

  ADVANTAGE OF THE INVENTION According to this invention, it has high electrical resistance, the powder for high resistance rare earth magnets which can suppress the fall of a magnet characteristic to the minimum, its manufacturing method, rare earth magnet, its manufacturing method, and the rotor for motors using the rare earth magnet And a motor using the same.

  Hereinafter, the best mode for carrying out the present invention will be described. In addition, this invention is not limited to the Example shown below.

As a rare earth magnet powder, a composition of Nd _12.6 Co _17.4 B _6.5 Ga _0.3 Al _0.5 Zr _0.1 Fe _bal with an atomic ratio which is a powder for an Nd-Fe-B anisotropic magnet prepared using a known HDDR method. An ingot was prepared. The ingot was homogenized by holding at 1120 ° C. for 20 hours. The homogenized ingot was heated from room temperature to 500 ° C. and held in a hydrogen atmosphere, and further heated to 850 ° C. and held. Subsequently, the alloy was held in a vacuum atmosphere at 850 ° C. and then cooled to obtain an alloy having a recrystallized texture (crystal grains) of a fine ferromagnetic phase. This alloy was pulverized in an argon gas using a jaw crusher and a brown mill to obtain a rare earth magnet powder having an average particle size of 300 μm or less.

For the surface treatment of rare earth magnet powder with rare earth oxide, 1 g of dysprosium (Dy) 2,4-pentanedionate, which is a rare earth complex, was dissolved in 100 ml of isopropyl alcohol. Similarly, for SiO ₂ surface treatment, 12.5 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), 2.4 ml of water, methyl alcohol Surface treatment and molding were performed by sequentially mixing the following steps using a solution in which 3.75 ml and 0.025 ml of dibutyltin dilaurate were mixed and allowed to stand at a temperature of 25 ° C. overnight.
(1) 100 kg of Dy ₂ O ₃ surface treatment solution is added to 1 kg of rare earth magnet powder and stirred, and then heat-treated in vacuum at 150 ° C. for 1 hour and 350 ° C. for 1 hour. A treated powder having a Dy oxide coating on the entire surface of the magnet powder was obtained. Some organic groups remain in this treated powder. The thickness of the coating is about 0.1-0.2μm, about 1% by volume of the powder. Most of the coating is amorphous and has some crystallinity. Depending on the surface treatment of the rare earth magnet powder itself, the oxide film Is substantially not formed.
(2) Add 50 ml of SiO ₂ surface treatment solution to 1 kg of the treated powder, stir, then heat-treat in vacuum at 150 ° C for 1 hour to cover the surface of the rare earth magnet powder with Dy oxide A treated powder with Si oxide coating was obtained. The thickness of the coating is about 0.2-0.3 μm, about 1% by volume of the powder, most is amorphous and has some crystallinity.
(3) The processing powder is filled into a mold, and then the rare earth is applied at a temporary molding pressure of 0.5 t / cm ² while being magnetically oriented by applying a magnetic field of 796 kA / m (10 kOe) to the mixture in the mold. A temporary compact of magnet powder was formed.
(4) Using a molding apparatus having a heat source, the temporary compact was hot molded in Ar at a molding temperature of 800 ° C., a holding time of 10 minutes, and a molding pressure of 5 t / cm ² to obtain a bulk rare earth magnet. FIG. 1 is a cross-sectional view schematically showing a cross section of the obtained rare earth magnet. As shown in FIG. 1, in the rare earth magnet 1, the surface of the rare earth magnet particles 2 is uniformly formed with a Dy oxide coating of about 0.1 μm thick, which is a rare earth oxide 3, and the surface is further oxidized with Si, which is a metal compound 4. The object is formed a little thicker and binds the rare earth magnet particles 2 to each other. Further, as shown in FIG. 1B of the enlarged view shown by the broken line in FIG. 1A, the anisotropic magnet powder becomes an aggregate of a large number of crystal grains 5. At this time, if the crystal grains 5 have an average grain size equal to or smaller than the single magnetic domain grain size, it is preferable to improve the coercive force.

  The density, coercive force, maximum energy product and electrical resistivity of the obtained rare earth magnet were measured. The magnet density was determined from the size and mass of the rare earth magnet. The magnet characteristics were measured using a vibrating sample magnetometer (BHV-525 manufactured by Riken Denshi Co., Ltd.) after the test piece was magnetized at 3184 kA / m (40 kOe). The electrical resistivity was measured by a four-probe method using a K705RM manufactured by KYOWARIKEN.

Table 1 shows the results. The obtained rare earth magnet has excellent properties such as a density of 7.3 g / cm ³ or more, a coercive force of 716.4 kA / m (9.0 kOe) or more, a maximum energy product of 159.2 MJ / m ³ (20 MGOe) or more, and an electric resistivity of 2000 μΩcm or more. It is clear that it has high strength because it is formed by hot forming.

On the other hand, the combination of the surface treatment with rare earth oxide and the SiO ₂ surface treatment according to the present invention is Nd _12.4 Dy _0.6 Co ₂₀ B _6.2 Ga _0.4 Al _1.5 Zr _{0.1 in} terms of atomic ratio having a coercive force of 1544.2 kA / m (19.4 kOe). It was also found to be effective for anisotropic HDDR powder with Fe _bal component composition. That is, the magnet produced by using the powder for a magnet, the magnet density 7.6 g / cm ^3, the coercive force 1512.4 k A / m (19.0kOe) , the maximum energy product 199MJ / m ³ (25MGOe), characteristics of the electrical resistivity 3500μΩcm Had a value. From this, it is possible to produce a magnet having high electric resistance and high strength without impairing the characteristics of the powder used by using the present invention for the Nd-Fe-B anisotropic magnet powder. Made possible.

For surface treatment of rare earth magnet powder with rare earth oxide, 1.6g of rare earth complex holmium (Ho) 2,2,6,6-tetramethyl-3,5-heptanedionate is dissolved in 300ml of isopropyl alcohol. Used. Similarly, in the Al ₂ O ₃ surface treatment, 40 g of aluminum 2,4-pentane dionate was dissolved in 300 ml of toluene, and the following steps were sequentially performed for surface treatment and molding.
(1) To 1 kg of rare earth magnet powder, add 300 ml of Ho ₂ O ₃ surface treatment solution, stir while evaporating the solvent, and then in vacuum at 190 ° C for 1 hour and 500 ° C for 1 hour Heat treatment was performed to obtain a treated powder similar to that in Example 1.
(2) To 1 kg of the treated powder, 300 ml of SiO ₂ surface treatment solution was added, stirred while evaporating the solvent, and then heat-treated in vacuum at 600 ° C. for 1 hour.
(3) The processing powder was filled into a mold, and a rare-earth magnet powder temporary compact was formed while orienting the magnetic field in the same manner as in Example 1.
(4) The temporary compact was hot-molded in the same manner as in Example 1 to obtain a bulk rare earth magnet.

The density, coercive force, maximum energy product and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet has a density of 7.3 g / cm ³ or more, a coercive force of 716.4 kA / m (9.0 kOe) or more, a maximum energy product of 159.2 MJ / m ³ (20 MGOe) or more, and an electrical resistivity. It was found that both have excellent characteristics of 2000 μΩcm or more.

For the surface treatment of rare earth magnet powder with rare earth oxide, 2 g of dysprosium (Dy) 2,4-pentanedionate, which is a rare earth complex, was dissolved in 200 ml of isopropyl alcohol. Similarly, for the TiO ₂ surface treatment, 26 g of titanium diisopropoxide (bis 2,4-pentane dionate), 1 ml of water, 0.025 ml of dibutyltin dilaurate are dissolved in 100 ml of isopropyl alcohol and used in the following steps. The surface treatment and molding were performed sequentially.
(1) To 1 kg of rare earth magnet powder, 200 ml of Dy ₂ O ₃ surface treatment solution is added and stirred, and then heat treated at 150 ° C for 1 hour and 350 ° C for 1 hour in vacuum. Obtained.
(2) To 1 kg of the treated powder, 100 ml of the TiO ₂ surface treatment solution was added and stirred, and then heat-treated at 400 ° C. for 1 hour in a vacuum to obtain a treated powder similar to Example 1.
(3) The treated powder was filled in a mold, and a rare-earth magnet powder temporary compact was formed while orienting the magnetic field in the same manner as in Example 1.
(4) The temporary compact was hot-molded in the same manner as in Example 1 to obtain a bulk rare earth magnet.

The density, coercive force, maximum energy product and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet has a density of 7.3 g / cm ³ or more, a coercive force of 716.4 A / m (9.0 kOe) or more, a maximum energy product of 159.2 MJ / m ³ (20 MGOe) or more, and an electrical resistivity. It was found that both have excellent characteristics of 2000 μΩcm or more.

For surface treatment of rare earth magnet powder with rare earth oxides, 1.56 g of thulium (Tm) 2,2,6,6-tetramethyl-3,5-heptanedionate, a rare earth complex, is dissolved in 300 ml of methyl alcohol. Used. Similarly, for SiO ₂ surface treatment, 0.025 ml of C ₂ H ₅ O— (Si (C ₂ H ₅ O) ₂ —O) _m —C ₂ H ₅ (m is 6 to 8, average is 7), Surface treatment and molding were carried out by sequentially performing the following steps using a solution in which 2.2 ml of water, 0.025 ml of ethyl alcohol and 0.025 ml of dibutyltin dilaurate were mixed and left at a temperature of 25 ° C. overnight.
(1) To 1 kg of rare earth magnet powder, add 300 ml of Tm ₂ O ₃ surface treatment solution and stir, then heat-treat in vacuum at 180 ° C for 1 hour and 450 ° C for 1 hour. A treated powder similar to Example 1 was obtained.
(2) To 1 kg of the treated powder, 50 ml of SiO ₂ surface treatment solution was added and stirred, followed by heat treatment at 150 ° C. for 1 hour in vacuum.
(3) The treated powder was filled in a mold, and a rare earth magnet powder temporary compact was formed in the same manner as in Example 1 while aligning the magnetic field.
(4) Using a molding apparatus having a heat source, a bulk molded rare earth magnet was obtained by hot molding in Ar, with a molding temperature of 750 ° C., a holding time of 20 minutes, and a molding pressure of 5 t / cm ² .

The density, coercive force, maximum energy product and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet has a density of 7.3 g / cm ³ or more, a coercive force of 716.4 kA / m (9.0 kOe) or more, a maximum energy product of 159.2 MJ / m ³ (20 MGOe) or more, and an electrical resistivity. It was found that both have excellent characteristics of 2000 μΩcm or more.

For surface treatment of rare earth magnet powder with rare earth oxide, ytterbium (Yb) 6, 6, 7, 7, 8, 8, 8-heptafluoro-2.2-dimethyl-3, 5-octanedio, which is a rare earth complex, is used. Nate 2.30 g was dissolved in 200 ml of ethyl alcohol and used. Similarly, for the SiO ₂ surface treatment, 0.025 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), water 4.8 ml, methyl alcohol 0.025 ml and 0.025 ml of dibutyltin dilaurate were mixed, and the solution was left at a temperature of 25 ° C. for one day and night.
(1) To 1 kg of rare earth magnet powder, 300 ml of Yb ₂ O ₃ surface treatment solution was added and stirred, and then heat-treated at 170 ° C for 1 hour and 400 ° C for 1 hour in vacuum. A treated powder similar to Example 1 was obtained.
(2) To 1 kg of the treated powder, 50 ml of SiO ₂ surface treatment solution was added and stirred, followed by heat treatment at 150 ° C. for 1 hour in vacuum.
(3) The treated powder was filled in a mold and, as in Example 1, a temporary molded body of rare earth magnet powder was obtained while being magnetically oriented.
(4) The temporary compact was hot-molded in the same manner as in Example 1 to obtain a bulk rare earth magnet.

The density, coercive force, maximum energy product, and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet has a density of 7.3 g / cm ³ or more, a coercive force of 716.4 kA / m (9.0 kOe) or more, a maximum energy product of 159.2 MJ / m ³ (20 MGOe) or more, and an electrical resistivity. It was found that both have excellent characteristics of 2000 μΩcm or more.

For surface treatment of rare earth magnet powder with rare earth oxide, ytterbium (Yb) 6, 6, 7, 7, 8, 8, 8-heptafluoro-2.2-dimethyl-3, 5-octanedio, which is a rare earth complex, is used. 4.60 g of Nate was dissolved in 400 ml of ethyl alcohol. Similarly, ZrO ₂ surface treatment uses a solution in which 17.1 g of zirconium n-butoxide, 1 ml of water, and 0.025 ml of dibutyltin dilaurate are mixed with 100 ml of n-butyl alcohol. Molding was performed.
(1) 400 kg of Yb ₂ O ₃ surface treatment solution was added to 1 kg of rare earth magnet powder, stirred, and then heat-treated in vacuum at 170 ° C. for 1 hour and 400 ° C. for 1 hour. A treated powder similar to 1 was obtained.
(2) To 1 kg of the treated powder, 100 ml of ZrO ₂ surface treatment solution was added and stirred, followed by heat treatment at 200 ° C. for 1 hour in vacuum.
(3) The processing powder was filled into a mold, and a rare-earth magnet powder temporary compact was formed while orienting the magnetic field in the same manner as in Example 1.
(4) The temporary compact was hot-molded in the same manner as in Example 1 to obtain a bulk rare earth magnet.

The density, coercive force, maximum energy product, and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet has a density of 7.3 g / cm ³ or more, a coercive force of 716.4 kA / m (9.0 kOe) or more, a maximum energy product of 159.2 MJ / m ³ (20 MGOe) or more, and an electrical resistivity. It was found that both have excellent characteristics of 2000 μΩcm or more.

For the surface treatment of rare earth magnet powder with rare earth oxide, 2.25 g of erbium (Er) (III) isopropoxide, which is a rare earth complex, was dissolved in 300 ml of isopropyl alcohol. Similarly, in the ZnO surface treatment, 21 g of zinc 2,4-pentanedionate was dissolved in 100 ml of toluene, and the following steps were sequentially performed for surface treatment and molding.
(1) A surface treatment solution of 300 ml of E rare earth oxide is added to 1 kg of rare earth magnet powder and stirred, followed by heat treatment at 350 ° C. for 1 hour in a vacuum, and the same treatment as in Example 1. A powder was obtained.
(2) To 1 kg of the treated powder, 100 ml of ZnO surface treatment solution was added and stirred, followed by heat treatment at 300 ° C. for 1 hour in vacuum.
(3) The processing powder was filled into a mold, and a rare-earth magnet powder temporary compact was formed while orienting the magnetic field in the same manner as in Example 1.
(4) A temporary molded body was hot-formed in the same manner as in Example 1 to obtain a bulk rare earth magnet.

The density, coercive force, maximum energy product and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet has a density of 7.3 g / cm ³ or more, a coercive force of 716.4 kA / m (9.0 kOe) or more, a maximum energy product of 159.2 MJ / m ³ (20 MGOe) or more, It was found that both have an excellent electrical resistivity of 2000 μΩcm or more.

For the surface treatment of rare earth magnet powder with rare earth oxide, 1 g of dysprosium (Dy) 2,4-pentanedionate, which is a rare earth complex, was dissolved in 100 ml of isopropyl alcohol. Similarly, in the surface treatment of silicon nitride, 11.1 g of poly (1,1-dimethylsilazane) having a molecular weight of 500 to 900 was dissolved in 100 ml of toluene, and the following steps were sequentially performed for surface treatment and molding. .
(1) Add 100 ml of Dy ₂ O ₃ surface treatment solution to 1 kg of rare earth magnet powder, stir, and then heat-treat in vacuum at 150 ° C for 1 hour and 350 ° C for 1 hour. A treated powder similar to Example 1 was obtained.
(2) To 1 kg of the treated powder, 100 ml of a silicon nitride surface treatment solution was added and stirred, followed by heat treatment at 800 ° C. for 1 hour in a vacuum.
(3) The processing powder was filled into a mold, and a rare-earth magnet powder temporary compact was formed while orienting the magnetic field in the same manner as in Example 1.
(4) The temporary compact was hot-molded in the same manner as in Example 1 to obtain a bulk rare earth magnet.

The density, coercive force, maximum energy product, and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet has a density of 7.3 g / cm ³ or more, a coercive force of 716.4 kA / m (9.0 kOe) or more, a maximum energy product of 159.2 MJ / m ³ (20 MGOe) or more, It was found that both have an excellent electrical resistivity of 2000 μΩcm or more.

As the rare earth magnet powder, Nd—Fe—B based anisotropic magnet powder prepared by using a known UPSET method was used. The specific procedure is as follows. First, an ingot having a component composition of atomic composition Nd _13.7 Co _6.5 B _5.5 Ga _0.6 Fe _Bal was prepared. The ingot was melted at high frequency, and the molten metal was sprayed onto a single roll rotating at a peripheral speed of 30 m / s to obtain an Nd—Fe—B-based ultra-quenched ribbon. This was pulverized with a mortar to prepare an average particle size of 350 μm or less. Next, the pulverized ultra-quenched ribbon was filled into a cylindrical container made of mild steel, the inside of the container was evacuated, and the cylindrical container was sealed. The container was heated at a high frequency to 800 ° C. and then compressed uniaxially using a press. Subsequently, the Nd—Fe—B magnet material was taken out from the container, and a rare earth magnet powder having an average particle size of 300 μm or less was obtained using a coffee mill.

For surface treatment of rare earth magnet powder with rare earth oxide, 0.75 g of erbium (Er) (III) isopropoxide, which is a rare earth complex, was dissolved in 100 ml of isopropyl alcohol. Similarly, for SiO ₂ surface treatment, 5 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), 1 ml of water, 45 ml of methyl alcohol, Surface treatment and molding were performed by sequentially mixing the following steps using a solution which was mixed with 0.025 ml of dibutyltin dilaurate and allowed to stand at a temperature of 25 ° C. overnight.
(1) To 1 kg of rare earth magnet powder, 100 ml of a surface treatment solution of E rare earth oxide was added and stirred, followed by heat treatment at 350 ° C. for 1 hour in a vacuum, and the same treatment as in Example 1 A powder was obtained.
(2) To 1 kg of the treated powder, 50 ml of SiO ₂ surface treatment solution was added and stirred, followed by heat treatment at 150 ° C. for 1 hour in vacuum.
(3) The processing powder was filled into a mold, and a rare-earth magnet powder temporary compact was formed while orienting the magnetic field in the same manner as in Example 1.
(4) The temporary compact was hot-molded in the same manner as in Example 1 to obtain a bulk rare earth magnet.

The density, coercive force, maximum energy product, and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet has a density of 7.3 g / cm ³ or more, a coercive force of 716.4 kA / m (9.0 kOe) or more, a maximum energy product of 159.2 MJ / m ³ (20 MGOe) or more, and an electrical resistivity. It was found that both have excellent characteristics of 2000 μΩcm or more.

Comparative Example 1

Using the rare earth magnet powder not subjected to the surface treatment with the rare earth oxide and the SiO ₂ surface treatment, the following steps were sequentially performed for the surface treatment and the molding. A rare earth magnet was produced in the same manner as in Example 1.
(1) Rare earth magnet magnet powder not subjected to surface treatment was filled in a mold, and then a rare earth magnet powder temporary compact was formed while orienting the magnetic field in the same manner as in Example 1.
(2) The temporary compact was hot-molded in the same manner as in Example 1 to obtain a bulk rare earth magnet.

The density, coercive force, maximum energy product, and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet had the characteristic that the maximum energy product was excellent. However, since the rare earth magnet powder was not subjected to surface treatment with rare earth oxides or SiO ₂ surface treatment, it was a rare earth magnet with an extremely low electrical resistivity of 140 μΩcm.

Comparative Example 2

For the SiO ₂ surface treatment of rare earth magnet powder, 25 ml of C ₂ H ₅ O— (Si (C ₂ H ₅ O) ₂ —O) _m —C ₂ H ₅ (m is 6 to 8, average is 7) Then, 2.2 ml of water, 25 ml of ethyl alcohol, and 0.025 ml of dibutyltin dilaurate were mixed, and the solution was allowed to stand at a temperature of 25 ° C. for one day and night. In this comparative example, only the SiO ₂ surface treatment was applied to the rare earth magnet powder without performing the surface treatment with the rare earth oxide.
(1) To 1 kg of the rare earth magnet powder, 50 ml of SiO ₂ surface treatment solution was added and stirred, and then heat treatment was performed in vacuum at 150 ° C. for 1 hour to obtain a treated powder.
(2) The treated powder was filled in a mold, and a rare-earth magnet powder temporary compact was formed while orienting the magnetic field in the same manner as in Example 1.
(3) The temporary compact was hot-molded in the same manner as in Example 1 to obtain a bulk rare earth magnet.

The density, coercive force, maximum energy product, and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet had a characteristic of excellent electrical resistivity. However, since the surface treatment with rare earth oxides was not performed on the rare earth magnet magnet powder, the rare earth magnet had a maximum energy product as low as 57.3 MJ / m ³ (7.2 MGOe).

Comparative Example 3

For the surface treatment of rare earth magnet powder with rare earth oxide, 0.74 g of dysprosium acetate (Dy) (III), which is a rare earth complex, was dissolved in 100 ml of water and used. Similarly, for SiO ₂ surface treatment, 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average 4), water 4.8 ml, methyl alcohol 25 ml Then, using a solution mixed with 0.025 ml of dibutyltin dilaurate and allowed to stand at a temperature of 25 ° C. for one day and night, the following steps were sequentially performed for surface treatment and molding.
(1) To 1 kg of rare earth magnet powder, 100 ml of Dy ₂ O ₃ surface treatment solution is added and stirred, and then heat treated at 150 ° C. for 1 hour and 350 ° C. for 1 hour in vacuum. Got.
(2) To 1 kg of the treated powder, 50 ml of SiO ₂ surface treatment solution was added and stirred, followed by heat treatment at 150 ° C. for 1 hour in vacuum.
(3) The treated powder was filled in a mold, and then a rare earth magnet powder temporary compact was formed while orienting the magnetic field in the same manner as in Example 1.
(4) The temporary compact was hot-molded in the same manner as in Example 1 to obtain a bulk rare earth magnet.

Table 1 shows the results of measuring the density, coercive force, maximum energy product, and electrical resistivity of the rare earth magnets obtained in the same manner as in Example 1. The obtained rare earth magnet had excellent characteristics with respect to electrical resistivity. However, in the case of surface treatment with rare earth oxides using an aqueous solution for rare earth magnet magnet powder, the holding power is as low as 103.5 kA / m (1.3 kOe) and the maximum energy product is 13.1 MJ / m ³ (1.64 MGOe). Value of rare earth magnet. This is thought to be due to the oxidation of the powder with water.

Comparative Example 4

For the surface treatment of rare earth magnet powder with rare earth oxide, 1 g of dysprosium (Dy) 2,4-pentanedionate, which is a rare earth complex, was dissolved in 100 ml of isopropyl alcohol. In this comparative example, instead of the SiO ₂ surface treatment, a phosphate chemical conversion treatment was performed on the rare earth magnet powder subjected to the surface treatment with the rare earth oxide. The composition of the treatment liquid is 20 g / l phosphoric acid, 4 g / l boric acid, and 4 g / l magnesium oxide. Surface treatment and molding were performed by sequentially performing the following steps.
(1) Add 100 ml of Dy ₂ O ₃ surface treatment solution to 1 kg of rare earth magnet powder, stir, then heat-treat in vacuum at 150 ° C for 1 hour and 350 ° C for 1 hour. A powder was obtained.
(2) To 1 kg of the treated powder, 50 ml of a phosphate chemical conversion treatment solution was added and stirred, and then heat treatment was performed at 180 ° C. for 1 hour in a vacuum.
(3) The treated powder was filled in a mold, and then a rare earth magnet powder temporary molded body was formed in the mixture in the mold while being magnetically oriented in the same manner as in Example 1.
(4) The temporary compact was hot-molded in the same manner as in Example 1 to obtain a bulk rare earth magnet.

The density, coercive force, maximum energy product and electrical resistivity of the obtained rare earth magnet were measured in the same manner as in Example 1. As shown in Table 1, the obtained rare earth magnet has a low coercive force of 55.7 kA / m (0.7 kOe), maximum energy product of 4.8 MJ / m ³ (0.6 MGOe), and electrical resistivity of 180 μΩcm. It became. This is presumably because the phosphate melted during the hot forming at 800 ° C. and the rare earth oxide film was destroyed.

  FIG. 3 is a 1/4 cross-sectional view of a concentrated winding surface magnet motor (12 stator poles, 8 rotor poles) to which the high resistance rare earth magnet of the present invention is applied. The outer side is an aluminum case 17, the inner side is a stator 18, and has u-phase windings 11 and 12, v-phase windings 13 and 14, and w-phase windings 15 and 16. The stator 18 is a laminated body of electromagnetic steel sheets. On the rotor iron 20, the rare earth magnet obtained in Example 1 was used, and a surface magnet 19 having a cross-sectional shape as shown in the figure was arranged. Reference numeral 21 denotes an axis. The motor manufactured using the rare earth magnet of Example 1 had a high continuous output of 1.8 kW.

  Furthermore, since the rare earth magnet in this embodiment has high electrical resistance and low eddy current loss, it generates less heat from the magnet and is advantageous in thermal design.

Comparative Example 5

  A motor was manufactured in the same manner as in Example 10 except that the rare earth magnet obtained in Comparative Example 1 was used. The manufactured motor had a low continuous output of 1.2kW.

The cross-sectional schematic diagram of the rare earth magnet of this invention. FIG. 4 is a quarter cross-sectional view of a concentrated winding surface magnet type motor using the high electric resistance rare earth magnet of the present invention.

Explanation of symbols

1 ... rare-earth magnet, 2 ... powder for rare earth magnet, 3 ... amorphous or / and rare earth oxide crystalline, 4 ... Al amorphous or / and crystalline ₂ O _3, SiO _2, silicon nitride, TiO ₂ , ZnO, ZrO ₂ 1 type or plural types, 5 .. crystal grains, 11, 12... U-phase winding, 13, 14... V-phase winding, 15, 16. ... stator, 19 ... magnet, 20 ... rotor iron, 21 ... shaft.

Claims (16)

At least a part of the surface of the rare earth magnet particle includes at least one rare earth of terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu). A compound containing an oxide is coated, and at least a part of the surface of the rare earth magnet particle coated with the compound containing the rare earth oxide is coated with at least Al ₂ O ₃ , SiO ₂ , silicon nitride, TiO ₂ , ZnO and ZrO ₂ . A powder for a high-resistance rare earth magnet, which is coated with one kind of metal compound. In claim 1, the entire surface of the rare-earth magnet particles, a high resistance earth powder for a magnet of a compound characterized in that it overturned be containing the rare earth oxide.   3. The high resistance rare earth magnet powder according to claim 1, wherein the rare earth magnet particles have an average particle size of 1 to 500 [mu] m.   4. The powder for a high resistance rare earth magnet according to claim 1, wherein the rare earth magnet particles are an Nd—Fe—B alloy.   The powder for high resistance rare earth magnet according to any one of claims 1 to 4, wherein the rare earth magnet particles have anisotropy.   6. The powder for a high resistance rare earth magnet according to claim 1, wherein the rare earth oxide and the metal compound are made of at least one of amorphous and crystalline. In the rare earth magnet powder , the formula RL ₃ [R is at least one of terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu). species of the rare earth oxide, L is a ligand of the _{organic, {CO (CH 3) CHCO} (CH 3)} - _{ions, {CO (C (CH 3} ) 3) CHCO (C (CH 3) 3) } ⁻ Ion, {CO (C ₃ F ₇ ) CHCO (C (CH ₃ ) ₃ )} ⁻ ion, {CO (CF ₃ ) CHCO (CF ₃ )} ⁻ β-diketonato ion of any of the ions, (O— i-C ₃ H ₇₎ ^- ions and _{(O-C 2 H 4 -OCH} 3) - is added and stirred organic solvent of rare earth complex represented by an organic group of any of the anions of the ion] Then , after performing a heat treatment in deoxygenation and coating the rare earth magnet powder surface with the compound containing the rare earth oxide , Al ₂ O ₃ , SiO ₂ , silicon nitride, TiO ₂ , ZnO and ZrO ₂ are coated with at least one metal compound. Rare earth coated with a compound containing at least one rare earth oxide of terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu) the powder for a magnet, an organic solvent medium of _{Al 2 O 3, SiO 2,} T iO 2, ZnO and metallic compound containing at least one metal alkoxide and a metal diketonate to generate at least one metal compound of ZrO ₂ are added and stirred, followed by heat treatment in oxygen, or the powder for rare earth magnet compound is coated comprising the rare earth oxide, a low polar organic solvent medium in the polysilazane to generate silicon nitride of a metal compound are added and stirred, followed by heat treatment in oxygen, the powder for the rare-earth magnet Al ₂ O _3, SiO _2, silicon nitride, TiO _2, of ZnO and ZrO ₂ small With method of producing a powder for a high-resistance earth magnet characterized by having the step of coating the one metal compound. Rare earth magnet coated with a compound containing at least one rare earth oxide of terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu) to use _{powder, Al 2 O 3, SiO 2} , and a metal compound containing at least one metal alkoxide and a metal diketonate to produce TiO _2, at least one metal compound of ZnO and ZrO _2, water and a water-soluble organic A mixture with a solvent is added and stirred, followed by heat treatment in deoxygenation, and at least one metal compound of Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZnO and ZrO ₂ is added to the rare earth magnet powder. The manufacturing method of the powder for high resistance rare earth magnets characterized by having the process to coat | cover.   10. The method for producing a powder for a high resistance rare earth magnet according to claim 7, wherein the rare earth magnet powder has anisotropy. 11. The metal compound according to claim 7, wherein the rare earth oxide and the metal compound of any one of Al ₂ O ₃ , SiO ₂ , silicon nitride, TiO ₂ , ZnO, and ZrO ₂ are at least amorphous and crystalline. The manufacturing method of the powder for high resistance rare earth magnets characterized by consisting of one side.   A rare earth magnet comprising a hot-formed body of powder for a high resistance rare earth magnet according to any one of claims 1 to 6.   Filling a mold for filling the powder for a high resistance rare earth magnet according to any one of claims 1 to 6 or the powder for a high resistance rare earth magnet produced by the production method according to any one of claims 7 to 11. A step of forming a temporary molded body in the mold by pressurizing the high-resistance rare earth magnet powder while orienting the magnetic field, and a hot forming step of the temporary molded body. A method for producing a rare earth magnet. The method for producing a rare earth magnet according to claim 13, wherein the hot forming step is performed by heat compression. The rotor for motors which has a shaft part, a body part, and a magnet formed in the outer peripheral surface of the body part, The magnet is the rare earth magnet according to claim 12, The manufacturing method according to claim 13 or 14 A rotor for motors comprising any of the rare earth magnets manufactured by   A motor having a stator and a rotor, wherein the rotor comprises the rotor according to claim 15.

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