JP4234581B2 - Rare earth magnet, manufacturing method thereof and motor - Google Patents

Description

  The present invention relates to a rare earth magnet having high electrical resistance and a method for manufacturing the same. The present invention also relates to a motor using a rare earth magnet.

  Conventionally, inexpensive ferrite magnets have been widely used as permanent magnet motors. However, the use of higher performance rare earth magnets has increased year by year as rotary electricity has become smaller and higher performance. Yes. Typical rare earth magnets include Sm—Co based magnets and Nd—Fe—B based magnets, and development to achieve further higher performance and lower costs is underway.

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

For example, a rare earth magnet having a structure in which rare earth magnet magnetic particles are bound with an inorganic insulating material such as SiO ₂ and / or Al ₂ O ₃ particles has been proposed (see, for example, Patent Document 1).

JP-A-10-32427 (Claims)

Is the prior art described above, when the magnetic powder for the rare-earth magnet is a rare earth magnet having a sintered wearing structure of SiO ₂ and / or _Al 2 _{O 3} particles, SiO ₂ and / or _Al 2 O between the rare-earth magnetic powder _{When 3} is present, the electric resistance of the rare earth magnet can be increased. However, when SiO ₂ and / or Al ₂ O ₃ is added to the rare earth magnet, the magnetic properties are greatly deteriorated. This is difficult to apply to motors with medium to high output.
Although the prior art can increase the electric resistance of the rare earth magnet, it has caused a significant decrease in the magnet characteristics.

  An object of the present invention is to provide a rare earth magnet having a high electrical resistance and less deterioration in magnet characteristics and a method for producing the same.

The present invention relates to a rare earth magnet, the rare earth magnet particles and the following formula (I) existing between the rare earth magnet particles:
[Chemical formula 4]
RO _x C _y (I)
(Wherein R is terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), or lutetium (Lu)). And an amorphous rare earth oxide-containing compound.

Further, rare earth magnet particles and the following formula (I) existing between the rare earth magnet particles:
[Chemical formula 5]
RO _x C _y (I)
(Wherein R is terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), or lutetium (Lu)). In a method for producing a rare earth magnet having an amorphous rare earth oxide-containing compound, the following formula (II)
[Chemical formula 6]
RL ₃ (II)
(Wherein L is an organic ligand, (CO (CH ₃ ) CHCO (CH ₃ )) ⁻ ion, (CO (C (CH ₃ ) ₃ ) CHCO (C (CH ₃ ) ₃ )) ⁻ Anion, an organic group of an anion such as β-diketonato ion such as (CO (C ₃ F ₇ ) CHCO (C (CH ₃ ) ₃ )) ⁻ ion or (CO (CF ₃ ) CHCO (CF ₃ )) ⁻ ion And (2) a step of mixing a solution in which a rare earth complex represented by (1) is dissolved in an organic solvent and a magnetic powder for a rare earth magnet, and a step of subjecting the mixture to a heat treatment in deoxygenation.

  According to the present invention, a rare earth magnet having high electrical resistance and suppressing deterioration of magnet characteristics is provided.

  In order 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 particles. On the other hand, it is necessary to increase the electric resistance of the rare earth magnet. In order to satisfy both of these, it has been found that each of the rare earth magnet particles can be covered with a material that can suppress the deterioration of the magnet characteristics and has high electric resistance, and has led to the present invention.

  Rare earth magnet particles generally tend to cause chemical changes such as reaction with metals and organic compounds, surface oxidation, and the like, thereby deteriorating magnet properties. For this reason, it is desired that the surface coating agent for rare earth magnet particles has high electrical resistance and can maintain magnet characteristics after the magnet is produced. The present inventors have clarified that the amorphous carbon component-containing rare earth oxide represented by the general formula (I) satisfies this requirement.

In addition, in coating with the carbon component-containing rare earth oxide represented by the general formula (I), the rare earth represented by the general formula (II) can be used to maintain the magnet characteristics without increasing the volume fraction. It has been found that it is effective to use a complex and coat by wet processing. This is because the surface of the rare earth magnet particles can be coated with amorphous RO _x C _y with a uniform and thin film by performing wet processing. By using an alcohol-based low-boiling solvent as a solvent for dissolving RL ₃ , amorphous RO _x C _y can be generated on the surface of the rare earth magnet particle without altering the surface of the rare earth magnet particle. . Further, by using an organic group of β-diketonato ion that can be decomposed and removed at a low temperature of 500 ° C. or less and oxygen-free as L as a ligand, it is possible to suppress the formation of a carbon compound on the surface of rare earth magnet particles. Is possible. Β-diketonato ions that satisfy this requirement include (CO (CH ₃ ) CHCO (CH ₃ )) ⁻ ion, (CO (C (CH ₃ ) ₃ ) CHCO (C (CH ₃ ) ₃ )) ⁻ ion, (CO (C ₃ F ₇ ) CHCO (C (CH ₃ ) ₃ )) ⁻ ions, (CO (CF ₃ ) CHCO (CF ₃ )) ⁻ ions, and the like.

A magnet made of rare earth magnet particles on the surface of which amorphous RO _x C _y represented by the general formula (I) is formed becomes thermally unstable when the temperature is higher than 600 ° C. However, even when the rare earth magnet was subjected to a heat treatment at 600 ° C. or lower, the magnet properties at room temperature showed little change before and after the heat treatment. In addition, the surface treatment film made of amorphous RO _x C _y does not shatter even if the magnetic powder is compression-molded, and remains on the surface of the magnetic powder. Therefore, the magnet is compression-molded using the rare earth magnet magnetic powder. It is found that it is effective in stabilizing the magnetic properties and increasing electrical resistance.

FIG. 1 shows a rare earth magnet according to the invention. The rare earth magnet 1 is composed of rare earth magnet particles 2 and an amorphous carbon component-containing rare earth oxide 3. Rare earth magnet particles are composed 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. In consideration of improvement in magnet characteristics, the rare earth magnet magnetic powder used as a raw material for the rare earth magnet (rare earth magnet particles) is preferably an anisotropic rare earth magnet magnetic powder prepared by the HDDR method or hot plastic working. . When the rare earth magnet magnetic powder is an anisotropic rare earth magnet magnetic powder prepared by the HDDR method or hot plastic working, an aggregate of a large number of crystal grains 4 as shown in FIG. FIG. 2 is an enlarged view of a portion A in FIG. At this time, if the crystal grains 4 have an average grain size equal to or smaller than the single magnetic domain grain size, it is preferable to improve the coercive force. Examples of the rare earth magnet 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 type magnets are preferable. However, it is not limited to Nd—Fe—B magnets. In some cases, two or more kinds of rare earth magnet particles may be mixed in the rare earth magnet. For example, 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 invention, the “Nd—Fe—B 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 one or more of other rare earth elements such as Dy, Tb and the like. The substitution can be performed by adjusting the blending amount of the raw material alloy. By this 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 other transition metals such as Co. By this 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 particles is preferably 1 to 500 μm. If the average particle size is less than 1 μm, the specific surface area of the magnetic powder is large, and the influence of oxidative degradation is large, so there is a concern that the magnet characteristics of the rare earth magnet will deteriorate. On the other hand, if the average particle diameter of the rare earth magnet particles 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 manufactured using magnetic powder for anisotropic rare earth magnet as a raw material, the main phase in the magnetic powder for rare earth magnet (Nd ₂ in Nd-Fe-B magnets) exceeds 500 μm. It is difficult to align the orientation direction of (Fe ₁₄ B phase). The particle size of the rare earth magnet particles is controlled by adjusting the particle size of the rare earth magnet magnetic powder that is the raw material of the magnet. The average particle diameter of the rare earth magnet particles can be calculated from the SEM image.

  The present invention relates to an isotropic magnet manufactured from 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 any of these. 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 magnetic 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 an Nd ₂ Fe ₁₄ B phase, a predetermined amount of Nd, Fe, and B is blended. As the magnetic powder for rare earth magnets, those produced using a known method may be used, or commercially available products may be used. Preferably, magnetic powder for anisotropic rare earth magnets manufactured using the HDDR method or the UPSET method utilizing hot composition processing is used. Such magnetic powder for anisotropic rare earth magnet is an aggregate of a large number of crystal grains. The crystal grains constituting the magnetic powder for anisotropic rare earth magnet 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, Thereafter, 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 subjected to plastic working hot after pulverization and temporary molding.

The magnetic powder for anisotropic rare earth magnet 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 magnetic powder to be used is an anisotropic magnet powder, an anisotropic rare earth magnet can be obtained by temporarily forming the rare earth magnet magnetic powder while aligning the magnetic field. 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 10 to 20 kOe.

The magnetic powder for the anisotropic rare earth magnet after the surface treatment filled in the mold is molded to obtain a bulk magnet. In addition, the operation | work which hardens the magnetic powder for anisotropic rare earth magnets after surface treatment by the above-mentioned temporary forming shall not correspond to the "molding" in this invention. For the main forming performed after the temporary forming, a known apparatus usually used for magnet production can be used. Preferably, it is preferable to form by hot forming. In the case of forming by using the hot forming method, the magnetic powder for rare earth magnet as a raw material can be sufficiently plastically deformed to obtain a high-density rare earth magnet. The hot forming method is not particularly defined. For example, a hot press can be used. The molding pressure is about 1 to 10 t / cm ² . The molding temperature is 500 to 600 ° C., and the pressing time is suitably 5 to 30 minutes. If molding is performed at 500 ° C. or lower, the density of the magnet is not sufficient, and if molding is performed at a temperature exceeding 600 ° C., the magnetic powder reacts with the rare earth oxide covering the periphery, leading to a decrease in coercive force. A normal hot forming atmosphere is a vacuum of 10 Pa or less or an inert gas flow atmosphere.

  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.

  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 motor using a rare earth magnet with improved insulation on the surface of rare earth magnet particles according to the present invention will be described. For reference, FIG. 3 shows a quarter sectional view of a concentrated winding surface magnet type motor to which the high resistance rare earth magnet of the present invention is applied. In the drawing, 11 is a u-phase winding, 12 is a u-phase winding, 13 is a v-phase winding, 14 is a v-phase winding, 15 is a w-phase winding, 16 is a w-phase winding, 17 is An aluminum case, 18 is a stator, 19 is a magnet, 20 is a rotor iron, and 21 is a shaft. The rare earth magnet of the present invention has a high electric resistance and also has excellent magnet characteristics. For this reason, the motor manufactured using the rare earth magnet of the present invention can easily increase the continuous output of the motor, and can be said to be suitable as a medium output to large output motor. Moreover, since the motor manufactured 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. It is also 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.

Examples will be described below.
[Example 1]

As the magnetic powder for rare earth magnets, magnetic powder for Nd—Fe—B based anisotropic magnets prepared using a known HDDR method was used. The specific procedure is as follows. First, an ingot having a component composition of Nd _12.6 Fe balance Co _17.4 B _6.5 Ga _0.3 Al _0.5 Zr _0.1 was prepared. The ingot was homogenized by holding at 1120 ° C. for 20 hours. The homogenized ingot was heated to a room temperature of 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 magnetic powder for a rare earth magnet having an average particle size of 300 μm or less.

_RO x _{C y} surface treatment of the magnetic powder for the rare-earth magnet was carried out using a solution of dysprosium pentanedionate Nate 1g is a rare earth complex in isopropyl alcohol 100 ml.

(1) 7500 ml of RO _x C _y surface treatment solution was added to 1 kg of rare earth magnet magnetic powder, and the solvent was removed by stirring. The treated magnetic powder was heat-treated in vacuum at 150 ° C. for 1 hour, 350 ° C., 1 hour and 600 ° C. for 30 minutes.

(2) The treated magnetic powder produced in (1) was filled in a mold. Subsequently, by applying a magnetic field to the mixture in the mold, the magnetic powder for anisotropic rare earth magnet was temporarily molded while being magnetically oriented. The orientation magnetic field was 10 kOe, and the temporary molding pressure was 0.5 t / cm ² .

(3) The temporary molded body produced in the above (2) was molded by hot molding in Ar to obtain a bulk rare earth magnet. A molding apparatus having a heat source was used for molding. The molding temperature was 600 ° C., the holding time was 10 minutes, and the molding pressure was 10 t / cm ² .

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. Magnet characteristics were measured using a vibrating sample magnetometer (BHV-525 manufactured by Riken Denshi Co., Ltd.) after magnetizing the test piece with 40 kOe. The electrical resistivity was measured by a four-probe method using K705RM manufactured by KYOWARIKEN. RO _x C _y in R, the elemental analysis of O and C by slicing a magnet to about 20nm using a focused ion beam, use an average value performed elemental analysis to select the five points in _RO x _{C y} It was. The results are shown in Table 1.

  The obtained rare earth magnet was found to have excellent characteristics in both maximum energy product and electrical resistivity.

On the other hand, the RO _x C _y surface treatment of the present invention is carried out with Nd _12.4 Fe balance Dy _0.6 Co ₂₀ B _6.2 Ga _0.4 Al _1.5 Zr _0.1 having a coercive force of 19.4 kOe. It was found that it is also effective for anisotropic HDDR magnetic powder having a component composition. That is, a magnet produced in the same manner as in Example 1 with respect to the magnetic powder for magnet has characteristic values of magnet density 7.0 g / cm ³ , coercive force 18.7 kOe, maximum energy product 17 MGOe, and electrical resistivity 2000 μΩcm. did. From this, it became possible to produce a magnet having a high electrical resistance without impairing the properties of the magnetic powder by using the present invention for the magnetic powder for Nd-Fe-B based anisotropic magnet.
[Example 2]

In _RO x _{C y} surface treatment of the magnetic powder for the rare-earth magnets, using a solution of holmium 2,2,6,6-tetramethyl-3,5-heptanedionate Nate 1.6g is a rare earth complex in isopropyl alcohol 300ml .

(1) 21,000 ml of RO _x C _y surface treatment solution was added to 1 kg of rare earth magnet magnetic powder, and the solvent was removed by stirring. The treated magnetic powder was heat-treated in a vacuum at 190 ° C. for 1 hour, 500 ° C., 1 hour, and 600 ° C. for 30 minutes.

(2) The treated magnetic powder produced in (1) was filled in a mold. Subsequently, by applying a magnetic field to the mixture in the mold, the rare earth magnet magnetic powder was temporarily molded while being magnetically oriented. The orientation magnetic field was 10 kOe, and the temporary molding pressure was 0.5 t / cm ² .

(3) The temporary molded body produced in the above (2) was molded by hot molding in Ar to obtain a bulk rare earth magnet. A molding apparatus having a heat source was used for molding. The molding temperature was 600 ° C., the holding time was 10 minutes, and the molding pressure was 10 t / cm ² .

  The density, coercive force, maximum energy product, electrical resistivity, and elemental analysis of the obtained rare earth magnet were measured in the same manner as in Example 1. The results are shown in Table 1.

The obtained rare earth magnet was found to have excellent characteristics in both maximum energy product and electrical resistivity.
[Example 3]

In _RO x _{C y} surface treatment of the magnetic powder for the rare-earth magnets, using a solution of thulium 2,2,6,6-tetramethyl-3,5-heptanedionate Nate 1.6g is a rare earth complex in methyl alcohol 300ml .

(1) 21,000 ml of RO _x C _y surface treatment solution was added to 1 kg of rare earth magnet magnetic powder, and the solvent was removed by stirring. The treated magnetic powder was heat-treated in vacuum at 180 ° C. for 1 hour, 450 ° C., 1 hour, and 600 ° C. for 30 minutes.

(2) The treated magnetic powder produced in (1) was filled in a mold. Subsequently, by applying a magnetic field to the mixture in the mold, the rare earth magnet magnetic powder was temporarily molded while being magnetically oriented. The orientation magnetic field was 10 kOe, and the temporary molding pressure was 0.5 t / cm ² .

(3) The temporary molded body produced in the above (2) was molded by hot molding in Ar to obtain a bulk rare earth magnet. A molding apparatus having a heat source was used for molding. The molding temperature was 600 ° C., the holding time was 20 minutes, and the molding pressure was 10 t / cm ² .

  The density, coercive force, maximum energy product, electrical resistivity, and elemental analysis of the obtained rare earth magnet were measured in the same manner as in Example 1. The results are shown in Table 1.

The obtained rare earth magnet was found to have excellent characteristics in both maximum energy product and electrical resistivity.
[Example 4]

In _RO x _{C y} surface treatment of the magnetic powder for the rare-earth magnet, ytterbium 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-octanedionato Nate 2 is a rare earth complex. A solution obtained by dissolving 30 g in 200 ml of ethyl alcohol was used.

(1) 13500 ml of RO _x C _y surface treatment solution was added to 1 kg of rare earth magnet magnetic powder, and the solvent was removed by stirring. The treated magnetic powder was heat treated in vacuum at 170 ° C. for 1 hour, 400 ° C., 1 hour and 600 ° C. for 30 minutes.

(2) The treated magnetic powder produced in (1) was filled in a mold. Subsequently, by applying a magnetic field to the mixture in the mold, the rare earth magnet magnetic powder was temporarily molded while being magnetically oriented. The orientation magnetic field was 10 kOe, and the temporary molding pressure was 0.5 t / cm ² .

(3) The temporary molded body produced in the above (2) was molded by hot molding in Ar to obtain a bulk rare earth magnet. A molding apparatus having a heat source was used for molding. The molding temperature was 600 ° C., the holding time was 10 minutes, and the molding pressure was 10 t / cm ² .

  The density, coercive force, maximum energy product, electrical resistivity, and elemental analysis of the obtained rare earth magnet were measured in the same manner as in Example 1. The results are shown in Table 1.

The obtained rare earth magnet was found to have excellent characteristics in both maximum energy product and electrical resistivity.
[Example 5]

In _RO x _{C y} surface treatment of the magnetic powder for the rare-earth magnets, using a solution of erbium (111) 2,4-pentanedionate Nate 1g is a rare earth complex in isopropyl alcohol 100 ml.

(1) 7200 ml of RO _x C _y surface treatment solution was added to 1 kg of rare earth magnet magnetic powder, and the solvent was removed by stirring. The treated magnetic powder was heat-treated in vacuum at 150 ° C. for 1 hour, 350 ° C., 1 hour and 600 ° C. for 30 minutes.

(2) The treated magnetic powder produced in (1) was filled in a mold. Subsequently, by applying a magnetic field to the mixture in the mold, the rare earth magnet magnetic powder was temporarily molded while being magnetically oriented. The orientation magnetic field was 10 kOe, and the temporary molding pressure was 0.5 t / cm ² .

(3) The temporary molded body produced in the above (2) was molded by hot molding in Ar to obtain a bulk rare earth magnet. A molding apparatus having a heat source was used for molding. The molding temperature was 600 ° C., the holding time was 10 minutes, and the molding pressure was 10 t / cm ² .

  The density, coercive force, maximum energy product, electrical resistivity, and elemental analysis of the obtained rare earth magnet were measured in the same manner as in Example 1. The results are shown in Table 1.

The obtained rare earth magnet was found to have excellent characteristics in both maximum energy product and electrical resistivity.
[Example 6]

In _RO x _{C y} surface treatment of the magnetic powder for the rare-earth magnets, using a solution of dysprosium pentanedionate Nate 1g is a rare earth complex in isopropyl alcohol 100 ml.

(1) To 1 kg of magnetic powder for rare earth magnet, 2500 ml of RO _x C _y surface treatment solution was added and stirred to remove the solvent. The treated magnetic powder was heat-treated in vacuum at 150 ° C. for 1 hour, 350 ° C., 1 hour and 600 ° C. for 30 minutes.

(2) The treated magnetic powder produced in (1) was filled in a mold. Subsequently, by applying a magnetic field to the mixture in the mold, the rare earth magnet magnetic powder was temporarily molded while being magnetically oriented. The orientation magnetic field was 10 kOe, and the temporary molding pressure was 0.5 t / cm ² .

(3) The temporary molded body produced in the above (2) was molded by hot molding in Ar to obtain a bulk rare earth magnet. A molding apparatus having a heat source was used for molding. The molding temperature was 550 ° C., the holding time was 10 minutes, and the molding pressure was 10 t / cm ² .

  The density, coercive force, maximum energy product, electrical resistivity, and elemental analysis of the obtained rare earth magnet were measured in the same manner as in Example 1. The results are shown in Table 1.

The obtained rare earth magnet was found to have excellent characteristics in both maximum energy product and electrical resistivity.
[Example 7]

Nd—Fe—B-based anisotropic magnet powder prepared using a known UPSET method was used as the rare earth magnet magnetic powder. The specific procedure is as follows. First, an ingot having a component composition of Nd _13.7 Fe balance Co _6.7 B _5.5 Ga _0.6 was prepared. The ingot was melted at a high frequency, and the molten metal was sprayed onto a piece 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 powder having an average particle size of 300 μm or less was obtained using a coffee mill.

For the RO _x C _y surface treatment of the magnetic powder for rare earth magnet, a solution in which 1 g of dysprosium 2,4-pentanedionate, which is a rare earth complex, was dissolved in 100 ml of isopropyl alcohol was used.

(1) 7500 ml of RO _x C _y surface treatment solution was added to 1 kg of rare earth magnet magnetic powder, and the solvent was removed by stirring. The treated magnetic powder was heat-treated in vacuum at 150 ° C. for 1 hour, 350 ° C., 1 hour and 600 ° C. for 30 minutes.

(2) The treated magnetic powder produced in (1) was filled in a mold. Subsequently, by applying a magnetic field to the mixture in the mold, the rare earth magnet magnetic powder was temporarily molded while being magnetically oriented. The orientation magnetic field was 10 kOe, and the temporary molding pressure was 0.5 t / cm ² .

(3) The temporary molded body produced in the above (2) was molded by hot molding in Ar to obtain a bulk rare earth magnet. A molding apparatus having a heat source was used for molding. The molding temperature was 600 ° C., the holding time was 15 minutes, and the molding pressure was 10 t / cm ² .

  The density, coercive force, maximum energy product, electrical resistivity, and elemental analysis of the obtained rare earth magnet were measured in the same manner as in Example 1. The results are shown in Table 1.

  The obtained rare earth magnet was found to have excellent characteristics in both maximum energy product and electrical resistivity.

In Examples 1 to 7, the composition x and y of RO _x C _y were average values in the measurement range, and the range of variation was 1 ≦ x ≦ 4 and 0 ≦ y ≦ 20.
(Comparative Example 1)
A rare earth magnet was produced in the same manner as in Example 1 using the magnetic powder for rare earth magnet not subjected to the RO _x C _y surface treatment.

(1) A rare earth magnet magnetic powder not subjected to surface treatment was filled in a mold. Subsequently, by applying a magnetic field to the mixture in the mold, the rare earth magnet magnetic powder was temporarily molded while being magnetically oriented. The orientation magnetic field was 10 kOe, and the temporary molding pressure was 0.5 t / cm ² .

(2) The temporary molded body produced in (1) was molded by hot molding in Ar to obtain a bulk rare earth magnet. A molding apparatus having a heat source was used for molding. The molding temperature was 600 ° C., the holding time was 10 minutes, and the molding pressure was 10 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. The results are shown in Table 1.

The obtained rare earth magnet had excellent characteristics with respect to the maximum energy product. However, since the RO _x C _y surface treatment was not applied to the rare earth magnet magnetic powder, the electrical resistivity was a low value.
(Comparative Example 2)
Using a solution of dysprosium pentanedionate Nate 1g is a rare earth complex in isopropyl alcohol 100 ml, was _RO x _{C y} surface treatment of the rare-earth magnetic powder.

(1) 7500 ml of RO _x C _y surface treatment solution was added to 1 kg of rare earth magnet magnetic powder, and the solvent was removed by stirring. The treated magnetic powder was heat-treated in vacuum at 150 ° C. for 1 hour, 350 ° C., 1 hour and 600 ° C. for 30 minutes.

(2) The treated magnetic powder produced in (1) was filled in a mold. Subsequently, by applying a magnetic field to the mixture in the mold, the rare earth magnet magnetic powder was temporarily molded while being magnetically oriented. The orientation magnetic field was 10 kOe, and the temporary molding pressure was 0.5 t / cm ² .

(3) The temporary molded body produced in the above (2) was molded by hot molding in Ar to obtain a bulk rare earth magnet. A molding apparatus having a heat source was used for molding. The molding temperature was 800 ° C., the holding time was 10 minutes, and the molding pressure was 10 t / cm ² .

  The density, coercive force, maximum energy product, electrical resistivity, and elemental analysis of the obtained rare earth magnet were measured in the same manner as in Example 1. The results are shown in Table 1.

The obtained rare earth magnet had excellent characteristics with respect to electrical resistivity. However, the rare earth magnet has a bad value regarding the maximum energy product. This is presumably because carbon atoms existed as impurities about 10 times as many atoms as R atoms in the RO _x C _y film formed on the surface of the rare earth magnet magnetic powder. Since a large amount of carbon atoms were contained as impurities in the RO _x C _y film, the magnet molded at a high temperature of 800 ° C. was considered to be thermally unstable, and the magnetic properties were greatly deteriorated.
(Comparative Example 3)
Using a solution of dysprosium pentanedionate Nate 1g is a rare earth complex in isopropyl alcohol 100 ml, was _RO x _{C y} surface treatment of the rare-earth magnetic powder.

(1) 7500 ml of RO _x C _y surface treatment solution was added to 1 kg of rare earth magnet magnetic powder and stirred. The treated magnetic powder was heat-treated in vacuum at 150 ° C. for 1 hour, 350 ° C., 1 hour and 600 ° C. for 30 minutes.

(2) The treated magnetic powder produced in (1) was filled in a mold. Subsequently, by applying a magnetic field to the mixture in the mold, the rare earth magnet magnetic powder was temporarily molded while being magnetically oriented. The orientation magnetic field was 10 kOe, and the temporary molding pressure was 0.5 t / cm ² .

(3) The temporary molded body produced in the above (2) was molded by hot molding in Ar to obtain a bulk rare earth magnet. A molding apparatus having a heat source was used for molding. The molding temperature was 400 ° C., the holding time was 20 minutes, and the molding pressure was 10 t / cm ² .

  The density, coercive force, maximum energy product, electrical resistivity, and elemental analysis of the obtained rare earth magnet were measured in the same manner as in Example 1. The results are shown in Table 1.

  The obtained rare earth magnet had excellent characteristics with respect to electrical resistivity. However, good values were not obtained for the maximum energy product. This is presumably because the molding temperature was as low as 400 ° C., the hardness of the magnetic powder was high, and the density as a magnet was low.

［実施例８］

[Example 8]

The rare earth magnet obtained in Example 1 was applied to a surface magnet type motor (12 stator poles, 8 rotor poles). FIG. 3 is a quarter cross-sectional view of the produced concentrated winding surface magnet motor. The stator 18 was a laminated body of electromagnetic steel sheets. A magnet 19 having a shape as illustrated on the rotor iron 20 was disposed. The motor manufactured using the rare earth magnet of Example 1 had a continuous output of 1.5 kW. Since the rare earth magnet of the present invention has high electric resistance and low eddy current loss, the magnet rarely generates heat, which is advantageous in thermal design. Moreover, it has excellent magnet characteristics. For this reason, it was shown that the continuous output of a motor can be raised easily.
(Comparative Example 4)
A motor was manufactured in the same manner as in Example 8 except that the rare earth magnet obtained in Comparative Example 1 was used. The manufactured motor had a continuous output of 1.0 kW.

  According to the present invention, a rare earth magnet having excellent magnet characteristics and high electric resistance has been realized. As a result, the motor efficiency of a motor using a rare earth magnet can be increased.

The cross-sectional schematic diagram of the rare earth magnet by one Example of this invention. The enlarged view of the part of A in FIG. 1 is a quarter sectional view of a surface magnet motor according to an embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rare earth magnet, 2 ... Rare earth magnet particle, 3 ... Amorphous carbon component containing rare earth oxide, 4 ... Crystal grain, 19 ... Magnet

Claims (9)

Rare earth magnet particles and the following formula (I) existing between the rare earth magnet particles
[Chemical formula 1]
RO _x C _y (I)
(Wherein, R terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), Ri ytterbium (Yb), or lutetium (Lu) Der, x and y, 1 ≦ x ≦ 4, 0 <y ≦ 20 )
And a compound containing an amorphous rare earth oxide containing a carbon component represented by:   The rare earth magnet according to claim 1, wherein the rare earth magnet particles have an average particle diameter of 1 to 500 μm.   The rare earth magnet according to claim 1 or 2, wherein the rare earth magnet magnetic powder is an Nd-Fe-B based magnetic powder.   The rare earth magnet according to claim 1, wherein the rare earth magnet is an anisotropic magnet. Rare earth magnet particles and the following formula (I) existing between the rare earth magnet particles
[Chemical formula 2]
RO _x C _y (I)
(Wherein, R terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), Ri ytterbium (Yb), or lutetium (Lu) Der, x and y, 1 ≦ x ≦ 4, 0 <y ≦ 20 )
And a compound containing an amorphous rare earth oxide containing a carbon component represented by the following formula (II):
[Chemical formula 3]
RL ₃ (II)
(Where, L is a ligand of the organic is 500 ° C. or less of low temperature and oxygen-free conditions in decomposition and removal is possible β- Jiketonatoio down organic group)
A rare earth magnet comprising: a step of mixing a solution of a rare earth complex represented by formula (2) dissolved in an organic solvent and a magnetic powder for a rare earth magnet; and a step of heat-treating the mixture in a deoxygenated state. Method. The method for producing a rare earth magnet according to claim 5 , wherein the heat treatment is performed at a temperature of 150 to 600 ° C. Filling the mold with the rare earth magnet magnetic powder that has undergone the heat treatment, a temporary molding step of temporarily molding the rare earth magnet magnetic powder while orienting the magnetic powder, and a main molding step of molding the rare earth magnet magnetic powder. method for producing a rare earth magnet according to claim 5 or 6, characterized in that it has. 8. The method of manufacturing a rare earth magnet according to claim 7 , wherein the main forming step forms the rare earth magnet magnetic powder at a forming temperature of 500 to 600 [deg.] C. by hot forming. Motor, which comprises using one of the rare-earth magnet according to claim 1-4.
more than

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