JP2012199423A - Production method of anisotropic magnetic powder and anisotropic bond magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce anisotropic magnetic powder exhibiting sufficiently high coersive force even if the amount of a rare earth compound used as a diffusion material is reduced.SOLUTION: The production method of anisotropic magnetic powder includes a step for obtaining HDDR powder by a hydrogenation-dehydrogenation recombination method, a step for preparing mixed powder by mixing a diffusion material containing a rare earth compound and the HDDR powder, and a step for diffusing the elements contained in the diffusion material into the HDDR powder by heating the mixed powder. The diffusion material contains the powder of at least one kind of compound selected from a group of the hydrides, fluorides, and iron compounds of Dy, Tb, Nd, Pr or La, and further contains aluminum powder.

Description

  The present invention relates to a method for producing anisotropic magnetic powder and an anisotropic bonded magnet.

  A rare earth bonded magnet is known as an embodiment of a rare earth magnet containing a rare earth element. Rare earth bonded magnets are used in various devices such as motors because they have excellent magnetic properties and can easily cope with complex shapes. Recently, various devices have been reduced in size and increased in efficiency, and accordingly, further improvement in magnetic properties of rare earth bonded magnets is required.

  As a method for producing a rare earth bonded magnet, the following method has been proposed. First, a diffusion material containing rare earth elements such as Tb and Dy is mixed with magnet powder (hereinafter referred to as “HDDR powder”) produced by the HDDR method (hydrocracking / dehydrogenation recombination method), and diffusion heat treatment is performed. By carrying out, anisotropic magnet powder in which rare earth elements are diffused on the surface and inside of HDDR powder is prepared. And this rare earth magnet magnet is knead | mixed with resin, a coupling agent, a lubricant, etc., and a rare earth bond magnet is produced (refer to patent documents 1). In this method of manufacturing a rare earth bonded magnet, coercive force and the like can be improved because anisotropic magnetic powder in which rare earth elements such as Tb and Dy are diffused is used.

Japanese Patent No. 3452254

  By the way, according to the conventional manufacturing method, the coercive force can be improved as the amount of rare earth used as the diffusing material is increased. However, rare earths have the problem of high raw material costs.

  The present invention relates to a method capable of producing anisotropic magnetic powder having a sufficiently high coercive force even when the amount of rare earth used as a diffusion material is reduced, and an anisotropic bond containing the anisotropic magnetic powder produced by this method. An object is to provide a magnet.

  In order to reduce the amount of the rare earth compound used as the diffusing material, the present inventors prepared a large number of diffusing materials by mixing rare earth compound powders and various material powders, and using them, anisotropic magnetic powders were prepared. Were prepared and evaluated. As a result, it has been found that a diffusion material obtained by adding aluminum powder to rare earth compound powder is useful for obtaining anisotropic magnetic powder having a sufficiently high coercive force. The present invention has been made based on such knowledge.

  That is, the anisotropic magnetic powder manufacturing method according to the present invention includes a step of obtaining HDDR powder subjected to the hydrocracking / dehydrogenation recombination method including the first rare earth element, and the second rare earth element. A step of preparing a mixed powder by mixing the diffusing material and HDDR powder, and a step of diffusing elements contained in the diffusing material into the HDDR powder by heating the mixed powder. It contains a powder of at least one compound selected from the group consisting of hydrides, fluorides and iron compounds of Dy, Tb, Nd, Pr or La as elements, and further contains an aluminum powder.

  According to this manufacturing method, since aluminum powder is used as part of the diffusing material, the amount of rare earth used as the diffusing material can be reduced, and anisotropic magnetic powder having a sufficiently high coercive force can be manufactured. The surface of the particles forming the aluminum powder may be oxidized.

  This manufacturing method has an advantage that a simple mixture of a powder of a second rare earth element hydride or the like and an aluminum powder can be used as the diffusion material, and the preparation of the diffusion material is easy. On the other hand, conventionally, when an alloy containing a rare earth element is used as the diffusing material, it has been necessary to go through a process of producing a metal alloy by arc melting or the like and pulverizing the obtained alloy to obtain the diffusing material.

  In order to stably manufacture anisotropic magnetic powder having a sufficiently high coercive force, it is preferable to employ the following configuration in the above manufacturing method. That is, the average particle diameter of the diffusing material is preferably 1/3 or less of the average particle diameter of the HDDR powder. The total amount of aluminum powder (including aluminum oxide) contained in the diffusing material is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the diffusing material.

  In order to produce anisotropic magnetic powder having a higher coercive force, in the above production method, the diffusing material preferably further contains at least one of copper powder and cobalt powder. In this case, the total amount of copper powder and cobalt powder contained in the diffusing material is preferably more than 0 parts by mass and 10 parts by mass or less with respect to 100 parts by mass of the diffusing material.

  The present invention provides an anisotropic bonded magnet including an anisotropic rare earth alloy powder produced by the above production method and a resin. Since the anisotropic bonded magnet of the present invention includes anisotropic magnetic powder having excellent magnetic properties, it has excellent magnetic properties. Further, since the amount of rare earth used for the raw material can be reduced, the raw material cost can be kept low. In addition, the anisotropic bonded magnet according to the present invention is prepared by first forming a molded body by molding the mixed powder obtained in the above-described manufacturing method in a magnetic field, and heating the molded body to be included in the diffusion material. It may be obtained by diffusing elements in HDDR powder.

  According to the present invention, anisotropic magnetic powder having a sufficiently high coercive force can be obtained even if the amount of rare earth used as a diffusing material is reduced.

It is a perspective view which shows an example of the rare earth bond magnet manufactured by shape | molding anisotropic magnetic powder. It is a graph which shows the result of an Example and a comparative example.

<Method for producing anisotropic magnetic powder>
The method for producing anisotropic magnetic powder according to the present embodiment includes an HDDR treatment step of preparing HDDR powder by subjecting a raw material compound containing a first rare earth element to treatment by hydrocracking / dehydrogenation recombination, and a rare earth A preparation process for preparing a diffusion material including powder and aluminum powder, a mixing process for preparing a mixed powder by mixing HDDR powder and a diffusion material, and an element contained in the diffusion material by heating the mixed powder. And a heating step for diffusing to the outer periphery. Details of each step will be described below.

  In the HDDR processing step, first, a raw material compound containing a first rare earth element is prepared. As the raw material compound, a compound or alloy obtained by a normal casting method such as a strip casting method, a book mold method, or a centrifugal casting method can be used. Further, a homogenization heat treatment may be performed. The raw material compound may contain an inevitable impurity derived from the raw material metal or the raw material compound or the production process.

  Any rare earth element may be used as the first rare earth element, preferably a light rare earth element, more preferably Nd and / or Pr.

  Note that in this specification, rare earth elements refer to scandium (Sc), yttrium (Y), and lanthanoid elements belonging to Group 3 of the long-period periodic table. Examples of lanthanoid elements include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy). ), Holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu) and the like. The rare earth elements can be classified into light rare earth elements and heavy rare earth elements. In the present specification, “heavy rare earth element” refers to Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and “light rare earth element” refers to Sc, Y, La, Ce, Pr, Nd, Sm, Eu.

  As a suitable composition of the raw material compound, an R—Fe—B-based material containing at least one of Nd and Pr as a rare earth element, 0.5 to 4.5% by mass of B, and the balance being Fe and inevitable impurities. What has a composition is mentioned. The raw material compound may further contain other elements such as Co, Ni, Mn, Al, Cu, Nb, Zr, Ti, W, Mo, V, Ga, Zn, and Si as necessary.

  From the viewpoint of obtaining magnetic powder having excellent magnetic properties, Fe is preferable as T (transition metal), and the composition of the R—Fe—B alloy is R: 25 to 35 mass%, B: 1 to 1.4. It is preferable that they are mass% and Fe: 65.6-72 mass%. R may be one or more selected from Y, La, Ce, Pr, Nd, Sm, Gd, Td, Dy, Ho, Er, Tm, and Lu. Among these, from the viewpoint of manufacturing cost and magnetic properties, R preferably contains Nd.

  The R content ρ (mass%) based on mass in the R-T-B magnetic powder is preferably 25 to 35 mass%, more preferably 27 to 33 mass%, although it depends on the type of rare earth metal used. It is.

  From the viewpoint of obtaining the effects of the present invention more highly and stably, the raw material compound preferably further contains Co in the Nd—Fe—B composition, and more preferably is rich in Nd, B, and Co. More specifically, the Nd content in the raw material compound is preferably 28 to 35% by mass, the B content is preferably 1 to 1.6% by mass, and the Co content is preferably 1 to 1% by mass. 15% by mass.

  After preparing the raw material compound which has the above-mentioned composition, the processing by HDDR method is performed. The HDDR method is a process of sequentially executing hydrogenation, disproportionation, dehydrogenation, and recombination. Details of the HDDR processing will be described below.

  First, the homogenization heat processing which hold | maintain a raw material compound for 5 to 100 hours at 1000-1200 degreeC in pressure reduction atmosphere (1 kPa or less) or inert gas atmosphere, such as argon and nitrogen, is performed. The homogenized raw material compound is preferably pulverized using a pulverizing means such as a stamp mill or a jaw crusher and then sieved. Thereby, a powdery raw material compound having a particle size of 10 mm or less can be prepared.

  In the hydrogen storage step, the powdery raw material compound is held in a hydrogen atmosphere having a hydrogen partial pressure of 100 to 300 kPa at a temperature of 100 to 200 ° C. for 0.5 to 2 hours. Thereby, hydrogen is occluded in the crystal lattice of the raw material compound.

Next, the raw material compound in which hydrogen is occluded is hydrocracked by holding it at a predetermined temperature in a hydrogen atmosphere to obtain a decomposition product. The hydrogen partial pressure during hydrocracking is preferably 10 to 100 kPa, and the temperature is preferably 700 to 850 ° C. By performing hydrogenolysis under such conditions, it is possible to obtain a rare earth compound powder comprising particles having magnetic anisotropy. The decomposition product obtained by hydrocracking includes a hydride such as RH _x and an iron compound such as α-Fe and Fe ₂ B. The decomposition products at this stage form a fine matrix of the order of 100 nm.

  Subsequently, by reducing the hydrogen partial pressure, hydrogen is released from the decomposition product to obtain anisotropic HDDR powder containing the first rare earth element. This HDDR powder has a composition equivalent to the above-mentioned raw material compound. The particle size of the HDDR powder is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 160 μm or less. For practical purposes, the lower limit of the particle size of the HDDR powder is preferably 1 μm or more, for example.

  The average particle size of the HDDR powder is preferably 1 to 300 μm, more preferably 5 to 300 μm, and still more preferably 20 to 200 μm, from the viewpoint of achieving a high coercive force of the anisotropic magnetic powder. If the average particle size of the HDDR powder exceeds 300 μm, it is difficult for rare earth elements to diffuse into the HDDR powder, and the magnetic properties of the anisotropic magnetic powder may be insufficient. On the other hand, if the average particle size of the HDDR powder is less than 1 μm, the rare earth element tends to be easily oxidized. In addition, the average particle diameter of the powder referred to in the present invention means the volume average particle diameter (D50) of the powder.

  The above-mentioned HDDR powder is produced using a fine pulverizer such as a jet mill, a ball mill, a vibration mill, or a wet attritor. HDDR powder is useful for producing rare earth magnets having sufficiently high density and excellent magnetic properties because the grain size of the crystal grains is small and anisotropic.

  In the preparation step, a rare earth powder containing the first rare earth element and the second rare earth element (Dy, Tb, Nd, Pr, or La) is prepared, and this is mixed with an aluminum powder to obtain a diffusion material. obtain. From the viewpoint of obtaining a rare earth magnet having a much higher coercive force, the second rare earth element is preferably a heavy rare earth element, more preferably Dy, Tb, or Nd.

  Examples of the rare earth powder containing the rare earth element include general rare earth compounds such as hydrides, halides, iron compounds, oxides and hydroxides of these elements, and rare earth metals. Among these, from the viewpoint of further improving the magnetic properties of the rare earth magnet, it is preferable to use a heavy rare earth compound having a heavy rare earth element as a constituent element.

The heavy rare earth compound may contain an element other than the heavy rare earth metal element, and may be an alloy of the heavy rare earth metal and a metal other than the rare earth metal. The heavy rare earth compound is preferably a hydride or fluoride, more preferably a hydride, from the viewpoint of a rare earth magnet having even more excellent magnetic properties. When hydrides or fluorides are used as the heavy rare earth compounds, these compounds are easily decomposed, so that the second rare earth element can be diffused sufficiently uniformly even in HDDR powder having a fine structure. Can do. Due to these factors, a rare earth magnet having more excellent magnetic properties can be obtained. Preferred heavy rare earth compounds include DyH ₂ , DyF ₃ , NdH ₂ and TbH ₂ .

  The average particle diameter of the rare earth powder forming a part of the diffusing material is preferably 10 μm or less, more preferably 5 μm or less, and further preferably 1 μm or less. For practical purposes, the lower limit of the average particle size of the rare earth powder is preferably 0.1 μm or more, for example.

  The diffusing material further contains an aluminum powder in addition to the rare earth powder. The average particle size of the aluminum powder is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. For practical purposes, the lower limit of the average particle diameter of the aluminum powder is preferably 1 μm or more, for example.

  The content of the aluminum powder in the diffusing material is preferably 1 to 50 parts by mass, more preferably 10 to 40 parts by mass, and still more preferably 20 to 30 parts with respect to 100 parts by mass of the diffusing material. If the content of aluminum powder is less than 1 part by mass, the amount of rare earth used tends to be insufficiently reduced, while if it exceeds 50 parts by mass, the coercive force of anisotropic magnetic powder tends to be insufficient. is there.

  The diffusion material may further contain at least one of copper powder and cobalt powder. By including an appropriate amount of copper powder and / or cobalt powder in the diffusing material, anisotropic magnetic powder having even more excellent magnetic properties can be obtained. The particle sizes of the copper powder and the cobalt powder are preferably 30 μm or less, more preferably 20 μm or less, and still more preferably 10 μm or less. For practical purposes, the lower limit of the particle size of the copper powder and the cobalt powder is preferably, for example, 1 μm or more. In addition, the surface of the particle | grains which make copper powder or cobalt powder may be oxidized.

  When the diffusing material further contains one of copper powder and cobalt powder, the content of the copper powder or cobalt powder is preferably more than 0 parts by mass and 10 parts by mass or less with respect to 100 parts by mass of the diffusing material. More preferably, it is 1-5 mass parts. In this case, from the viewpoint of achieving a high coercive force of the anisotropic magnetic powder, the ratio A / B between the aluminum powder content A and the copper powder or cobalt powder content B in the diffusion material is preferably 0.1 to 500. Yes, more preferably 4 to 300.

  When the diffusing material contains both copper powder and cobalt powder, the total amount of copper powder and cobalt powder is preferably more than 0 parts by mass and 10 parts by mass or less with respect to 100 parts by mass of the diffusing material. It is more preferable that it is 1-5 mass parts. In this case, from the viewpoint of achieving a high coercive force of the anisotropic magnetic powder, the ratio A / C of the aluminum powder content A and the total amount C of the copper powder and the cobalt powder in the diffusion material is preferably 0.1 to 500. Yes, more preferably 4 to 300.

  From the viewpoint of high diffusibility with respect to the HDDR powder, the average particle diameter of the diffusing material is preferably 1/3 or less of the average particle diameter of the HDDR powder, and more preferably 5 μm or less. The diffusing material can be obtained, for example, by mixing the above powder into a container at a predetermined mixing ratio and then mixing for 1 to 30 minutes using a specs mixer. Instead of preparing a diffusing material by mixing a plurality of powders in the adjusting step, a plurality of powders forming the diffusing material and HDDR powder may be mixed together in the mixing step described below.

  In the mixing step, HDDR powder and a diffusion material are mixed to prepare a mixed powder. The mixed powder can be obtained, for example, by mixing the HDDR powder and the diffusing material in a predetermined mixing ratio into a container and then mixing for 1 to 30 minutes using a specs mixer. The mixing is preferably performed in an inert gas atmosphere such as argon gas from the viewpoint of suppressing the oxidation of the diffusing material and HDDR powder. In addition, the mixing method is not particularly limited, and for example, a method using a V mixer, a ball mill, or a reiki machine may be used.

  The mixing ratio of the HDDR powder and the diffusing material is such that the content of the diffusing material in the mixed powder is preferably 0.5 to 5% by mass, more preferably 1 to 4% by mass, and still more preferably 1.5 to 3.5% by mass. The ratio should be%. When the content is less than 0.5% by mass, the amount of diffusion of the second rare earth element tends to be small, and it is difficult to obtain a sufficiently large coercive force and squareness ratio improving effect. On the other hand, when the content exceeds 5% by mass, the second rare earth element diffuses into the HDDR powder, the residual magnetic flux density tends to decrease, and the material cost tends to increase.

  In the heating step, the mixed powder is heated to diffuse the elements contained in the diffusing material to the outer periphery of the HDDR powder. Specifically, the mixed powder is kept under reduced pressure or an inert gas atmosphere such as argon gas, preferably at 700 to 1100 ° C., more preferably at 750 to 950 ° C., and still more preferably at 800 to 900 ° C. for 10 minutes to 12 hours. To do. By heating under such conditions, the second rare earth element diffuses into the outer peripheral portion of the HDDR powder together with aluminum, and the inner layer rich in the first rare earth element and the second rare earth element covering the inner layer are rich. It is inferred that particles having an outer layer are formed. Thereby, anisotropic magnetic powder having a sufficiently high coercive force is obtained. In addition, although there are fine cracks in the HDDR powder, the diffusion material can enter the cracks and fill the cracks. For this reason, the oxidation resistance and strength of the anisotropic magnetic powder and the finally obtained rare earth bonded magnet can be improved.

  In the heating process, if the heating temperature of the mixed powder is too high or the heating time is too long, phase decomposition of the HDDR powder occurs, and high magnetic properties may be impaired. On the other hand, if the heating temperature of the mixed powder is too low or the heating time is too short, the diffusion of the second rare earth element tends not to proceed sufficiently. Therefore, it is preferable to set the heating temperature and the heating time according to the types of the first and second rare earth elements and the particle size of the HDDR powder.

  According to the manufacturing method according to the present embodiment, since the aluminum powder is used as a part of the diffusing material, the amount of the rare earth compound used as the diffusing material can be reduced, and the anisotropic magnetic powder having a sufficiently high coercive force can be obtained. Can be manufactured. Moreover, according to the said manufacturing method, what mixed simply and powders, such as a 2nd rare earth element hydride powder, and aluminum powder can be used as a diffusion material, Compared with the case where a diffusion material is manufactured from an alloy, a diffusion material Is easy to prepare.

<Anisotropic bonded magnet>
FIG. 1 is a perspective view of a rare earth bonded magnet using anisotropic magnetic powder produced by the above method as a raw material. The rare earth bonded magnet 10 shown in the figure contains particles having a rare earth compound as a main component and a resin filled between the particles.

  The rare earth bonded magnet 10 can be obtained by injection molding or compression molding a kneaded mixture of anisotropic magnetic powder, resin and molding aid (for example, a lubricant such as zinc stearate). Since the rare earth bonded magnet 10 uses aluminum powder as a part of the diffusing material, it can be manufactured at a low raw material cost. In addition to this, the rare earth bonded magnet 10 is manufactured from anisotropic magnetic powder having the same or superior magnetic properties as the conventional one, and therefore has sufficiently excellent magnetic properties.

  In the above embodiment, the mixed powder is heated to diffuse the second rare earth element and aluminum in the HDDR powder, and the obtained anisotropic magnetic powder and resin are mixed to obtain a bonded magnet. Prior to the heating step, the mixed powder may be molded, and the resulting molded body may be heated. The second rare earth element and aluminum can be more efficiently diffused into the HDDR powder by heating the molded body in which the HDDR powder and the diffusion material are in close contact with the powder. A rare earth bonded magnet may be obtained by impregnating a resin after heating with a molded article as necessary.

  The content of the present invention will be described in detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[Measurement item]
(1) Average particle diameter (D50)
The average particle size (D50) of the HDDR powder, the diffusing material, and the anisotropic magnetic powder was measured using HELOS (trade name) manufactured by Nippon Laser Co., Ltd.
(2) Magnetic properties Magnetic properties of anisotropic magnetic powder obtained by heat-treating HDDR powder and diffusing material were measured using a vibrating sample magnetometer (VSM). From the obtained results, coercive force (Hcj), residual magnetic flux density (Br), and squareness ratio (Hk / Hcj) were determined.

[Preparation of HDDR powder]
(1) Preparation of Nd ₂ Fe ₁₄ B powder (average particle diameter (D50): 160 μm) A raw material compound having the following composition containing Nd ₂ Fe ₁₄ B as a main component was prepared by a strip casting method.
<Composition of raw material compound>
Nd: 28.1% by mass
B: 1.1% by mass
Fe: 66.4 mass%
Co: 3.5% by mass
Inevitable impurities: balance

This raw material compound was held in a reduced pressure atmosphere (1 kPa or less) in a temperature range of 1000 to 1200 ° C. for 24 hours (homogenization heat treatment step). The product (Nd ₂ Fe ₁₄ B) obtained by the homogenization heat treatment was pulverized using a stamp mill and sieved to obtain a raw material powder (particle diameter of 1 to 2 mm). This raw material powder was filled in a molybdenum-made container, loaded into a tubular heat treatment furnace having an infrared heating method, and subjected to a treatment by hydrocracking / dehydrogenation recombination (HDDR treatment) under the following conditions.

  First, a hydrogen occlusion process was performed in which a raw material powder was held for 2 hours at a hydrogen partial pressure of 100 to 300 kPa and a temperature of 100 ° C. in a hydrogen gas atmosphere. Subsequently, the hydrocracking step of lowering the hydrogen partial pressure in the furnace and raising the temperature in the furnace to hold the raw material powder storing the hydrogen gas for 1.5 hours under the conditions of a hydrogen partial pressure of 40 kPa and a temperature of 850 ° C. Went.

Thereafter, the hydrogen pressure was reduced while maintaining the temperature in the furnace at 850 ° C., and a dehydrogenation recombination step was performed. Thus, HDDR-treated anisotropic magnetic powder was obtained. The obtained magnetic powder was pulverized using a stamp mill in a nitrogen gas atmosphere and sieved to obtain Nd ₂ Fe ₁₄ B powder having an average particle size of 160 μm. Table 1 shows the magnetic properties of the Nd ₂ Fe ₁₄ B powder.

[Preparation of diffusion material]
(1) DyH ₂ used as a diffusion material together with aluminum powder and the like was prepared as follows. First, Dy powder was occluded at 350 ° C. for 1 hour in a hydrogen atmosphere, followed by treatment at 600 ° C. for 1 hour in an Ar atmosphere to obtain a Dy hydride. The obtained Dy hydride was confirmed to be DyH ₂ by X-ray diffraction measurement. The DyH ₂ powder obtained do put ball milling in ethanol, average particle size (D50) was DyH ₂ powder 1 [mu] m.
(2) NdH ₂ used as a diffusion material together with aluminum powder and the like was prepared as follows. First, Nd powder was occluded at 350 ° C. for 1 hour in a hydrogen atmosphere, followed by treatment at 600 ° C. for 1 hour in an Ar atmosphere to obtain a Nd hydride. The obtained Nd hydride was confirmed to be NdH ₂ by X-ray diffraction measurement. The NdH ₂ powder obtained do put ball milling in ethanol, average particle size (D50) was NdH ₂ powder 1 [mu] m.
(3) An aluminum powder having an average particle diameter (D50) of 10 μm (manufactured by Soegawa Riken, purity 99.9% by mass) was prepared.
(4) A copper powder having an average particle size (D50) of 10 μm (manufactured by Soegawa Riken, purity 99 mass%) was prepared.
(5) A cobalt powder having a mean particle size (D50) of 10 μm (manufactured by High Purity Chemical Laboratory, purity 99 mass%) was prepared.

(Examples 1-5)
Nd ₂ Fe ₁₄ B powder having an average particle diameter of 160 μm, DyH ₂ powder and aluminum powder as diffusion materials were mixed using a spec mixer to prepare a mixed powder. Table 2 shows the mixing ratio of the Nd ₂ Fe ₁₄ B powder and the diffusion material. These mixed powders were subjected to a diffusion treatment by heat treatment at 800 ° C. for 8 hours in an argon gas flow at atmospheric pressure to obtain anisotropic magnetic powders. The magnetic properties of anisotropic magnetic powder were evaluated using a vibrating sample magnetometer. Table 2 shows the results.

(Example 6)
Anisotropic magnetic powder was prepared and evaluated in the same manner as in Example 1 except that DyH ₂ powder having an average particle diameter of 70 μm was used and the blending ratio shown in Table 2 was used. Table 2 shows the results.

(Example 7)
Anisotropic magnetic powder was prepared and evaluated in the same manner as in Example 1 except that NdH ₂ and Al powder were used as the diffusing agent and the blending ratios shown in Table 2 were used. Table 2 shows the results.

(Comparative Examples 1 and 2) An anisotropic magnetic powder was used in the same manner as in Example 1 except that only DyH ₂ powder was used as the diffusing material and the mixing ratio shown in Table 3 was used without using aluminum powder. Prepared and evaluated. Table 3 shows the results.

(Comparative Example 3)
An anisotropic magnetic powder was prepared and evaluated in the same manner as in Example 1 except that only the aluminum powder was used as the diffusion material and the mixing ratio shown in Table 3 was used without using the DyH ₂ powder. It was. Table 3 shows the results.

(Examples 8 to 11)
Anisotropic magnetic powder was prepared and evaluated in the same manner as in Example 1 except that DyH ₂ powder, aluminum powder and copper powder were used as the diffusing material and the mixing ratios shown in Table 4 were used. Table 4 shows the results.

(Examples 12 to 16)
Anisotropic magnetic powder was prepared and evaluated in the same manner as in Example 1 except that DyH ₂ powder, aluminum powder, and cobalt powder were used as the diffusing material and the mixing ratios shown in Table 5 were used. Table 5 shows the results.

(Comparative Examples 4-6)
Instead of using Nd ₂ Fe ₁₄ B powder and aluminum powder as the diffusing material, 85 Nd-15Al alloy, 70Nd-30Cu alloy or 80Dy-20Al alloy having a particle size of 90 μm or less are used, and the mixing ratios shown in Table 6 are used. An anisotropic magnetic powder was prepared and evaluated in the same manner as in Example 1 except that. Table 6 shows the results.

  FIG. 2 is a graph plotting the coercivity of anisotropic magnetic powders according to Examples 1 to 4 and Comparative Examples 1 and 2.

  10 ... Anisotropic bonded magnet

Claims (5)

Obtaining a rare earth compound powder that has been subjected to a hydrocracking / dehydrogenation recombination process containing a first rare earth element;
Mixing a diffusion material containing a second rare earth element and the rare earth compound powder to prepare a mixed powder;
Heating the mixed powder to diffuse the elements contained in the diffusing material into the rare earth compound powder;
With
The diffusing material contains a powder of at least one compound selected from the group consisting of a hydride of Dy, Tb, Nd, Pr or La as the second rare earth element, a fluoride, and an iron compound, and an aluminum powder A method for producing anisotropic magnetic powder, further comprising:   The method according to claim 1, wherein an average particle diameter of the diffusing material is not more than one third of an average particle diameter of the rare earth compound powder.   The method according to claim 1 or 2, wherein the total amount of aluminum powder contained in the diffusing material is 1 to 50 parts by mass with respect to 100 parts by mass of the diffusing material.   The diffusion material further contains at least one of copper powder and cobalt powder, and the total amount of copper powder and cobalt powder contained in the diffusion material is more than 0 parts by mass and 10 parts by mass or less with respect to 100 parts by mass of the diffusion material. The method according to any one of claims 1 to 3, wherein:   The anisotropic bonded magnet containing the anisotropic magnetic powder manufactured by the method as described in any one of Claims 1-4, and resin.

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