JP2008069415A - Method of manufacturing magnetic material for bonded magnet and rare earth bonded magnet produced by using this magnetic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a magnetic material for bonded magnets having high magnetic characteristics, strong corrosion resistance and weather resistance, and a bonded magnet produced by using this magnetic material. <P>SOLUTION: A treatment process is implemented for sticking a metal evaporation material containing at least one element selected from the group consisting of Dy, Tb, Ho, Er, Tm, Gd, Nd, Sm, Pr, Ce, La, Y, Zr, Cr, Mo, V, Ga, Zn, Cu, Mg, Li, Al, Mn, Nb and Ti, on the surface of a raw material containing a rare earth element and iron. The treatment process includes: a first process for heating a treatment room for implementing this treatment process, and forming a metal vapor environment in the treatment room by evaporating the metal evaporation material preliminarily arranged in this treatment room; and a second process for feeding the raw material kept at a temperature lower than the temperature in the treatment room, and selectively sticking the metal evaporation material to the surface of the raw material by the temperature difference between the inside of the treatment room and the raw material while moving the raw material in this treatment room. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a magnetic material for a bonded magnet and a rare earth bonded magnet produced using the magnetic material.

  Bonded magnets are manufactured using a compression molding machine or injection molding machine by mixing a powdered magnetic material and a resin binder, so they can be manufactured in thin or complex shapes, and have high dimensional accuracy. It has excellent features not found in sintered magnets. For this reason, it is used for products in various fields such as automobiles and electronics, and the demand is increasing year by year. Here, since magnetic materials of typical rare earth bonded magnets such as Nd—Fe—B based bonded magnets and Sm—Fe—N based bonded magnets contain rare earth elements and iron, they are easily oxidized when exposed to the atmosphere. There is a problem that the magnetic properties gradually deteriorate depending on the use environment.

In order to solve such a problem, for example, the surface of the raw material powder obtained by further pulverizing the raw material piece obtained by dissolving the raw material and quenching by the roll quenching method is covered with an oxide film such as an aluminum oxide film. Thus, it is known to obtain a magnetic material for a bonded magnet (Patent Document 1, Patent Document 2). And the magnetic material produced in this way is shape | molded with the resin binder, and the rare earth bond magnet is produced.
Japanese Patent Laid-Open No. 2002-363607 (for example, refer to the description of claims) Japanese Patent Application Laid-Open No. 2004-31761 (for example, see the description of the scope of claims)

  In the above, by covering the surface of the raw material with an oxide film, the magnetic properties can be prevented from being lowered and the corrosion resistance and weather resistance can be improved. Since further reductions in weight and power consumption are required, it is not sufficient to prevent a decrease in magnetic properties due to the use environment, as in the above-described conventional technology, and it has higher magnetic properties. Development of bonded magnets is desired.

  Therefore, in view of the above points, an object of the present invention is to provide a method for producing a magnetic material for a bonded magnet having high magnetic properties, strong corrosion resistance, and weather resistance, and a bonded magnet produced using this magnetic material. .

  In order to solve the above-described problems, a method for producing a magnetic material for a bonded magnet according to the present invention is provided on the surface of a powdery raw material containing a rare earth element and iron, with Dy, Tb, Ho, Er, Tm, Gd, Nd Metal evaporation containing at least one selected from Sm, Pr, Ce, La, Y, Zr, Cr, Mo, V, Ga, Zn, Cu, Mg, Li, Al, Mn, Nb, Ti A method of manufacturing a magnetic material for a bonded magnet including a processing step for adhering a material, wherein the processing step heats a processing chamber in which the processing step is performed, and the metal evaporation material disposed in advance in the processing chamber The first step of evaporating to form a metal vapor atmosphere in the processing chamber, and the raw material kept lower than the temperature in the processing chamber are charged into this processing chamber, and while moving the raw material in this processing chamber, By temperature difference between Characterized in that it comprises a second step of selectively depositing the metal evaporating material in the raw material surface.

  According to this, after disposing the metal evaporation material in the processing chamber, the processing chamber is heated to form a metal vapor atmosphere, and then the raw material kept lower than the temperature in the processing chamber is put into the processing chamber. For example, when a normal temperature raw material is put into a processing chamber heated to a high temperature, metal atoms in the metal vapor atmosphere are selectively attached and deposited only on the surface of the raw material. At that time, if the raw material is moved in the processing chamber and kept for a predetermined time, a thin film of metal evaporation material is formed over the entire surface of the raw material, and further, the raw material heated by radiant heat by being put into a high temperature processing chamber Some of the metal atoms attached to the surface of the metal diffuse into the grain boundaries.

  Since the magnetic material obtained by the above method has a metal evaporation material such as Dy diffused not only on its surface but also on the crystal grain boundary, when a rare earth bond is produced using this magnetic material, the demagnetization curve The squareness is improved, the maximum energy product (BHmax) and the residual magnetic flux density (Br) showing magnetic characteristics are remarkably improved, and the coercive force is also improved. Further, the heat resistance is improved by improving the coercive force, and the presence of a metal evaporation material such as Dy on the raw material surface and the crystal grain boundary provides strong corrosion resistance and weather resistance. Further, when the above method is used, productivity is improved by depositing and depositing the metal evaporating material at a high speed, and the metal evaporating material selectively adheres only to the surface of the raw material. Even when rare earth metals such as these are used, the metal evaporation material can be used effectively, and thus the manufacturing cost can be reduced.

  If the metal vapor atmosphere is saturated in the processing chamber, the metal evaporation material may be formed on the surface of the raw material at a high speed.

  In addition, after performing the treatment step, in order to further promote the diffusion of metal atoms on the surface of the raw material to the crystal grain boundary, if necessary, after carrying out the treatment step, the metal evaporation material on the surface under a predetermined temperature It is preferable to include the 1st heat treatment process which heats the raw material which adhered.

  In this case, after the first heat treatment step, the second heat treatment step of heating the raw material having the metal evaporation material attached to the surface at a temperature lower than the heat treatment temperature in the first heat treatment step is included. In this case, the coercive force can be further increased by removing the distortion of the magnetic material.

  In order to solve the above problems, the rare-earth bonded magnet of the present invention is formed by molding a magnetic material obtained by the manufacturing method according to any one of claims 1 to 4 together with a resin binder. And

  As described above, the method for producing a magnetic material for a bonded magnet according to the present invention and the bonded magnet using this magnetic material have the effect of having high magnetic properties, strong corrosion resistance, and weather resistance under high productivity. .

  Referring to FIG. 1, 1 selectively deposits and deposits a metal evaporation material M such as Dy or Tb at a high speed on the surface of a raw material containing a rare earth element and iron, and further adheres to the surface. This is a processing apparatus suitable for producing a magnetic material for a bonded magnet by diffusing metal atoms into crystal grain boundaries. The processing apparatus 1 includes a vacuum chamber 11 having a substantially hexagonal cross section that constitutes a processing chamber 10. The vacuum chamber 11 is attached to a support means 2 composed of a pedestal 21 installed on the floor and support plates 22a and 22b provided at a predetermined interval and perpendicular to the pedestal 21.

  The rotating shafts 23a and 23b are provided with bearings (not shown) at predetermined height positions from the pedestals 21 of the supporting plates 22a and 22b so as to protrude toward the inside of the supporting plates 22a and 22b and on the same horizontal line. ), And one end of each of the rotating shafts 23a and 23b having the cooling means 231 is connected to the side walls 11a and 11b of the vacuum chamber 11, respectively. A pulley 24 is provided at the other end of one rotating shaft 23 a protruding from one support plate 22 a, and between this pulley 24 and a pulley 32 provided on a rotating shaft 31 of the motor 3 provided on the base 21. The belt V is hung. Accordingly, when the motor 3 is operated to rotate the rotation shafts 23a and 23b, the vacuum chamber 11 can rotate about the rotation shafts 23a and 23b at a predetermined rotation speed (for example, 1 rpm).

On the outer periphery of the vacuum chamber 11, a stainless steel heat insulating material 41 having a reflective surface on the inner side is provided so as to cover substantially the whole, and a nichrome filament is provided inside the heat insulating material 41. An electric heater 42 is disposed and constitutes the heating means 4.
Then, after the vacuum chamber 11 is depressurized as described later, the processing chamber 10 can be heated to a predetermined temperature (for example, 600 ° C. to 1700 ° C.) substantially uniformly by heating the vacuum chamber 11 with the heating unit 4.

  Openings are respectively provided in the upper surface and the lower surface of the vacuum chamber 11, and open / close valves 5a and 5b are attached to the respective openings. Each of the on-off valves 5a and 5b is a butterfly valve having a known structure, for example, and has valve bodies 51 attached to the openings on the upper surface and the lower surface of the vacuum chamber 11, respectively. In the valve main body 51, a rotatable circular valve body and a valve seat on which the valve body is seated are provided. Then, a drive shaft (not shown) provided in the valve body 51 is operated manually or electrically, so that the valve body is located between the valve closing position where the valve body is seated on the valve seat and the valve opening position where the valve body is separated from the valve seat. It can be opened and closed by turning the valve body.

An exhaust pipe 6 or a hopper 7 provided with a coupling (not shown) at one end is detachably attached to the valve body 51 on the side facing the vacuum chamber 11. The other end of the bellows-like exhaust pipe 6 is connected to a vacuum exhaust means 61 including a turbo molecular pump, a cryopump, a diffusion pump, a rotary pump, and the like. Then, when the exhaust pipe 6 is connected to the valve body 51 of one of the on-off plates 5b at the closed position of both the on-off valves 5a, 5b, the vacuum exhaust means 61 is activated and the on-off valve 5b is opened, the processing chamber 10 is opened. The pressure can be reduced to a predetermined pressure (for example, 1 × 10 ⁻⁵ Pa).

On the other hand, the hopper 7 is made of a metal that can be hermetically sealed, and the inside constitutes the preparation chamber 70. The chute portion 71 below the hopper 7 is provided with another open / close valve 72 including a rotatable circular valve body and a valve seat on which the valve body is seated. 70 is sealed. When the raw material to be described later is charged into the processing chamber 10, after the raw material is stored in the hopper 70, an exhaust pipe (not shown) is connected to the tip of the chute portion 71 to operate the vacuum exhaust means and open the on-off valve 72. The preparatory chamber 70 is depressurized to a predetermined pressure (for example, 1 × 10 ⁻³ Pa).

  The raw material is a known material used for rare earth isotropic bonded magnets and rare earth anisotropic bonded magnets, and powders containing rare earth elements such as Nd and Sm and iron are used. For example, raw materials containing rare earth elements such as Nd and Sm and iron are mixed at a predetermined composition ratio and once melted, and then raw material flakes are obtained by quenching the raw material melt by a roll quenching method. A material obtained by pulverizing flakes into a fine powder is used as a raw material.

  On the other hand, the metal evaporation material M is stored in the storage chamber 12 provided on the inner wall of the vacuum chamber 11 so as to be positioned on the same line of the rotary shafts 23a and 23b. The storage chamber 12 is composed of a cylindrical member, and a flange 12a is provided on a surface opened inside the vacuum chamber 11 so as to cover a part of the opening. Thereby, when the vacuum chamber 11 is rotated, the metal evaporating material M arranged in the storage chamber 12 can be prevented from jumping out into the processing chamber 10 by the flange 12a. At least two storage chambers 12 are arranged at equal intervals in the circumferential direction on the inner wall of the vacuum chamber 11, and surround the periphery of the raw material charged into the processing chamber 10 through the on-off valves 5a and 5b. You may form cyclically | annularly over the whole inner wall face of the vacuum chamber 12, so that M may be arrange | positioned.

  The metal evaporation material M is capable of producing a bonded magnet having high magnetic properties and strong corrosion resistance and weather resistance. For example, Dy, Tb, Ho, Er, Tm, Gd, Nd, Sm, Pr, Ce, La , Y, Zr, Cr, Mo, V, Ga, Zn, Cu, Mg, Li, Al, Mn, Nb, containing at least one selected from Ti, for example, granular or massive Things are stored in the storage chamber 12.

By the way, for example, when Al ₂ O ₃ often used in a general vacuum apparatus is used as the material of the vacuum chamber 11, for example, when the metal evaporation material M is set to Dy, a metal vapor atmosphere is formed in the processing chamber 10. Dy and Al ₂ O ₃ in the vapor atmosphere react to form a reaction product on the surface, and Al atoms may enter the Dy vapor atmosphere. For this reason, the components of the vacuum chamber 11 and the on-off valves 5a and 5b are made of a material that does not react with the metal evaporation material M, or these materials are lined on the inner wall of the vacuum chamber 11 constituting the processing chamber 10 or the like. It is prepared from what is formed as a film (when the metal evaporation material M is Dy, for example, it is prepared from Mo, W, V, Ta or an alloy thereof, CaO, Y ₂ O ₃ , or a rare earth oxide).

  Next, production of a magnetic material for a bonded magnet using the processing apparatus 1 and production of a bonded magnet using this magnetic material will be described. First, in a state where the heat insulating material 41 is removed, the granular metal evaporation material M is stored in the storage chamber 12 through an opening (not shown) formed on the side surface of the vacuum chamber 11. The particle diameter of the metal evaporating material M is appropriately selected according to the type thereof. For example, when the metal evaporating material M is Dy or Tb, the particle diameter of Dy or Tb is preferably in the range of 10 to 1000 μm. When the particle size is 10 μm or less, it is difficult to handle ignitable Dy and Tb grains. On the other hand, when the particle size exceeds 1000 μm, it takes time to evaporate. Further, the total amount of the metal evaporating material M stored in the storage chamber 12 is the time required for forming the metal evaporating material M with a predetermined film thickness on the raw material surface so that the yield of the metal evaporating material M is increased. It is only necessary to continue the metal vapor atmosphere in the vacuum chamber 11.

Next, after the heat insulating material 41 is attached again, the exhaust pipe 6 is connected to the valve main body 51 of the other on-off valve 5b on the lower side while the on-off valves 5a and 5b are closed, and then the vacuum exhaust means 61 is operated. At the same time, the drive shaft is operated to open the other on-off valve 5b. Then, the processing chamber 10 is depressurized to a predetermined pressure (for example, 1 to 10 ⁻⁵ Pa) according to the type of the metal evaporation material M stored in the storage chamber 12, and then the heating unit 4 is operated to set the predetermined temperature (for example, 600). The processing chamber 10 is heated to ˜1700 ° C. For example, when the metal evaporation material M is Dy, the processing chamber 10 is once depressurized to, for example, 1 × 10 ⁻⁵ Pa, and then the processing chamber 10 is heated in the range of 1000 ° C. to 1700 ° C. At a temperature lower than 1000 ° C., the vapor pressure at which Dy can be deposited and deposited at high speed on the surface of the raw material put into the vacuum chamber 11 is not reached. On the other hand, when the temperature exceeds 1700 ° C., the deposition time on the raw material becomes extremely short.

When the processing chamber 10 reaches a predetermined temperature, a metal vapor atmosphere having a predetermined vapor pressure (in the case of Dy, for example, a vapor pressure of 10 Pa at 1300 ° C.) is formed in the processing chamber 10. While forming the metal vapor atmosphere in the processing chamber 10, in the preparation chamber 70 of the hopper 7, after storing the raw material produced as described above, an exhaust pipe (not shown) is connected to the tip of the chute portion 71, and vacuum exhaust means And the opening / closing valve 72 is opened, and the preparation chamber 70 is decompressed to a predetermined pressure (for example, 1 × 10 ⁻⁵ Pa). The raw material stored in the preparation chamber may be in the form of a lump, flake or powder.

Further, in the preparation chamber 70, under the reduced pressure, for example, a cleaning pretreatment for removing an oxide film or moisture on the surface of the raw material may be performed. The cleaning pretreatment includes a step of heating the preparation chamber 70 to a predetermined temperature after the pressure in the preparation chamber 70 reaches a predetermined value (for example, 10 × 10 ⁻⁵ Pa), or a gas introduction means (not shown). In this process, an inert gas such as Ar is introduced, a high-frequency power source is activated to generate plasma in the preparation chamber 70, and cleaning is performed with plasma while moving the raw material in the preparation chamber 70. When the cleaning pretreatment is completed, the raw material is set to a temperature of room temperature to 200 ° C.

  Next, when the formation of the metal vapor atmosphere in the processing chamber 10 and the decompression of the preparation chamber 70 (including the cleaning of the raw material) are completed, the open / close valve 72 is closed and the exhaust pipe is removed from the tip of the chute portion 71. Then, an inert gas such as Ar is introduced through a gas introduction means (not shown) so that a pressure difference of two digits or more is generated between the processing chamber 10 and the preparation chamber 70, and the pressure in the preparation chamber 70 is set to a predetermined value. (For example, 1000 Pa).

  In this state, after connecting the tip of the chute portion 71 of the hopper 7 to the valve body 51 of the one on-off valve 5a located on the upper side, when the on-off valves 5a and 72 are opened, the raw material in the preparation chamber 70 is obtained. The dead weight passes through the on-off valves 72 and 5a and enters the processing chamber 10. In this case, since there is a pressure difference between the processing chamber 10 and the preparation chamber 70, the inert gas enters the processing chamber 10 from the preparation chamber 70 into the processing chamber 10, and the pressure in the processing chamber 10 increases. Thus, although evaporation stops once (the operation of the heating means 4 is not stopped), it is possible to prevent metal atoms in the metal evaporation atmosphere from entering the preparation chamber 70 side.

Next, when the introduction of the raw material into the processing chamber 10 is completed, the on-off valves 5a and 72 are closed to isolate the processing chamber 10 and the preparation chamber 70 from each other, and then the hopper 7 is removed. When the pressure of the vacuum chamber 11 exhausted through the vacuum exhaust means reaches a predetermined value (for example, 10 × 10 ⁻² Pa) again, the metal evaporation material M is re-evaporated and the metal vapor is transferred to the processing chamber 10. An atmosphere is formed. When the metal vapor atmosphere is formed, the on-off valve 5b is closed, the exhaust pipe 6 is removed, the motor 3 is operated, and the vacuum chamber 11 is rotated at a predetermined number of revolutions and held for a predetermined time.

  In this case, due to the temperature difference between the raw material lower than the temperature in the processing chamber 10 and the processing chamber 10, metal atoms in the metal vapor atmosphere are deposited on the surface of the raw material at high speed and selectively. Then, by rotating the vacuum chamber 11 and moving the raw material in the processing chamber 10, a metal evaporation material is formed over the entire surface of the raw material. At that time, the raw material is put into a high-temperature processing chamber and heated to a predetermined temperature by radiant heat, and as a result, some of the metal atoms adhering to the surface of the raw material are diffused into the crystal grain boundary (processing step). ).

  Next, after holding for a predetermined time, the heating unit 4 is stopped, an inert gas such as Ar is introduced through a gas introduction unit (not shown), the processing chamber 10 is vented, and a recovery container (not shown) is placed on the lower side. When the on-off valve 5b is connected to the valve body 51 of the on-off valve 5b and the on-off valve 5b is opened, the surface of the raw material is covered with the film of the metal evaporation material M in the recovery container, and the bond diffused to the crystal grain boundary. Magnetic material for the magnet is recovered.

Depending on the size (granularity) of the raw material, even if it is put into the high temperature processing chamber 10 during the above processing, the temperature does not rise to a predetermined temperature, and the diffusion of metal atoms adhering to the surface to the crystal grain boundary is insufficient. There is a risk of becoming. In this case, after the formation of the metal vapor atmosphere in the processing chamber 10 is stopped, the exhaust pipe 6 is connected again to the valve body 51 of the other lower on-off valve 5b to operate the vacuum exhaust means 61 and the other The on-off valve 5b is opened and the processing chamber 10 is decompressed again to a predetermined pressure (10 × 10 ⁻³ Pa).

  Next, the heating means 4 is actuated again, and heat treatment is performed on the film on which the metal evaporating material M is formed at a predetermined temperature (for example, 400 ° C. to 1000 ° C.) for a predetermined time, and diffusion to the grain boundaries is performed. May be promoted (first diffusion step). Subsequent to the first heat treatment, it is preferable to perform a heat treatment for removing strain at a predetermined temperature (for example, 350 ° C. to 700 ° C.) lower than the heat treatment for a predetermined time (for example, 30 minutes) (second heat treatment step). . As a result, a metal evaporation material is formed over the entire surface, and a magnetic material in which metal atoms attached to the surface are diffused to the crystal grain boundaries and uniformly distributed is obtained.

  Next, according to the kind of the powdered magnetic material obtained by the above treatment, it is pulverized as it is or appropriately to a particle size of 5 to 300 μm, and then mixed with a resin binder such as PPS to form a known structure Is formed into a rare-earth bonded magnet having a predetermined shape using a compression molding machine or an injection molding machine. In this case, the rare earth bonded magnet is easily oxidized when exposed to the atmosphere, and there is a problem that the magnetic properties gradually deteriorate depending on the use environment. However, a metal evaporation material such as Dy or Tb having extremely high corrosion resistance and weather resistance. Is present on the surface and grain boundaries, it has strong corrosion resistance and weather resistance.

  In addition, the magnetic material obtained by the above method has a metal evaporation material such as Dy diffused not only on its surface but also on the crystal grain boundary. Therefore, when a rare earth bond is produced using this magnetic material, demagnetization is achieved. The squareness of the curve is improved, the maximum energy product (BHmax) and the residual magnetic flux density (Br) showing magnetic characteristics are remarkably improved, and the coercive force is also improved, so that the magnetic characteristics are improved. Note that even if a rare earth bond is produced using a magnetic material that has been appropriately pulverized to a predetermined particle size after performing the above treatment on the bulk material, the grain boundary phase has a rich phase such as Dy or Tb that has good corrosion resistance. Therefore, the magnetic characteristics are not deteriorated.

(Sample 1) First, a magnetic material for a rare earth isotropic bonded magnet is obtained as a sample 1 by a known method as follows. In this case, the raw material powder as a starting material is for an Nd—Fe—B ultra-rapidly cooled isotropic bonded magnet, and a composition (at%) of Nd ₁₃ Fe ₈₄ Co ₂ B ₁ is vacuum-dissolved. Later, it was quenched with a water-cooled copper roll and then pulverized. The particle size of this raw material powder was 10 to 60 μm.

Next, using the processing apparatus 1, a metal evaporation material was deposited on the surface of the raw material by the above method. In this case, an alloy obtained by mixing Dy, Nd, Ce, Zr, Cr, Al, and Nb at a composition ratio of 1: 1: 0.5: 1: 1: 1: 1 is used as the metal evaporation material M. The granular product was stored in the storage chamber 12. Further, the processing chamber 10 was evacuated to 10 ⁻³ Pa, and the heating temperature of the processing chamber 10 by the heating unit 4 was set to 1000 ° C., and the processing was performed for 1 minute. In this case, after the temperature of the processing chamber reached 600 ° C., the vacuum chamber 11 was rotated at a rotation speed of 0.2 rpm.

  Next, the surface of the raw material powder on which the metal evaporation material M was formed is subjected to a first heat treatment at a temperature of 800 ° C. for 30 minutes, followed by a second heat treatment at a temperature of 600 ° C. for 20 minutes. (Annealing treatment) was performed to obtain the magnetic material.

(Sample 2) First, a magnetic material for a rare earth isotropic bonded magnet is obtained as a sample 2 by a known method as follows. In this case, the raw material powder as a starting material is a raw material powder for an Nd—Fe—B exchange spring isotropic bonded magnet, and a composition (at%) of Nd ₄ Fe ₇₆ B ₂₀ is vacuum-dissolved. Then, the ribbon after ultra-rapid cooling with a water-cooled copper roll was pulverized. The particle size of this raw material powder was 5 to 20 μm.

Next, using the processing apparatus 1, a metal evaporation material was deposited on the surface of the raw material by the above method. In this case, as the metal evaporation material M, Dy, Tb, Pr, La, Mo, V, and Ga are mixed at a composition ratio of 1: 1: 1: 0.2: 0.2: 0.2: 0.2. Granules were stored in the storage chamber 12 using the alloy obtained above. Further, the processing chamber 10 was evacuated to 10 ⁻⁸ Pa, and the heating temperature of the processing chamber 10 by the heating unit 4 was set to 1200 ° C., and the processing was performed for 2 minutes. In this case, after the temperature of the processing chamber reached 800 ° C., the vacuum chamber 11 was rotated at a rotation speed of 0.5 rpm.

  Next, the surface of the raw material powder on which the metal evaporating material M was formed is subjected to a first heat treatment at a temperature of 600 ° C. for 60 minutes, and subsequently, a second heat treatment is performed at a temperature of 500 ° C. for 5 minutes. (Annealing treatment) was performed to obtain the magnetic material (sample 2).

(Sample 3) First, a magnetic material for a rare earth anisotropic bonded magnet is obtained as Sample 2 by a known method as follows. In this case, the raw material powder as a starting material is for an Nd—Fe—B HDDR anisotropic bonded magnet, and an ingot having a composition (at%) of Nd ₂ Fe ₁₄ B ₁ is used as a vacuum high frequency induction melting furnace. After performing solution treatment for 12 hours at an in-furnace temperature of 1100 ° C., the ingot was subjected to HDDR treatment at 800 ° C. The particle size of this raw material powder was 20 to 80 μm.

Next, using the processing apparatus 1, a metal evaporation material was deposited on the surface of the raw material by the above method. In this case, as the metal evaporation material M, an alloy obtained by mixing Dy, Tb, Y, Cu, and Zn at a composition ratio of 1: 1: 1: 1: 1 is used. Stowed. Further, the processing chamber 10 was evacuated to 10 ⁻⁶ Pa, and the heating temperature of the processing chamber 10 by the heating unit 4 was set to 1000 ° C., and the processing was performed for 5 minutes. In this case, the vacuum chamber 11 was rotated at a rotation speed of 0.3 rpm after the temperature of the processing chamber reached 900 ° C.

  Next, the surface of the raw material powder on which the metal evaporation material M was formed is subjected to a first heat treatment at a temperature of 800 ° C. for 60 minutes, followed by a second heat treatment at a temperature of 600 ° C. for 30 minutes. (Annealing treatment) was performed to obtain the magnetic material (sample 3).

(Sample 4) First, a magnetic material for a rare earth isotropic bonded magnet is obtained as a sample 4 by a known method as follows. In this case, the starting material powder as a starting material is for Sm—Fe—N isotropic bonded magnets, and the composition (at%) of Sm ₂ Zr _0.2 Fe ₁₆ Mn ₁ is vacuum-dissolved. Later, flakes were prepared by a super-quenching method, and after nitriding at 600 ° C., pulverization was performed. The particle size of this raw material powder was 10 to 50 μm.

Next, using the processing apparatus 1, a metal evaporation material was deposited on the surface of the raw material by the above method. In this case, an alloy obtained by mixing Ho, Er, Sm, Mg, Zn at a composition ratio of 1: 1: 1: 1: 1 is used as the metal evaporation material M, and the granular material is stored in the storage chamber 12. Stowed. Further, the processing chamber 10 was evacuated to 10 ⁻⁵ Pa, and the heating temperature of the processing chamber 10 by the heating unit 4 was set to 800 ° C., and the processing was performed for 5 minutes. In this case, after the temperature of the processing chamber reached 550 ° C., the vacuum chamber 11 was rotated at a rotation speed of 1 rpm.

  Next, the surface of the raw material powder on which the metal evaporation material M was formed is subjected to a first heat treatment at a temperature of 550 ° C. for 180 minutes, and subsequently, a second heat treatment is performed at a temperature of 400 ° C. for 60 minutes. (Annealing treatment) was performed to obtain the magnetic material (sample 4).

(Sample 5) First, a magnetic material for a rare earth anisotropic bonded magnet is obtained as Sample 5 by a known method as follows. In this case, the raw material powder as the starting material is for an Sm—Fe—N anisotropic bonded magnet, and the composition (at%) of Sm ₂ Ti _0.2 Fe ₁₆ Co ₁ is vacuum-dissolved. Thereafter, the flakes rapidly cooled by the strip casting method were obtained by pulverizing after nitriding at 600 ° C. The particle size of this raw material powder was 5 to 20 μm.

Next, using the processing apparatus 1, a metal evaporation material was deposited on the surface of the raw material by the above method. In this case, an alloy obtained by mixing Tm, Gd, Li, Ti, Zn, Sm, and Mn at a composition ratio of 1: 1: 1: 1: 1: 1: 1 is used as the metal evaporation material M. The product was stored in the storage chamber 12. In addition, the processing chamber 10 was evacuated to 10 ⁻⁴ Pa, and the heating temperature of the processing chamber 10 by the heating unit 4 was set to 900 ° C., and the processing was performed for 1 minute. In this case, after the temperature of the processing chamber reached 580 ° C., the vacuum chamber 11 was rotated at a rotation speed of 2 rpm.

  Next, the surface of the raw material powder on which the metal evaporation material M was formed is subjected to a first heat treatment at a temperature of 550 ° C. for 120 minutes, and subsequently, a second heat treatment is performed at a temperature of 450 ° C. for 20 minutes. (Annealing treatment) was performed to obtain the magnetic material (sample 5).

  Samples 1 to 5 obtained as described above were mixed with 12 nylon in a proportion of 1 to 5% by weight, and then injection molded with a known injection molding machine to produce a rare earth isotropic bonded magnet, rare earth anisotropic A bonded magnet was obtained.

  FIG. 2 is a table showing the magnetic properties and heat-resistant temperatures of the rare earth isotropic bonded magnets and rare earth anisotropic bonded magnets produced as described above. In this case, the magnetic properties and heat resistance temperature when the rare earth isotropic bond magnet and the rare earth anisotropic bond magnet were obtained by the above procedure without performing the film formation and diffusion treatment of the metal evaporation material M on each raw material were compared. It is also shown as an example. The heat-resistant temperature is obtained when the permeance by the flux loss method is set to 5.

  According to this, in Example 1, since each metal element of the metal evaporation material M is efficiently diffused to the crystal grain boundary and the squareness is improved, the rare earth isotropic bond having a maximum energy product of 10MG0e or more. It can be seen that a magnet and a maximum energy product of 15MG0e rare earth anisotropic bonded magnet are obtained. That is, in Example 1, it turns out that the maximum energy product and the residual magnetic flux density are remarkably improved as compared with the comparative example. Moreover, in the thing of Example 1, it turns out that heat-resistant temperature has become twice or more compared with the thing of a comparative example by having a high coercive force of 14 k0e or more.

The figure which illustrates roughly the structure of the processing apparatus of this invention. The table | surface which shows the magnetic characteristic of the bond magnet obtained in Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Processing apparatus 10 Processing chamber 11 Vacuum chamber 12 Storage chamber M Metal magnetic material

Claims (5)

Dy, Tb, Ho, Er, Tm, Gd, Nd, Sm, Pr, Ce, La, Y, Zr, Cr, Mo, V, Ga, Zn on the surface of the powdery raw material containing rare earth elements and iron A method for producing a magnetic material for a bonded magnet comprising a treatment step of attaching a metal evaporation material containing at least one selected from Cu, Mg, Li, Al, Mn, Nb, and Ti, The processing step includes heating a processing chamber in which the processing step is performed, evaporating the metal evaporation material previously disposed in the processing chamber to form a metal vapor atmosphere in the processing chamber, and a temperature in the processing chamber. A second step in which the metal evaporation material is selectively attached to the surface of the raw material due to the temperature difference between the processing chamber and the raw material while the raw material kept low is put into the processing chamber and the raw material is moved in the processing chamber And including Method of manufacturing a magnetic material for a bonded magnet to symptoms. The method for producing a magnetic material for a bond magnet according to claim 1, wherein the metal vapor atmosphere is saturated in the processing chamber. 3. The magnet for a bonded magnet according to claim 1, further comprising a first heat treatment step of heating a raw material having a metal evaporation material attached to a surface at a predetermined temperature after performing the treatment step. 4. Material manufacturing method. The method includes a second heat treatment step of heating the raw material having the metal evaporation material attached to the surface thereof at a temperature lower than the heat treatment temperature in the first heat treatment step after performing the first heat treatment step. Item 4. A method for producing a magnetic material for a bonded magnet according to Item 3. 5. A rare earth bonded magnet obtained by molding a magnetic material obtained by the manufacturing method according to claim 1 together with a resin binder.

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