KR101704298B1 - Method for preparing rare-earth permanent magnet - Google Patents

Method for preparing rare-earth permanent magnet Download PDF

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Publication number
KR101704298B1
KR101704298B1 KR1020150169995A KR20150169995A KR101704298B1 KR 101704298 B1 KR101704298 B1 KR 101704298B1 KR 1020150169995 A KR1020150169995 A KR 1020150169995A KR 20150169995 A KR20150169995 A KR 20150169995A KR 101704298 B1 KR101704298 B1 KR 101704298B1
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South Korea
Prior art keywords
rare earth
heavy rare
sintered magnet
earth element
sheet
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KR1020150169995A
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Korean (ko)
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이형주
이재령
박건민
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현대자동차주식회사
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0293—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/14—Both compacting and sintering simultaneously
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/08—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)
  • Hard Magnetic Materials (AREA)

Abstract

The present invention relates to a method for preparing a rare-earth permanent magnet, which can perform spreading and surface coating concurrently on a heavy rare-earth element by using a heavy rare-earth element-applied sheet. The method for preparing a rare-earth permanent magnet according to an embodiment of the present invention comprises: a preparation step of preparing a heavy rare-earth element-applied sheet by applying a heavy rare-earth element paste including a heavy rare-earth element to a surface of a metal sheet; a cutting step of cutting the heavy rare-earth element-applied sheet; a wrapping step of wrapping a surface of a sintered magnet in the heavy rare-earth element-applied sheet so that the heavy rare-earth element paste comes in contact with the surface of the sintered magnet; and a first heating step of forming, by heating the sintered magnet wrapped in the heavy rare-earth element-applied sheet, a metal coating layer on the surface of the sintered magnet while spreading the heavy rare-earth element included in the heavy rare-earth element paste into the sintered magnet.

Description

METHOD FOR PREPARING RARE-EARTH PERMANENT MAGNET BACKGROUND OF THE INVENTION [0001]

More particularly, the present invention relates to a method for producing a rare earth permanent magnet in which heavy rare earth elements are diffused and surface-coated using a sheet coated with a heavy rare earth element. To a rare earth permanent magnet manufacturing method capable of improving the performance of the permanent magnet while simplifying it.

Generally, a hybrid vehicle in a broad sense means to drive a vehicle by efficiently combining two or more kinds of power sources. In most cases, the hybrid vehicle means a vehicle that obtains a driving force by an engine and an electric motor. Hybrid Electric Vehicle (HEV).

In recent years, research on hybrid vehicles has been actively pursued in response to the demand for improving fuel efficiency and developing environmentally friendly products.

In such a hybrid vehicle, an engine and an electric motor are provided as a power source, and the electric motor is driven by receiving power from a battery mounted on the vehicle. The electric motor for a vehicle as described above is constituted by winding a coil on a stator core The stator and the rotor disposed inside the stator are the main components, and the rotor is constituted by inserting permanent magnets into the rotor core.

In order to obtain high output and high efficiency of the electric motor for a vehicle as described above, a high-performance permanent magnet is required.

Therefore, a rare earth permanent magnet such as an NdFeB sintered magnet which can achieve a magnetic force improvement of 3 to 5 times that of a conventional ferrite magnet is used to lighten the motor and improve the efficiency of the vehicle.

However, the rare-earth permanent magnet as described above is likely to generate eddy current inside the permanent magnet due to the high conductivity and low specific resistance of the magnet, so that the temperature of the permanent magnet is raised and the temperature rise of the permanent magnet causes a decrease in the magnetic flux density Or it is liable to cause irreversible magnetization of the permanent magnet due to an increase in temperature, which has a problem of causing a fatal motor performance deterioration.

In order to improve the coercive force of the conventional NdFeB sintered magnet, a technique of intergranular diffusion of a heavy rare earth element such as dysprosium (Dy) or terbium (Tb) from the surface of the NdFeB sintered magnet has been developed .

However, since the cost of heavy rare earth elements is high during the grain boundary diffusion process, the manufacturing cost is increased, and after the grain boundary diffusion, a post-treatment process such as a surface coating process for improving corrosion resistance is required.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as an admission that the prior art is known to those skilled in the art.

Patent Registration No. 10-1534717 (Jun. 17, 2009)

Disclosed is a rare earth permanent magnet manufacturing method capable of simultaneously performing diffusion of a heavy rare earth element and surface coating of a permanent magnet, thereby simplifying a manufacturing process and reducing manufacturing cost.

A rare earth permanent magnet manufacturing method capable of improving performance such as coercive force and durability of a permanent magnet while minimizing the consumption of heavy rare earth elements.

According to an embodiment of the present invention, there is provided a method of manufacturing a rare earth permanent magnet, comprising: preparing a heavy rare earth coated sheet by applying a heavy rare earth paste containing a heavy rare earth element to a surface of a metal sheet; A cutting process for cutting the heavy rare earth coated sheet; Wrapping the surface of the sintered magnet with the heavy rare earth element coated sheet such that the heavy rare earth paste is in contact with the surface of the sintered magnet; And a first heat treatment step of heating the sintered magnet packed with the heavy rare earth element coated sheet to form a metal coating layer on the surface of the sintered magnet while diffusing the heavy rare earth element contained in the heavy rare earth paste into the sintered magnet .

The heavy rare earth paste may be characterized in that a heavy rare earth element, an adhesive, and ethanol are mixed.

The heavy rare earth element preferably includes at least one of dysprosium (Dy) and terbium (Tb).

The adhesive is preferably a ceramic adhesive containing alumina (Al 2 O 3 ) and silica (SiO 2 ).

The metal sheet may be a Ni-Zn thin film sheet having a thickness of 5 to 30 탆.

Preferably, the primary heat treatment is performed in an inert atmosphere at a temperature of 800 to 900 ° C. for 8 to 12 hours to form a metal coating layer on the surface of the sintered magnet while diffusing the heavy rare earth element into the sintered magnet.

A method of manufacturing a rare-earth permanent magnet according to an embodiment of the present invention includes: a cooling step of cooling the sintered magnet in which heavy rare earth elements are intergranularly diffused by using an inert gas after the first heat treatment step; And a second heat treatment step of performing heat treatment in an inert atmosphere at a temperature of 500 to 700 ° C for 1 to 2 hours to remove the stress of the sintered magnet in which heavy rare earth elements are intergranularly diffused.

According to the embodiment of the present invention, it is possible to uniformly diffuse the rare earth permanent magnet throughout the rare earth rare earth element while minimizing the consumption of the heavy rare earth element, thereby improving the magnet performance such as coercive force.

In addition, by simultaneously applying and coating a plurality of permanent magnet blocks, the manufacturing process is simplified, the manufacturing time is shortened, the productivity is improved, and the manufacturing cost is reduced.

1 is a flowchart illustrating a method of manufacturing a rare-earth permanent magnet according to an embodiment of the present invention,
2 is a view for explaining a finishing process and a packing process according to an embodiment of the present invention,
3 is a cross-sectional view of a sintered magnet packed with a heavy rare earth sheet according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments. For reference, the same numbers in this description refer to substantially the same elements and can be described with reference to the contents described in the other drawings under these rules, and the contents which are judged to be obvious to the person skilled in the art or repeated can be omitted.

1 is a flowchart illustrating a method of manufacturing a rare-earth permanent magnet according to an embodiment of the present invention.

As shown in FIG. 1, the rare earth permanent magnet manufacturing method according to an embodiment of the present invention includes a preparation process for preparing the heavy rare earth application sheet 20, a process for rubbing the middle rare earth application sheet 20, A packing process of wrapping the sintered magnet 10 with the sheet 20 and a primary heat treatment process of forming a metal coating layer on the surface of the sintered magnet 10 while diffusing the heavy rare earth element by heating.

In the preparation process according to an embodiment of the present invention, the heavy rare earth paste 22 is applied to the surface of the metal sheet 21 to provide the heavy rare earth application sheet 20.

At this time, it is preferable to use a thin sheet of nickel (Ni) -zinc (Zn) having a thickness of 5 to 30 μm. Thus, the metal sheet 21 is adhered to the surface of the sintered magnet 10 in the first heat treatment process to form a metal coating layer for coating the sintered magnet 10, so that a separate sheet removing and coating process can be omitted, The process can be simplified and the productivity can be improved.

On the other hand, the metal sheet 21 forms a metal coating layer on the surface of the sintered magnet 10 in the first heat treatment process. When the metal sheet 21 has a thickness of less than 5 탆, it is difficult to handle the prepared heavy rare earth coated sheet 20, When the thickness of the metal coating layer formed after the heat treatment is thin, the corrosion resistance of the rare earth permanent magnet produced is reduced. When the thickness is more than 30 탆, the performance of the permanent magnet produced may be lowered.

The heavy rare earth paste 22 is prepared by mixing a heavy rare earth element and an adhesive in a ratio of 1: 1, and may be adjusted depending on the thickness of the magnet to be produced. Further, ethanol may be further added to the metal sheet so as to be sprayed using a spray nozzle or the like.

In the present invention, it is preferable to use a ceramic adhesive including alumina (Al 2 O 3 ) and silica (SiO 2 ) as the adhesive agent because alumina (Al 2 O 3 ), silica (SiO 2 ) The characteristics of the adhesive should not be changed during the heat treatment of the metal coating layer while the heavy rare earth element is diffused.

DyF 3 and TbF 3 particles were used as heavy rare earth elements. A heavy rare earth paste (22) was prepared by mixing heavy rare earth elements with an adhesive and ethanol in a weight ratio of 1: 1: 1, and sprayed with a spray nozzle And sprayed onto the surface of the metal sheet to form a heavy rare earth coating sheet 20.

The middle rare earth paste 22 may be sprayed onto one side of the metal sheet 21 but the present invention is not limited thereto and may be applied to one surface of the metal sheet 21 The middle rare earth paste 22 may be applied or painted to the middle rare earth paste sheet 22 and the amount of ethanol may be adjusted to adjust the viscosity according to the application method of the heavy rare earth paste 22 .

FIG. 2 is a view for explaining a finishing process and a packing process according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view showing a sintered magnet packed with a heavy rare earth sheet according to an embodiment of the present invention.

As shown in FIGS. 2 and 3, when the heavy rare earth coating sheet 20 is prepared as described above, the middle rare earth coating sheet 20 is cut according to the shape and size of the sintered magnet 10 The middle rare earth coating sheet 20 is attached to the surface of the sintered magnet 10 so that the surface coated with the heavy rare earth paste 22 comes into contact with the surface of the sintered magnet 10 during the packaging process.

At this time, depending on the shape and size of the sintered magnet 10, the heavy rare earth coating sheet 20 can be cut into one piece or several pieces, and such a cutting process can be performed before the preparing process.

When the packaging process is completed as described above, a nickel-zinc metal thin film is attached to the surface of the sintered magnet 10 while diffusing the heavy rare earth element of the heavy rare earth element spread sheet 20 into the sintered magnet in the first heat treatment process The sintered magnet 10 packed with the heavy rare earth element spread sheet 20 is heated to form a metal coating layer.

In this case, the first heat treatment is preferably performed at 800 to 900 ° C. for 8 to 12 hours in an inert atmosphere.

This is because the sintered magnet is prevented from being oxidized by reacting with oxygen by performing in an inert atmosphere filled with a vacuum (6 × 10 -6 torr or less) or argon (Ar) or nitrogen (N) It is possible to prevent degradation in performance.

On the other hand, when the temperature is lower than 800 ° C, the intergranular diffusion of heavy rare earth elements is not smooth. If the temperature exceeds 900 ° C, the cost for raising the temperature is increased. If the temperature is excessively increased, the metal coating layer may be deformed, .

In addition, when the heat treatment time is less than 8 hours, the intergranular diffusion of the rare earth elements is not sufficiently performed, and when the heat treatment time exceeds 12 hours, the primary heat treatment cost is increased, which is limited to 8 to 12 hours.

Preferably, the rare earth permanent magnet manufacturing method according to an embodiment of the present invention includes a cooling process for fixing the interlayer diffusion of heavy rare earth elements, and a cooling process for removing the stress of the sintered magnet 10 generated during grain boundary diffusion A second heat treatment process may be performed.

In the cooling process, an inert gas such as argon or nitrogen gas is used as a cooling gas, and the sintered magnet 10 is quenched to an ordinary temperature by an air cooling method. Accordingly, it is possible to improve the quality of the rare-earth permanent magnet produced by fixing the medium rare earth element diffused in the grain boundary to the inside of the sintered magnet 10.

After the cooling process, heat treatment is performed at 500 to 700 ° C for 1 to 2 hours in the secondary heat treatment process to remove the stress generated in the sintered magnet.

In this case, when heat treatment is performed at a temperature of less than 500 ° C, it takes a long time to remove stress, resulting in deteriorated productivity. When the temperature exceeds 700 ° C, the quality of rare earth permanent magnets produced by changing the distribution of heavy rare earth elements It is limited to the above conditions.

Hereinafter, effects of the present invention will be described with reference to Examples and Comparative Examples of the present invention.

A method of manufacturing a sintered magnet used in Examples and Comparative Examples of the present invention will be described.

ingredient Nd Dy Cu B Fe Content (wt%) 21.0 4.02 0.07 0.92 Remainder

After the composition having the composition shown in Table 1 was dissolved in a vacuum atmosphere, an alloy thin plate was produced by a strip casting method using a roll of copper material, exposed to hydrogen gas at 0.11 MPa at room temperature for reaction, Vacuum is carried out while raising the temperature to release hydrogen and then a fine powder having an average particle size of 5 μm is prepared in a jet mill using high pressure nitrogen and then subjected to magnetic field molding at a pressure of 3 T and 1 ton / Respectively.

The molded body thus prepared was sintered in a sintering furnace in an argon (Ar) atmosphere at a temperature of 1070 캜 for 4 hours, and then heat-treated at 850, 550, and 500 캜 for three hours each for two hours. , Followed by cleaning and drying with nitric acid and distilled water to prepare a sintered magnet 10.

Embodiment of the present invention is 10 hours rare earth coating sheet 20 to a temperature of the after wrapping the surface of the sintered magnet 10 is provided as described above, 800 ~ 900 ℃ in vacuo (6 × 10 -6 torr or less) conditions Heat treatment was performed, and the resultant was air-cooled to room temperature using argon gas, and then heat-treated at 500 to 700 ° C for 4 hours.

At this time, the heavy rare earth element coated sheet 20 is formed by mixing a ceramic adhesive containing heavy rare earth element (TbF 3 ), alumina (Al 2 O 3 ), silica (SiO 2 ) and ethanol in a ratio of 1: The rare earth paste was prepared by spraying on one surface of a Ni-Zn thin film having a thickness of 20 mu m.

Comparative Example 1 is a sintered magnet 10 prepared as described above and Comparative Example 2 is a sintered magnet 10 in which zinc powder (Zn-flakes 65 wt%, Binder 10 wt%, Organic pigments 10 wt%) was added to the sintered magnet 10 prepared as described above After electrostatic spray coating, the coating was dried at a temperature of 100 캜 to provide a base coating having a thickness of 30 탆, and then a top coating having a thickness of 10 탆 was carried out in the same manner.

In Comparative Example 3, a mixed solution obtained by mixing TbF 3 powder having a particle size of 5 μm and ethanol at a ratio of 1: 1 was applied to the sintered magnet 10 prepared as described above by a spray method, and after hot air drying, 10 -6 torr or less) at 800-900 ° C for 10 hours, air-cooled to room temperature using argon gas, and heat-treated at 500-700 ° C for 4 hours to diffuse the heavy rare earth element Base coating and top coating were carried out in the same manner as in Example 2.

division Coercivity
iHc (kOe) Composition (wt%) Salt spray test High temperature and high pressure test Nd Dy Tb Cu B × × Comparative Example 1 24.12 21.0 4.02 - 0.07 0.92 ○ ○ Comparative Example 2 23.53 21.0 4.02 - 0.07 0.92 ○ ○ Comparative Example 3 30.85 20.5 4.02 0.16 0.69 0.92 ○ ○ Example 31.16 20.4 4.03 0.20 0.69 0.92 ○ ○

Table 2 is a table showing the composition, coercive force, corrosion resistance and durability of the permanent magnets produced according to Examples of the present invention and Comparative Examples 1 to 3.

At this time, the salt spray test was carried out at 35 ° C in a 5% NaCl saline environment for 24 hours, and the high temperature and high pressure test was conducted at 121 ° C and 100% RH for 12 hours.

As can be seen from Table 2, in Comparative Example 1 in which no coating layer is formed, it can be understood that both the corrosion resistance and the durability do not satisfy the standard values.

On the other hand, in Comparative Example 2 in which the base coating and the top coating were applied to the surface of the sintered magnet, the durability and the corrosion resistance meet the reference value, but the coercive force is as low as 23.53 kOe.

Compared to Comparative Examples 1 and 2, in which the base rare earth element was diffused by intergranular diffusion and base coating and top coating were performed, the coercive force was increased to 30.85 kOe as the heavy rare earth element was diffused into the magnet and the content of Tb was increased by 0.16% It can be seen that it is improved.

On the other hand, in the embodiment prepared according to the present invention, the metal sheet of the heavy rare earth element coated sheet is attached to the surface of the sintered magnet to form the metal coating layer, so that the heavy rare earth element is coated on the surface of the sintered magnet The diffusion of the heavy rare earth element in the grain boundary diffusion is increased by about 25%, and the coercive force is also improved.

That is, according to the embodiment of the present invention, it is possible to simultaneously form the metal-based diffusion layer and the intergranular diffusion of the heavy rare earth element, thereby simplifying the manufacturing process and securing durability and corrosion resistance, .

Although the present invention has been described with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined in the following claims. It can be understood that

10: sintered magnet 20: heavy rare earth coating sheet
21: metal sheet 22: heavy rare earth paste

Claims (7)

A preparation process of applying a heavy rare earth paste containing a heavy rare earth element to the surface of a metal sheet to prepare a heavy rare earth coating sheet;
A cutting process for cutting the heavy rare earth coated sheet;
Wrapping the surface of the sintered magnet with the heavy rare earth element coated sheet such that the heavy rare earth paste is in contact with the surface of the sintered magnet; And
And a primary heat treatment step of heating the sintered magnet packed with the heavy rare earth element coated sheet to form a metal coating layer on the surface of the sintered magnet while diffusing the heavy rare earth element contained in the heavy rare earth paste into the sintered magnet Wherein the rare earth permanent magnet is produced by the following method.
The method according to claim 1,
In the heavy rare earth paste,
Wherein a rare earth element is mixed with an adhesive and ethanol.
The method of claim 2,
Wherein the heavy rare earth element comprises at least one of dysprosium (Dy) and terbium (Tb).
The method of claim 2,
Wherein the adhesive is a ceramic adhesive comprising alumina (Al 2 O 3 ) and silica (SiO 2 ).

The method according to claim 1,
The metal sheet may include:
Wherein the Ni-Zn thin film sheet is a Ni-Zn thin film sheet having a thickness of 5 to 30 mu m.
The method according to claim 1,
In the first heat treatment process,
Treated at 800 to 900 占 폚 in an inert atmosphere for 8 to 12 hours to form a metal coating layer on the surface of the sintered magnet while intergranularly diffusing the heavy rare earth element into the sintered magnet.
The method of claim 6,
After the first heat treatment process,
A cooling process for cooling the sintered magnet in which heavy rare earth elements are intergranular diffused by using an inert gas; And
Further comprising a second heat treatment step of performing heat treatment in an inert atmosphere at a temperature of 500 to 700 ° C for 1 to 2 hours to remove stress of the sintered magnet having intergranular rare earth elements diffused therein.
KR1020150169995A 2015-12-01 2015-12-01 Method for preparing rare-earth permanent magnet KR101704298B1 (en)

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN113299476A (en) * 2021-06-24 2021-08-24 安徽大地熊新材料股份有限公司 Large-size neodymium iron boron diffusion magnet and preparation method thereof
CN113555176A (en) * 2020-04-23 2021-10-26 现代自动车株式会社 Method for manufacturing rare earth permanent magnet and rare earth permanent magnet manufactured thereby

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Publication number Priority date Publication date Assignee Title
CN113555176A (en) * 2020-04-23 2021-10-26 现代自动车株式会社 Method for manufacturing rare earth permanent magnet and rare earth permanent magnet manufactured thereby
US20210335540A1 (en) * 2020-04-23 2021-10-28 Hyundai Motor Company Method of manufacturing rare-earth permanent magnet and rare-earth permanent magnet manufactured by the same
CN113299476A (en) * 2021-06-24 2021-08-24 安徽大地熊新材料股份有限公司 Large-size neodymium iron boron diffusion magnet and preparation method thereof
CN113299476B (en) * 2021-06-24 2023-02-17 安徽大地熊新材料股份有限公司 Large-size neodymium iron boron diffusion magnet and preparation method thereof

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