CN115621028A - High-orientation-degree sintered neodymium-iron-boron magnet and preparation method thereof - Google Patents

High-orientation-degree sintered neodymium-iron-boron magnet and preparation method thereof Download PDF

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CN115621028A
CN115621028A CN202211253362.2A CN202211253362A CN115621028A CN 115621028 A CN115621028 A CN 115621028A CN 202211253362 A CN202211253362 A CN 202211253362A CN 115621028 A CN115621028 A CN 115621028A
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orientation
magnetic field
iron boron
neodymium iron
boron
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钟俊杰
陈翔
何厚生
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Anhui Hanhai New Material Co ltd
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Anhui Hanhai New Material Co ltd
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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
    • H01F41/0273—Imparting anisotropy
    • 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
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0576—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together pressed, e.g. hot working
    • 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
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
    • 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
    • H01F41/0266—Moulding; Pressing

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

Abstract

The invention relates to the technical field of rare earth permanent magnet materials, in particular to a high-orientation-degree sintered neodymium-iron-boron magnet and a preparation method thereof, wherein the method comprises the steps of placing neodymium-iron-boron powder in a mold, arranging an ultrasonic transducer outside the mold, and connecting the ultrasonic transducer with an ultrasonic generator; then, the mould is placed in an alternating magnetic field, ultrasonic vibration is assisted, directional pre-adjustment is carried out, then the mould is adjusted into a constant magnetic field, and final orientation is carried out; the invention carries on the directional preconditioning of the magnetic powder through exerting the alternating magnetic field, in this process, assist with the ultrasonic vibration, increase the displacement amplitude of the magnetic powder, guarantee each magnetic particle is not influenced each other while formal orientation, in order to obtain the high degree of orientation; the technical scheme provided by the invention overcomes the defects existing in the prior art that the fluidity of magnetic powder is improved by introducing a solvent, so that the orientation degree of the magnetic powder is improved, and has the advantages of simple operation steps, small influence on a product system and good stability after orientation.

Description

High-orientation-degree sintered neodymium-iron-boron magnet and preparation method thereof
Technical Field
The invention relates to the technical field of rare earth permanent magnet materials, in particular to a high-orientation-degree sintered neodymium iron boron magnet and a preparation method thereof.
Background
The Nd-Fe-B magnet becomes a rare earth permanent magnet material with the highest comprehensive hard magnetic performance and the fastest development since the emergence of the Nd-Fe-B magnet in 1983, the Nd-Fe-B magnet is called a third generation rare earth permanent magnet material, and the theoretical magnetic energy product of the Nd-Fe-B magnet material can reach 512kJ/m 3 。
The magnetic energy product of the magnet material depends on the remanence and the coercive force, and under the condition that the coercive force is high enough, the improvement of the remanence of the magnet is a key factor for preparing the high-performance neodymium iron boron magnet. Remanence is mainly determined by the saturation magnetization, the degree of orientation and the density of the material. To improve the orientation degree of the magnet, various methods can be adopted, for example, the process conditions of the rapid cooling cast sheet are adjusted, the orientation degree can be improved by preparing fine alloy sheets with uniform structures, and the fluidity during magnetic powder compression molding is a key factor influencing the orientation degree.
In the prior art, for example, chinese patent with publication number "CN 105931833A" discloses a method for preparing a sintered nd-fe-b permanent magnet material with high orientation degree, and specifically discloses mixing nd-fe-b powder particles with an organic solvent to prepare a slurry, pouring the slurry into a mold, performing non-pressure orientation in a magnetic field to obtain high orientation degree, obtaining a green body with a certain density through cold isostatic pressing, and finally performing sintering densification and tempering heat treatment to obtain a magnet. In the specific embodiment part, the maximum magnetic energy product of the sintered NdFeB permanent magnet material prepared based on the technical scheme reaches 422kJ/m 3 。
Also, for example, chinese patent publication No. CN 107393709A discloses a method for preparing a high-orientation anisotropic bonded magnet by cold isostatic pressing, in which a thermosetting resin, a curing agent, and an organic solvent equivalent to 40wt% to 150wt% of the thermosetting resin are uniformly mixed to prepare a binder premix, 30Vol% to 60Vol% of anisotropic bonded magnetic powder is added to a binder solution, and the mixture is uniformly stirred to prepare a low-viscosity high-suspension magnetic slurry; the solvent plays a role of a lubricant when the magnetic slurry is oriented;
also, as disclosed in chinese patent publication No. CN 115050564A, a high-orientation neodymium iron boron magnet and a method for preparing the same are disclosed, in the technical scheme, an acrylic emulsion is specifically used as an organic solvent, a wetting effect of the acrylic emulsion is utilized to perform primary orientation on powder, primary orientation treatment is realized through the primary orientation, primary curing is realized after drying of the surface by heat drying, then vacuum pressing is performed, residual acrylic emulsion is removed through a low-pressure immersion cleaning mode, secondary orientation is performed at the same time, the strength of an orientation magnetic field is increased in the orientation process, and final high orientation is realized.
It should be noted that, the above prior art solutions all include a method of adding additional raw materials to increase the flowability of the powder so that the powder obtains a higher degree of orientation in the magnetic field, however, these additional raw materials added in the system all need to be removed by adding additional steps, which not only causes the steps of powder treatment to become complicated, but also causes the highly oriented magnetic powder to easily lose a certain degree of orientation during subsequent impurity removal, and results cannot be expected.
Disclosure of Invention
The embodiment of the invention aims to provide a preparation method of a high-orientation-degree sintered neodymium-iron-boron magnet, which overcomes the defects of the existing method of improving powder flowability by adding raw materials.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for preparing a high-orientation degree sintered neodymium-iron-boron magnet comprises the steps of placing neodymium-iron-boron powder in a mold, wherein an ultrasonic transducer is arranged outside the mold and connected with an ultrasonic generator; then the mould is firstly placed in an alternating magnetic field, ultrasonic vibration is assisted, directional pre-adjustment is carried out, then the mould is adjusted to be a constant magnetic field, and final orientation is carried out.
In a further technical solution, the method further comprises: and putting the finally oriented powder into a hydraulic device for cold isostatic pressing, wherein the pressing force is 100-300MPa, and obtaining a pressed compact.
In a further technical solution, the method further comprises: putting the pressed blank into a 1050-1080 ℃ vacuum sintering furnace for sintering and forming, then directly filling normal-temperature argon or liquid argon into the sintering furnace, rapidly cooling to below 60 ℃, discharging, and preparing a sintered neodymium iron boron green body;
and machining the sintered neodymium iron boron blank to obtain a neodymium iron boron semi-finished product, performing two-stage heat treatment on the neodymium iron boron semi-finished product, cooling to below 60 ℃, and discharging to obtain a neodymium iron boron finished product.
In a further technical scheme, the two-stage heat treatment of the neodymium iron boron semi-finished product specifically comprises the following steps:
primary heat treatment: placing the neodymium iron boron semi-finished product in a vacuum sintering furnace, raising the temperature of the vacuum sintering furnace to 890-920 ℃, and carrying out heat preservation treatment for 2.5-4h;
secondary heat treatment: controlling the temperature of the vacuum sintering furnace to be 480-520 ℃, and carrying out heat preservation treatment for 3.5-6h.
In a further technical scheme, the ultrasonic transducer can generate high-frequency vibration of 20-60kHz on the mold.
In a further technical scheme, the frequency of the alternating magnetic field is 10-50Hz, and the magnetic field intensity is 1.0-2.5T.
In a further technical scheme, the strength of the constant magnetic field is 1.5-3T.
The invention also provides a high-orientation degree sintered neodymium-iron-boron magnet prepared based on the method.
Compared with the prior art, in the technical scheme provided by the invention, when the magnetic powder is oriented by the external magnetic field, the alternating magnetic field is applied firstly, so that the magnetic powder particles continuously rotate and displace, the magnetic powder particles are mutually dislocated, the position is vacated, and preparation is made for subsequent formal orientation. Through the technical scheme provided by the invention, the magnetic powder particles are ensured not to be influenced mutually, so that the integral orientation degree is improved.
The technical scheme provided by the invention overcomes the defects that the fluidity of magnetic powder is improved by introducing a solvent in the prior art, so that the orientation degree of the magnetic powder is improved, and has the advantages of simple operation steps, small influence on a product system and good stability after orientation.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
In order to make the technical means, the creation features, the achievement purposes and the effects of the invention easy to understand, the invention is further clarified with the specific embodiments.
As mentioned above, the invention provides a method for preparing a high-orientation degree sintered neodymium-iron-boron magnet, which comprises the steps of placing neodymium-iron-boron powder in a mold, wherein an ultrasonic transducer is arranged outside the mold and connected with an ultrasonic generator; then the mould is firstly placed in an alternating magnetic field, ultrasonic vibration is assisted, directional pre-adjustment is carried out, then the mould is adjusted to be a constant magnetic field, and final orientation is carried out.
According to the technical scheme, when the magnetic powder is oriented by the external magnetic field, the alternating magnetic field is applied firstly, so that the magnetic powder particles continuously rotate and displace, the magnetic powder particles are mutually dislocated, the position is vacated, and preparation is made for subsequent formal orientation. By the technical scheme provided by the invention, the magnetic powder particles are not influenced mutually, so that the integral orientation degree is improved.
It should be noted that, in the present invention, the ultrasonic transducer and the ultrasonic generator together form an ultrasonic vibration system, and the ultrasonic vibration system can convert 220V and 50Hz electric energy into high frequency electric energy, and then convert the high frequency electric energy into high frequency vibration by the ultrasonic transducer, so that the magnetic powder in the mold receives a great ultrasonic acceleration, and the directional pre-adjustment of the magnetic powder in the mold is realized by matching with the alternating magnetic field.
In some embodiments, the ultrasonic transducer may generate 20-60kHz high frequency vibrations on the mold.
The frequency of the alternating magnetic field is 10-50Hz, and the magnetic field intensity is 1.0-2.5T.
The strength of the constant magnetic field is 1.5-3T.
Further, according to the invention, the method also comprises the step of putting the finally oriented powder into a hydraulic device for cold isostatic pressing, wherein the pressing force is 100-300MPa, and a green compact is obtained. It should be noted that, by adopting isostatic cool pressing, the pressures from all directions are equal, so that the obtained high orientation degree cannot be damaged, and the pressed compact density distribution is uniform, thereby greatly improving the problems of uneven shrinkage caused by uneven sintering density, and further crack generation and edge-knocking corner dropping.
Further, according to the invention, the method also comprises the steps of putting the pressed blank into a 1050-1080 ℃ vacuum sintering furnace for sintering and forming, then directly filling normal-temperature argon or liquid argon into the sintering furnace, rapidly cooling to below 60 ℃ and discharging to obtain a sintered neodymium iron boron green body;
and machining the sintered neodymium iron boron blank to obtain a neodymium iron boron semi-finished product, performing two-stage heat treatment on the neodymium iron boron semi-finished product, cooling to below 60 ℃, and discharging to obtain a neodymium iron boron finished product.
In the traditional preparation process, after a blank is pressed by utilizing magnetic field orientation, the blank is sintered in a high vacuum or pure inert atmosphere to reach a high density of over 95 percent of theoretical density, two-stage heat treatment at the temperature of about 900 ℃ and at the temperature of about 500 ℃ is carried out to ensure that a neodymium iron boron finished product obtains high coercive force, and then the sintered blank is mechanically processed according to the shape and size precision of practical application. However, in the existing preparation process, for the blank with a larger specification and size, the processing time is inevitably prolonged to ensure that the intrinsic coercivity of the blank in the depth direction achieves better consistency, which leads to high production cost and high energy consumption of equipment.
According to the scheme, the tempering operation is not performed after the high-temperature sintering process is finished, but the high-temperature sintering process directly enters the machining process, so that the specification and the size of the neodymium iron boron product to be tempered are reduced, and then the heat treatment is performed, so that the problem that the tempering heat treatment is insufficient for large-size blanks in the early stage is directly avoided, the heat treatment efficiency is directly and effectively improved, the heat treatment effect is improved, and the heat treatment is more sufficient; moreover, by adopting the technical scheme, the tempering heat treatment process after high-temperature sintering is omitted, the time for preparing the neodymium iron boron is shortened, and the energy consumption of equipment is reduced.
In the invention, the effect of improving the intrinsic coercivity is achieved by performing two-stage heat treatment on the machined neodymium iron boron semi-finished product with smaller specification size, and in some embodiments, the two-stage heat treatment performed on the neodymium iron boron semi-finished product specifically comprises:
primary heat treatment: placing the neodymium iron boron semi-finished product in a vacuum sintering furnace, raising the temperature of the vacuum sintering furnace to 890-920 ℃, and carrying out heat preservation treatment for 2.5-4h;
secondary heat treatment: controlling the temperature of the vacuum sintering furnace to be 480-520 ℃, and carrying out heat preservation treatment for 3.5-6h.
As known to those skilled in the art, in NdFeB magnets, nd 2 Fe 14 Phase B (T) 1 Phase) + Nd 1.1 Fe 4 B 4 Phase (T) 2 Phase) has a grain refining point of about 900 deg.C, T 1 +T 2 The ternary eutectic temperature point of the + Nd-rich phase is about 500 ℃; in the process of heat treatment, the temperature is controlled to be close to the temperature points and is kept, so that the internal structure of the neodymium iron boron magnet is stabilized in the same state, the generation of abnormal phase structures is reduced, and the consistency of intrinsic coercivity of the neodymium iron boron semi-finished product in the thickness direction is ensured.
Further preferably, in the first-stage heat treatment, the temperature of the vacuum sintering furnace is preferably controlled to be 900-910 ℃, and the holding time is preferably 3-3.5h.
Further preferably, in the secondary heat treatment, the temperature of the vacuum sintering furnace is preferably controlled to be 500-510 ℃, and the holding time is preferably 4-5h.
According to the method provided by the invention, in the processes of primary heat treatment and secondary heat treatment, the temperature rise rate of the vacuum sintering furnace is 2-6 ℃/min.
After the primary heat treatment is finished, the temperature in the air-cooled vacuum sintering furnace is firstly increased to 75-85 ℃, and then the temperature is increased to enter the secondary heat treatment. Further preferably, in the air cooling process, the temperature reduction rate of the vacuum sintering furnace is controlled to be 4-10 ℃/min.
The preparation method of the high-orientation degree sintered neodymium-iron-boron magnet provided by the invention is further explained by specific examples.
It should be noted that the neodymium iron boron powder used in the following examples is prepared according to the conventional preparation process, and has an average particle size of 3.5 μm and a component of Nd 29.5 Fe 69.1 Ga 0.2 Nb 0.2 B 1.0 。
Example 1
In this example, neodymium iron boron powder (Nd) 29.5 Fe 69.1 Ga 0.2 Nb 0.2 B 1.0 ) The ultrasonic transducer is arranged in a mould, the outside of the mould is provided with the ultrasonic transducer, the ultrasonic transducer is connected with an ultrasonic generator, and the ultrasonic transducer can generate high-frequency vibration of 20-60kHz on the mould;
placing the die in an alternating magnetic field, and performing directional pre-adjustment by assisting ultrasonic vibration, wherein the frequency of the alternating magnetic field is 20Hz, and the magnetic field intensity is 2.0T;
adjusting the magnetic field environment to be a constant magnetic field, and carrying out final orientation, wherein the strength of the constant magnetic field is 2.5T;
placing the finally oriented powder into a hydraulic device for cold isostatic pressing, wherein the pressing force is 200MPa, and obtaining a pressed blank;
putting the pressed blank into a vacuum sintering furnace at 1080 ℃ for sintering and forming, then directly filling normal-temperature argon or liquid argon into the sintering furnace, rapidly cooling to below 60 ℃, discharging, and preparing a sintered neodymium iron boron green body;
and machining the sintered neodymium iron boron blank to obtain a neodymium iron boron semi-finished product, performing two-stage heat treatment on the neodymium iron boron semi-finished product, cooling to below 60 ℃, and discharging to obtain a neodymium iron boron finished product.
The two-stage heat treatment of the neodymium iron boron semi-finished product specifically comprises the following steps:
primary heat treatment: placing the neodymium iron boron semi-finished product in a vacuum sintering furnace, raising the temperature of the vacuum sintering furnace to 910 ℃ at the temperature rise rate of 5 ℃/min, and carrying out heat preservation treatment for 3h;
air-cooling the vacuum sintering furnace, and reducing the temperature of the vacuum sintering furnace to 80 ℃ at a cooling rate of 5 ℃/min;
secondary heat treatment: controlling the temperature of the vacuum sintering furnace to 510 ℃ at the heating rate of 5 ℃/min, and carrying out heat preservation treatment for 4h.
Through tests, the magnetic performance of the finished neodymium iron boron product is as follows: br =1.486T, hci =1208kA/m, (BH) max =438kJ/m 3 。
Cutting the prepared neodymium iron boron finished product, respectively testing the intrinsic coercive force of the inner side and the outer side, wherein the difference value of the intrinsic coercive force of the inner side and the outer side is 2.6Oe through the test; therefore, the neodymium iron boron finished product has better consistency of intrinsic coercive force.
The foregoing shows and describes the general principles, essential features, and inventive features of this invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (8)

1. A method for preparing a high-orientation degree sintered neodymium-iron-boron magnet is characterized by comprising the steps of placing neodymium-iron-boron powder in a mold, wherein an ultrasonic transducer is arranged outside the mold and connected with an ultrasonic generator; then the mould is firstly placed in an alternating magnetic field, ultrasonic vibration is assisted, directional pre-adjustment is carried out, then the mould is adjusted to be a constant magnetic field, and final orientation is carried out.
2. The method of claim 1, further comprising: and putting the finally oriented powder into a hydraulic device for cold isostatic pressing, wherein the pressing force is 100-300MPa, and obtaining a pressed compact.
3. The method of claim 2, further comprising: putting the pressed blank into a 1050-1080 ℃ vacuum sintering furnace for sintering and forming, then directly filling normal-temperature argon or liquid argon into the sintering furnace, rapidly cooling to below 60 ℃, discharging, and preparing a sintered neodymium iron boron green body;
and machining the sintered neodymium iron boron blank to obtain a neodymium iron boron semi-finished product, performing two-stage heat treatment on the neodymium iron boron semi-finished product, cooling to below 60 ℃, and discharging to obtain a neodymium iron boron finished product.
4. The method according to claim 3, wherein the two-stage heat treatment of the neodymium iron boron semi-finished product is specifically:
primary heat treatment: placing the neodymium iron boron semi-finished product in a vacuum sintering furnace, raising the temperature of the vacuum sintering furnace to 890-920 ℃, and carrying out heat preservation treatment for 2.5-4h;
secondary heat treatment: controlling the temperature of the vacuum sintering furnace to be 480-520 ℃, and carrying out heat preservation treatment for 3.5-6h.
5. The method according to claim 1, wherein the ultrasonic transducer is capable of generating high frequency vibrations on the mold at 20-60 kHz.
6. The method of claim 1, wherein the alternating magnetic field has a frequency of 10-50Hz and a magnetic field strength of 1.0-2.5T.
7. The method according to claim 1, wherein the strength of the constant magnetic field is 1.5-3T.
8. The high-orientation degree sintered neodymium-iron-boron magnet prepared according to the method of any one of claims 1 to 7.
CN202211253362.2A 2022-10-13 2022-10-13 High-orientation-degree sintered neodymium-iron-boron magnet and preparation method thereof Pending CN115621028A (en)

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