CN113299476B - Large-size neodymium iron boron diffusion magnet and preparation method thereof - Google Patents
Large-size neodymium iron boron diffusion magnet and preparation method thereof Download PDFInfo
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- CN113299476B CN113299476B CN202110706856.0A CN202110706856A CN113299476B CN 113299476 B CN113299476 B CN 113299476B CN 202110706856 A CN202110706856 A CN 202110706856A CN 113299476 B CN113299476 B CN 113299476B
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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
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- 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
Abstract
The invention discloses a large-size neodymium iron boron diffusion magnet and a preparation method thereof, wherein the preparation method comprises the steps of firstly forming a heavy rare earth metal layer on the surface of a metal foil to obtain a modified metal foil; then combining N pieces of neodymium iron boron magnets to be diffused and sintered with N-1 pieces of the modified metal foil to obtain a combined body; and finally, carrying out heat treatment on the combined body to obtain the large-size neodymium iron boron diffusion magnet. The preparation method has the advantages of simple process, strong flexibility, realization of two working procedures of diffusion and bonding in one heat treatment process, and low energy consumption. The metal foil is thin, heavy rare earth participates in diffusion in the form of metal simple substances, the diffusion effect is better, the performance of the magnet after diffusion bonding is higher, and the application prospect is achieved.
Description
Technical Field
The invention belongs to the field of rare earth permanent magnet materials, and particularly relates to a preparation method of a large-size neodymium iron boron diffusion magnet, and the large-size neodymium iron boron diffusion magnet obtained by diffusion through the preparation method.
Background
The sintered neodymium-iron-boron magnet is a magnetic material with the strongest magnetism so far, is widely applied to the fields of aerospace, automobile industry, electronic and electric appliances, medical instruments, energy-saving motors, new energy, wind power generation and the like, and is a permanent magnetic material with the fastest development and the best market prospect at present. The sintered neodymium-iron-boron magnet has the outstanding advantages of high magnetic energy product, high coercive force, high energy density, high cost performance, good mechanical property and the like, and plays an important role in the high and new technology field. Through research and development for more than 30 years, reasonable alloy components and mature preparation technology are provided, so that the residual magnetism and the maximum magnetic energy product of the sintered neodymium-iron-boron magnet reach more than 90% of a theoretical value, but the coercive force of the sintered neodymium-iron-boron magnet is less than 30% of the theoretical value, and how to improve the coercive force of the sintered neodymium-iron-boron magnet becomes a key problem in the magnetic material industry.
At present, the common method for preparing the high-coercivity sintered neodymium-iron-boron magnet is to add heavy rare earth elements Dy and/or Tb, and mainly comprises three modes: (1) Dy and/or Tb metal is directly added during alloy smelting; (2) Adding powder containing Dy and/or Tb into the powder in a double-alloy mode; (3) Dy and/or Tb are/is diffused in the sintered NdFeB magnet through the intergranular rare earth-rich phase. Among the three ways, the sintered NdFeB magnet containing Dy and/or Tb is prepared by a grain boundary diffusion way, has higher comprehensive magnetic performance, only needs to consume a small amount of Dy and/or Tb, and is the most studied way at present.
The common sintered NdFeB magnet grain boundary diffusion method comprises the following steps: surface coating + heat treatment, vapor deposition + heat treatment, magnetron sputtering + heat treatment and the like. However, the diffusion speed of the heavy rare earth element Dy and/or Tb from the surface of the magnet into the interior of the magnet along the grain boundary of the magnet is very slow, and for a large-sized neodymium iron boron diffusion magnet with the minimum dimension direction exceeding 10mm, the diffusion time is long, a large amount of energy is consumed, and the production efficiency is low, so that the minimum dimension direction of the general diffusion magnet needs to be less than 6mm. . Aiming at the diffusion of a large-size (the minimum size direction is more than or equal to 10 mm) NdFeB magnet, the currently disclosed scheme mainly comprises the following steps:
a process for preparing composite magnetic body from Nd-Fe-B magnetic sheets is disclosed in Chinese patent application with publication No. CN103839669A, which features that multiple magnetic sheets with surface roughness Ra less than 10.0 microns are combined and contact with each other by self-weight and/or pressurizing mode, and the pressure on the contact surface between magnetic sheets is 0.002kg/cm 2 ～100.0kg/cm 2 (ii) a The magnetic sheet is heat treated at 600-1100 deg.c for 1.0-24.0 hr. The method can be used for manufacturing the neodymium iron boron magnetic sheet manufactured based on the grain boundary diffusion process into the composite magnet with any thickness.
Chinese patent application publication No. CN107958761a discloses a welded ndfeb magnet and a method for manufacturing the same, which comprises slicing a sintered ndfeb magnet, stacking the Dy-infiltrated or Tb-infiltrated thin magnets in the thickness direction, and performing welding heat treatment at 880920 ℃. The method overcomes the defect that the prior traditional method can not prepare the high-performance and high-coercivity magnet, and simultaneously overcomes the defect that the bulk thickness neodymium iron boron magnet can not be prepared by Dy or Tb permeation treatment.
The Chinese patent application with the publication number of CN109003802A discloses a method for preparing a low-cost high-performance bulk neodymium-iron-boron magnet by grain boundary diffusion, which selects dysprosium, terbium, iron, aluminum, copper and gallium alloy powder as a diffusion source to be coated on an oriented or non-oriented surface of 2-8 mm, and then selects a proper number of magnets to be overlaid and put into a sintering furnace for diffusion bonding treatment according to the final size of a finished product to obtain the bulk high-performance sintered magnet. The neodymium iron boron magnet prepared by the method has high performance and low cost.
Chinese patent application publication No. CN110993311a discloses a method for preparing a high-performance bulk neodymium-iron-boron magnet by grain boundary diffusion, wherein one coated surface of each thin sheet neodymium-iron-boron magnet is coated with an RxMy alloy film layer, the other coated surface is coated with a GaFb alloy film layer, a plurality of thin sheets of neodymium-iron-boron magnets coated with the RxMy alloy film layers and the GaFb alloy film layers are laminated and arranged in the thickness direction without intervals to obtain a laminated parison, and then the laminated parison is subjected to heat treatment in a vacuum environment or an inert gas protection environment to obtain the high-performance bulk neodymium-iron-boron magnet. In the heat treatment process, element interdiffusion occurs between each thin neodymium iron boron magnet and the RxMy alloy film layer and the GaFb alloy film layer which are coated on the thin neodymium iron boron magnet to form a transition layer; the preparation method has the advantages that the limitation of a crystal boundary diffusion technology on the size of the neodymium iron boron magnet is broken through, the preparation of the high-performance bulk neodymium iron boron magnet is realized, the coercive force of the bulk neodymium iron boron magnet is obviously improved, and the influence on remanence is reduced.
The prior art implementation steps are mainly to bring the diffusion source into contact with the magnet in some way, or to subject the magnet to a diffusion heat treatment, or to bond the diffused magnet into a bulk. Although the above prior art is capable of achieving the preparation of bulk diffusion magnets, there are some problems, mainly including: (1) the contact process of the diffusion source and the magnet is complex and has poor flexibility, and (2) the diffusion heat treatment and the bonding are divided into two procedures, two heat treatments are needed, the process flow is long, and the energy consumption is large.
Further, chinese patent application No. CN111599587a discloses a method for preparing a large-size heat-deformable ndfeb magnet, which first uses a strip-casting method to prepare a low-melting-point rare earth alloy thin strip as a welding agent, and sandwiches a diffusion alloy thin strip between two to-be-welded heat-deformable ndfeb magnets, and performs heat treatment to prepare the large-size high-coercivity heat-deformable ndfeb magnet.
The technology effectively overcomes the problems of the prior diffusion technology, but has the defects that the technology mainly comprises the following steps: (1) the rare earth alloy thin strip prepared by the strip casting method has thicker thickness (between 30 and 100 mu m), and the thicker alloy thin strip can reduce the overall magnetic performance of the magnet because the rare earth alloy thin strip is a non-magnetic substance; (2) in the thicker rare earth alloy thin strip, a certain rare earth percentage content is needed to ensure the coercive force of the final magnet, more rare earth elements are needed to be added to ensure the rare earth percentage content, otherwise, the percentage content of the rare earth elements is too low, and the improvement on the coercive force of the final magnet is very limited; (3) the alloy used is M-Cu alloy, M is Pr, nd or Dy, and after alloying, the chemical activity of rare earth elements is reduced, the diffusion power is insufficient, and the diffusion effect is limited.
Disclosure of Invention
In view of the above, the present invention needs to provide a method for preparing a large-sized ndfeb diffusion magnet, in which a modified aluminum foil or copper foil is used as a diffusion source and an adhesive to diffuse and bond a plurality of magnets, so as to obtain a large-sized diffusion magnet. The contact process of the diffusion source and the magnet is simple, the flexibility is strong, two working procedures of diffusion and bonding are simultaneously realized in one heat treatment process, the process flow is short, and the energy consumption is low. And because the thickness of the copper foil or the aluminum foil is thinner, the heavy rare earth takes part in diffusion in the form of a metal simple substance, the diffusion effect is better, and the performance of the magnet after diffusion bonding is higher.
In order to achieve the purpose, the invention provides a preparation method of a large-size neodymium iron boron diffusion magnet, which comprises the following steps:
forming a heavy rare earth metal layer on the surface of a metal foil to obtain a modified metal foil, wherein the metal foil is an aluminum foil or a copper foil;
combining N pieces of neodymium iron boron magnets to be diffused and sintered and N-1 pieces of the modified metal foils to obtain a combined body, wherein N is more than or equal to 3, and the modified metal foils are respectively arranged between the adjacent neodymium iron boron magnets to be diffused and sintered;
and carrying out heat treatment on the combined body to obtain the large-size neodymium iron boron diffusion magnet.
Further, the thickness of the metal foil is 1-8 μm; heavy rare earth metal layers are formed on two surfaces of the metal foil, and the total thickness of the heavy rare earth metal layers is 6-20 mu m.
In a further scheme, the heavy rare earth metal layer is formed on the surface of the metal foil in a deposition mode, and the deposition mode is selected from one of magnetron sputtering, thermal evaporation and multi-arc ion plating.
In a further aspect, the heavy rare earth metal in the heavy rare earth metal layer is selected from dysprosium or terbium.
In a further scheme, the neodymium iron boron magnet to be diffused is prepared by RE 2 Fe 14 A magnet in which phase B is a main magnetic phase, wherein RE is at least one of rare earth elements;
the thickness of the neodymium iron boron magnet to be diffused and sintered in the minimum size direction is 3-6mm.
Further scheme, in the combination, the thickness of the 1 st piece of sintered neodymium iron magnetic body and the N piece of sintered neodymium iron boron magnetic body equals, is half of all the other magnet thickness respectively.
In a further scheme, the temperature of the heat treatment is 850-950 ℃, and the heat preservation time is 5-30h.
Further, the heat treatment is carried out while a pressure of 0.1 to 10MPa is applied in the combined direction of the assembly.
In a further scheme, the heat treatment also comprises secondary heat treatment, wherein the temperature of the secondary heat treatment is 460-600 ℃, and the time is 3-6h.
The invention also provides a large-size neodymium iron boron diffusion magnet which is obtained by adopting the preparation method of any one of the above-mentioned materials.
Compared with the prior art, the invention has the following beneficial effects:
compared with the coating diffusion and coating diffusion processes, the preparation method provided by the invention omits the processes of coating and coating on the surface of the magnet, can be used for carrying out batch deposition modification on the metal foil, and then cutting the metal foil into a required shape for diffusion of magnets to be diffused with different sizes, and has the characteristics of flexible process and easiness in operation. Compared with the diffusion magnet combined bonding technology, the invention combines the magnet diffusion and bonding procedures into a whole, realizes diffusion and bonding in one heat treatment process, shortens the heat treatment time and saves the energy.
In the preparation method, the copper foil or the aluminum foil is thinner, and the overall thickness of the modified metal foil is also thinner, so that the influence of the addition of the modified metal foil on the remanence of the magnet is smaller. Under the condition that the total rare earth content in the modified metal foil and the rare earth alloy thin strip is the same, the modified metal foil is thinner, so that the mass fraction of the rare earth is higher, and the diffusion effect is better; under the condition that the percentage content of the rare earth in the modified metal foil is the same as that in the rare earth alloy thin strip, the total amount of the rare earth in the modified metal foil is less due to the thinner thickness of the modified metal foil, so that the rare earth resource can be saved. Meanwhile, the heavy rare earth in the diffusion method takes part in diffusion in the form of metal simple substances, the diffusion effect is better, and the performance of the magnet after diffusion bonding is higher.
The diffusion method can be used for preparing the large-size neodymium iron boron magnet with the minimum size direction larger than 10mm, and the large-size neodymium iron boron magnet obtained by the diffusion method has high coercivity.
Detailed Description
In order that the invention may be more fully understood, reference will now be made to the specific embodiments illustrated. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The invention provides a preparation method of a large-size neodymium iron boron diffusion magnet, which comprises the following steps:
forming a heavy rare earth metal layer on the surface of a metal foil to obtain a modified metal foil, wherein the metal foil is an aluminum foil or a copper foil;
combining N pieces of neodymium iron boron magnets to be diffused and sintered and N-1 pieces of the modified metal foils to obtain a combined body, wherein N is more than or equal to 3, and the modified metal foils are respectively arranged between the adjacent neodymium iron boron magnets to be diffused and sintered;
and carrying out heat treatment on the combined body to obtain the large-size neodymium iron boron diffusion magnet.
According to the invention, the modified metal foil is obtained by forming the heavy rare earth metal layer on the surface of the metal foil, and then the modified metal foil is directly attached to the sintered neodymium-iron-boron magnet to be diffused, so that the processes of coating, coating and the like on the surface of the magnet are omitted, wherein the metal foil can be subjected to batch deposition modification and then cut into a required shape for diffusion of the magnets to be diffused with different sizes, and the process is flexible and easy to operate; the modified metal foil is used as a diffusion source and an adhesive, so that the diffusion and the adhesion of a plurality of magnets are realized in the one-time heat treatment process, and finally, a large-size diffusion magnet is obtained, and the process flow is short and the energy consumption is low. The diffusion method has small influence on the remanence of the magnet, the diffusion effect is good, and the performance of the diffused magnet is good.
Furthermore, the thickness of the metal foil and the thickness of the heavy rare earth metal layer in the invention can be adjusted according to the needs, on one hand, the diffusion effect is ensured, the performance of the magnet is improved, on the other hand, the remanence of the magnet is not influenced, and in one or more embodiments of the invention, the thickness of the metal foil is 1-8 μm; heavy rare earth metal layers are formed on two surfaces of the metal foil, and the total thickness of the heavy rare earth metal layers is 6-20 mu m.
Further, the forming method of the heavy rare earth metal layer in the present invention is not particularly limited, and a method conventional in the art may be adopted, and in one or more embodiments of the present invention, the heavy rare earth metal layer is formed on the surface of the metal foil by deposition, and further, in one or more embodiments of the present invention, the deposition method is selected from one of magnetron sputtering, thermal evaporation, and multi-arc ion plating, and it is understood that the selection of the deposition method is not particularly limited, and since the deposition methods are all known in the art, they will not be specifically described herein.
Further, the choice of the heavy rare earth metal in the heavy rare earth metal layer in the present invention is not particularly limited, and any heavy rare earth metal that can be used in the art for magnet diffusion can be used in the present invention, and in one or more embodiments of the present invention, the heavy rare earth metal in the heavy rare earth metal layer is selected from dysprosium or terbium.
Further, in one or more embodiments of the present invention, the ndfeb magnet to be diffusion-sintered is RE 2 Fe 14 And a B phase which is a magnet of a main magnetic phase, wherein RE is at least one of rare earth elements. It is to be understood that sintered nd-fe-b magnets conventionally used in the art may be used in the present invention without particular limitations on specific compositions thereof, and the like.
In one or more embodiments of the present invention, the thickness of the ndfeb magnet to be diffusion-sintered in the minimum dimension direction is 3-6mm, and the minimum dimension direction may form any angle with the easy magnetization direction of the magnet.
Further, in the combination, because the 1 st piece that is located the combination outside is waited to diffuse the sintered neodymium iron magnet and the N is waited to diffuse the sintered neodymium iron boron magnet and is all single face diffusion, and the magnet of combination inside is two-sided diffusion, consequently, the thickness of 1 st piece magnet and N magnet equals, is half of all the other arbitrary magnet thickness in the combination respectively.
Further, the magnet is generally subjected to a heat treatment after diffusion, and since the magnet heat treatment is known in the art, adjustments to the heat treatment parameters can be made based on experience in the art, in one or more implementations of the invention, the heat treatment is at a temperature of 850 ℃ to 950 ℃ and for a holding time of 5 to 30 hours.
In one or more embodiments of the present invention, as a preferable aspect of the present invention, the heat treatment is performed while applying a pressure of 0.1 to 10MPa in the direction of assembly of the assembly, and the diffusion effect of the magnet is promoted by pressurization, so that the adhesive strength is increased, thereby further improving the performance of the magnet after diffusion.
In one or more embodiments of the invention, as a preferable method of the invention, the heat treatment further comprises a secondary heat treatment, wherein the temperature of the secondary heat treatment is 460-600 ℃, and the time is 3-6h, and the structural defects and internal stress inside the magnet are eliminated through the secondary heat treatment, so that the structural structure is further optimized, and the performance of the magnet is improved.
The second aspect of the invention provides a large-size neodymium-iron-boron diffusion magnet, which is obtained by adopting the preparation method of the first aspect of the invention.
The technical solution of the present invention will be more clearly and completely described below with reference to specific embodiments.
Example 1
Obtaining the modified aluminum foil
And depositing 3 mu m dysprosium metal layers on two surfaces of the aluminum foil with the thickness of 1 mu m respectively by utilizing a thermal evaporation deposition technology to obtain the modified aluminum foil 1.
To obtain a combined body
Pr with performance of N52 6 Nd 24 Fe 69 B, processing the sintered neodymium-iron-boron magnet into a magnet to be diffused (marked as a magnet to be diffused 1) with the minimum dimension direction of 4mm, wherein the minimum dimension direction is parallel to the easy magnetization direction; 3 pieces of modified aluminum foil 1 are inserted between 4 pieces of magnets to be diffused to obtain a combined body 1, wherein the thickness of the 1 st piece of magnet and the 4 th piece of magnet is 2mm.
Thermal treatment
After the assembly 1 was heat-treated at 850 ℃ for 30 hours, the diffusion magnet was further heat-treated at 500 ℃ for 5 hours to obtain a large-sized neodymium-iron-boron diffusion magnet having a diffusion direction dimension of 12mm, which was designated as sample 1.
Example 2
Obtaining the modified aluminum foil
The same as in example 1.
To obtain a combined body
Pr with performance of 50M 6 Nd 23.5 Dy 0.8 Fe 68.7 B, processing the sintered neodymium-iron-boron magnet into a magnet to be diffused (marked as a magnet to be diffused 2) with the minimum dimension direction of 3mm, wherein the minimum dimension direction is vertical to the easy magnetization direction; 4 pieces of modified aluminum foil 1 are inserted between 5 pieces of magnets to be diffused to obtain a combined body 2, wherein the thickness of the 1 st piece and the 5 th piece of magnets is 1.5mm.
Thermal treatment
After the assembly 2 was heat treated at 875 ℃ for 10 hours, the diffusion magnet was heat treated at 520 ℃ for 5 hours a second time to obtain a large size ndfeb diffusion magnet with a diffusion dimension of 12mm, which was designated as sample 2.
Example 3
Obtaining the modified aluminum foil
And (3) respectively depositing 5 mu m terbium metal layers on two surfaces of the aluminum foil with the thickness of 8 mu m by utilizing a magnetron sputtering coating technology to obtain the modified aluminum foil 2.
To obtain a combined body
Pr with performance of 48H 6 Nd 24.5 Tb 0.8 Fe 67.7 B, processing the sintered neodymium iron boron magnet into a magnet to be diffused (marked as a magnet to be diffused 3) with the minimum dimension direction of 5mm, wherein the minimum dimension direction and the easy magnetization direction form an angle of 45 degrees; 4 pieces of modified aluminum foil 2 are inserted between 5 pieces of magnets to be diffused to obtain a combined body 3, wherein the thickness of the 1 st piece of magnet and the 5 th piece of magnet is 2.5mm.
Thermal treatment
The assembly 3 was heat treated at 900 c for 20 hours while applying a pressure of 1MPa in the assembly direction of the assembly to obtain a large size ndfeb diffusion magnet having a diffusion direction dimension of 20mm, which was designated as sample 3.
Example 4
Obtaining the modified aluminum foil
The same as in example 3.
To obtain a combined body
Nd with 45SH performance 28.5 Tb 2 Fe 67.9 Al 0.2 Cu 0.2 Ga 0.2 B, processing the sintered neodymium-iron-boron magnet into a magnet to be diffused (marked as a magnet to be diffused 4) with the minimum size direction of 6mm, wherein the minimum size direction is parallel to the easy magnetization direction; 2 pieces of modified aluminum foil 2 are inserted between 3 pieces of magnets to be diffused to obtain a combined body 4, wherein the thickness of the 1 st magnet and the 3 rd magnet is 3mm.
Thermal treatment
Heat-treating the combined body 4 at 925 deg.C for 10 hr while applying a pressure of 5MPa in the combined direction of the combined body; and then carrying out secondary heat treatment on the diffusion magnet at 600 ℃ for 3 hours to obtain a large-size neodymium iron boron diffusion magnet with the diffusion direction size of 12mm, and marking as a sample 4.
Example 5
Obtaining a modified copper foil
And (3) respectively depositing 7 mu m terbium metal layers on two surfaces of the copper foil with the thickness of 3 mu m by utilizing a multi-arc ion plating technology to obtain the modified copper foil 1.
To obtain a combined body
Pr with performance of 50M 6 Nd 23.5 Dy 0.8 Fe 68.7 B, processing the sintered neodymium iron boron magnet into a magnet to be diffused (marked as a magnet to be diffused 5) with the minimum dimension direction of 3mm, wherein the minimum dimension direction and the easy magnetization direction form an angle of 45 degrees; 5 pieces of modified copper foil 1 are inserted between 6 pieces of magnets to be diffused to obtain a combined body 5, wherein the thickness of the 1 st piece of magnet and the 6 th piece of magnet is 1.5mm.
Thermal treatment
Heat-treating the assembly 5 at 850 ℃ for 20 hours while applying a pressure of 0.5MPa in the assembly direction of the assembly; and then carrying out secondary heat treatment on the diffusion magnet at 500 ℃ for 6 hours to obtain a large-size neodymium iron boron diffusion magnet with the diffusion direction size of 15mm, and marking as a sample 5.
Example 6
Obtaining a modified copper foil
The same as in example 5.
To obtain a combined body
Pr with performance of N52 6 Nd 24 Fe 69 B, processing the sintered neodymium-iron-boron magnet into a magnet to be diffused (marked as a magnet to be diffused 6) with the minimum dimension direction of 4mm, wherein the minimum dimension direction is vertical to the easy magnetization direction; 3 pieces of modified copper foil 1 are inserted between 4 pieces of magnets to be diffused to obtain a combined body 6, wherein the thickness of the 1 st piece and the 4 th piece of magnets is 2mm.
Thermal treatment
Heat-treating the assembly 6 at 900 deg.C for 15 hr while applying a pressure of 0.1MPa along the assembly direction of the assembly; the diffusion magnet was heat treated twice at 460 c for 6 hours to obtain a large size neodymium iron boron diffusion magnet with a diffusion direction dimension of 12mm, which was designated sample 6.
Example 7
Obtaining a modified copper foil
And depositing 10 mu m dysprosium metal layers on two surfaces of the copper foil with the thickness of 8 mu m respectively by utilizing a magnetron sputtering coating technology to obtain the modified copper foil 2.
To obtain a combined body
Pr with performance of 48H 6 Nd 24.5 Tb 0.8 Fe 67.7 B, processing the sintered neodymium iron boron magnet into a magnet to be diffused (marked as a magnet to be diffused 7) with the minimum dimension direction of 5mm, wherein the minimum dimension direction and the easy magnetization direction form an angle of 30 degrees; 7 pieces of modified copper foil 2 are inserted between 8 pieces of magnets to be diffused to obtain a combined body 7, wherein the thickness of the 1 st magnet and the 8 th magnet is 2.5mm.
Thermal treatment
Heat-treating the combined body 7 at 925 deg.C for 8 hr while applying a pressure of 5MPa in the combined direction of the combined body; the diffusion magnet was then heat treated a second time at 550 c for 4 hours to obtain a large size ndfeb diffusion magnet with a diffusion dimension of 35mm, as in example 7.
Example 8
Obtaining a modified copper foil
The same as in example 7.
To obtain a combined body
Nd with 45SH performance 28.5 Tb 2 Fe 67.9 Al 0.2 Cu 0.2 Ga 0.2 B, processing the sintered neodymium iron boron magnet into a magnet to be diffused (marked as a magnet to be diffused 8) with the minimum size direction of 6mm, wherein the minimum size direction and the easy magnetization direction form an angle of 60 degrees; and (3) inserting 8 pieces of modified copper foil 2 between 9 pieces of magnets to be diffused to obtain a combined body 8, wherein the thickness of the 1 st piece of magnet and the 9 th piece of magnet is 3mm.
Thermal treatment
The combined body 8 was subjected to heat treatment at 950 ℃ for 5 hours while applying a pressure of 10MPa in the combined direction of the combined body, to obtain a large-size neodymium iron boron diffusion magnet having a diffusion direction size of 48mm, which was denoted as sample 8.
Comparative example 1
Obtaining thin strip of aluminum-terbium alloy
An aluminum-terbium alloy thin strip having a thickness of 30 μm (the thickness was the thinnest thickness obtainable in the prior art) was produced by the method disclosed in CN111599587a (the composition of the alloy thin strip was the same as that of the modified aluminum foil of example 3).
To obtain a combined body
Pr with performance of 48H 6 Nd 24.5 Tb 0.8 Fe 67.7 B, processing the sintered neodymium iron boron magnet into a magnet to be diffused (marked as a magnet to be diffused 9) with the minimum dimension direction of 5mm, wherein the angle between the direction of 5mm and the easy magnetization direction is 45 degrees; 4 thin strips of aluminum-terbium alloy were inserted between 5 magnets to be diffused to obtain a combined body in which the thickness of the 1 st and 5 th magnets was 2.5mm.
Thermal treatment
The assembly was heat treated at 900 ℃ for 20 hours, during which a pressure of 1MPa was applied in the assembly direction of the assembly. And obtaining a large-size neodymium iron boron diffusion magnet with the diffusion direction size of 20mm, and marking as D1.
Comparative example 2
Obtaining a copper-dysprosium alloy ribbon
A copper-dysprosium alloy thin strip having a thickness of 30 μm (the thickness is the thinnest thickness obtainable in the prior art) was prepared by the method disclosed in CN111599587A (the amount of dysprosium in the same area alloy thin strip was the same as that in the modified copper foil in example 8).
To obtain a combined body
Nd with 45SH performance 28.5 Tb 2 Fe 67.9 Al 0.2 Cu 0.2 Ga 0.2 B, processing the sintered NdFeB magnet into a magnet to be diffused (marked as a magnet 10 to be diffused) with the minimum size direction of 6mm, wherein the angle of 60 degrees is formed between the 6mm direction and the easy magnetization direction; and (3) inserting 8 copper-dysprosium alloy thin strips between 9 magnets to be diffused to obtain a combined body, wherein the thickness of the 1 st magnet and the 9 th magnet is 3mm.
Thermal treatment
The combined body 8 was heat-treated at 950 ℃ for 5 hours while applying a pressure of 10MPa in the combined direction of the combined body. And obtaining a large-size neodymium iron boron diffusion magnet with the diffusion direction size of 48mm, and marking as D2.
Test example
Magnetic properties of the magnets to be diffused 1 to 10, examples 1 to 8 and comparative examples 1 to 2 were measured by comparison at room temperature (23. + -. 1 ℃) using a magnetic property tester according to the requirements of GB/T3217-2013 "permanent magnet (hard magnetic) material-magnetic test method", and the results are shown in Table 1.
TABLE 1 comparison of magnetic Properties of magnets to be diffused 1 to 10, examples 1 to 8 and comparative examples 1 to 2
From the comparison between the implementation process of the embodiment and the data in table 1, it can be found that compared with the magnet before diffusion, the remanence of the embodiment is reduced by about 0.1kGs, the coercive force of the embodiment is improved by more than 4kOe and maximally exceeds 9kOe, and the large-size neodymium iron boron diffusion magnet can be obtained by using the method. Compared with the comparative example, under the condition that the percentage content of the rare earth is the same (example 3 and comparative example 1), the coercive force of the magnet prepared by the technology of the invention is equivalent to that of the comparative example, but the remanence of the magnet is obviously higher than that of the comparative example; under the condition that the total rare earth amount is the same and the thickness of the metal layer is close (example 8 and comparative example 2), the remanence of the magnet prepared by the technology of the invention is equivalent to that of the comparative example, but the coercive force is obviously higher than that of the comparative example. Namely, the comprehensive performance of the magnet prepared by the technology of the invention is superior to that of the comparative example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The preparation method of the large-size neodymium iron boron diffusion magnet is characterized by comprising the following steps of:
forming a heavy rare earth metal layer on the surface of a metal foil in a deposition mode to obtain a modified metal foil, wherein the metal foil is an aluminum foil or a copper foil;
combining N pieces of neodymium iron boron magnets to be diffused and sintered and N-1 pieces of the modified metal foils to obtain a combined body, wherein N is more than or equal to 3, and the modified metal foils are respectively arranged between the adjacent neodymium iron boron magnets to be diffused and sintered;
and carrying out heat treatment on the combined body to obtain the large-size neodymium iron boron diffusion magnet.
2. The production method according to claim 1, wherein the metal foil has a thickness of 1 to 8 μm; heavy rare earth metal layers are formed on two surfaces of the metal foil, and the total thickness of the heavy rare earth metal layers is 6-20 mu m.
3. The method according to claim 1, wherein the deposition method is one selected from magnetron sputtering, thermal evaporation, and multi-arc ion plating.
4. The method of claim 1, wherein the heavy rare earth metal in the heavy rare earth metal layer is selected from dysprosium or terbium.
5. The preparation method of claim 1, wherein the neodymium-iron-boron magnet to be diffusion-sintered is RE 2 Fe 14 A magnet in which phase B is a main magnetic phase, wherein RE is at least one of rare earth elements;
the thickness of the neodymium iron boron magnet to be diffused and sintered in the minimum size direction is 3-6mm.
6. The method according to claim 1, wherein the thickness of the 1 st ndfeb magnet to be diffusion-sintered and the thickness of the nth ndfeb magnet to be diffusion-sintered are equal to each other and are respectively half of the thickness of the remaining magnets.
7. The method according to claim 1, wherein the heat treatment temperature is 850 to 950 ℃ and the holding time is 5 to 30 hours.
8. The production method according to claim 1, wherein the heat treatment is performed while applying a pressure of 0.1 to 10MPa in a combined direction of the assembly.
9. The method of claim 1, wherein the heat treatment further comprises a secondary heat treatment at a temperature of 460-600 ℃ for a time of 3-6 hours.
10. A large-sized neodymium-iron-boron diffusion magnet, characterized in that it is obtained by the production method according to any one of claims 1 to 9.
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