CN111710519B - Method for preparing neodymium-iron-boron magnet through grain boundary diffusion - Google Patents
Method for preparing neodymium-iron-boron magnet through grain boundary diffusion Download PDFInfo
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- CN111710519B CN111710519B CN202010631985.3A CN202010631985A CN111710519B CN 111710519 B CN111710519 B CN 111710519B CN 202010631985 A CN202010631985 A CN 202010631985A CN 111710519 B CN111710519 B CN 111710519B
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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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- 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
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Abstract
The invention provides a method for preparing a neodymium iron boron magnet by grain boundary diffusion, which comprises the step of subjecting a basic neodymium iron boron magnet with the thickness of 8-12 mm to a dilute inorganic acid solutionDrying after treatment; the diffusion alloy sheet Pr 50 Tb 20 Cu 30 Attaching the neodymium iron boron magnet to the upper surface and the lower surface of the dried basic neodymium iron boron magnet, then placing the neodymium iron boron magnet in a hot pressing furnace, vacuumizing the hot pressing furnace, starting to apply pressure of 20-30 MPa when the temperature is raised to 700-800 ℃ in a vacuum state, maintaining the pressure for 7-10 h, then releasing the pressure to normal pressure, vacuumizing again, continuing to raise the temperature to 850-950 ℃, and preserving the heat for 1-2 h; and annealing the diffused sample in a vacuum furnace at different temperatures in sequence. The invention can produce the neodymium iron boron magnet with satisfactory magnet coercive force, residual magnetism and sample thickness.
Description
The application is divided into separate applications by taking an invention patent with the application date of 2017-11-29, the application number of 201711223146.2 and the name of 'a preparation method of a neodymium-iron-boron magnet' as a parent.
Technical Field
The invention relates to the technical field of magnet preparation, in particular to a method for preparing a neodymium iron boron magnet through crystal boundary diffusion.
Background
As an important metal functional material, the sintered NdFeB magnet has wide application in numerous fields such as aerospace, information electronics, energy, traffic, communication, medical treatment and health and the like. In many fields, such as electric vehicles, hybrid vehicles, wind power generation and the like, a sintered NdFeB magnet is required to have a higher coercive force so as to meet the use requirement at a certain temperature.
Alloying heavy rare earth to form highly magnetocrystalline anisotropy (NdDy) 2 Fe 14 The B hard magnetic phase can obviously improve the coercive force of the magnet and reduce the magnetic performance attenuation caused by high temperature, but simultaneously, Dy atoms and Fe atoms can form anti-iron coupling to cause the decline of remanence, and the magnetic field intensity of the permanent magnet generated under the limit environment at high temperature can also decline.
As an improvement, a fluoride coating grain boundary diffusion of dysprosium and a saturated steam permeation technology of dysprosium developed by domestic and foreign researchers become research hotspots for improving the performance of a sintered neodymium-iron-boron magnet. Patent CN200810179949.7 describes arranging alloy powder on the surface of the sintered magnet, the powder is a rare earth intermetallic compound, the heat treatment temperature is 20 ℃ ~ (Ts-10) ° c, Ts is the sintering temperature of the sintered magnet. The sintered magnet includes a minimum portion equal to or less than 20 mm. Patent CN200810179949.7 describes a heat treatment apparatus for diffusing heavy rare earth element RH into sintered magnets at 700-1000 c using heavy rare earth (Tb, Dy, Ho) hydride. However, for sintered nd-fe-b magnets, the diffusion depth of the current grain boundary infiltration technology is limited, heavy rare earth elements cannot diffuse into magnets with larger dimensions, the dimensional requirements on samples are strict, and generally only thin magnets (within 5 mm) can be processed. How to increase the diffusion thickness of the grain boundary diffusion magnet is the focus of current research.
Disclosure of Invention
The invention aims to overcome the defects and provide a method for preparing a neodymium iron boron magnet by grain boundary diffusion, which can produce a magnet with satisfactory coercive force, remanence and sample thickness.
In order to solve the technical problems, the invention adopts the technical scheme that:
the invention provides a method for preparing a neodymium iron boron magnet by grain boundary diffusion, which comprises the following steps:
step 1: processing a commercial neodymium iron boron magnet into a thickness of 8-12 mm along an orientation force direction to obtain a basic neodymium iron boron magnet, then soaking the basic neodymium iron boron magnet in a hydrochloric acid solution with a volume concentration of 3-5% or a nitric acid solution with a volume concentration of 3-5%, then carrying out ultrasonic treatment on a neodymium iron boron sheet soaked in the hydrochloric acid solution or the nitric acid solution for 5-10 min under a vacuum condition, and then drying for 20-120 min at the temperature of 120-140 ℃;
step 2: the diffusion alloy sheet Pr 50 Tb 20 Cu 30 Adhering to the upper and lower surfaces of the base neodymium-iron-boron magnet treated in the step 1, then placing in a hot pressing furnace, vacuumizing the hot pressing furnace until the vacuum degree reaches 1 multiplied by 10 -2 Heating the hot pressing furnace below Pa, when the temperature reaches 700-800 ℃, applying pressure of 20-30 MPa, maintaining the pressure for 7-10 h, then releasing the pressure to normal pressure, and then vacuumizing the hot pressing furnace again until the vacuum degree reaches 1 x 10 -2 Continuously heating to 850-950 ℃ below Pa, and keeping the temperature for 1-2 h;
and step 3: and (3) annealing the sample diffused in the step (2) in a vacuum furnace at 500-600 ℃, and then annealing at 400-450 ℃ to obtain the target product.
The invention has the beneficial effects that: 1) after the basic magnet is soaked in an inorganic acid solution, the diffusion alloy and the basic magnet are diffused in a low-temperature (700-800 ℃) pressurized (20-30 MPa) state, the diffusion kinetic energy of the molten diffusion alloy is increased due to the existence of the pressure, so that heavy rare earth elements in the molten diffusion alloy are diffused and distributed in a crystal boundary phase along the crystal boundary phase and are distributed in a crystal boundary phase, and then the heavy rare earth elements in the crystal boundary phase are diffused at a high temperature (850-950) to form a heavy rare earth metal-rich shell structure on the surface layer of a main phase crystal grain, so that the heavy rare earth elements enter the main phase as substitute elements and form a continuous area with high rare earth content at the boundary of the main phase, and the coercive force of a neodymium iron boron product is greatly improved, and the remanence almost has no influence; meanwhile, after the grain boundary is permeated by the heavy rare earth, the grain boundary rare earth-rich phase is more continuous and clearer, and the effect of isolation, exchange and coupling is more effective; (2) compared with the traditional grain boundary diffusion method, the method has the advantages that the diffusion depth is deeper, the size requirement on the diffusion magnet is not strict, and the applicability is wider, namely the neodymium iron boron magnet with satisfactory magnet coercive force, residual magnetism and sample thickness can be prepared by the method.
Detailed Description
In order to explain technical contents, structural features, and objects and effects of the present invention in detail, the following description is given in detail with reference to the embodiments.
The most key concept of the invention is as follows: the neodymium iron boron magnet with satisfactory magnet coercive force, residual magnetism and sample thickness is prepared by soaking a basic magnet (common commercially available neodymium iron boron) in an inorganic acid solution, promoting heavy rare earth elements to diffuse along a crystal boundary in a low-temperature pressurizing mode, and enabling the heavy rare earth elements distributed in the crystal boundary phase to form a rare earth element-rich shell layer on the surface layer of a main phase crystal grain at high temperature.
The invention provides a method for preparing a neodymium iron boron magnet by grain boundary diffusion, which comprises the following steps:
step 1: processing a commercial neodymium-iron-boron magnet into a thickness of 8-12 mm along an orientation force direction to obtain a basic neodymium-iron-boron magnet, soaking the basic neodymium-iron-boron magnet in a hydrochloric acid solution with a volume concentration of 3-5% or a nitric acid solution with a volume concentration of 3-5% for 5-20 min, and then drying for 20-120 min at 120-140 ℃;
step 2: attaching diffusion alloy sheets to the upper and lower surfaces of the base neodymium-iron-boron magnet treated in the step (1), then placing the base neodymium-iron-boron magnet in a hot pressing furnace, vacuumizing the hot pressing furnace until the vacuum degree reaches 1 multiplied by 10 -2 Heating the hot pressing furnace below Pa, when the temperature reaches 700-800 ℃, applying pressure of 20-30 MPa, maintaining the pressure for 7-10 h, then releasing the pressure to normal pressure, and then vacuumizing the hot pressing furnace again until the vacuum degree reaches 1 x 10 -2 Continuously heating to 850-950 ℃ below Pa, and keeping the temperature for 1-2 h;
and step 3: annealing the sample diffused in the step (2) in a vacuum furnace at 500-600 ℃, and then annealing at 400-450 ℃ to obtain a target product;
wherein the diffusion alloy sheet is a low melting point diffusion alloy R 1 -R 2 -TM, wherein R 1 Is Pr or Nd, R 2 Dy or Tb, TM is any one of Cu, Al, Zn or Fe.
The working principle of the invention is as follows: firstly, the existing neodymium iron boron magnet is cut into a thickness of 8-12 mm to be used as a basic magnet, an oxidation layer and oil stain of the basic magnet are removed by using a dilute hydrochloric acid solution or a dilute nitric acid solution which has no influence on the performance of the magnet, meanwhile, the magnet after acid soaking and drying is beneficial to promoting the heavy rare earth elements in the later-stage diffusion alloy to be attached to the surface of the magnet, then, the magnet is diffused under the condition of pressurization (20-30 MPa) at low temperature (700-800 ℃), the diffusion kinetic energy of the molten diffusion alloy is increased due to the existence of pressure, so that the heavy rare earth elements (Tb/Dy) in the molten diffusion alloy are diffused and distributed in a phase along the grain boundary and in a grain boundary phase, meanwhile, the direction (C axis) of the grain boundary vertical to the pressure is widened to a certain extent, and researches show that the A surface vertical to the C axis is a surface to which is difficult to be attached by a diffusing agent from the crystallographic orientation, the defect is made up to a certain extent by widening along the C axis, then the heavy rare earth elements with a grain boundary phase are diffused at a high temperature (850-950 ℃) to form a heavy rare earth metal-rich shell structure on the surface layer of a main phase grain, then annealing treatment is carried out in a mode of firstly carrying out high temperature (500-600 ℃) and then carrying out low temperature (400-450 ℃), the heavy rare earth elements are used as a substitute phase to enter the main phase through ring-to-ring buckling among the steps, and a continuous region with high rare earth content is formed at the boundary of the main phase, so that the coercive force of the neodymium iron boron product is greatly improved, and the remanence almost has no influence. Meanwhile, after the grain boundary is permeated by the heavy rare earth, the grain boundary rare earth-rich phase is more continuous and clearer, and the isolation exchange coupling effect is more effective.
From the above description, the beneficial effects of the present invention are: (1) after the basic magnet is soaked in an inorganic acid solution, the diffusion alloy and the basic magnet are diffused in a low-temperature (700-800 ℃) pressurized (20-30 MPa) state, the diffusion kinetic energy of the molten diffusion alloy is increased due to the existence of the pressure, so that heavy rare earth elements in the molten diffusion alloy are diffused and distributed in a crystal boundary phase along the crystal boundary phase and are distributed in a crystal boundary phase, and then the heavy rare earth elements in the crystal boundary phase are diffused at a high temperature (850-950) to form a heavy rare earth metal-rich shell structure on the surface layer of a main phase crystal grain, so that the heavy rare earth elements enter the main phase as substitute elements and form a continuous area with high rare earth content at the boundary of the main phase, and the coercive force of a neodymium iron boron product is greatly improved, and the remanence almost has no influence; meanwhile, after the grain boundary is permeated by the heavy rare earth, the grain boundary rare earth-rich phase is more continuous and clearer, and the effect of isolation, exchange and coupling is more effective; (2) compared with the traditional grain boundary diffusion method, the method has the advantages that the diffusion depth is deeper, the size requirement on the diffusion magnet is not strict, and the applicability is wider, namely the neodymium iron boron magnet with satisfactory magnet coercive force, residual magnetism and sample thickness can be prepared by the method.
Further, the specific operation of step 1 is: soaking a neodymium iron boron magnet in a hydrochloric acid solution or a nitric acid solution with the volume concentration of 3-5%, then carrying out ultrasonic treatment on the neodymium iron boron sheet soaked in the hydrochloric acid solution or the nitric acid solution for 5-10 min under the vacuum condition, and then drying the neodymium iron boron sheet in an environment with the temperature of 120-140 ℃ for 20-120 min.
According to the description, when the neodymium iron boron sheet is treated by the inorganic acid solution, the soaking time is shortened by performing ultrasonic treatment under the vacuum condition, and the vacuum environment is kept, so that the phenomenon that the adhesion of heavy rare earth elements in the later period is influenced due to the reoccurrence of an oxide layer in the surface treatment process is avoided.
Further, the power of ultrasonic treatment in the step 1 is 700-800W, and the temperature is 40-50 ℃.
Furthermore, the thickness of the diffusion alloy sheet is 0.1-0.25 mm.
Furthermore, in the step 3, the time of annealing treatment at 500-600 ℃ is 1-5 h, and the time of annealing treatment at 400-450 ℃ is 1-3 h.
Example 1
A method for preparing a neodymium iron boron magnet by grain boundary diffusion comprises the following steps:
step 1: processing a commercial neodymium-iron-boron magnet into 5mm 10mm 8mm (8mm is thickness) to obtain a basic neodymium-iron-boron magnet (the basic neodymium-iron-boron magnet comprises, by mass, 5.9% of Pr, 23.4% of Nd, 1% of Dy, 0.98% of B, 0.1% of Al, 0.1% of Cu, 0.1% of Zr and 68.42% of Fe), soaking the basic neodymium-iron-boron magnet in a hydrochloric acid solution with the volume concentration of 3%, then performing ultrasonic treatment on a neodymium-iron-boron sheet soaked in the hydrochloric acid solution under the vacuum condition (the power of the ultrasonic treatment is 700W, the temperature is 50 ℃) for 10min, and then drying in an environment with the temperature of 120 ℃ for 120 min;
step 2: diffusing alloy sheet (prepared by rapid hardening process and having Pr component) with thickness of 0.1mm 50 Tb 20 Cu 30, Diffusion alloy (numerical value represents atomic percent) is attached to the upper surface and the lower surface of the base neodymium iron boron magnet treated in the step 1, then the base neodymium iron boron magnet is placed in a hot pressing furnace, the hot pressing furnace is vacuumized until the vacuum degree reaches 1 multiplied by 10 -2 Heating the autoclave below Pa, applying pressure of 30MPa when the temperature reaches 700 ℃, maintaining the pressure for 7h, releasing the pressure to normal pressure, vacuumizing the autoclave again until the vacuum degree reaches 1 × 10 -2 Continuously heating to 850 ℃ below Pa, and keeping the temperature for 2 h;
and step 3: and (3) annealing the sample diffused in the step (2) in a vacuum furnace at 500 ℃ for 5h, and then annealing at 400 ℃ for 3h to obtain the target product.
And (3) detection: the magnetic parameters of the product were tested and the results are shown in table 1.
Example 2
A method for preparing a neodymium iron boron magnet by grain boundary diffusion comprises the following steps:
step 1: processing a commercial neodymium-iron-boron magnet into 5mm 10mm 12mm (12mm is thickness) to obtain a basic neodymium-iron-boron magnet (the basic neodymium-iron-boron magnet comprises, by mass, 5.9% of Pr, 23.4% of Nd, 1% of Dy, 0.98% of B, 0.1% of Al, 0.1% of Cu, 0.1% of Zr and 68.42% of Fe), soaking the basic neodymium-iron-boron magnet in a nitric acid solution with the volume concentration of 5%, then performing ultrasonic treatment on neodymium-iron-boron slices soaked in the nitric acid solution under the vacuum condition (the power of ultrasonic treatment is 800W, the temperature is 40 ℃) for 5min, and then drying in an environment with the temperature of 140 ℃ for 20 min;
step 2: diffusing alloy sheet (prepared by rapid hardening process and having Pr component) with thickness of 0.25mm 50 Tb 20 Cu 30, (numerical value represents atomic percent) are attached to the upper surface and the lower surface of the base neodymium-iron-boron magnet treated in the step 1, then the base neodymium-iron-boron magnet is placed in a hot pressing furnace, the hot pressing furnace is vacuumized until the vacuum degree reaches 1 multiplied by 10 -2 Heating the autoclave below Pa, applying pressure of 20MPa when the temperature reaches 800 deg.C, maintaining the pressure for 10h, relieving the pressure to normal pressure, vacuumizing the autoclave again until the vacuum degree reaches 1 × 10 -2 Continuously heating to 950 ℃ below Pa, and keeping the temperature for 1 h;
and step 3: and (3) annealing the sample diffused in the step (2) in a vacuum furnace at 600 ℃ for 1h, and then annealing at 450 ℃ for 1h to obtain the target product.
And (3) detection: the magnetic parameters of the product were tested and the results are shown in table 1.
Example 3
A method for preparing a neodymium iron boron magnet by grain boundary diffusion comprises the following steps:
step 1: processing a commercial neodymium-iron-boron magnet into 5mm 10mm (10mm is thickness) to obtain a basic neodymium-iron-boron magnet (the basic neodymium-iron-boron magnet comprises, by mass, 5.9% of Pr, 23.4% of Nd, 1% of Dy, 0.98% of B, 0.1% of Al, 0.1% of Cu, 0.1% of Zr and 68.42% of Fe), soaking the basic neodymium-iron-boron magnet in a hydrochloric acid solution with the volume concentration of 4%, then performing ultrasonic treatment on neodymium-iron-boron slices soaked in the hydrochloric acid solution under the vacuum condition (the power of the ultrasonic treatment is 750W, the temperature is 45 ℃) for 7min, and then drying in an environment with the temperature of 130 ℃ for 60 min;
step 2: diffusing alloy sheet (prepared by rapid hardening process and having Pr component) with thickness of 0.15mm 50 Tb 20 Cu 30, Diffusion alloy (numerical value represents atomic percent) is attached to the upper surface and the lower surface of the base neodymium iron boron magnet treated in the step 1, then the base neodymium iron boron magnet is placed in a hot pressing furnace, the hot pressing furnace is vacuumized until the vacuum degree reaches 1 multiplied by 10 -2 Heating the autoclave below Pa, applying pressure 25MPa when the temperature reaches 750 deg.C, maintaining the pressure for 8h, relieving the pressure to normal pressure, vacuumizing the autoclave again until the vacuum degree reaches 1 × 10 -2 Continuously heating to 900 ℃ below Pa, and keeping the temperature for 1.5 h;
and step 3: and (3) annealing the sample diffused in the step (2) in a vacuum furnace at 550 ℃ for 3h, and then annealing at 420 ℃ for 2h to obtain the target product.
And (3) detection: the magnetic parameters of the product were tested and the results are shown in table 1.
Comparative example 1
Original product (basic magnet)
And (3) detection: the magnetic parameters of the product were tested and the results are shown in table 1.
Comparative example 2
The other steps are the same as the example 2, except that the treatment in the step 1 adopts alcohol soaking, and ultrasonic treatment is carried out for 10min under normal pressure; in step 2, no pressurization treatment was performed.
Comparative example 3
The other steps are the same as example 2 except that the treatment in step 1 is performed by soaking in alcohol under normal pressureUltrasonic treatment is carried out for 10 min; after the operation low-temperature pressurization treatment of the step 2, high-temperature diffusion is not carried out, namely: diffusing alloy sheet (prepared by rapid hardening process and having Pr component) with thickness of 0.15mm 50 Tb 20 Cu 30, Diffusion alloy (numerical value represents atomic percent) is attached to the upper surface and the lower surface of the base neodymium iron boron magnet treated in the step 1, then the base neodymium iron boron magnet is placed in a hot pressing furnace, the hot pressing furnace is vacuumized until the vacuum degree reaches 1 multiplied by 10 -2 And (4) raising the temperature of the hot pressing furnace below Pa, starting to apply pressure of 25MPa when the temperature reaches 750 ℃, and maintaining the pressure for 8 hours.
Table 1 parameters for examples 1 to 3 and comparative products.
The results in table 1 show that the method provided by the invention can obviously improve the intrinsic coercivity of the ndfeb magnet when the thicker base ndfeb magnet is modified, and has little influence on remanence and almost no influence.
In summary, in the method for preparing the neodymium iron boron magnet by grain boundary diffusion provided by the invention, after the base magnet is soaked in an inorganic acid solution, the diffusion alloy and the base magnet are diffused in a low-temperature (700-800 ℃) pressurized (20-30 MPa) state, the diffusion kinetic energy of the molten diffusion alloy is increased by the existence of the pressure, so that heavy rare earth elements in the molten diffusion alloy are diffused and distributed in a grain boundary phase and a grain boundary phase along the grain boundary, and then the heavy rare earth elements in the grain boundary phase are diffused at a high temperature (850-950) state to form a heavy rare earth metal-rich shell structure on the surface layer of a main phase grain, so that the heavy rare earth elements enter the main phase as substitute elements, and a continuous region with high rare earth content is formed at the boundary of the main phase, so that the coercive force of the neodymium iron boron product is greatly improved, and the remanence is hardly influenced; meanwhile, after the grain boundary is permeated by the heavy rare earth, the grain boundary rare earth-rich phase is more continuous and clearer, and the effect of isolation, exchange and coupling is more effective; compared with the traditional grain boundary diffusion method, the method has the advantages that the diffusion depth is deeper, the size requirement on the diffusion magnet is not strict, and the applicability is wider, namely the neodymium iron boron magnet with satisfactory magnet coercive force, residual magnetism and sample thickness can be prepared by the method.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (3)
1. A method for preparing a neodymium iron boron magnet through grain boundary diffusion is characterized by comprising the following steps:
step 1: processing a commercial neodymium iron boron magnet into a thickness of 8-12 mm along an orientation force direction to obtain a basic neodymium iron boron magnet, soaking the basic neodymium iron boron magnet in a hydrochloric acid solution with the volume concentration of 3-5%, then performing ultrasonic treatment on a neodymium iron boron sheet soaked in the hydrochloric acid solution for 5-10 min under a vacuum condition, and drying for 20-120 min at the temperature of 120-140 ℃; in the step 1, the power of ultrasonic treatment is 700-800W, and the temperature is 40-50 ℃;
step 2: the diffusion alloy sheet Pr 50 Tb 20 Cu 30 Adhering to the upper and lower surfaces of the base neodymium-iron-boron magnet treated in the step 1, then placing in a hot pressing furnace, vacuumizing the hot pressing furnace until the vacuum degree reaches 1 multiplied by 10 -2 Heating the hot pressing furnace below Pa, when the temperature reaches 700-800 ℃, applying pressure of 20-30 MPa, maintaining the pressure for 7-10 h, then releasing the pressure to normal pressure, and then vacuumizing the hot pressing furnace again until the vacuum degree reaches 1 x 10 -2 Continuously heating to 850-950 ℃ below Pa, and keeping the temperature for 1-2 h;
and step 3: annealing the sample diffused in the step (2) in a vacuum furnace at 500-600 ℃, and then annealing at 400-450 ℃ to obtain a target product; in the step 3, the time of annealing treatment at 500-600 ℃ is 1-5 h, and the time of annealing treatment at 400-450 ℃ is 1-3 h;
the basic neodymium-iron-boron magnet consists of, by mass, 5.9% of Pr, 23.4% of Nd, 1% of Dy, 0.98% of B, 0.1% of Al, 0.1% of Cu, 0.1% of Zr and 68.42% of Fe.
2. The method for preparing the neodymium-iron-boron magnet through grain boundary diffusion according to claim 1, wherein the thickness of the diffusion alloy sheet is 0.1-0.25 mm.
3. A method for preparing a neodymium iron boron magnet through crystal boundary diffusion is characterized by comprising the following steps:
step 1: processing a commercial neodymium iron boron magnet with the thickness of 10mm into 5mm 10mm to obtain a basic neodymium iron boron magnet, then soaking the basic neodymium iron boron magnet in a hydrochloric acid solution with the volume concentration of 4%, then carrying out ultrasonic treatment on a neodymium iron boron sheet soaked in the hydrochloric acid solution for 7min under the vacuum condition, and then drying for 60min in an environment at 130 ℃;
the basic neodymium-iron-boron magnet comprises the following components in percentage by mass: pr: 5.9 percent; nd: 23.4 percent; dy: 1 percent; b: 0.98 percent; al: 0.1 percent; cu: 0.1 percent; zr: 0.1% and Fe: 68.42 percent;
the power of ultrasonic treatment is 750W, and the temperature is 45 ℃;
step 2: diffusing alloy sheet Pr with the thickness of 0.15mm 50 Tb 20 Cu 30 Adhering the upper and lower surfaces of the basic neodymium-iron-boron magnet treated in the step 1, then placing the basic neodymium-iron-boron magnet in a hot pressing furnace, vacuumizing the hot pressing furnace until the vacuum degree reaches 1 multiplied by 10 -2 Heating the autoclave below Pa, applying pressure 25MPa when the temperature reaches 750 deg.C, maintaining the pressure for 8h, relieving the pressure to normal pressure, vacuumizing the autoclave again until the vacuum degree reaches 1 × 10 -2 Continuously heating to 900 ℃ below Pa, and keeping the temperature for 1.5 h;
and 3, step 3: and (3) annealing the sample diffused in the step (2) in a vacuum furnace at 550 ℃ for 3h, and then annealing at 420 ℃ for 2h to obtain a target product.
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| CN110111961B (en) * | 2019-03-12 | 2024-03-12 | 宁波雄海稀土速凝技术有限公司 | Preparation method of high-coercivity neodymium-iron-boron magnet and neodymium-iron-boron magnet |
| CN110136953B (en) * | 2019-06-17 | 2022-04-26 | 江苏科技大学 | Preparation method of composite neodymium iron boron magnet with coercivity gradient distribution characteristic |
| CN110556244B (en) * | 2019-08-27 | 2021-07-06 | 安徽省瀚海新材料股份有限公司 | Process for preparing high-coercivity neodymium-iron-boron magnet by diffusion method |
| CN111161950B (en) * | 2020-03-19 | 2024-05-07 | 浙江凯文磁业有限公司 | Pretreatment device and treatment process for heavy rare earth grain boundary permeation |
| CN112420305A (en) * | 2020-11-10 | 2021-02-26 | 四川大学 | Grain boundary diffusion method for improving magnetic property of rare earth permanent magnetic material |
| CN112941457B (en) * | 2021-01-21 | 2022-09-20 | 华南理工大学 | Alloy composite grain boundary diffusant for neodymium iron boron magnet and preparation method and application thereof |
| CN113380528B (en) * | 2021-06-15 | 2022-08-19 | 中钢天源股份有限公司 | Method for remolding sintered neodymium iron boron grain boundary |
| CN113571279B (en) * | 2021-07-23 | 2024-05-03 | 包头天和磁材科技股份有限公司 | Magnet and method for manufacturing the same |
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| JP4433282B2 (en) * | 2004-01-23 | 2010-03-17 | Ｔｄｋ株式会社 | Rare earth magnet manufacturing method and manufacturing apparatus |
| WO2008120784A1 (en) * | 2007-03-30 | 2008-10-09 | Tdk Corporation | Process for producing magnet |
| JP5328161B2 (en) * | 2008-01-11 | 2013-10-30 | インターメタリックス株式会社 | Manufacturing method of NdFeB sintered magnet and NdFeB sintered magnet |
| CN102181820A (en) * | 2011-06-16 | 2011-09-14 | 安徽大地熊新材料股份有限公司 | Method for enhancing coercivity of neodymium-iron-boron magnet material |
| CN104064346B (en) * | 2014-05-30 | 2016-08-17 | 宁波同创强磁材料有限公司 | A kind of neodymium iron boron magnetic body and preparation method thereof |
| CN104388951B (en) * | 2014-11-24 | 2017-06-06 | 上海交通大学 | A kind of grain boundary decision method for improving sintered NdFeB magnetic property |
| CN104851545B (en) * | 2015-05-21 | 2017-11-17 | 王怡 | A kind of permanent-magnet material preparation method with grain boundary decision layer |
| CN105755441B (en) * | 2016-04-20 | 2019-01-11 | 中国科学院宁波材料技术与工程研究所 | A kind of method that magnetron sputtering method expands infiltration heavy rare earth raising coercivity of sintered ndfeb |
| CN106409497B (en) * | 2016-08-31 | 2018-06-08 | 浙江东阳东磁稀土有限公司 | A kind of method of neodymium iron boron magnetic body grain boundary decision |
| CN107256795A (en) * | 2017-06-27 | 2017-10-17 | 北京科技大学 | The method that performance Nd Fe B sintered magnet is prepared using two step grain boundary diffusion process |
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