CN112382500B - Preparation method of laser pulse perforation auxiliary diffusion high-coercivity neodymium iron boron - Google Patents
Preparation method of laser pulse perforation auxiliary diffusion high-coercivity neodymium iron boron Download PDFInfo
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- CN112382500B CN112382500B CN202011322861.3A CN202011322861A CN112382500B CN 112382500 B CN112382500 B CN 112382500B CN 202011322861 A CN202011322861 A CN 202011322861A CN 112382500 B CN112382500 B CN 112382500B
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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
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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
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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
Abstract
The invention discloses a preparation method of laser pulse perforation auxiliary diffusion high-coercivity neodymium iron boron, which comprises the following steps: smelting heavy rare earth metals such as Dy and the like and low-melting-point metals such as Al and the like according to an atomic ratio to form a mother alloy, carrying out high-energy ball milling on the mother alloy to form nano-to micron-sized powder, and mixing the powder with an organic solvent to form a diffusion source mixed solution; perforating the surface of the neodymium iron boron magnet by using femtosecond to nano laser pulse to form a coalball-shaped magnet; immersing the coal ball-shaped magnet into the diffusion source mixed solution, taking out the magnet, presintering the magnet at low temperature under the protection of nitrogen, and obtaining the magnet with the diffusion source coating inside and on the surface of the magnet; and finally, carrying out heat treatment on the magnet under the protection of argon and a strong magnetic field to obtain the neodymium iron boron magnet with high coercivity. The invention improves the specific surface area of the coating layer and the magnet, enables the heavy rare earth element to be diffused in the magnet in a three-dimensional way, effectively improves the distribution uniformity of the heavy rare earth element in the magnet, and improves the coercive force of the neodymium iron boron permanent magnet.
Description
Technical Field
The invention relates to the technical field of magnetic materials, in particular to a preparation method of a high-coercivity sintered neodymium-iron-boron magnet.
Background
The coercive force enhancement mechanism is always one of the complex and interesting key scientific problems of the permanent magnetic material. The coercivity of the ternary sintered neodymium iron boron is obviously deteriorated along with the rise of temperature, and in order to meet the requirement of high-temperature use, the room-temperature coercivity of the ternary sintered neodymium iron boron needs to be enhanced. The coercivity of an actual magnet is converted from a magnetocrystalline anisotropy field by a certain microstructure. The traditional preparation method needs elements such as heavy rare earth Dy/Tb to replace Nd to improve the main phase so as to realize the enhancement of the coercive force. However, the use of heavy rare earth Dy/Tb results in a large increase in material cost, and the antiferromagnetic coupling of the heavy rare earth with the magnetic moment of transition group elements results in a decrease in saturation magnetization and maximum energy product. In addition, microstructure optimization can be converted into higher coercive force, the main regulation and control directions comprise grain boundary phase thickening and distribution optimization, grain size refinement, heavy rare earth distribution optimization and the like, and the research hotspots of the low-non-heavy rare earth neodymium iron boron permanent magnet material are found at present. The research on the coercivity mechanism of the sintered neodymium-iron-boron permanent magnet material and the development of a coercivity enhancing technology on the basis of the research result are to realize high-quality utilization of expensive and scarce heavy rare earth resources, and are the problems which are urgently needed to be solved in the application of rare earth permanent magnet materials in the fields of new energy and energy conservation and emission reduction.
The traditional crystal boundary diffusion treatment technology mainly adopts the modes of coating, deposition, plating, sputtering, sticking and the like, the heavy rare earth crystal boundary diffusion technology is characterized in that heavy rare earth-containing materials (metal, hydride, fluoride, oxide and the like) are covered on the surface of a magnet, heavy rare earth diffuses into the magnet along a crystal boundary phase during high-temperature treatment, and meanwhile, a shell layer rich in the heavy rare earth is formed on the surface layer of a crystal grain, so that a prepared magnet forms a nucleus with high saturation magnetization and a Dy/Tb shell layer structure rich in a high anisotropy field, the formation of a reverse domain on the surface layer of the crystal grain is effectively inhibited, the coercive force of the magnet is improved under the condition that the remanence is hardly reduced, the use amount of the heavy rare earth is also reduced, and the high maximum magnetic energy product and the coercive force of the magnet are enhanced. However, the conventional grain boundary diffusion technology is to coat the surface of the magnet, because the diffusion depth of the heavy rare earth element is limited, the heavy rare earth element is not uniformly distributed in the magnet, the coercive force is enhanced limitedly, and the excessive heavy rare earth element enters one side of the coating layer of the magnet by increasing the heat treatment temperature and time, so that the structure of the magnet is broken, and the coercive force of the magnet is reduced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a preparation method of laser pulse perforation auxiliary diffusion high-coercivity neodymium iron boron.
In order to solve the problems, the technical scheme adopted by the invention is as follows:
a preparation method of laser pulse perforation assisted diffusion high-coercivity neodymium iron boron comprises the following steps:
(1) preparation of diffusion source: smelting heavy rare earth metal and low-melting-point metal according to an atomic ratio to form a master alloy, carrying out high-energy ball milling on the master alloy to form nano-to micron-sized powder, and mixing the powder with an organic solvent to form a diffusion source mixed solution;
(2) and (3) neodymium iron boron laser perforation: perforating the surface of the neodymium iron boron magnet by using femtosecond to nanosecond laser pulses to form a coalball-shaped magnet;
(3) coating the surface and the inside of the neodymium iron boron: immersing the coal ball-shaped magnet into the diffusion source mixed solution, taking out the magnet, presintering the magnet at low temperature under the protection of nitrogen, and obtaining the magnet with the diffusion source coating inside and on the surface of the magnet;
(4) heat treatment under a magnetic field: and (4) carrying out heat treatment on the magnet obtained in the step (3) under the protection of argon and a strong magnetic field to obtain the neodymium iron boron magnet with high coercivity.
Specifically, the heavy rare earth metal in the step (1) is one or two of heavy rare earth elements Dy and Tb, the low-melting-point metal is one or two of low-melting-point metals Al and Cu, and the atomic ratio of the heavy rare earth metal to the low-melting-point metal is 0.1-10: 1; the high-energy ball milling time is 10-24 h, and the organic solvent is acetone or ethanol solution.
Specifically, the femtosecond to nanosecond laser pulse in the step (2) has the laser wavelength of 800-1560 nm, the pulse duration of 1 ps-10 ns, the pulse intensity of 100 uJ-100 mJ, the spot size of 5-100 μm and the distance between holes of 10 μm-10 mm.
Specifically, the low-temperature pre-sintering time in the step (3) is 1-10 hours, and the temperature is 80-150 ℃.
Specifically, the strong magnetic field in the step (4) is 7-12T, the heat treatment temperature is 600-1000 ℃, and the heat treatment time is 5-8 h.
Compared with the prior art, the invention has the following implementation effects:
compared with the mode provided by the Chinese invention patent (CN104795228B, a method for preparing a high-performance neodymium iron boron magnet by diffusing Dy/Cu alloy in a crystal boundary diffusion mode), the laser pulse perforation auxiliary diffusion high-coercivity neodymium iron boron preparation method provided by the invention has the advantages that fine coal ball-shaped cavities are formed inside the magnet through a laser perforation technology, and the specific surface area of a coating layer and the magnet is improved by coating a heavy rare earth diffusion source inside and on the surface of the magnet, so that the heavy rare earth element is subjected to three-dimensional diffusion inside the magnet, the distribution uniformity of the heavy rare earth element inside the magnet is effectively improved, and the coercivity of the neodymium iron boron material is improved.
Drawings
Fig. 1, schematic diagram of laser perforation of the surface of neodymium iron boron.
Fig. 2 shows the coercive force of the ndfeb magnets obtained by laser perforation assisted diffusion (examples 1 and 2) and the ndfeb magnets obtained by the conventional surface coating diffusion process (comparative examples 1 and 2).
Detailed Description
The present invention will be further described with reference to the following specific embodiments and comparative examples.
Example 1: a preparation method of laser pulse perforation assisted diffusion high-coercivity neodymium iron boron comprises the following steps:
step (1) preparation of a diffusion source:
smelting heavy rare earth metal Tb and low-melting-point metal Al according to an atomic ratio of 0.3:1 to form a master alloy, carrying out high-energy ball milling on the master alloy for 12 hours to form nano-to micron-sized powder, and mixing the powder with an acetone solution to form a diffusion source mixed solution;
and (2) carrying out neodymium iron boron laser perforation:
using femtosecond to nanosecond laser pulse, wherein the laser wavelength is 800nm, the pulse duration is 300fs, the pulse intensity is 150uJ, the spot size is 10 μm, holes are punched on the surface of the neodymium iron boron magnet with the size of 10mm multiplied by 10mm, the shape of the holes is shown in figure 1, the distance between the holes is 0.5mm, and a coalball-shaped magnet is formed;
step (3), coating the surface and the inside of the neodymium iron boron:
immersing the coal ball-shaped magnet into the diffusion source mixed solution, taking out, presintering at the low temperature of 80 ℃ for 2h under the protection of nitrogen, and obtaining the magnet with the diffusion source coating inside and on the surface of the magnet;
step (4) heat treatment under a magnetic field:
and (4) carrying out heat treatment on the magnet obtained in the step (3) for 8h under the protection of argon and a strong magnetic field (7T), wherein the temperature is 800 ℃, so as to obtain the neodymium iron boron magnet with high coercivity, and the magnetic performance is shown in figure 2.
Comparative example 1:
the preparation procedure is the same as in example 1, except that there is no step (2), i.e., a conventional surface diffusion coating process is employed.
Example 2:
step (1) preparation of a diffusion source:
smelting heavy rare earth metal Dy and low-melting-point metal Al according to an atomic ratio of 0.5:1 to form a mother alloy, carrying out high-energy ball milling on the mother alloy for 24 hours to form nano-to micron-sized powder, and mixing the powder with an acetone solution to form a diffusion source mixed solution;
step (2), neodymium iron boron laser perforation:
using femtosecond to nanosecond laser pulse, wherein the laser wavelength is 800nm, the pulse duration is 1ns, the pulse intensity is 100uJ, the light spot size is 25 mu m, the surface of the neodymium iron boron magnet with the size of 20mm multiplied by 20mm is perforated, and the distance between the holes is 1mm, so as to form a coalball-shaped magnet;
and (3) coating the surface and the inside of the neodymium iron boron:
immersing the coal ball-shaped magnet into the diffusion source mixed solution, taking out, and presintering at the low temperature of 100 ℃ for 4 hours under the protection of nitrogen to obtain the magnet with the diffusion source coating inside and on the surface of the magnet;
step (4) heat treatment under a magnetic field:
and (4) carrying out heat treatment on the magnet obtained in the step (3) for 6 h under the protection of argon and a strong magnetic field (9T), wherein the temperature is 1000 ℃, and thus obtaining the neodymium iron boron magnet with high coercivity.
Comparative example 2:
the preparation procedure is the same as in example 2, except that there is no step (2), i.e., a conventional surface diffusion coating process is used.
Claims (5)
1. A preparation method of laser pulse perforation assisted diffusion high-coercivity neodymium iron boron is characterized by comprising the following steps:
(1) preparation of diffusion source: smelting heavy rare earth metal and low-melting-point metal according to an atomic ratio to form a master alloy, carrying out high-energy ball milling on the master alloy to form nano-to micron-sized powder, and mixing the powder with an organic solvent to form a diffusion source mixed solution;
(2) and (3) neodymium iron boron laser perforation: perforating the surface of the neodymium iron boron magnet by using femtosecond to nanosecond laser pulses to form a coalball-shaped magnet;
(3) coating the surface and the inside of the neodymium iron boron: immersing the coal ball-shaped magnet into the diffusion source mixed solution, taking out the magnet, presintering the magnet at low temperature under the protection of nitrogen, and obtaining the magnet with the diffusion source coating inside and on the surface of the magnet;
(4) heat treatment under a magnetic field: and (4) carrying out heat treatment on the magnet obtained in the step (3) under the protection of argon and a strong magnetic field to obtain the neodymium iron boron magnet with high coercivity.
2. The method according to claim 1, wherein the heavy rare earth metal in step (1) is one or two of Dy and Tb heavy rare earth elements, the low-melting metal is one or two of Al and Cu low-melting metal, and the atomic ratio of the heavy rare earth metal to the low-melting metal is 0.1-10: 1; the high-energy ball milling time is 10-24 h, and the organic solvent is acetone or ethanol solution.
3. The method according to claim 1, wherein the femtosecond to nanosecond laser pulse of step (2) has a laser wavelength of 800 to 1560nm, a pulse duration of 200fs to 10ns, a pulse intensity of 100uJ to 100mJ, a spot size of 5 to 100 μm, and a hole pitch of 10 μm to 10 mm.
4. The method according to claim 1, wherein the low-temperature pre-sintering time in the step (3) is 1-10 hours, and the temperature is 80-150 ℃.
5. The method according to claim 1, wherein the high magnetic field in step (4) is 7-12T, the heat treatment temperature is 600-1000 ℃, and the heat treatment time is 5-8 h.
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| CN107093516A (en) * | 2017-04-14 | 2017-08-25 | 华南理工大学 | A kind of grain boundary decision method for improving neodymium iron boron magnetic body coercivity and heat endurance |
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