CN118692803A - A manufacturing process for low eddy current loss neodymium iron boron magnet - Google Patents
A manufacturing process for low eddy current loss neodymium iron boron magnet Download PDFInfo
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- CN118692803A CN118692803A CN202410888883.8A CN202410888883A CN118692803A CN 118692803 A CN118692803 A CN 118692803A CN 202410888883 A CN202410888883 A CN 202410888883A CN 118692803 A CN118692803 A CN 118692803A
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- 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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- 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
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- 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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Abstract
The invention discloses a manufacturing process of a neodymium-iron-boron magnet with low eddy current loss, which comprises the steps of arranging cladding areas and non-cladding areas which are alternately distributed at each diffusion surface of the neodymium-iron-boron magnet, forming a cladding layer at each cladding area by adopting a diffusing agent containing heavy rare earth elements and high-resistivity compounds, and then performing diffusion treatment by adopting a heat treatment process to diffuse the diffusing agent at each cladding area into the inside of the neodymium-iron-boron magnet to form a diffusing magnet with a high-low resistance distribution structure; the method has the advantages that the resistivity of the neodymium-iron-boron magnet is improved, the coercive force of the neodymium-iron-boron magnet is improved, the processing technology is simple, and the mass production is easy.
Description
Technical Field
The invention relates to a manufacturing process of a neodymium-iron-boron magnet, in particular to a manufacturing process of a neodymium-iron-boron magnet with low eddy current loss.
Background
The neodymium-iron-boron rare earth permanent magnet material is used as a third-generation rare earth permanent magnet material and has the characteristics of high remanence, high magnetic energy product and high coercivity. The application field and the application amount of the neodymium-iron-boron rare earth permanent magnet material are increased year by year, and the neodymium-iron-boron rare earth permanent magnet material is widely used for information technology, biomedical diagnosis and treatment equipment, aerospace equipment, novel energy equipment and the like at present, and especially for rotary power equipment such as traction motors, engines and the like.
However, due to the self-characteristics of the neodymium-iron-boron rare earth permanent magnet material, the resistivity is low, and in a high-frequency alternating electromagnetic field environment, obvious eddy current loss can be generated in the neodymium-iron-boron rare earth permanent magnet material, so that the temperature of the neodymium-iron-boron magnet is increased, the magnetic performance is easily reduced greatly, and even the demagnetizing phenomenon occurs. The conventional solution is to add a substance with high resistivity such as oxide or fluoride to the magnet powder to increase the resistivity of the entire neodymium-iron-boron magnet, thereby reducing eddy current heating, but this approach can increase the resistivity but can lead to a decrease in the magnet performance.
In chinese patent application CN104051104a, a method for preparing a laminated neodymium-iron-boron magnet is disclosed, in which a component layer containing a rare earth compound is a first component layer, a component layer not containing a rare earth compound is a second component layer, the first component layer and the second component layer are alternately laminated, and the thickness of each layer is equal. According to the preparation method, the resistivity of the neodymium-iron-boron magnet is greatly improved under the condition that the coercive force is not obviously reduced by alternately using two different layered magnets (namely a first component layer and a second component layer). However, in the preparation method, after two different layered magnets are prepared according to the required number, the layered magnets are stacked and arranged, and then the subsequent process can be performed, so that the processing procedure is complex and the batch production is not easy.
The Chinese patent application with publication number of CN104425092A discloses a preparation method of a neodymium-iron-boron magnet with crystal boundary for diffusing nonmetallic substances, which comprises the steps of contacting a nonmetallic source containing C, N, B and other nonmetallic atoms with the neodymium-iron-boron magnet and then performing heat treatment in a closed space to enable the nonmetallic atoms to enter the crystal boundary inside the neodymium-iron-boron magnet, so that the effect of improving the resistivity of the neodymium-iron-boron magnet is realized. However, the coercive force of the NdFeB magnet is obviously reduced by the preparation method.
Disclosure of Invention
The invention aims to solve the technical problem of providing the manufacturing process of the neodymium-iron-boron magnet with low eddy current loss, which not only can improve the coercive force of the neodymium-iron-boron magnet, but also has the advantages of simpler processing process and easy mass production.
The technical scheme adopted for solving the technical problems is as follows: a manufacturing process of a neodymium-iron-boron magnet with low eddy current loss comprises the steps of arranging cladding areas and non-cladding areas which are alternately distributed at each diffusion surface of the neodymium-iron-boron magnet, forming a cladding layer in each cladding area by adopting a diffusing agent containing heavy rare earth elements and high-resistivity compounds, and then performing diffusion treatment by adopting a heat treatment process to diffuse the diffusing agent at each cladding area into the inside of the neodymium-iron-boron magnet to form the diffusing magnet with a high-low resistance fluctuation distribution structure.
A manufacturing process of a neodymium-iron-boron magnet with low eddy current loss comprises the following steps:
Step 1, selecting n of the orientation surfaces of the NdFeB magnet and other surfaces except the orientation surfaces of the NdFeB magnet, taking all the selected surfaces as diffusion surfaces, wherein n is more than or equal to 0 and less than or equal to the number of the other surfaces of the NdFeB magnet except the orientation surfaces of the NdFeB magnet;
Step 2, respectively arranging at least two cladding areas on each diffusion surface, namely, the other areas except the cladding areas on each diffusion surface are called non-cladding areas, wherein one non-cladding area is arranged between two adjacent cladding areas or one cladding area is arranged between two adjacent non-cladding areas on each diffusion surface;
Step 3, forming a coating layer on each coating layer of each diffusion surface respectively, wherein the material of each coating layer is a diffusion agent; the dispersing agent is R 1-a-bTaAb or a mixture of R 1-a-bTaAb and MX, R 1-a-bTaAb is one or more of Dy, tb and Ho which are heavy rare earth elements, T is one or more of La, ce, pr, nd, gd, al, co, cu, ga, zr, ti, nb, fe, A is one or more of H, O, N, C, F, cl, B, a and b are weight percentages, a is more than or equal to 0wt% and less than 20wt%, b is more than or equal to 0wt% and less than 5wt%; MX is a compound with resistivity not less than 10mΩ & mm, M is one or more of Al, cu, ca, zr, co, fe, si, mn, mg, nb, ti, and X is one or more of O, N, F, cl, B.
And 4, performing diffusion treatment by adopting a heat treatment process, wherein the heat treatment process is to firstly keep the temperature at 700-1000 ℃ for 1-40 h, and then keep the temperature at 400-600 ℃ for 1-10 h. The diffusing agent at each cladding region diffuses into the inside of the neodymium-iron-boron magnet, so that the resistivity of each diffusion surface is distributed in a high-low fluctuation mode, and the resistivity of each cladding region is higher than that of the non-cladding region adjacent to each diffusion surface.
The cladding layer of each diffusion surface is formed by a screen printing process, a magnetron sputtering process or a spraying process.
When the dispersing agent is a mixture of R 1-a-bTaAb and MX, the mass content of R 1-a-bTaAb in the mixture is not lower than that of MX in the mixture.
The mass ratio of R 1-a-bTaAb to MX in the mixture is (50-99): (1-50).
The average particle size of the dispersing agent is 0.2-40 mu m.
The total weight of the coating layers on all the diffusion surfaces is 0.3-3% of the weight of the neodymium-iron-boron magnet.
The minimum distance between two adjacent non-cladding areas on each diffusion surface is 0.1-2 mm.
The minimum distance between two adjacent non-cladding areas on each diffusion surface is 0.5-1 mm.
The minimum distance between two adjacent cladding areas on each diffusion surface is 0.5-5 mm.
The minimum distance between two adjacent cladding areas on each diffusion surface is 1-3 mm.
Each of the uncoated regions is circular or rectangular in shape, respectively.
The neodymium-iron-boron magnet is of a cuboid structure, and the thickness of the neodymium-iron-boron magnet is 0.1 mm-20 mm.
Compared with the prior art, the invention has the advantages that the alternating cladding areas and the non-cladding areas are arranged on each diffusion surface of the neodymium-iron-boron magnet, namely, each diffusion surface is provided with one non-cladding area between two adjacent cladding areas or one cladding area between two adjacent non-cladding areas, after the cladding material of each cladding area is the cladding layer of the dispersing agent, the heat treatment process is adopted to carry out diffusion treatment, so that high-resistivity compounds in the dispersing agent enter the neodymium-iron-boron magnet at high temperature, the resistivity of the cladding area of the neodymium-iron-boron magnet is improved, and as the cladding areas and the non-cladding areas alternate, the resistivity of the cladding area on the neodymium-iron-boron magnet is higher than that of the non-cladding area of the neodymium-iron-boron magnet, so that the diffused neodymium-iron-boron magnet is a diffusion magnet with a high-low-resistance distribution structure, the overall resistivity is improved, eddy current loss can be effectively reduced, and the coercive force of the cladding area of the neodymium-iron-boron magnet can be improved, and the whole coercive force of the neodymium-iron-boron magnet can be improved by adopting the current mature process, and the cladding layer can be formed into any whole neodymium-iron-boron magnet with different whole structures, thus the laminated independent processing process is easier, and the whole processing is easier.
Drawings
FIG. 1 is a schematic flow chart of a manufacturing process of a low eddy current loss NdFeB magnet according to the present invention;
fig. 2 is a schematic perspective view of a sintered nd-fe-b magnet surface coating diffusion source in the manufacturing process of the low eddy current loss nd-fe-b magnet according to the first embodiment of the present invention;
fig. 3 is a schematic perspective view of a sintered nd-fe-b magnet surface coating diffusion source in the manufacturing process of the low eddy current loss nd-fe-b magnet according to the second embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the embodiments of the drawings.
Embodiment one: as shown in FIG. 1, in the manufacturing process of the neodymium-iron-boron magnet with low eddy current loss, cladding areas and non-cladding areas which are alternately distributed are arranged at each diffusion surface of the neodymium-iron-boron magnet, and after a cladding layer is formed at each cladding area by adopting a diffusing agent containing heavy rare earth elements and high-resistivity compounds, the diffusing agent at each cladding area is diffused by adopting a heat treatment process, so that the diffusing agent at each cladding area is diffused into the inside of the neodymium-iron-boron magnet, and the diffusing magnet with a high-low-resistance distribution structure is formed.
In fig. 1, (a) is a schematic perspective view of a sintered nd-fe-b magnet after the surface of the sintered nd-fe-b magnet is coated with a diffusion source; (b) A partial longitudinal section schematic diagram of the sintered NdFeB magnet surface coated with a diffusion source; (c) Is a partial schematic longitudinal section of a sintered NdFeB diffusion magnet;
In this embodiment, by arranging alternating cladding regions and non-cladding regions on each diffusion surface of the neodymium-iron-boron magnet, that is, each diffusion surface, there is one non-cladding region between two adjacent cladding regions or one cladding region between two adjacent non-cladding regions, after each cladding region covering material is the cladding layer of the diffusing agent, a heat treatment process is adopted to perform diffusion treatment, so that a high-resistivity compound in the diffusing agent enters the neodymium-iron-boron magnet at a high temperature, the resistivity of the cladding region of the neodymium-iron-boron magnet is improved, and as the cladding regions and the non-cladding regions alternate, the resistivity of the cladding region on the neodymium-iron-boron magnet is higher than that of the non-cladding region thereof, so that the diffused neodymium-iron-boron magnet is a diffusion magnet with a high-low resistance fluctuation distribution structure, the overall resistivity is improved, eddy current loss can be effectively reduced, and simultaneously, the coercive force of the cladding region of the neodymium-iron-boron magnet can be improved, and the coercive force of the neodymium-iron-boron magnet can be improved.
Embodiment two: a manufacturing process of a low-eddy-current-loss neodymium-iron-boron magnet comprises the following steps of:
Step 1, taking a commercial N50 magnet with magnetic performance B r＝14.12kGs,HcJ＝12.44kOe,Hk/HcJ =98.3% as a matrix, and then cutting into 5 NdFeB magnets with the specification of 20mm multiplied by 2mm (length multiplied by width multiplied by thickness) by linear cutting, wherein the orientation direction is parallel to the thickness direction (2 mm);
Step 2, putting 5 neodymium-iron-boron magnets into a 3% dilute nitric acid solution, and ultrasonically cleaning for 1min to remove impurities such as greasy dirt attached to the surfaces of the neodymium-iron-boron magnets; then putting the neodymium-iron-boron magnet into absolute ethyl alcohol, ultrasonically cleaning for 1min, and drying to prepare a coating diffusion source;
Grinding terbium hydride powder and dysprosium hydride powder respectively by using an air flow mill to obtain terbium hydride powder with the granularity of 2.7-3.0 mu m and dysprosium hydride powder with the granularity of 2.7-3.0 mu m, and grinding terbium fluoride powder, dysprosium iron powder, aluminum oxide powder, silicon oxide powder, magnesium oxide powder and calcium oxide powder respectively by using a ball mill to obtain terbium fluoride powder, dysprosium iron powder, aluminum oxide powder, silicon oxide powder, magnesium oxide powder and calcium oxide powder with average granularity of 3.5 mu m;
step 4, uniformly mixing terbium hydride powder with the granularity of 2.7-3.0 mu m and aluminum oxide powder with the average granularity of 3.5 mu m according to the weight ratio of 20:80 to obtain a first part of mixed powder, configuring the first part of mixed powder and alcohol according to the mass ratio of 1:1, and uniformly stirring to obtain a first part of dispersing agent;
Uniformly mixing terbium fluoride powder with average particle size of 3.5 μm and silicon oxide powder with average particle size of 3.5 μm according to a weight ratio of 40:60 to obtain a second mixed powder, configuring the second mixed powder and alcohol according to a mass ratio of 1:1, and uniformly stirring to obtain a second dispersing agent;
Mixing dysprosium hydride powder with the granularity of 2.7-3.0 mu m and magnesia powder with the average granularity of 3.5 mu m uniformly according to the weight ratio of 20:80 to obtain a third part of mixed powder, configuring the third part of mixed powder and alcohol according to the mass ratio of 1:1, and stirring uniformly to obtain a third part of dispersing agent;
Uniformly mixing dysprosium iron with average particle size of 3.5 μm and calcium oxide powder with average particle size of 3.5 μm according to a weight ratio of 50:50 to obtain fourth mixed powder, configuring the fourth mixed powder and alcohol according to a mass ratio of 1:1, and uniformly stirring to obtain fourth dispersing agent;
Uniformly mixing dysprosium fluoride powder with average particle size of 3.5 μm and magnesium oxide powder with average particle size of 3.5 μm according to a weight ratio of 60:40 to obtain a fifth mixed powder, configuring the fifth mixed powder and alcohol according to a mass ratio of 1:1, and uniformly stirring to obtain a fifth dispersing agent;
Step 5, coating the prepared first to fifth dispersing agents on preset coating areas on the orientation surfaces of the 5 neodymium-iron-boron magnets respectively in a printing mode, wherein the coated sintered neodymium-iron-boron magnets are shown in fig. 2; the length of the coating area on each neodymium-iron-boron magnet is the same, the width D is 0.5mm, 1mm, 3mm, 4mm and 5mm, the sintered neodymium-iron-boron magnets with the coating areas of 0.5mm, 1mm, 3mm, 4mm and 5mm are respectively called sample 1 to sample 5, the diffusion agent coated by sample 1 is a first diffusion agent, the diffusion agent coated by sample 2 is a second diffusion agent, the diffusion agent coated by sample 3 is a third diffusion agent, the diffusion agent coated by sample 4 is a fourth diffusion agent, the diffusion agent coated by sample 5 is a fifth diffusion agent, and the mixed weight of the mixed powder of sample 1 to sample 5 is 1.5wt%, 1.25wt%, 2.5wt%, 1.75wt% and 1.7wt% respectively;
Coated area width D, unit uncoated area size, diffuser type, diffuser weight gain for samples 1 through 5 and comparative sample 1 (N50 magnet) are shown in table 1:
TABLE 1
And 6, placing the coated 5 sintered neodymium-iron-boron magnets into a molybdenum box, and then placing the molybdenum box into a tube furnace for vacuum heat treatment to obtain the diffusion magnets, wherein the heat treatment process comprises the following steps: the diffusion treatment temperature is 900 ℃ and the diffusion treatment time is 12 hours; the aging treatment temperature is 500 ℃ and the aging treatment time is 5 hours.
Magnetic properties and coated area resistivity tests were performed on samples 1 to 5 of example two and comparative example sample 1 (N50 magnet), and the test results are shown in table 2:
TABLE 2
As can be seen from the analysis of table 2, samples 1 to 5 of the second example had 3.3 times, 3.6 times, 9.9 times, 9.6 times and 10.3 times higher resistivity, respectively, and the coercivity was higher, the drop in remanence was smaller, and squareness H k/HcJ was also maintained better than that of the comparative example (N50 magnet). From the aspect of resistivity improvement, the resistivity of the neodymium-iron-boron magnet is greatly improved after oxides are added into all the dispersing agents, and the increased resistance can reduce eddy current loss generated by the neodymium-iron-boron magnet in use mainly because the oxides are diffused into the surface of the neodymium-iron-boron magnet to increase the resistance.
Embodiment III: a manufacturing process of a neodymium-iron-boron magnet with low eddy current loss specifically comprises the following steps:
Step 1, taking a commercial 45H magnet with magnetic performance B r＝13.52kGs,HcJ＝17.94kOe,Hk/HcJ =98.5% as a matrix, and then cutting out 5 NdFeB magnets with the specification of 20mm multiplied by 1.8mm (length multiplied by width multiplied by thickness) by linear cutting, wherein the orientation direction is parallel to the thickness direction (1.8 mm);
Step 2, putting 5 slices into a 3% dilute nitric acid solution, and ultrasonically cleaning for 1min to remove impurities such as greasy dirt attached to the surface; then putting the neodymium-iron-boron magnet into absolute ethyl alcohol, ultrasonically cleaning for 1min, and drying to prepare a coating diffusion source;
Grinding terbium fluoride powder, dysprosium fluoride powder, holmium fluoride powder, aluminum oxide powder, magnesium oxide powder and calcium oxide powder by using a ball mill respectively to obtain terbium fluoride powder, dysprosium fluoride powder, holmium fluoride powder, aluminum oxide powder, magnesium oxide powder and calcium oxide powder with average particle sizes of 3.0 mu m;
Step 4, uniformly mixing terbium fluoride powder with the average particle size of 3.0 mu m and aluminum oxide powder with the average particle size of 3.0 mu m according to the weight ratio of 20:80 to obtain a sixth mixed powder, configuring the sixth mixed powder and alcohol according to the mass ratio of 1:1, and uniformly stirring to obtain a sixth dispersing agent;
Uniformly mixing terbium fluoride powder with the average particle size of 3.0 mu m and aluminum oxide powder with the average particle size of 3.0 mu m according to the weight ratio of 40:60 to obtain seventh mixed powder, configuring the seventh mixed powder and alcohol according to the mass ratio of 1:1, and uniformly stirring to obtain seventh dispersing agent;
Uniformly mixing dysprosium fluoride powder with the average particle size of 3.0 mu m and magnesium oxide powder with the average particle size of 3.0 mu m according to the weight ratio of 30:70 to obtain eighth mixed powder, configuring the eighth mixed powder and alcohol according to the mass ratio of 1:1, and uniformly stirring to obtain eighth dispersing agent;
Uniformly mixing holmium fluoride powder with the average particle size of 3.0 mu m and calcium oxide powder with the average particle size of 3.0 mu m according to the weight ratio of 50:50 to obtain ninth mixed powder, configuring the ninth mixed powder and alcohol according to the mass ratio of 1:1, and uniformly stirring to obtain ninth dispersing agent;
Uniformly mixing dysprosium fluoride powder with the average particle size of 3.0 mu m and magnesium oxide powder with the average particle size of 3.0 mu m according to the weight ratio of 40:60 to obtain tenth mixed powder, configuring the tenth mixed powder and alcohol according to the mass ratio of 1:1, and uniformly stirring to obtain tenth dispersing agent;
Step 5, covering a non-coating area preset on the orientation surface of the 5 neodymium-iron-boron magnets by using an adhesive tape, correspondingly coating the prepared sixth to tenth dispersing agents on the coating areas of the orientation surface of the 5 neodymium-iron-boron magnets in a spraying mode, wherein each coating area is rectangular and is spaced apart as shown in fig. 3; wherein, the width D of the coating area of the 5 neodymium-iron-boron magnets is 0.5mm, 1mm, 2mm, 4mm and 5mm respectively; taking the adjacent cladding area and the non-cladding area as a period, the period number of the 5 NdFeB magnets is 20, 10, 5, 4 and 2 respectively; the weight gain of the mixed powder of the 5-piece neodymium-iron-boron magnet is 1.9wt%, 1.25wt%, 2.9wt%, 1.45wt% and 3wt% respectively; sintered neodymium-iron-boron magnets with the width of the coating region of 0.5mm, 1mm, 2mm, 4mm and 5mm are respectively referred to as sample 6 to sample 10; the diffusion agent coated by sample 6 is the sixth diffusion agent, the diffusion agent coated by sample 7 is the seventh diffusion agent, the diffusion agent coated by sample 8 is the eighth diffusion agent, the diffusion agent coated by sample 9 is the ninth diffusion agent, the diffusion agent coated by sample 10 is the tenth diffusion agent, and the coating area spacing D, the number of cycles, the weight ratio of the diffusion agents, and the diffusion source weight gain of sample 6 to sample 10 and comparative sample 2 (45H magnet) are shown in table 3:
TABLE 3 Table 3
And 6, placing the coated 5 sintered neodymium-iron-boron magnets into a molybdenum box, and then placing the molybdenum box into a tube furnace for vacuum heat treatment to obtain the diffusion magnets, wherein the heat treatment process comprises the following steps: the diffusion treatment temperature is 900 ℃ and the diffusion treatment time is 10 hours; the aging treatment temperature is 500 ℃ and the aging treatment time is 4 hours.
Magnetic properties and coated area resistivity tests were performed on samples 6 to 10 of example three and comparative sample (45H magnet), and the test results are shown in table 4.
As can be seen from the analysis of Table 4, the coercive force of samples 6 to 10 of example III was increased by 4.19kOe, 6.31kOe, 5.71kOe, 1.64kOe, and 7.5kOe, respectively, and the residual magnetism was less degraded, and the squareness H k/HcJ was also maintained better than that of comparative example 2 (45H magnet). This is because, after high temperature treatment, the heavy rare earth Ho, dy or Tb diffuses into the inside of the neodymium-iron-boron magnet, substituting Nd in the main phase, and improving magnetocrystalline anisotropy of the neodymium-iron-boron magnet, thereby improving coercive force.
In summary, the manufacturing process of the neodymium-iron-boron magnet with low eddy current loss can improve coercive force and resistivity, and simultaneously ensure that the residual magnetism and squareness are reduced to a small extent.
Claims (13)
1. A manufacturing process of a neodymium-iron-boron magnet with low eddy current loss is characterized in that cladding areas and non-cladding areas which are alternately distributed are arranged on each diffusion surface of the neodymium-iron-boron magnet, a diffusion agent containing heavy rare earth elements and high-resistivity compounds is adopted in each cladding area to form a cladding layer, and then a heat treatment process is adopted to carry out diffusion treatment, so that the diffusion agent at each cladding area is diffused into the inside of the neodymium-iron-boron magnet, and a diffusion magnet with a high-low resistance distribution structure is formed.
2. The manufacturing process of a low eddy current loss neodymium iron boron magnet according to claim 1, comprising the steps of:
Step 1, selecting n of the orientation surfaces of the NdFeB magnet and other surfaces except the orientation surfaces of the NdFeB magnet, taking all the selected surfaces as diffusion surfaces, wherein n is more than or equal to 0 and less than or equal to the number of the other surfaces of the NdFeB magnet except the orientation surfaces of the NdFeB magnet;
Step 2, respectively arranging at least two cladding areas on each diffusion surface, namely, the other areas except the cladding areas on each diffusion surface are called non-cladding areas, wherein one non-cladding area is arranged between two adjacent cladding areas or one cladding area is arranged between two adjacent non-cladding areas on each diffusion surface;
Step 3, forming a coating layer on each coating layer of each diffusion surface respectively, wherein the material of each coating layer is a diffusion agent; the dispersing agent is R 1-a-bTaAb or a mixture of R 1-a-bTaAb and MX, R 1-a-bTaAb is one or more of Dy, tb and Ho which are heavy rare earth elements, T is one or more of La, ce, pr, nd, gd, al, co, cu, ga, zr, ti, nb, fe, A is one or more of H, O, N, C, F, cl, B, a and b are weight percentages, a is more than or equal to 0wt% and less than 20wt%, b is more than or equal to 0wt% and less than 5wt%; MX is a compound with resistivity not less than 10mΩ & mm, M is one or more of Al, cu, ca, zr, co, fe, si, mn, mg, nb, ti, and X is one or more of O, N, F, cl, B.
And 4, performing diffusion treatment by adopting a heat treatment process, wherein the heat treatment process is to firstly keep the temperature at 700-1000 ℃ for 1-40 h, and then keep the temperature at 400-600 ℃ for 1-10 h. The diffusing agent at each cladding region diffuses into the inside of the neodymium-iron-boron magnet, so that the resistivity of each diffusion surface is distributed in a high-low fluctuation mode, and the resistivity of each cladding region is higher than that of the non-cladding region adjacent to each diffusion surface.
3. The manufacturing process of a low eddy current loss neodymium iron boron magnet according to claim 2, wherein the coating layer of each diffusion surface is formed by a screen printing process, a magnetron sputtering process or a spraying process.
4. The process of claim 2, wherein when the diffusing agent is a mixture of R 1-a-bTaAb and MX, the mass content of R 1-a-bTaAb in the mixture is not lower than the mass content of MX in the mixture.
5. The manufacturing process of a low eddy current loss neodymium iron boron magnet according to claim 4, wherein the mass ratio of R 1-a-bTaAb and MX in the mixture is (50-99): (1-50).
6. The process for manufacturing a neodymium-iron-boron magnet with low eddy current loss according to claim 2, wherein the average particle size of the dispersing agent is 0.2-40 μm.
7. The manufacturing process of a low eddy current loss neodymium iron boron magnet according to claim 2, wherein the total weight of the coating layers on all the diffusion surfaces is 0.3-3% of the weight of the neodymium iron boron magnet.
8. The manufacturing process of a low eddy current loss neodymium iron boron magnet according to claim 2, wherein the minimum distance between two adjacent non-cladding areas on each diffusion surface is 0.1-2 mm.
9. The manufacturing process of a low eddy current loss neodymium iron boron magnet according to claim 8, wherein the minimum distance between two adjacent non-cladding regions on each diffusion surface is 0.5-1 mm.
10. The manufacturing process of a low eddy current loss neodymium iron boron magnet according to claim 2, wherein the minimum distance between two adjacent cladding areas on each diffusion surface is 0.5-5 mm.
11. The manufacturing process of a low eddy current loss neodymium iron boron magnet according to claim 10, wherein the minimum distance between two adjacent cladding areas on each diffusion surface is 1-3 mm.
12. The process of claim 10, wherein each of the non-clad regions is circular or rectangular in shape.
13. The manufacturing process of the neodymium-iron-boron magnet with low eddy current loss according to claim 10, wherein the neodymium-iron-boron magnet is of a cuboid structure, and the thickness of the neodymium-iron-boron magnet is 0.1 mm-20 mm.
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