CN114334416A - Method for preparing high-performance neodymium iron boron magnet by solid-liquid phase separation diffusion process - Google Patents
Method for preparing high-performance neodymium iron boron magnet by solid-liquid phase separation diffusion process Download PDFInfo
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- 238000009792 diffusion process Methods 0.000 title claims abstract description 133
- 239000007791 liquid phase Substances 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 33
- 229910001172 neodymium magnet Inorganic materials 0.000 title claims abstract description 14
- 238000005191 phase separation Methods 0.000 title abstract description 9
- 238000010438 heat treatment Methods 0.000 claims abstract description 54
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 37
- 239000000956 alloy Substances 0.000 claims abstract description 37
- 239000007790 solid phase Substances 0.000 claims abstract description 19
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- 238000000137 annealing Methods 0.000 claims abstract description 13
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- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 5
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- 239000000203 mixture Substances 0.000 claims description 16
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- 238000005245 sintering Methods 0.000 description 12
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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
-
- 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
Abstract
The invention relates to a method for preparing a high-performance neodymium iron boron magnet by a solid-liquid phase separation diffusion process. Performing primary liquid phase diffusion heat treatment on the magnet attached with the diffusion source at the temperature higher than the melting point of the auxiliary alloy B and less than or equal to 600 ℃ for 30-80 h; then, carrying out secondary solid phase diffusion heat treatment at the temperature of 800-900 ℃ for 0.5-3 h; finally, annealing heat treatment is carried out at the temperature of 400 ℃ and 500 ℃ for 3-5 h; the magnet is formed by taking main phase alloy A as RaFe100‑a‑bBbAnd the auxiliary alloy B is RcM100‑cIs prepared, wherein R is Pr20Nd80Or Pr25Nd75The alloy, M is one or more of Al, Cu, Zn, Co and Ni, a, b and c are the weight percentage content multiplied by 100 and satisfy the following conditions: a is more than or equal to 26 and less than or equal to 32, b is more than or equal to 0.9 and less than or equal to 1.1, and c is more than or equal to 55 and less than or equal to 95; the melting point of the secondary alloy B is less than 600 ℃.
Description
Technical Field
The invention relates to the technical field of rare earth magnetic materials, in particular to a method for preparing a high-performance sintered neodymium-iron-boron magnet by a solid-liquid phase separation diffusion process.
Background
Neodymium iron boron (NdFeB) as the third-generation rare earth permanent magnet material has excellent magnetic property and is of 'Magang'It is called as follows. In recent years, with rapid progress in industries such as hybrid cars and wind power generation, higher and higher requirements have been placed on the performance of sintered NdFeB magnets. Forming heavy rare earth Tb or Dy instead of Nd on the outer layer of crystal grains by grain boundary diffusion method (Tb/Dy)2Fe14The B shell is the most common and effective method for improving the magnetic property of the sintered NdFeB. The grain boundary diffusion process can be divided into liquid phase diffusion (diffusion source diffuses from the magnet surface along the molten grain boundary toward the inside of the magnet) and solid phase diffusion (diffusion source diffuses from the grain boundary toward the inside of the main phase grains). In the traditional heat treatment process (solid-liquid phase synergistic diffusion), liquid phase diffusion and solid phase diffusion are carried out simultaneously, the diffusion depth of a diffusion source is limited, the gradient of a crystal boundary diffusion magnet structure is large, and an anti-core-shell structure (the diffusion source content in crystal grains is higher than that of a crystal grain epitaxial layer), a core-shell structure, an incomplete core-shell structure and an original structure are sequentially formed in the magnet along the diffusion direction. Different structures have different magnetic domain inversion fields and obvious structural gradients, so that the squareness of the magnet is reduced, and the larger the thickness of the magnet is, the more obvious the squareness of the diffusion magnet is reduced. In addition, Dy or Tb diffuses into the crystal grains to form an anti-core-shell structure, and the remanence is also remarkably reduced.
At present, methods for improving the diffusion depth of the grain boundary mainly include a low-melting-point alloy method, a low-melting-point metal auxiliary method, a two-step grain boundary diffusion method (such as CN201710497739.1), a cyclic cryogenic pretreatment method (such as CN202110533903.6) and the like. The low melting point alloy method and the low melting point metal auxiliary method increase the diffusion depth by improving the fluidity of a diffusion source, but the diffusion depth is increased, the diffusion rate to the inside of crystal grains is also increased, the concentration gradient is high, and the squareness degree is poor. CN201710497739.1 adopts a two-step grain boundary diffusion process, takes a Dy or Tb ternary alloy thin strip with a low melting point as a diffusion source to prepare the high-performance sintered NdFeB magnet, but the problems of large concentration gradient of the diffusion source, thick shell layer of a core-shell structure and the like cannot be effectively solved. And CN202110533903.6 generates micro cracks between the matrix phase and the rare earth-rich phase through circulating cryogenic treatment, the micro cracks can be used as effective channels for grain boundary diffusion, the depth of the heavy rare earth element grain boundary diffusion is improved, but the cracks can reduce the mechanical property of the magnet, and simultaneously, the cracks can cause internal defects of the magnet, the defect positions can possibly become nucleation points of a reverse domain in the demagnetization process, and the coercive force of the magnet is reduced.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for preparing a high-performance sintered neodymium-iron-boron magnet by a solid-liquid phase separation diffusion process. The novel process separates liquid phase diffusion and solid phase diffusion in the grain boundary diffusion process, the diffusion depth is increased by the liquid phase diffusion, the shell thickness of the core-shell structure is controlled by the solid phase diffusion, and finally the high-performance grain boundary diffusion magnet with large diffusion depth and uniform core-shell structure is obtained.
The first purpose of the present invention is to provide a method for preparing a neodymium iron boron magnet (the mechanism schematic diagram is shown in fig. 1), which comprises the following steps: carrying out primary liquid phase diffusion heat treatment on the magnet attached with the diffusion source; then carrying out secondary solid phase diffusion heat treatment; finally, annealing heat treatment is carried out to obtain a diffusion magnet;
the magnet is made of a main phase alloy A and an auxiliary alloy B; the nominal component of the main phase alloy A is RaFe100-a-bBbThe nominal composition of the secondary alloy B is RcM100-cWherein R is Pr20Nd80、Pr25Nd75In the alloy, M is one or more of Al, Cu, Zn, Co and Ni, a, b and c are the weight percentage content multiplied by 100 and satisfy the following relations: a is more than or equal to 26 and less than or equal to 32, b is more than or equal to 0.9 and less than or equal to 1.1, and c is more than or equal to 55 and less than or equal to 95; the melting point of the auxiliary alloy B is lower than 600 ℃;
the diffusion source is particles containing Dy or Tb;
the temperature of the primary liquid phase diffusion heat treatment is higher than the melting point of the auxiliary alloy B and is less than or equal to 600 ℃, and the time is 30-80 h;
the temperature of the secondary solid phase diffusion heat treatment is 800-900 ℃, and the time duration is 0.5-3 h;
the temperature of the annealing heat treatment is 400-500 ℃, and the time duration is 3-5 h.
The diffusion source is high-melting-point particles containing Dy or Tb, the first-stage liquid phase diffusion heat treatment is carried out at the lower temperature of 400-600 ℃, the temperature is only higher than the melting point of a grain boundary phase, so that the diffusion source is only diffused along the molten grain boundary phase, the solid phase diffusion to crystal grains is negligible, and the diffusion source can be diffused to a deeper area in the magnet through the first-stage liquid phase diffusion heat treatment, and meanwhile, the diffusion source is prevented from entering the crystal grains; in the process of secondary solid phase diffusion heat treatment, a diffusion source which enters a crystal boundary phase diffuses into the crystal grains to form a core-shell structure; finally, the grain structure can be optimized and the grain defects can be reduced through annealing treatment. The method can separate liquid phase diffusion and solid phase diffusion in the crystal boundary diffusion process, the diffusion depth and the shell layer thickness of the core-shell structure are controllable, the formation of an anti-core-shell structure is avoided, the core-shell structure with larger depth and more uniform structure can be obtained, the uniformity of the diffusion magnet structure is improved, and the squareness of the diffusion magnet is obviously improved.
Preferably, the main phase alloy A accounts for 85-99% by mass, and the balance is the auxiliary alloy B.
Preferably, the particle diameter of the diffusion source is 50nm to 3 μm, and the weight increase ratio of the magnet to which the diffusion source is attached is 0.1% to 0.5%.
Preferably, the temperature of the primary liquid phase diffusion heat treatment is 400-600 ℃.
Preferably, the adhesion method is any one of spray coating, droplet coating and electrodeposition.
As the most preferred embodiment of the present invention, the preparation method comprises the steps of:
(1) preparing a magnet by adopting a main phase alloy A and an auxiliary alloy B; the nominal component of the main phase alloy A is RaFe100-a- bBbThe nominal composition of the secondary alloy B is RcM100-cWherein R is Pr20Nd80、Pr25Nd75In the alloy, M is one or more of Al, Cu, Zn, Co and Ni, a, b and c are the weight percentage content multiplied by 100 and satisfy the following relations: a is more than or equal to 26 and less than or equal to 32, b is more than or equal to 0.9 and less than or equal to 1.1, and c is more than or equal to 55 and less than or equal to 95; the melting point of the auxiliary alloy B is lower than 600 ℃;
(2) attaching diffusion sources to the upper and lower surfaces of the magnet; the diffusion source is particles containing Dy or Tb, the particle size of the diffusion source is 50 nm-3 mu m, and the weight gain ratio of the magnet attached to the diffusion source is 0.1% -0.5%; the adhesion method adopts any one of spraying, dripping and electrodeposition;
(3) performing primary liquid phase diffusion heat treatment on the magnet attached with the diffusion source, wherein the temperature of the primary liquid phase diffusion heat treatment is 400-600 ℃, and the time duration is 30-80 h; then, carrying out secondary solid phase diffusion heat treatment at the temperature of 800-900 ℃ for 0.5-3 h; finally, annealing heat treatment is carried out at 400-500 ℃ to obtain the diffusion magnet, wherein the time is 3-5 h.
The second purpose of the invention is to provide a neodymium iron boron magnet prepared according to the preparation method.
Compared with the prior art, the invention has the beneficial effects that:
(1) the method adopts a solid-liquid phase separation diffusion process to carry out grain boundary diffusion on the designed magnet, so that the separation of solid phase diffusion and liquid phase diffusion is realized, the diffusion depth can be increased by the liquid phase diffusion, the shell thickness of the core-shell structure is controlled by the solid phase diffusion, and the diffusion depth and the shell thickness can be regulated and controlled;
(2) the invention adopts the solid-liquid phase separation diffusion process to avoid the formation of an anti-core-shell structure in the diffusion magnet, increase the depth of the core-shell structure, improve the uniformity and the squareness of the magnet structure and comprehensively improve the magnetic performance of the diffusion magnet;
(3) the invention adopts the solid-liquid phase separation diffusion process to improve the effective utilization rate of Dy and Tb and save heavy rare earth resources.
Drawings
FIG. 1 is a schematic diagram of the solid-liquid phase co-diffusion process and the solid-liquid phase separation diffusion process.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and the following embodiments are used for illustrating the present invention and are not intended to limit the scope of the present invention.
The specific techniques or conditions not indicated in the examples are all conventional methods or techniques or conditions described in the literature of the field or according to the product specifications. The reagents and instruments used are conventional products which are available from normal commercial vendors, not indicated by manufacturers.
Comparative example 1
According to the nominal composition of the main phase alloy A, the alloy is (Pr)20Nd80)29Fe70B (wt.%), the nominal composition of the secondary alloy B is (Pr)20Nd80)70Cu30(wt.%) A, B two-component quick-setting thin strip was prepared, and after hydrogen crushing and dehydrogenation, coarse crushed magnetic powder was obtained, and then powder was obtained by jet milling to obtain 3 μm fine powder.
Mixing A, B two-component airflow grinding powder according to a mass ratio of 95:5 in a glove box, after fully and uniformly mixing, carrying out orientation forming under the protection of inert gas to obtain a green body, carrying out vacuum packaging on the green body, carrying out cold isostatic pressing, then putting the green body into a vacuum sintering furnace for sintering, carrying out heat preservation at 1050 ℃ for 2 hours, introducing argon for air cooling, carrying out primary heat treatment at 900 ℃ for 4 hours, and then carrying out secondary heat treatment at 450 ℃ for 4 hours to obtain a magnet C.
The prepared magnet C was subjected to BH test, and the results were as follows:
original magnet C: b isr＝14.24kG，Hcj＝13.63kOe，(BH)max＝49.20MGOe，Hk/Hcj＝96.1％
Comparative example 2
According to the nominal composition of the main phase alloy A, the alloy is (Pr)20Nd80)29Fe70B (wt.%), the nominal composition of the secondary alloy B is (Pr)20Nd80)70Cu30(wt.%) A, B two-component quick-setting thin strip was prepared, and after hydrogen crushing and dehydrogenation, coarse crushed magnetic powder was obtained, and then powder was obtained by jet milling to obtain 3 μm fine powder.
Mixing A, B two-component airflow grinding powder according to a mass ratio of 95:5 in a glove box, after fully and uniformly mixing, carrying out orientation forming under the protection of inert gas to obtain a green body, carrying out vacuum packaging on the green body, carrying out cold isostatic pressing, then putting the green body into a vacuum sintering furnace for sintering, carrying out heat preservation at 1050 ℃ for 2 hours, introducing argon for air cooling, carrying out primary heat treatment at 900 ℃ for 4 hours, and then carrying out secondary heat treatment at 450 ℃ for 4 hours to obtain a magnet C.
Cutting the magnet C into 4mm and 8mm in thickness along the orientation direction, and mixing ethanol and TbH3The nanoparticles were mixed according to 2 ml: 1g of the ratio configuration TbH3Spraying the nanometer ethanol suspension as diffusion source on the upper and lower surfaces of two-thickness magnet, drying at weight ratio of 0.50%, placing in a vacuum diffusion furnace, and vacuumizing to 3 × 10-3Pa below, diffusion heat treatment at 880 deg.C for 3 hr, and annealing heat treatment at 500 deg.C for 3 hr to obtain diffusion magnet C1(4mm) and C2(8mm)。
The prepared C1、C2Magnets of two thicknesses were subjected to the BH test, with the following results:
diffusion magnet C1：Br＝14.08kG，Hcj＝20.58kOe，(BH)max＝47.96MGOe，Hk/Hcj＝92.8％
Diffusion magnet C2：Br＝14.13kG，Hcj＝19.10kOe，(BH)max＝48.24MGOe，Hk/Hcj＝83.5％
Comparative example 3
According to the nominal composition of the main phase alloy A, the alloy is (Pr)20Nd80)29Fe70B (wt.%), the nominal composition of the secondary alloy B is (Pr)20Nd80)70Cu30(wt.%) A, B two-component quick-setting thin strip was prepared, and after hydrogen crushing and dehydrogenation, coarse crushed magnetic powder was obtained, and then powder was obtained by jet milling to obtain 3 μm fine powder.
Mixing A, B two-component airflow grinding powder according to a mass ratio of 95:5 in a glove box, after fully and uniformly mixing, carrying out orientation forming under the protection of inert gas to obtain a green body, carrying out vacuum packaging on the green body, carrying out cold isostatic pressing, then putting the green body into a vacuum sintering furnace for sintering, carrying out heat preservation at 1050 ℃ for 2 hours, introducing argon for air cooling, carrying out primary heat treatment at 900 ℃ for 4 hours, and then carrying out secondary heat treatment at 450 ℃ for 4 hours to obtain a magnet C.
Cutting magnet C into 4mm and 8mm in thickness along the orientation direction, and mixing ethanol and DyH3The nanoparticles were mixed according to 2 ml: 1g of DyH3Spraying the nanometer ethanol suspension as diffusion source on the upper and lower surfaces of two-thickness magnet, drying at weight ratio of 0.50%, placing in a vacuum diffusion furnace, and vacuumizing to 3 × 10-3Pa below, diffusion heat treatment at 880 deg.C for 3 hr, and annealing heat treatment at 500 deg.C for 3 hr to obtain diffusion magnet C3(4mm) and C4(8mm)。
The prepared C3、C4Magnets of two thicknesses were subjected to the BH test, with the following results:
diffusion magnet C3：Br＝14.10kG，Hcj＝17.63kOe，(BH)max＝48.03MGOe，Hk/Hcj＝91.8％
Diffusion magnet C4：Br＝14.16kG，Hcj＝16.36kOe，(BH)max＝48.36MGOe，Hk/Hcj＝82.3％
Example 1
According to the nominal composition of the main phase alloy A, the alloy is (Pr)20Nd80)29Fe70B (wt.%), the nominal composition of the secondary alloy B is (Pr)20Nd80)70Cu30(wt.%) A, B two-component quick-setting thin strip was prepared, and after hydrogen crushing and dehydrogenation, coarse crushed magnetic powder was obtained, and then powder was obtained by jet milling to obtain 3 μm fine powder.
Mixing A, B two-component airflow grinding powder according to a mass ratio of 95:5 in a glove box, after fully and uniformly mixing, carrying out orientation forming under the protection of inert gas to obtain a green body, carrying out vacuum packaging on the green body, carrying out cold isostatic pressing, then putting the green body into a vacuum sintering furnace for sintering, carrying out heat preservation at 1050 ℃ for 2 hours, introducing argon for air cooling, carrying out primary heat treatment at 900 ℃ for 4 hours, and then carrying out secondary heat treatment at 450 ℃ for 4 hours to obtain a magnet C.
Cutting the magnet C into 4mm and 8mm in thickness along the orientation direction, and mixing ethanol and TbH3The nanoparticles were mixed according to 2 ml: 1g of the ratio configuration TbH3Spraying the nanometer ethanol suspension as diffusion source on the upper and lower surfaces of two-thickness magnet, drying at weight ratio of 0.25%, placing in a vacuum diffusion furnace, and vacuumizing to 3 × 10-3Pa below, performing low temperature liquid phase diffusion heat treatment at 580 deg.C for 50 hr, performing high temperature solid phase diffusion heat treatment at 880 deg.C for 3 hr, and performing annealing heat treatment at 500 deg.C for 3 hr to obtain diffusion magnet C5(4mm) and C6(8mm)。
The prepared C5、C6Magnets of two thicknesses were subjected to the BH test, with the following results:
diffusion magnet C5：Br＝14.26kG，Hcj＝20.83kOe，(BH)max＝49.56MGOe，Hk/Hcj＝96.3％
Diffusion magnet C6：Br＝14.30kG，Hcj＝20.25kOe，(BH)max＝49.83MGOe，Hk/Hcj＝93.2％
Example 2
According to the nominal composition of the main phase alloy A, the alloy is (Pr)20Nd80)29Fe70B (wt.%), the nominal composition of the secondary alloy B is (Pr)20Nd80)70Cu30(wt.%) A, B two-component quick-setting thin strip was prepared, and after hydrogen crushing and dehydrogenation, coarse crushed magnetic powder was obtained, and then powder was obtained by jet milling to obtain 3 μm fine powder.
Mixing A, B two-component airflow grinding powder according to a mass ratio of 95:5 in a glove box, after fully and uniformly mixing, carrying out orientation forming under the protection of inert gas to obtain a green body, carrying out vacuum packaging on the green body, carrying out cold isostatic pressing, then putting the green body into a vacuum sintering furnace for sintering, carrying out heat preservation at 1050 ℃ for 2 hours, introducing argon for air cooling, carrying out primary heat treatment at 900 ℃ for 4 hours, and then carrying out secondary heat treatment at 450 ℃ for 4 hours to obtain a magnet C.
Dividing the magnet C in the direction of orientationCutting into 4mm and 8mm thick, mixing ethanol and TbH3The nanoparticles were mixed according to 2 ml: 1g of the ratio configuration TbH3Spraying the nanometer ethanol suspension as diffusion source on the upper and lower surfaces of two-thickness magnet, drying at weight ratio of 0.50%, placing in a vacuum diffusion furnace, and vacuumizing to 3 × 10-3Pa below, performing low temperature liquid phase diffusion heat treatment at 580 deg.C for 50 hr, performing high temperature solid phase diffusion heat treatment at 880 deg.C for 3 hr, and performing annealing heat treatment at 500 deg.C for 3 hr to obtain diffusion magnet C7(4mm) and C8(8mm)。
The prepared C7、C8Magnets of two thicknesses were subjected to the BH test, with the following results:
diffusion magnet C7：Br＝14.23kG，Hcj＝22.03kOe，(BH)max＝49.17MGOe，Hk/Hcj＝96.4％
Diffusion magnet C8：Br＝14.25kG，Hcj＝21.36kOe，(BH)max＝49.43MGOe，Hk/Hcj＝92.5％
Example 3
According to the nominal composition of the main phase alloy A, the alloy is (Pr)20Nd80)29Fe70B (wt.%), the nominal composition of the secondary alloy B is (Pr)20Nd80)70Cu30(wt.%) A, B two-component quick-setting thin strip was prepared, and after hydrogen crushing and dehydrogenation, coarse crushed magnetic powder was obtained, and then powder was obtained by jet milling to obtain 3 μm fine powder.
Mixing A, B two-component airflow grinding powder according to a mass ratio of 95:5 in a glove box, after fully and uniformly mixing, carrying out orientation forming under the protection of inert gas to obtain a green body, carrying out vacuum packaging on the green body, carrying out cold isostatic pressing, then putting the green body into a vacuum sintering furnace for sintering, carrying out heat preservation at 1050 ℃ for 2 hours, introducing argon for air cooling, carrying out primary heat treatment at 900 ℃ for 4 hours, and then carrying out secondary heat treatment at 450 ℃ for 4 hours to obtain a magnet C.
The magnet C was cut into a thickness of 4mm and 8mm in the orientation direction,mixing ethanol and DyH3The nanoparticles were mixed according to 2 ml: 1g of DyH3Spraying the nanometer ethanol suspension as diffusion source on the upper and lower surfaces of two-thickness magnet, drying at weight ratio of 0.50%, placing in a vacuum diffusion furnace, and vacuumizing to 3 × 10-3Pa below, performing low temperature liquid phase diffusion heat treatment at 580 deg.C for 50 hr, performing high temperature solid phase diffusion heat treatment at 880 deg.C for 3 hr, and performing annealing heat treatment at 500 deg.C for 3 hr to obtain diffusion magnet C9(4mm) and C10(8mm)。
The prepared C9、C10Magnets of two thicknesses were subjected to the BH test, with the following results:
diffusion magnet C9：Br＝14.23kG，Hcj＝18.82kOe，(BH)max＝48.99MGOe，Hk/Hcj＝95.8％
Diffusion magnet C10：Br＝14.26kG，Hcj＝17.75kOe，(BH)max＝49.48MGOe，Hk/Hcj＝91.6％
The results of comparison of the remanence, coercive force, maximum magnetic energy, and squareness of each magnet in the above comparative example and example are shown in table 1.
Table 1 remanence, coercive force, maximum magnetic energy, and squareness of each magnet in comparative example and example
Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (8)
1. The preparation method of the neodymium iron boron magnet is characterized by comprising the following steps: carrying out primary liquid phase diffusion heat treatment on the magnet attached with the diffusion source; then carrying out secondary solid phase diffusion heat treatment; finally, annealing heat treatment is carried out to obtain a diffusion magnet;
the magnet is made of a main phase alloy A and an auxiliary alloy B; the nominal component of the main phase alloy A is RaFe100-a-bBbThe nominal composition of the secondary alloy B is RcM100-cWherein R is Pr20Nd80、Pr25Nd75In the alloy, M is one or more of Al, Cu, Zn, Co and Ni, a, b and c are the weight percentage content multiplied by 100 and satisfy the following relations: a is more than or equal to 26 and less than or equal to 32, b is more than or equal to 0.9 and less than or equal to 1.1, and c is more than or equal to 55 and less than or equal to 95; the melting point of the auxiliary alloy B is lower than 600 ℃;
the diffusion source is particles containing Dy or Tb;
the temperature of the primary liquid phase diffusion heat treatment is higher than the melting point of the auxiliary alloy B and is less than or equal to 600 ℃, and the time is 30-80 h;
the temperature of the secondary solid phase diffusion heat treatment is 800-900 ℃, and the time duration is 0.5-3 h;
the temperature of the annealing heat treatment is 400-500 ℃, and the time duration is 3-5 h.
2. The method according to claim 1, wherein the main phase alloy A accounts for 85-99% by mass.
3. The production method according to claim 1 or 2, wherein the particle size of the diffusion source is 50nm to 3 μm.
4. The method according to any one of claims 1 to 3, wherein the magnet weight gain ratio of the adhesion diffusion source is 0.1% to 0.5%.
5. The method as claimed in any one of claims 1 to 4, wherein the temperature of the primary liquid phase diffusion heat treatment is 400-600 ℃.
6. The method according to any one of claims 1 to 5, wherein the adhering method is any one of spray coating, droplet coating and electrodeposition.
7. The method according to claim 1 to 6, comprising the steps of:
(1) preparing a magnet by adopting a main phase alloy A and an auxiliary alloy B; the nominal component of the main phase alloy A is RaFe100-a-bBbThe nominal composition of the secondary alloy B is RcM100-cWherein R is Pr20Nd80、Pr25Nd75In the alloy, M is one or more of Al, Cu, Zn, Co and Ni, a, b and c are the weight percentage content multiplied by 100 and satisfy the following relations: a is more than or equal to 26 and less than or equal to 32, b is more than or equal to 0.9 and less than or equal to 1.1, and c is more than or equal to 55 and less than or equal to 95; the melting point of the auxiliary alloy B is lower than 600 ℃;
(2) attaching diffusion sources to the upper and lower surfaces of the magnet; the diffusion source is particles containing Dy or Tb, the particle size of the diffusion source is 50 nm-3 mu m, and the weight gain ratio of the magnet attached to the diffusion source is 0.1% -0.5%; the adhesion method adopts any one of spraying, dripping and electrodeposition;
(3) performing primary liquid phase diffusion heat treatment on the magnet attached with the diffusion source, wherein the temperature of the primary liquid phase diffusion heat treatment is 400-600 ℃, and the time duration is 30-80 h; then, carrying out secondary solid phase diffusion heat treatment at the temperature of 800-900 ℃ for 0.5-3 h; finally, annealing heat treatment is carried out at 400-500 ℃ to obtain the diffusion magnet, wherein the time is 3-5 h.
8. A neodymium iron boron magnet, which is characterized by being prepared by the preparation method of claims 1-7.
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| WO2023116234A1 (en) * | 2021-12-21 | 2023-06-29 | 北京工业大学 | Method for preparing high-performance neodymium-iron-boron magnet through solid-liquid phase separation diffusion process |
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