Halbach array magnet assembly and integrated preparation method thereof

Abstract

The invention relates to the technical field of Halbach array magnet assemblies, and particularly discloses a Halbach array magnet assembly and an integrated preparation method thereof, and the method comprises the steps: designing the components of a blank magnet, the powder particle size of the components and an orientation current adopted when the blank magnet is prepared, and obtaining the blank magnet through material mixing, compression molding and sintering; arranging two opposite side surfaces on the blank magnet as welding surfaces, and forming a welding surface group by the two opposite welding surfaces; the included angle of the C-axis direction of every two adjacent blank magnets is 5-90 degrees, and a pre-machined piece is obtained; then carrying out surface treatment, and coating a rare earth layer on the welding surface of the pre-processing sheet; a plurality of pre-machined pieces are stacked, a high-temperature welding coating is arranged between every two adjacent pre-machined pieces, then welding heat treatment and tempering treatment are conducted in sequence, and then cutting, surface protection treatment and integrated magnetizing are conducted in sequence to obtain the high-strength and high-heat-resistance composite material. The Halbach array magnet assembly obtained through the method has good anti-shearing capacity and three-point bending force, and cracking does not occur.

Description

Technical Field

[0001] This application relates to the technical field of Halbach array magnet components, and more specifically, to a Halbach array magnet component and an integrated preparation method thereof. Background Art

[0002] In the assembly process of traditional Halbach array magnet components, the neodymium iron boron magnets need to be magnetized first and then assembled. For example, if three neodymium iron boron magnets are required to form a Halbach array, the three magnets need to be sintered separately first, then processed, electroplated to form semi-finished products with coatings, magnetized separately, and finally assembled by gluing.

[0003] The preparation method of this kind of Halbach array magnet component requires separate sintering, processing, electroplating, and magnetization for each magnet, and finally assembly. On the one hand, it is easy to lead to low operation efficiency; on the other hand, each magnet has a specific orientation direction after magnetization. When the arrangement directions of the magnets are different, the magnetic force of each magnet is different, and the magnets attract and repel each other, resulting in the phenomenon of flipping between the magnets during the assembly of the Halbach array magnet component. If glue is used for assembly, the shear resistance between the magnets is likely to be poor; if welding is used for assembly, during the cooling after high-temperature welding, it is also easy to cause cracking due to different shrinkage ratios in different directions of each magnet, ultimately resulting in poor shear resistance of the entire magnet component. Summary of the Invention

[0004] The Halbach array magnet component obtained by the traditional preparation method is prone to poor shear resistance between the magnets and cracking. To solve the above technical problems, this application provides a Halbach array magnet component and an integrated preparation method thereof.

[0005] In the first aspect, this application provides the following technical solution: An integrated preparation method of a Halbach array magnet component, comprising the following steps: Step 1: Design the composition of the blank magnet, the powder particle size of the magnet, and the orientation current used when preparing the blank magnet. After mixing, pressing into shape, and sintering, a blank magnet is obtained; Step 2: Prepare a pre-processed sheet: Set two opposite side surfaces of the blank magnet as welding surfaces, and form a group of welding surface groups with the two opposite welding surfaces; the included angle between the C-axis directions of two adjacent blank magnets is 5-90°, and a pre-processed sheet is obtained; Step 3: Surface treatment and / or rare earth alloy coating: Perform surface treatment on the pre-processed sheet, and then coat a rare earth layer on the welding surface of the pre-processed sheet; Step 4: Stacking: Stack multiple pre-processed sheets, and a high-temperature welding coating is provided between adjacent pre-processed sheets to obtain a stacked magnet; Step 5: Diffusion welding: The stacked magnet is successively subjected to welding heat treatment and tempering treatment to obtain a welded magnet; Step 6: Successively perform cutting, surface protection treatment, and integral magnetization to obtain a Halbach array magnet assembly; The number of blank magnets in the second step is not less than 2; The raw material of the rare earth layer in the third step is one of rare earth simple substances, rare earth alloys, and rare earth compounds; The raw material of the high-temperature welding coating in the fourth step is a welding aid, and the welding aid is a low-melting-point alloy containing rare earth elements or rare earth metal simple substances.

[0006] The degree of orientation refers to whether the units (crystals) constituting the magnet are all arranged along the expected direction (C-axis direction). The C-axis direction refers to the orientation direction and the direction opposite to the orientation direction. When the included angle of the C-axis is 90°, the welding difficulty is the greatest. This is because after high-temperature welding, due to the composition of the blank magnet and the included angle of the C-axis direction, the shrinkage ratio difference of the blank magnet material is the largest, so it is also easier to appear the phenomena of poor bonding force and cracking.

[0007] In the composition of the blank magnet used in this application, in addition to neodymium iron boron, Co, Dy, and Tb are also added; the powder particle size of the composition reaches the required size range by a jet mill. The two cooperate with each other, which is beneficial to reducing the shrinkage ratio difference of the blank magnet material.

[0008] In the second step of this application, the number of blank magnets used is not less than 2, and the specific number is determined according to the requirements of the actual Halbach array magnet assembly. In the third step, through surface treatment, it is easier to coat the rare earth layer on the welding surface of the pre-processed sheet, and the thickness of the rare earth layer is uniform, which is also beneficial to forming a sufficient and uniform connection between adjacent pre-processed sheets. Coupled with the high-temperature welding coating provided between adjacent pre-processed sheets in the fourth step, the integrity of the stacked magnet is better.

[0009] At the same time, the raw material of the rare earth layer is one of rare earth simple substances, rare earth alloys, and rare earth compounds, the raw material of the high-temperature welding coating is a low-melting-point alloy containing rare earth elements or rare earth metal simple substances, and the thickness of the high-temperature welding coating is consistent with the thickness of the rare earth layer, which is beneficial to forming a tight connection during the welding process, improving the bonding force between pre-processed sheets, and thus improving the bonding force of the formed whole.

[0010] In Step 5, after welding heat treatment and tempering treatment, a better bonding force can be achieved between adjacent pre-processed sheets, and the phenomenon of cracking is not likely to occur. In addition, the composition, magnetic powder particle size, crystal orientation degree, etc. of the blank magnet used in this application are all designed as required. By adjusting the shrinkage and expansion characteristics of the material, it is even less likely for the welded magnet to crack.

[0011] Finally, the welded magnet obtained after welding heat treatment and tempering treatment is cut, surface protected, and integrally magnetized according to the dimensional requirements. This is not only convenient to operate but also has high processing efficiency. Finally, the required Halbach array magnet assembly is obtained as required.

[0012] Further, the median particle size of the powder for manufacturing the blank magnet in Step 1 is 3.2 - 8 μm.

[0013] In this application, the magnetic powder used in the blank magnet is obtained by gas atomization after the raw materials are melted, and the particle size of the magnetic powder is controlled by gas atomization. The particle size of the powder used in the blank magnet is related to the addition amount of Dy and / or Tb in the composition, as well as the parameters used in the pressing and sintering operations. When the magnetic powder has the above particle size range, it can cooperate with the addition amount of Dy and / or Tb in the blank magnet, so that the sintering temperature of adjacent blank magnets remains the same, which is convenient for subsequent welding at the same temperature.

[0014] Further, in Step 1, the pressing pressure for pressing is 2 - 5 MPa, and the pressing time is 3 - 5 s; the isostatic pressure is 180 - 200 MPa, and the pressing time is 5 - 15 s; the orientation current used is 0 - 200 A.

[0015] In the process of pressing, it is first preliminarily shaped by the pressing pressure, and then the isostatic pressure is used to further increase the compactness. Moreover, in the process of pressing, the orientation current is synchronously used to make the orientation degree of the grain units of the blank magnet reach the specified requirements.

[0016] Further, in Step 2, two adjacent blank magnets are blank magnet a and blank magnet b respectively. The C-axis direction of blank magnet a is perpendicular to the welding surface, the C-axis angle between blank magnet a and blank magnet b is 90°, the composition used in blank magnet a is: Co content ≤ 5%, Dy and / or Tb content ≤ 5%; the composition used in blank magnet b is: Co content 10 - 20%, Dy and / or Tb content ≤ 10%.

[0017] When the C-axis angle between two adjacent blank magnets is 90°, by controlling the Co content, Dy and / or Tb content of the blank magnet, especially the limitation of the Co content, it is beneficial to prevent the Halbach array magnet assembly finally obtained from cracking.

[0018] Further, in the second step, three adjacent blank magnets are respectively blank magnet a, blank magnet b, and blank magnet c. The C-axis direction of the blank magnet a is perpendicular to the welding surface, the C-axis direction of the blank magnet b forms an angle of 45° with the welding surface, and the C-axis direction of the blank magnet c is parallel to the welding surface. The composition used in the blank magnet a is: Co content ≤ 5%, Dy and / or Tb content ≤ 5%; the composition used in the blank magnet b is: Co content 5 - 18%, Dy and / or Tb content ≤ 10%; the composition used in the blank magnet c is: Co content 10 - 20%, Dy and / or Tb content ≤ 10%.

[0019] Further, in the third step, the surface is treated until the flatness reaches 0.02 - 0.08 mm.

[0020] In the third step of the present application, surface treatment is used to make the surface flatness of the pre-processed sheet reach the above range, which is more conducive to coating the rare earth layer and is also conducive to diffusion welding treatment after coating the high-temperature welding coating, and it is not easy for the magnet assembly to crack.

[0021] Further, in the fifth step, the temperature condition of the welding heat treatment is 700 - 1500 °C, and the welding heat treatment time is 4 - 40 h; Then tempering treatment is carried out under the condition of 450 - 700 °C, and the tempering treatment time is 2 - 5 h.

[0022] By performing welding heat treatment and tempering treatment in sequence under the above conditions, it is not only conducive to improving the overall bonding performance of the magnet assembly, but also conducive to reducing the possibility of the magnet assembly cracking.

[0023] Further, in the sixth step, the welded magnet is first cut into a black sheet assembly according to the product size requirements, the black sheet assembly is subjected to surface protection treatment, and then the magnetizing coil is wound around the surface-protected black sheet assembly in a winding form, and integral magnetizing treatment is carried out under a magnetic field of 4.5 T.

[0024] In the present application, integral magnetizing is carried out on the entire magnet assembly obtained after stacking and welding, and the operation efficiency is high; and the assembled magnet assembly can not only reach the expected orientation direction during the magnetizing process, but also is not easy to crack.

[0025] Further, in the fourth step, no high-temperature welding coating is provided between adjacent pre-processed sheets.

[0026] When the high-temperature welding coating is not set, the pre-processed sheets coated with rare-earth layers adjacent to each other are directly welded together to form a magnet assembly. However, compared with the magnet assembly formed by welding and heat treatment of the pre-processed sheets with the high-temperature welding coating, its overall bonding strength and anti-cracking effect are relatively poor.

[0027] In a second aspect, the present application provides the following technical solution: A Halbach array magnet assembly is obtained by using the integrated preparation method of a Halbach array magnet assembly described above.

[0028] In summary, the present application has the following beneficial effects: 1. In the present application, the magnetic powder composition used in the blank magnet, the particle size of the powder for manufacturing the magnet, and the orientation current used when preparing the blank magnet are all designed to improve the shrinkage and expansion characteristics of the blank magnet. Then, the surface of the pre-processed sheet is treated to achieve a high flatness. After coating with a rare-earth layer and a high-temperature welding coating, and then through welding heat treatment, tempering treatment, and integrated magnetization, it is beneficial to make the obtained Halbach array magnet assembly have a good three-point bending force, and it is not easy for cracks to appear between adjacent single magnets.

[0029] 2. In the present application, the contents of Co, Dy, and Tb components in the blank magnet are limited. In combination with the median particle size of the magnetic powder selected in the blank magnet, the overall bonding strength of the Halbach array magnet assembly is further improved, and it is also less likely for the magnet assembly to have cracking problems. Specific Embodiments Examples

[0030] Example 1: An integrated preparation method of a Halbach array magnet assembly includes the following steps: Step 1: Design the compositions of blank magnet a and blank magnet b (both are neodymium-iron-boron blank magnets), melt the alloy sheets, hydrogen crush, grind the powder by air jet milling, and after mixing, compacting, and sintering, obtain the blank magnet; Among them, in the composition of blank magnet a, the Co content is 1 wt%, and the Dy and Tb contents are both 0 wt%. The D50 of the magnetic powder obtained after air jet milling is 4.8 μm; In the composition of blank magnet b, the Co content is 15 wt%, the Dy content is 2 wt%, and the Tb content is 0 wt%. The D50 of the magnetic powder obtained after air jet milling is 4.2 μm.

[0031] I. Preparation of blank magnet a: Alloy melting; During the pressing process, first press the obtained mixed material for 3 s under the condition that the pressing pressure is 5 MPa, and keep the current at 200 A while applying the pressing pressure. After pressing, neither the pressing pressure nor the current is applied. Then, only apply the isostatic pressure of 180 MPa without applying current and keep pressing for 10 s to make the blank after pressing more compact. During the sintering process, sinter at a temperature of 1070 °C for 4 h to finally obtain the blank magnet a.

[0032] II. Preparation of the blank magnet b Alloy melting; During the pressing process, first press the obtained mixed material for 3 s under the condition that the pressing pressure is 5 MPa, and keep the current at 200 A while applying the pressing pressure. After pressing, neither the pressing pressure nor the current is applied. Then, only apply the isostatic pressure of 180 MPa without applying current and keep pressing for 10 s to make the blank after pressing more compact. During the sintering process, sinter at a temperature of 1070 °C for 4 h to finally obtain the blank magnet b.

[0033] Step 2: Prepare the pre-processed sheet: Set the two opposite side surfaces of the blank magnet a and the blank magnet b as the welding surfaces, and form a group of welding surfaces with the two opposite welding surfaces; the included angle between the C-axis directions of the adjacent blank magnet a and the blank magnet b is 90° (the C-axis direction of the blank magnet a is the vertical direction, and the C-axis direction of the blank magnet b is the horizontal direction) to obtain the pre-processed sheet a and the pre-processed sheet b.

[0034] Step 3: Surface treatment and / or rare earth alloy coating: Grind the surfaces of the pre-processed sheet a and the pre-processed sheet b respectively until the flatness reaches 0.02 mm, and then coat a rare earth layer on the welding surface. The thickness of the rare earth layer is 5 μm; the raw material used is PrNd70Al5Ga5Cu10 alloy powder.

[0035] Step 4: Stacking: Stack multiple pre-processed sheets, and set a high-temperature welding coating between the adjacent pre-processed sheets to obtain a stacked magnet; among them, the thickness of the high-temperature welding coating is the same as that of the rare earth layer, and its raw material is a welding assistant, specifically PrNd70Al5Ga5Cu10.

[0036] Step 5: Diffusion welding: Perform welding heat treatment and tempering treatment on the stacked magnet in sequence to obtain a welded magnet; among them, the temperature of the welding heat treatment is 920 °C and the time is 2 h; the temperature of the tempering treatment is 500 °C and the time is 5 h.

[0037] Step 6: Cutting, surface protection treatment, and integrated magnetization: First, cut the welded magnet into black sheet components according to the product size requirements, perform surface protection treatment on the black sheet components, then wind the magnetization coil to achieve a set angle for the magnetization direction, and conduct integrated magnetization treatment under a 4.5T magnetic field to finally obtain the Halbach array magnet assembly.

[0038] Observation with an MR3000 metallographic microscope found that the maximum crack of the Halbach array magnet assembly prepared in Example 1 was 0 mm, and the longest crack was 0 mm.

[0039] Cut the magnet into a specification of 8 mm × 3 mm × 1.5 mm, measure the three-point bending force. The middle indenter is directly opposite the weld seam, and the other two points support, with a distance of 3 mm from the center. Finally, the measured three-point bending force between the magnets is 102 N.

[0040] Example 2: An integrated preparation method for a Halbach array magnet assembly, which is different from Example 1 in that: in the blank magnet a used in Step 1, the D50 of the magnetic powder is 3.5 μm, the orientation current used in preparing the blank magnet a is 150 A, and after sintering at a temperature of 1030 °C for 4 h, the blank magnet a is obtained; In the blank magnet b, the Dy content is 0 wt%, the D50 of the magnetic powder in the blank magnet b is 3.5 μm, the orientation current used in preparing the blank magnet b is 150 A, and after sintering at a temperature of 1030 °C for 4 h, the blank magnet b is obtained.

[0041] The thickness of the rare earth layer coated in Step 3 is 8 μm, and the raw material used is Dy75Ni20Al5 alloy powder.

[0042] In Step 4, the raw material in the high-temperature welding coating is Dy75Ni20Al5. In Step 5, the temperature of the welding heat treatment used in diffusion welding is 850 °C, and tempering treatment is carried out at 600 °C for 2 h.

[0043] Observation with an MR3000 metallographic microscope found that the maximum crack of the Halbach array magnet assembly prepared in Example 2 was 0 mm, the longest crack was 0 mm; and the three-point bending force between the magnets was 105 N.

[0044] Example 3: An integrated preparation method for a Halbach array magnet assembly, which is different from Example 1 in that: in the composition of the blank magnet a used in Step 1, the Co content is 5 wt%, the Dy content is 2 wt%, the orientation current used in preparing the blank magnet a is 150 A, and after sintering at 1080 °C for 4 h, the blank magnet a is obtained; In the green magnet b, the Co content is 20 wt%, the Dy content is 5 wt%, the D50 of the magnetic powder in the green magnet b is 4.8 μm, the orientation current used in preparing the green magnet b is 150 A, and the green magnet b is obtained after sintering at a temperature of 1080 °C for 4 h.

[0045] In step three, the flatness after surface treatment is 0.06 mm, the thickness of the coated rare earth layer is 18 μm, and the raw material is Tb10PrNd75Al15.

[0046] In step four, the raw material in the high-temperature welding coating used is Tb10PrNd75Al15, welding is carried out at a condition of 1080 °C for 4 h, and then tempering treatment is carried out at a condition of 450 °C for 4 h.

[0047] Observed by using an MR3000 metallographic microscope, the maximum crack of the Halbach array magnet assembly prepared in Example 3 is 0 mm, the longest crack is 0 mm; and the three-point bending force between the magnets is 98 N.

[0048] Example 4: An integrated preparation method of a Halbach array magnet assembly, which is different from Example 1 in that: in the composition of the green magnet a in step one, the Co content is 10%, the Dy content is 4 wt%, the D50 of the magnetic powder in the green magnet a is 8 μm, and the orientation current used in preparing the green magnet a is 50 A, and sintering is carried out at a temperature of 1095 °C for 4 h to obtain the green magnet a; In the composition of the green magnet b, the Co content is 25%, the Dy content is 10 wt%, the D50 of the magnetic powder in the green magnet b is 8 μm, and the orientation current used in preparing the green magnet b is 50 A, and sintering is carried out at a temperature of 1095 °C for 4 h to obtain the green magnet b.

[0049] In step three, the thickness of the coated rare earth layer is 20 μm, and the raw material therein is Dy5PrNd65Cu30.

[0050] In step four, the raw material in the high-temperature welding coating used is Dy5PrNd65Cu30.

[0051] In step five, the temperature of the welding heat treatment used in diffusion welding is 950 °C.

[0052] Observed by using an MR3000 metallographic microscope, the maximum crack of the Halbach array magnet assembly prepared in Example 4 is 0 mm, the longest crack is 0 mm; and the three-point bending force between the magnets is 91 N.

[0053] Example 5: An integrated preparation method of a Halbach array magnet assembly, which is different from Example 1 in that: green magnet a, green magnet b and green magnet c are used.

[0054] Among them, in the green magnet a, the Co content is 1 wt%, the Dy content is 5 wt%, the Tb content is 0 wt%, and the D50 of the magnetic powder in the green magnet a is 3.2 μm; when manufacturing the green magnet a, it is pressed for 3 s under the condition that the pressing pressure is 5 MPa, and while applying the pressing pressure, the current is maintained at 200 A. After pressing, neither the pressing pressure nor the current is applied; then, only the isostatic pressure of 180 MPa is applied without applying current, and the pressing is maintained for 10 s to make the green body after pressing more compact; finally, it is sintered at 1060 °C for 4 h to obtain the green magnet a; In the green magnet b, the Co content is 7 wt%, the Dy content is 2 wt%, the Tb content is 0 wt%, and the D50 of the magnetic powder in the green magnet b is 4.1 μm; when manufacturing the green magnet b, it is pressed for 3 s under the condition that the pressing pressure is 5 MPa, and while applying the pressing pressure, the current is maintained at 200 A. After pressing, neither the pressing pressure nor the current is applied; then, only the isostatic pressure of 180 MPa is applied without applying current, and the pressing is maintained for 10 s to make the green body after pressing more compact; finally, it is sintered at 1070 °C for 4 h to obtain the green magnet b; In the green magnet c, the Co content is 15 wt%, the Dy content is 7 wt%, the Tb content is 3 wt%, and the D50 of the magnetic powder in the green magnet c is 4.5 μm; when manufacturing the green magnet c, it is pressed for 3 s under the condition that the pressing pressure is 5 MPa, and while applying the pressing pressure, the current is maintained at 200 A. After pressing, neither the pressing pressure nor the current is applied; then, only the isostatic pressure of 180 MPa is applied without applying current, and the pressing is maintained for 10 s to make the green body after pressing more compact; finally, it is sintered at 1060 °C for 4 h to obtain the green magnet c.

[0055] In step three, the flatness of the surfaces of the green magnet b and the green magnet a after surface treatment is 0.04 mm. A rare earth layer with a thickness of 15 μm is coated between the green magnet b and the green magnet a, and its raw material is Pr70Dy5Cu25; The flatness of the surfaces of the green magnet c and the green magnet b after surface treatment is 0.02 mm, and a rare earth layer with a thickness of 15 μm is coated between the green magnet c and the green magnet b, and its raw material is Pr70Dy5Cu25.

[0056] In step four, a high-temperature welding coating is coated between the green magnet b and the green magnet a, and the raw material is Pr70Dy5Cu25. It is welded at 1060 °C for 4 h, and then tempered at 500 °C for 2 h; A high-temperature welding coating is coated between the green magnet c and the green magnet b, and the raw material is Pr70Dy5Cu25. It is welded at 1060 °C for 4 h, and then tempered at 500 °C for 2 h.

[0057] Observed by using an MR3000 metallographic microscope, the maximum crack opening of the Halbach array magnet assembly obtained in Example 5 is 0 mm, the longest crack is 0 mm; and the three-point bending force between the magnets is 91 N.

[0058] Example 6: An integrated preparation method of a Halbach array magnet assembly, which is different from Example 5 in that: In the green magnet a, the Co content is 5 wt%, the Dy content is 0 wt%, the Tb content is 0 wt%, and the D50 of the magnetic powder in the green magnet a is 4 μm; when manufacturing the green magnet a, while applying a pressing pressure, the current is maintained at 150 A; finally, sintering is carried out at 1030 °C for 4 h to obtain the green magnet a; In the green magnet b, the Co content is 13 wt%, the Dy content is 2 wt%, the Tb content is 0 wt%, and the D50 of the magnetic powder in the green magnet b is 4 μm; when manufacturing the green magnet b, while applying a pressing pressure, the current is maintained at 120 A; finally, sintering is carried out at 1030 °C for 4 h to obtain the green magnet b; In the green magnet c, the Co content is 20 wt%, the Dy content is 3 wt%, the Tb content is 5 wt%, and the D50 of the magnetic powder in the green magnet c is 3.5 μm; when manufacturing the green magnet c, while applying a pressing pressure, the current is maintained at 150 A; finally, sintering is carried out at 1030 °C for 4 h to obtain the green magnet c.

[0059] In Step 3, the flatness of the surfaces of the green magnet b and the green magnet a after surface treatment is 0.08 mm, and a rare earth layer with a thickness of 10 μm is coated between the green magnet b and the green magnet a, and its raw material is Pr70Cu30; The flatness of the surfaces of the green magnet c and the green magnet b after surface treatment is 0.04 mm, and a rare earth layer with a thickness of 10 μm is coated between the green magnet c and the green magnet b, and its raw material is Pr70Cu30.

[0060] In Step 4, a high-temperature welding coating is coated between the green magnet b and the green magnet a, the raw material is Pr70Cu30, welding treatment is carried out at 1030 °C for 4 h, and then tempering treatment is carried out at 450 °C for 5 h; A high-temperature welding coating is coated between the green magnet c and the green magnet b, the raw material is Pr70Cu30, welding treatment is carried out at 1030 °C for 4 h, and then tempering treatment is carried out at 450 °C for 5 h.

[0061] Observed by using an MR3000 metallographic microscope, the maximum crack opening of the Halbach array magnet assembly obtained in Example 6 is 0 mm, the longest crack is 0 mm; and the three-point bending force between the magnets is 95 N.

[0062] Example 7: An integrated preparation method of a Halbach array magnet assembly, which is different from Example 5 in that: In the blank magnet a, the Co content is 5 wt%, the Dy content is 1 wt%, the Tb content is 0 wt%, and the D50 of the magnetic powder in the blank magnet a is 3.56 μm; when manufacturing the blank magnet a, while applying a pressing pressure, the current is maintained at 150 A; finally, it is sintered at 1040 °C for 4 h to obtain the blank magnet a; In the blank magnet b, the Co content is 12 wt%, the Dy content is 1 wt%, the Tb content is 0 wt%, and the D50 of the magnetic powder in the blank magnet b is 3.5 μm; when manufacturing the blank magnet b, while applying a pressing pressure, the current is maintained at 120 A; finally, it is sintered at 1040 °C for 4 h to obtain the blank magnet b; In the blank magnet c, the Co content is 8 wt%, the Dy content is 0 wt%, the Tb content is 0 wt%, and the D50 of the magnetic powder in the blank magnet c is 4 μm; when manufacturing the blank magnet c, while applying a pressing pressure, the current is maintained at 150 A; finally, it is sintered at 1040 °C for 4 h to obtain the blank magnet c.

[0063] In step three, the flatness of the surfaces of the blank magnet b and the blank magnet a after surface treatment is 0.08 mm. A rare earth layer with a thickness of 5 μm is coated between the blank magnet b and the blank magnet a. The raw material of the rare earth layer is PrNd70Al5Ga5Cu10; The flatness of the surfaces of the blank magnet c and the blank magnet b after surface treatment is 0.08 mm, and a rare earth layer with a thickness of 5 μm is coated between the blank magnet c and the blank magnet b, and its raw material is PrNd70Al5Ga5Cu10.

[0064] In step four, a high-temperature welding coating is coated between the blank magnet b and the blank magnet a. The raw material is PrNd70Al5Ga5Cu10. It is welded at 1040 °C for 4 h and then tempered at 450 °C for 4 h; A high-temperature welding coating is coated between the blank magnet c and the blank magnet b. The raw material is PrNd70Al5Ga5Cu10. It is welded at 1040 °C for 4 h and then tempered at 450 °C for 4 h.

[0065] Observed by using an MR3000 metallographic microscope, the maximum crack of the Halbach array magnet assembly prepared in Example 1 is 0 mm, the longest crack is 0 mm; and the three-point bending force between the magnets is 90 N.

[0066] Example 8: An integrated preparation method of a Halbach array magnet assembly, which is different from Example 5 in that: In the green magnet a, the Co content is 1 wt%, the Dy content is 1 wt%, the Tb content is 0 wt%, and the D50 of the magnetic powder in the green magnet a is 8 μm; when manufacturing the green magnet a, while applying a pressing pressure, the current is maintained at 150 A; finally, it is sintered at 1095 °C for 4 h to obtain the green magnet a; In the green magnet b, the Co content is 5 wt%, the Dy content is 1.5 wt%, the Tb content is 0 wt%, and the D50 of the magnetic powder in the green magnet b is 8 μm; when manufacturing the green magnet b, while applying a pressing pressure, the current is maintained at 120 A; finally, it is sintered at 1095 °C for 4 h to obtain the green magnet b; In the green magnet c, the Co content is 25 wt%, the Dy content is 1 wt%, the Tb content is 8 wt%, and the D50 of the magnetic powder in the green magnet c is 8 μm; when manufacturing the green magnet c, while applying a pressing pressure, the current is maintained at 150 A; finally, it is sintered at 1095 °C for 4 h to obtain the green magnet c.

[0067] In step three, the flatness of the surfaces of the green magnet b and the green magnet a after surface treatment is 0.02 mm, and a rare earth layer with a thickness of 10 μm is coated between the green magnet b and the green magnet a. The raw material of the rare earth layer is Tb3Al97; The flatness of the surfaces of the green magnet c and the green magnet b after surface treatment is 0.04 mm, and a rare earth layer with a thickness of 10 μm is coated between the green magnet c and the green magnet b, and its raw material is Tb3Al97.

[0068] In step four, a high-temperature welding coating is coated between the green magnet b and the green magnet a. The raw material is Tb3Al97, and it is welded at 700 °C for 4 h and then tempered at 600 °C for 3 h; A high-temperature welding coating is coated between the green magnet c and the green magnet b. The raw material is Tb3Al97, and it is welded at 1065 °C for 4 h and then tempered at 600 °C for 3 h.

[0069] Observed by using an MR3000 metallographic microscope, the maximum crack of the Halbach array magnet assembly prepared in Example 1 is 0 mm, and the longest crack is 0 mm; and the three-point bending force between the magnets is 82 N.

[0070] Comparative Example Comparative Example 1: A preparation method of a Halbach array magnet assembly, the difference from Example 1 is that: In the green magnet a used in Step 1, the Co content is 1 wt%, the Dy content is 2 wt%, the orientation current used in preparing the green magnet a is 150 A, and it is sintered at a temperature of 1080 °C for 4 h to obtain the green magnet a; in the green magnet b used, the Co content is 1 wt%, the Dy content is 2 wt%, the D50 of the magnetic powder in the green magnet b is 4.8 μm, the orientation current used in preparing the green magnet b is 200 A, and it is sintered at a temperature of 1080 °C for 4 h to obtain the green magnet b.

[0071] In Step 3, the flatness obtained after surface treatment is 0.05 mm, the thickness of the coated rare earth layer is 5 μm, and the raw material therein is PrNd70Al5Ga5Cu10.

[0072] In Step 4, no high-temperature welding coating is used, the temperature of the welding heat treatment is controlled at 1030 °C, and tempering treatment is carried out at 450 °C for 5 h.

[0073] Observation with an MR3000 metallurgical microscope found that the maximum crack of the Halbach array magnet assembly prepared in Comparative Example 1 is 2 mm, the longest crack is 16 mm; and the three-point bending force between the magnets is 45 N.

[0074] Comparative Example 2: A method for preparing a Halbach array magnet assembly, which is different from Example 1 in that: In the green magnet a used in Step 1, the Co content is 15 wt%, the Dy content is 2 wt%, and the orientation current used in preparing the green magnet a is 150 A; In the green magnet b used, the Co content is 15 wt%, the Dy content is 2 wt%, the D50 of the magnetic powder in the green magnet b is 4.8 μm, and the orientation current used in preparing the green magnet b is 150 A.

[0075] In Step 3, the flatness obtained after surface treatment is 0.08 mm, the thickness of the coated rare earth layer is 15 μm, and the raw material therein is PrNd85Ga10Cu5.

[0076] In Step 4, no high-temperature welding coating is used, the temperature of the welding heat treatment is controlled at 1050 °C, and tempering treatment is carried out at 500 °C for 5 h.

[0077] Observation with an MR3000 metallurgical microscope found that the maximum crack of the Halbach array magnet assembly prepared in Comparative Example 2 is 1 mm, the longest crack is 6 mm; and the three-point bending force between the magnets is 27 N.

[0078] From the data of the maximum crack, the longest crack and the three-point bending force between magnets obtained from the Halbach array magnet assemblies prepared in the examples and comparative examples, it can be seen that there are the maximum crack and the longest crack in both Comparative Example 1 and 2, which indicates that the Halbach array magnet assembly is prone to cracking problems during the preparation process; and the three-point bending force between magnets in the Halbach array magnet assemblies obtained in Comparative Example 1 and 2 is lower than that in the Halbach array magnet assemblies obtained in the examples, which indicates that the three-point bending force of the Halbach array magnet assemblies obtained by the methods in Comparative Example 1-2 is poor. Generally speaking, the contents of Co, Dy, and Tb in the blank magnet, as well as the setting of the high-temperature welding coating and the raw materials selected in the high-temperature welding coating, will all affect whether the prepared Halbach array magnet assembly cracks and the three-point bending force between magnets.

[0079] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. An integrated preparation method of a Halbach array magnet assembly, characterized in that: The steps include: Step 1: Design the composition of the blank magnet, the powder particle size for manufacturing the blank magnet, and the orientation current used in preparing the blank magnet, and obtain the blank magnet after mixing, pressing and sintering; Step 2: preparing a pre-processed sheet: setting two opposite side surfaces of the blank magnet as welding surfaces, and forming a set of welding surfaces with the two opposite welding surfaces; the angle between the C-axis directions of two adjacent blank magnets is 5-90°, and a pre-processed sheet is obtained; Step 3: Surface treatment and / or rare earth alloy coating: Surface treatment is performed on the pre-processed sheet, and then a rare earth layer is coated on the welding surface of the pre-processed sheet; Step 4: stacking: stacking a plurality of pre-processed sheets, and providing a high-temperature welding coating between adjacent pre-processed sheets to obtain a stacked magnet; Step 5: Diffusion welding: The stacked magnets are subjected to welding heat treatment and tempering treatment in sequence to obtain welded magnets; Step 6: Cutting, surface protection treatment, and integrated magnetization are performed in sequence to obtain a Halbach array magnet assembly; The raw material of the rare earth layer in step 3 is one of a rare earth element, a rare earth alloy and a rare earth compound; The raw material of the high-temperature welding coating in step 4 is a welding auxiliary agent, and the welding auxiliary agent is a low-melting-point alloy containing rare earth elements or a rare earth metal single substance.

2. The integrated preparation method of a Halbach array magnet assembly according to claim 1, characterized in that: The median particle size of the powder used to make the blank magnet in step 1 is 3.2-8 μm.

3. The integrated preparation method of a Halbach array magnet assembly according to claim 1, characterized in that: The pressing pressure used in the pressing molding in step 1 is 2-5MPa, the pressing time is 3-5s, and the orientation current used is 0-200A; then the orientation current is turned off and the isostatic pressure is maintained at 180-200MPa, and the pressing time is 5-15s.

4. The integrated preparation method of a Halbach array magnet assembly according to claim 1, characterized in that: In the step 2, the two adjacent blank magnets are blank magnet a and blank magnet b, the C-axis direction of the blank magnet a is perpendicular to the welding surface, the C-axis angle between the blank magnet a and the blank magnet b is 90°, and the composition used in the blank magnet a is: Co content ≤5%, Dy and / or Tb content ≤5%; the composition used in the blank magnet b is: Co content 10-20%, Dy and / or Tb content ≤10%.

5. The integrated preparation method of a Halbach array magnet assembly according to claim 1, characterized in that: In the step 2, the three adjacent blank magnets are blank magnet a, blank magnet b and blank magnet c, the C-axis direction of the blank magnet a is perpendicular to the welding surface, the C-axis direction of the blank magnet b is 45° to the welding surface, and the C-axis direction of the blank magnet c is parallel to the welding surface; the composition used in the blank magnet a is: Co content ≤5%, Dy and / or Tb content ≤5%; the composition used in the blank magnet b is: Co content 5-18%, Dy and / or Tb content ≤10%; the composition used in the blank magnet c is: Co content 10-20%, Dy and / or Tb content ≤10%.

6. The integrated preparation method of a Halbach array magnet assembly according to claim 1, characterized in that: In the step three, the surface is treated to a flatness of 0.02-0.08 mm.

7. The integrated preparation method of a Halbach array magnet assembly according to claim 1, characterized in that: In the step 5, the temperature condition of the welding heat treatment is 700-1500°C, and the welding heat treatment time is 4-40h; Then, the steel is tempered at 450-700°C for 2-5 hours.

8. The integrated preparation method of a Halbach array magnet assembly according to claim 1, characterized in that: In step six, the welding magnet is first cut into black sheet components according to product size requirements, the black sheet components are subjected to surface protection treatment, and then the magnetizing coil is wound around the black sheet components that have undergone surface protection treatment in the form of winding, and an integrated magnetizing treatment is performed under a magnetic field of 4.5T.

9. The integrated preparation method of a Halbach array magnet assembly according to claim 1, characterized in that: In the step 4, no high temperature welding coating is provided between adjacent pre-processed sheets.

10. A Halbach array magnet assembly, characterized in that: The magnet is prepared by the integrated preparation method of a Halbach array magnet assembly as described in any one of claims 1 to 9.