Sintered neodymium-iron-boron permanent magnet material with low coercive force temperature coefficient for new energy automobile

Abstract

The invention discloses a sintered neodymium-iron-boron permanent magnet material with a low coercive force temperature coefficient for a new energy automobile, and relates to the technical field of sintered neodymium-iron-boron permanent magnet materials. Collaborative optimization of high residual magnetism and high coercive force is realized through preparation of the sintered neodymium-iron-boron permanent magnet material; the performance bottleneck of a traditional sintered neodymium-iron-boron magnet material is broken through, and the energy density and the demagnetization resistance of the magnet are doubly improved, so that the magnet is excellent in high-temperature and high-intensity magnetic field environments.

Description

Technical Field

[0001] This invention relates to the field of sintered NdFeB permanent magnet materials, specifically to a sintered NdFeB permanent magnet material with a low coercivity temperature coefficient, its preparation method, and its application in new energy vehicles. Background Technology

[0002] In recent years, the global new energy vehicle industry has experienced rapid development. With increasing environmental awareness and increasingly stringent emission restrictions on traditional gasoline vehicles, new energy vehicles, as a green and efficient mode of transportation, have received widespread attention from governments and consumers worldwide. In China, the new energy vehicle industry has developed even more rapidly. In 2024, China's new energy vehicle production reached 10 million units, with sales approaching 9.5 million units, ranking first globally for many consecutive years.

[0003] Neodymium iron boron (NdFeB) permanent magnet materials play a crucial role in the drive motor, a core component of new energy vehicles. As the power source of new energy vehicles, the performance of the drive motor directly determines the vehicle's power, economy, and reliability. NdFeB permanent magnet materials, with their superior properties such as high remanence, high coercivity, and high energy product, can generate a strong magnetic field in a relatively small volume and weight, thereby significantly improving the power density and efficiency of the drive motor.

[0004] The temperature coefficient of coercivity directly affects the high-temperature demagnetization resistance of sintered NdFeB permanent magnet materials. The coercivity of sintered NdFeB permanent magnet materials decreases with increasing temperature. The temperature coefficient of coercivity of ordinary sintered NdFeB permanent magnet materials is approximately -0.8 to -0.6% / ℃. This means that under high-temperature conditions (such as exceeding 80~150℃), the coercivity may be lower than the demagnetization field strength in the working environment, leading to irreversible demagnetization and permanent degradation of equipment performance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a sintered NdFeB permanent magnet material and its preparation method. The obtained sintered NdFeB permanent magnet material has excellent magnetic properties, especially a low coercivity temperature coefficient, and can be applied in the field of new energy vehicles.

[0006] The technical problem to be solved by this invention is achieved by the following technical solution:

[0007] One objective of this invention is to provide a method for preparing sintered NdFeB permanent magnet materials, comprising the following steps:

[0008] S1. Vacuum melting and spinning are carried out according to the following raw material formula by weight percentage to obtain the spinning sheet;

[0009] PrNd 25~30%, Dy 2~3%, B 0.8~1%, Cu 0.1~0.3%, Co 0.6~0.8%, Tb 0.15~0.35%, Zr 0.1~0.3%, Ga 0.1~0.3%, balance Fe;

[0010] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0011] S3. Mix the neodymium iron boron powder with the additives evenly to obtain magnetic powder;

[0012] S4. The magnetic powder is subjected to orientation pressing and isostatic pressing to obtain a green body;

[0013] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material.

[0014] Furthermore, the additive is manganese fluorosilicate or nickel hypophosphite. The main purpose of using manganese fluorosilicate or nickel hypophosphite as an additive in this invention is to reduce the coercivity temperature coefficient of sintered NdFeB permanent magnet materials.

[0015] Furthermore, the amount of the additive is 0.3 to 0.5% of the weight of the NdFeB powder.

[0016] Furthermore, the vacuum melting temperature is 1400~1500℃. The purpose of vacuum melting is to improve the purity and uniformity of the alloy and to prevent oxidation of the components by isolating them from air.

[0017] Furthermore, the D50 particle size of the magnetic powder is 3~4 μm. The particle size distribution is precisely controlled through hydrogen crushing and air jet milling, resulting in more uniform particle size and improved molding performance and density of the magnetic powder.

[0018] Furthermore, the magnetic field strength of the orientation pressing is 1.5~3 T. Magnetic field orientation forming utilizes the interaction between magnetic powder and an external magnetic field to align the easy magnetization direction of the powder particles, making them consistent with the final magnetization direction of the magnet, thereby obtaining an anisotropic magnet.

[0019] Furthermore, the isostatic pressing pressure is 150~250 MPa. Isostatic pressing can increase the green compact density, improve density uniformity, optimize magnetic properties and orientation, and reduce sintering defects.

[0020] Furthermore, the vacuum sintering temperature is 1000~1100℃, and the time is 5~15 h. Sintering under vacuum conditions densifies the green body, reduces impurity adsorption and oxidation, and improves magnetic properties.

[0021] Furthermore, the aging treatment is divided into two stages. The first stage of aging treatment is carried out at a temperature of 800~900℃ for 2~5 hours; the second stage of aging treatment is carried out at a temperature of 400~500℃ for 3~8 hours. Aging treatment can eliminate internal stress, stabilize magnetic properties, and optimize the distribution of neodymium-rich phase.

[0022] The second objective of this invention is to provide a sintered NdFeB permanent magnet material prepared by the aforementioned preparation method.

[0023] The third objective of this invention is to provide the application of the aforementioned sintered NdFeB permanent magnet material in new energy vehicles.

[0024] The beneficial effects of this invention are: the invention achieves synergistic optimization of high remanence and high coercivity through the preparation of the sintered NdFeB permanent magnet material, breaks through the performance bottleneck of traditional sintered NdFeB magnet materials, and achieves a dual improvement in magnet energy density and anti-demagnetization ability, making it perform well in high temperature and strong magnetic field environments. Attached Figure Description

[0025] Figure 1 The demagnetization curve of the sintered NdFeB permanent magnet material prepared in Example 1;

[0026] Figure 2 The demagnetization curve is shown for the sintered NdFeB permanent magnet material prepared in Example 2. Detailed Implementation

[0027] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments and illustrations.

[0028] Example 1

[0029] S1. The raw materials are vacuum melted and spun at 1450°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.35 mm.

[0030] The composition is as follows: rNd 26.75%, Dy 2.70%, B 0.915%, Cu 0.15%, Co 0.70%, Tb 0.25%, Zr 0.18%, Ga 0.20%, with the balance being Fe.

[0031] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0032] S3. Mix NdFeB powder and manganese fluorosilicate evenly. The amount of manganese fluorosilicate is 0.5% of the weight of NdFeB powder to obtain magnetic powder with a D50 particle size of 4.2 μm.

[0033] S4. The magnetic powder is oriented, pressed, and isostatically pressed. The magnetic field strength is 1.5 T, and the isostatic pressing pressure is 210 MPa to obtain a green compact.

[0034] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1050℃ and the holding time is 10 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 870℃ and the holding time is 3 h; the second stage aging treatment temperature is 460℃ and the holding time is 5 h.

[0035] Example 2

[0036] S1. The raw materials are vacuum melted and spun at 1500°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.38 mm.

[0037] The composition is as follows: rNd 27.14%, Dy 2.68%, B 0.927%, Cu 0.18%, Co 0.54%, Tb 0.18%, Zr 0.16%, Ga 0.23%, with the balance being Fe.

[0038] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0039] S3. Mix NdFeB powder and manganese fluorosilicate evenly. The amount of manganese fluorosilicate is 0.4% of the weight of NdFeB powder to obtain magnetic powder with a D50 particle size of 4.0 μm.

[0040] S4. Orientation pressing and isostatic pressing of the magnetic powder are performed. The magnetic field strength is 2 T and the isostatic pressing pressure is 150 MPa to obtain the green body.

[0041] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1100℃ and the holding time is 5 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 800℃ and the time is 2 h; the second stage aging treatment temperature is 500℃ and the holding time is 8 h.

[0042] Example 3

[0043] S1. The raw materials are vacuum melted and spun at 1480°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.37 mm.

[0044] The composition is as follows: rNd 27.48%, Dy 2.94%, B 0.902%, Cu 0.18%, Co 0.74%, Tb 0.28%, Zr 0.12%, Ga 0.15%, with the balance being Fe.

[0045] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0046] S3. Mix NdFeB powder and manganese fluorosilicate evenly. The amount of manganese fluorosilicate is 0.35% of the weight of NdFeB powder to obtain magnetic powder with a D50 particle size of 3.8 μm.

[0047] S4. The magnetic powder is oriented, pressed, and isostatically pressed. The magnetic field strength is 1.8 T, and the isostatic pressing pressure is 250 MPa to obtain a green compact.

[0048] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1070℃ and the holding time is 15 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 900℃ and the holding time is 2 h; the second stage aging treatment temperature is 430℃ and the holding time is 8 h.

[0049] Example 4

[0050] S1. The raw materials are vacuum melted and spun at 1500°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.35 mm.

[0051] The composition is as follows: rNd 28.19%, Dy 2.53%, B 0.927%, Cu 0.18%, Co 0.64%, Tb 0.23%, Zr 0.19%, Ga 0.18%, with the balance being Fe.

[0052] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0053] S3. Mix NdFeB powder and manganese fluorosilicate evenly. The amount of manganese fluorosilicate is 0.5% of the weight of NdFeB powder to obtain magnetic powder with a D50 particle size of 4.5 μm.

[0054] S4. Orientation pressing and isostatic pressing of the magnetic powder are performed. The magnetic field strength is 3 T and the isostatic pressing pressure is 250 MPa to obtain the green body.

[0055] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1000℃ and the holding time is 10 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 820℃ and the holding time is 2 h; the second stage aging treatment temperature is 450℃ and the holding time is 6 h.

[0056] Example 5

[0057] S1. The raw materials are vacuum melted and spun at 1490°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.35 mm.

[0058] rNd 28.15%, Dy 2.83%, B 0.904%, Cu 0.18%, Co 0.73%, Tb 0.23%, Zr 0.16%, Ga 0.21%, balance Fe.

[0059] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0060] S3. Mix NdFeB powder and manganese fluorosilicate evenly. The amount of manganese fluorosilicate is 0.5% of the weight of NdFeB powder to obtain magnetic powder with a D50 particle size of 3.6 μm.

[0061] S4. The magnetic powder is oriented, pressed, and isostatically pressed. The magnetic field strength is 2.5 T, and the isostatic pressing pressure is 200 MPa to obtain a green compact.

[0062] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1060℃ and the holding time is 12 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 850℃ and the holding time is 3 h; the second stage aging treatment temperature is 480℃ and the holding time is 5 h.

[0063] Example 6

[0064] Sintered NdFeB permanent magnet materials were prepared according to the method in Example 1, except that manganese fluorosilicate was replaced with nickel hypophosphite.

[0065] S1. The raw materials are vacuum melted and spun at 1450°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.35 mm.

[0066] The composition is as follows: rNd 26.75%, Dy 2.70%, B 0.915%, Cu 0.15%, Co 0.70%, Tb 0.25%, Zr 0.18%, Ga 0.20%, with the balance being Fe.

[0067] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0068] S3. Mix NdFeB powder and nickel hypophosphite evenly, with the amount of nickel hypophosphite being 0.5% of the weight of NdFeB powder, to obtain magnetic powder with a D50 particle size of 4.2 μm.

[0069] S4. The magnetic powder is oriented, pressed, and isostatically pressed. The magnetic field strength is 1.5 T, and the isostatic pressing pressure is 210 MPa to obtain a green compact.

[0070] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1050℃ and the holding time is 10 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 870℃ and the holding time is 3 h; the second stage aging treatment temperature is 460℃ and the holding time is 5 h.

[0071] Example 7

[0072] Sintered NdFeB permanent magnet materials were prepared according to the method in Example 2, except that manganese fluorosilicate was replaced with nickel hypophosphite.

[0073] S1. The raw materials are vacuum melted and spun at 1500°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.38 mm.

[0074] The composition is as follows: rNd 27.14%, Dy 2.68%, B 0.927%, Cu 0.18%, Co 0.54%, Tb 0.18%, Zr 0.16%, Ga 0.23%, with the balance being Fe.

[0075] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0076] S3. Mix NdFeB powder and nickel hypophosphite evenly, with the amount of nickel hypophosphite being 0.4% of the weight of NdFeB powder, to obtain magnetic powder with a D50 particle size of 4.0 μm.

[0077] S4. Orientation pressing and isostatic pressing of the magnetic powder are performed. The magnetic field strength is 2 T and the isostatic pressing pressure is 150 MPa to obtain the green body.

[0078] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1100℃ and the holding time is 5 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 800℃ and the time is 2 h; the second stage aging treatment temperature is 500℃ and the holding time is 8 h.

[0079] Example 8

[0080] Sintered NdFeB permanent magnet materials were prepared according to the method in Example 3, except that manganese fluorosilicate was replaced with nickel hypophosphite.

[0081] S1. The raw materials are vacuum melted and spun at 1480°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.37 mm.

[0082] The composition is as follows: rNd 27.48%, Dy 2.94%, B 0.902%, Cu 0.18%, Co 0.74%, Tb 0.28%, Zr 0.12%, Ga 0.15%, with the balance being Fe.

[0083] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0084] S3. Mix NdFeB powder and nickel hypophosphite evenly, with the amount of nickel hypophosphite being 0.35% of the weight of NdFeB powder, to obtain magnetic powder with a D50 particle size of 3.8 μm.

[0085] S4. The magnetic powder is oriented, pressed, and isostatically pressed. The magnetic field strength is 1.8 T, and the isostatic pressing pressure is 250 MPa to obtain a green compact.

[0086] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1070℃ and the holding time is 15 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 900℃ and the holding time is 2 h; the second stage aging treatment temperature is 430℃ and the holding time is 8 h.

[0087] Example 9

[0088] Sintered NdFeB permanent magnet materials were prepared according to the method in Example 4, except that manganese fluorosilicate was replaced with nickel hypophosphite.

[0089] S1. The raw materials are vacuum melted and spun at 1500°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.35 mm.

[0090] The composition is as follows: rNd 28.19%, Dy 2.53%, B 0.927%, Cu 0.18%, Co 0.64%, Tb 0.23%, Zr 0.19%, Ga 0.18%, with the balance being Fe.

[0091] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0092] S3. Mix NdFeB powder and nickel hypophosphite evenly, with the amount of nickel hypophosphite being 0.5% of the weight of NdFeB powder, to obtain magnetic powder with a D50 particle size of 4.5 μm.

[0093] S4. Orientation pressing and isostatic pressing of the magnetic powder are performed. The magnetic field strength is 3 T and the isostatic pressing pressure is 250 MPa to obtain the green body.

[0094] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1000℃ and the holding time is 10 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 820℃ and the holding time is 2 h; the second stage aging treatment temperature is 450℃ and the holding time is 6 h.

[0095] Example 10

[0096] Sintered NdFeB permanent magnet materials were prepared according to the method in Example 5, except that manganese fluorosilicate was replaced with nickel hypophosphite.

[0097] S1. The raw materials are vacuum melted and spun at 1490°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.35 mm.

[0098] rNd 28.15%, Dy 2.83%, B 0.904%, Cu 0.18%, Co 0.73%, Tb 0.23%, Zr 0.16%, Ga 0.21%, balance Fe.

[0099] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0100] S3. Mix NdFeB powder and nickel hypophosphite evenly, with the amount of nickel hypophosphite being 0.5% of the weight of NdFeB powder, to obtain magnetic powder with a D50 particle size of 3.6 μm.

[0101] S4. The magnetic powder is oriented, pressed, and isostatically pressed. The magnetic field strength is 2.5 T, and the isostatic pressing pressure is 200 MPa to obtain a green compact.

[0102] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1060℃ and the holding time is 12 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 850℃ and the holding time is 3 h; the second stage aging treatment temperature is 480℃ and the holding time is 5 h.

[0103] Comparative Example 1

[0104] Sintered NdFeB permanent magnet materials were prepared according to the method in Example 5, except that manganese fluorosilicate was replaced with aluminum fluorosilicate.

[0105] S1. The raw materials are vacuum melted and spun at 1490°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.35 mm.

[0106] rNd 28.15%, Dy 2.83%, B 0.904%, Cu 0.18%, Co 0.73%, Tb 0.23%, Zr 0.16%, Ga 0.21%, balance Fe.

[0107] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0108] S3. Mix NdFeB powder and aluminum fluorosilicate evenly, with the amount of aluminum fluorosilicate being 0.5% of the weight of NdFeB powder, to obtain magnetic powder with a D50 particle size of 3.6 μm.

[0109] S4. The magnetic powder is oriented, pressed, and isostatically pressed. The magnetic field strength is 2.5 T, and the isostatic pressing pressure is 200 MPa to obtain a green compact.

[0110] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1060℃ and the holding time is 12 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 850℃ and the holding time is 3 h; the second stage aging treatment temperature is 480℃ and the holding time is 5 h.

[0111] Comparative Example 2

[0112] Sintered NdFeB permanent magnet materials were prepared according to the method in Example 5, except that manganese fluorosilicate was replaced with magnesium fluorosilicate.

[0113] S1. The raw materials are vacuum melted and spun at 1490°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.35 mm.

[0114] rNd 28.15%, Dy 2.83%, B 0.904%, Cu 0.18%, Co 0.73%, Tb 0.23%, Zr 0.16%, Ga 0.21%, balance Fe.

[0115] S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder;

[0116] S3. Mix neodymium iron boron powder with magnesium fluorosilicate evenly. The amount of magnesium fluorosilicate is 0.5% of the weight of neodymium iron boron powder to obtain magnetic powder with a D50 particle size of 3.6 μm.

[0117] S4. The magnetic powder is oriented, pressed, and isostatically pressed. The magnetic field strength is 2.5 T, and the isostatic pressing pressure is 200 MPa to obtain a green compact.

[0118] S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1060℃ and the holding time is 12 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 850℃ and the holding time is 3 h; the second stage aging treatment temperature is 480℃ and the holding time is 5 h.

[0119] Comparative Example 3

[0120] Sintered NdFeB permanent magnet materials were prepared according to the method in Example 5, except that manganese fluorosilicate was not added.

[0121] S1. The raw materials are vacuum melted and spun at 1490°C according to the following weight percentage formula to obtain a spun sheet with a thickness of 0.35 mm.

[0122] rNd 28.15%, Dy 2.83%, B 0.904%, Cu 0.18%, Co 0.73%, Tb 0.23%, Zr 0.16%, Ga 0.21%, balance Fe.

[0123] S2. The belt-spun sheet is subjected to hydrogen crushing and air jet milling to obtain magnetic powder with a D50 particle size of 3.6 μm;

[0124] S3. The magnetic powder is oriented, pressed, and isostatically pressed. The magnetic field strength is 2.5 T, and the isostatic pressing pressure is 200 MPa to obtain a green compact.

[0125] S4. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material. The vacuum sintering temperature is 1060℃ and the holding time is 12 h. The aging treatment is divided into two stages: the first stage aging treatment temperature is 850℃ and the holding time is 3 h; the second stage aging treatment temperature is 480℃ and the holding time is 5 h.

[0126] The magnetic properties of the sintered NdFeB permanent magnet materials prepared in Examples 1-10 and Comparative Examples 1-3 were tested respectively, and the test results are shown in Table 1. The magnetic properties were tested according to GB / T3217-2013.

[0127] Table 1 Magnetic properties of sintered NdFeB permanent magnet materials

[0128]

[0129] As shown in Table 1, compared with Comparative Examples 1-3, the sintered NdFeB permanent magnet materials prepared in Examples 1-5 exhibit superior magnetic properties and lower coercivity temperature coefficients by adding manganese fluorosilicate or nickel hypophosphite. A lower coercivity temperature coefficient indicates less influence of temperature on coercivity and higher temperature stability.

[0130] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing sintered NdFeB permanent magnet material, characterized in that, Includes the following steps: S1. Vacuum melting and spinning are carried out according to the following raw material formula by weight percentage to obtain the spinning sheet; PrNd 25~30%, Dy 2~3%, B 0.8~1%, Cu 0.1~0.3%, Co 0.6~0.8%, Tb 0.15~0.35%, Zr 0.1~0.3%, Ga 0.1~0.3%, balance Fe; S2. The strip is crushed by hydrogen and milled by air jet milling to obtain neodymium iron boron powder; S3. Mix the neodymium iron boron powder with the additives evenly to obtain magnetic powder; S4. The magnetic powder is subjected to orientation pressing and isostatic pressing to obtain a green body; S5. The green blank is subjected to vacuum sintering and aging treatment to obtain sintered NdFeB permanent magnet material.

2. The preparation method according to claim 1, characterized in that: The additive is manganese fluorosilicate; preferably, the amount of the additive is 0.3 to 0.5% of the weight of the NdFeB powder.

3. The preparation method according to claim 1, characterized in that: The vacuum melting temperature is 1400~1500℃.

4. The preparation method according to claim 1, characterized in that: The magnetic powder has a D50 particle size of 3~4 μm.

5. The preparation method according to claim 1, characterized in that: The magnetic field strength for orientation suppression is 1.5~3 T.

6. The preparation method according to claim 1, characterized in that: The pressure for the isostatic pressing process is 150~250MPa.

7. The preparation method according to claim 1, characterized in that: The vacuum sintering temperature is 1000~1100℃, and the time is 5~15 h.

8. The preparation method according to claim 1, characterized in that: The aging process is divided into two stages. The first stage of aging is performed at a temperature of 800~900℃ for 2~5 hours. The second stage of aging is performed at a temperature of 400~500℃ for 3~8 hours.

9. The sintered NdFeB permanent magnet material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the sintered NdFeB permanent magnet material according to claim 9 in new energy vehicles.

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