Neodymium-iron-boron magnet material and preparation method and application thereof

Abstract

The invention discloses a neodymium-iron-boron magnet material and a preparation method and application thereof. The preparation method comprises the following steps: S1, smelting and casting a raw material composition to obtain a throwing sheet; s2, pulverizing the throwing sheets to obtain powder; s3, pressing the powder to obtain a green body; and S4, sintering the green body to obtain the product. Wherein the raw material composition does not comprise heavy rare earth elements, and the mass ratio of Pr in the light rare earth element Re is 30-50 wt%; the throwing sheet comprises a first columnar crystal, the width of the first columnar crystal is 2-4 microns, and the first columnar crystal accounts for not less than 60% of all columnar crystals; and the X50 particle size of the powder is 2.0-3.7 [mu] m. The obtained neodymium-iron-boron magnet material can still have excellent magnetic performance under the condition that no heavy rare earth element exists, and particularly, the neodymium-iron-boron magnet material can have high residual magnetism, high intrinsic coercive force and high magnetic energy product at the same time.

Description

Technical Field

[0001] The present invention relates to a neodymium-iron-boron magnet material, a preparation method thereof and an application thereof. Background Art

[0002] In the preparation of existing neodymium-iron-boron magnets, both traditional processes and diffusion processes require the use of a certain amount of heavy rare earth elements such as gadolinium, terbium, dysprosium, holmium, yttrium and other elements. Among them, to ensure the preparation of high energy product and high coercivity magnet materials, traditional processes often need to add a certain amount of heavy rare earth elements to achieve high coercivity. For example, based on the addition of Dy / Tb, the formed Dy2Fe 14 B phase, Tb2Fe 14 The magnetocrystalline anisotropy field of the B phase is much higher than that of Nd2Fe 14 B phase, thus achieving high coercivity; however, the saturation magnetic polarization intensity of the crystal formed after adding heavy rare earth elements is much lower than that of Nd2Fe 14 B phase, which will lead to a significant reduction in the energy product. The diffusion process is based on the traditional process, and optimally distributes heavy rare earth elements or alloys to the periphery of the crystal, that is, the heavy rare earth elements are distributed in a gradient from the surface to the inside of the magnet; however, this method also has defects such as uneven temperature resistance of the magnet and time-consuming and laborious.

[0003] In addition, both the traditional process of adding heavy rare earth elements and the diffusion process have the problems of high price and limited resources of heavy rare earth elements.

[0004] Therefore, there is an urgent need to develop a preparation process for neodymium-iron-boron magnets that does not contain heavy rare earth elements and can effectively improve the energy product and coercivity without a diffusion process. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defect that the neodymium-iron-boron magnet material in the prior art cannot have both high energy product and high intrinsic coercivity, and provides a neodymium-iron-boron magnet material, a preparation method thereof and an application thereof. Without adding heavy rare earth elements, the neodymium-iron-boron magnet material can still maintain excellent magnetic properties; specifically, it can have high remanence while having both high energy product and high intrinsic coercivity.

[0006] To achieve the above object, the present invention adopts the following technical solutions.

[0007] The present invention provides a preparation method for a neodymium-iron-boron magnet material, which comprises the following steps:

[0008] S1. Melting and casting the raw material composition to obtain a flake;

[0009] S2. Pulverizing the flake to obtain powder;

[0010] S3. Pressing the powder to obtain a green body;

[0011] S4. Sinter the green body to obtain the NdFeB magnet material;

[0012] Among them,

[0013] The raw material composition does not include heavy rare earth elements and includes the following components by mass percentage:

[0014] Re: 28.8 - 30.7 wt%, where Re is a light rare earth element, and Re includes Pr and Nd; the mass proportion of Pr in Re is 30 - 50 wt%;

[0015] M: 0.1 - 0.3 wt%, where M includes Cu and / or Al;

[0016] X: 0.35 - 0.5 wt%, where X includes one or more of Zr, Ti, and Nb;

[0017] B: 0.88 - 0.96 wt%;

[0018] Ga: 0.25 - 0.5 wt%;

[0019] Co: 0 - 2 wt%;

[0020] And the balance is Fe and inevitable impurities;

[0021] wt% represents the mass percentage of the total mass of the raw material composition;

[0022] The flake includes a first columnar crystal, the width of the first columnar crystal is 2 - 4 μm, and the proportion of the first columnar crystal in all columnar crystals is not less than 60%;

[0023] The X50 particle size of the powder is 2.0 - 3.7 μm.

[0024] In the present invention, the proportion of the first columnar crystal in all columnar crystals can be obtained by calculating the area occupied by the first columnar crystal in the microscopic photograph taken by a metallographic microscope. Those skilled in the art can understand its specific meaning.

[0025] In the present invention, through the regulation of the raw material formula (especially the proportion of Pr and the cooperation of other elements) and process parameters (especially the size of the flake columnar crystal and the particle size of the powder), it is possible to ensure that the obtained magnet material has a high magnetic energy product, high intrinsic coercivity, and high remanence without adding heavy rare earth elements and without a diffusion process, and it is also possible to ensure that the obtained magnet material has extremely low contents of trace elements such as carbon, oxygen, and nitrogen.

[0026] Furthermore, through relevant research, it is found in the present invention that without adding heavy rare earth elements or without adopting a diffusion process, such as not performing the processes of spin casting columnar crystal size and powder particle size, it is difficult to improve the corresponding effects simply through formula optimization.

[0027] In the present invention, the meaning of the X50 particle size refers to the particle diameter at which the particle size distribution is 50%, that is, the volume content of particles smaller than this particle diameter accounts for 50% of all particles. Those skilled in the art can understand its specific meaning.

[0028] In some embodiments, the content of Re is 28.8 - 30.2, for example, 29.9 wt%.

[0029] In some embodiments, the mass proportion of Pr in Re is 30 - 45 wt%, for example, 34%.

[0030] In some embodiments, the content of M is 0.1 - 0.2 wt%.

[0031] In some embodiments, the content of X is 0.35 - 0.4 wt%.

[0032] In some embodiments, the content of B is 0.88 - 0.92 wt%.

[0033] In some embodiments, the content of Pr is 8 - 15 wt%, for example, 8.97 wt%, 10.4 wt%, 12.96 wt%, 13.45 wt%, 13.59 wt% or 14.95 wt%.

[0034] In some embodiments, the content of Nd is 14 - 21 wt%, for example, 14.95 wt%, 15.84 wt%, 16.45 wt%, 16.61 wt%, 20.3 wt% or 20.93 wt%.

[0035] In some embodiments, M is Cu, and the content of Cu is 0.1 - 0.3 wt%, for example, 0.2 wt%.

[0036] In some embodiments, X is Zr, and the content of Zr is 0.35 - 0.5 wt%, for example, 0.4 wt%.

[0037] In some embodiments, the content of Ga is 0.3 - 0.5 wt%, for example, 0.35 wt% or 0.45 wt%.

[0038] In some embodiments, the content of Co is 0 - 1 wt% and not 0, for example, 0.5 wt%.

[0039] In some preferred embodiments, the raw material composition comprises the following components by mass percentage:

[0040] Pr: 8 - 15 wt%;

[0041] Nd: 14 - 21 wt%;

[0042] M: 0.1 - 0.3 wt%, where M comprises Cu and / or Al;

[0043] X: 0.35 - 0.5 wt%, where X comprises one or more of Zr, Ti, and Nb;

[0044] B: 0.88 - 0.96 wt%;

[0045] Ga: 0.25 - 0.5 wt%;

[0046] Co: 0 - 2 wt%;

[0047] and the balance of Fe and inevitable impurities.

[0048] In some specific embodiments, the raw material composition comprises the following components:

[0049] Pr: 10.4 wt%; Nd: 20.3 wt%; Cu: 0.2 wt%; Zr: 0.35 wt%; B: 0.92 wt%; Ga: 0.35 wt%; Co: 0.5 wt%; and the balance of Fe; the proportion of Pr in the Re is 34%.

[0050] In some specific embodiments, the raw material composition comprises the following components:

[0051] Pr: 10.4 wt%; Nd: 20.3 wt%; Cu: 0.2 wt%; Zr: 0.35 wt%; B: 0.92 wt%; Ga: 0.35 wt%; Co: 0.1 wt%; and the balance of Fe; the proportion of Pr in the Re is 34%.

[0052] In some specific embodiments, the raw material composition comprises the following components:

[0053] Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance of Fe; the proportion of Pr in the Re is 45%.

[0054] In some specific embodiments, the raw material composition comprises the following components:

[0055] Pr: 13.59 wt%; Nd: 16.61 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.35 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 45%.

[0056] In some specific embodiments, the raw material composition comprises components with the following contents:

[0057] Pr: 12.96 wt%; Nd: 15.84 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.35 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 45%.

[0058] In some specific embodiments, the raw material composition comprises components with the following contents:

[0059] Pr: 14.95 wt%; Nd: 14.95 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 50%.

[0060] In some specific embodiments, the raw material composition comprises components with the following contents:

[0061] Pr: 8.97 wt%; Nd: 20.93 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 30%.

[0062] In some specific embodiments, the raw material composition comprises components with the following contents:

[0063] Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.96 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 45%.

[0064] In some specific embodiments, the raw material composition comprises components with the following contents:

[0065] Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.88 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 45%.

[0066] In some specific embodiments, the raw material composition comprises components in the following contents:

[0067] Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.2 wt%; Zr: 0.5 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 45%.

[0068] In some specific embodiments, the raw material composition comprises components in the following contents:

[0069] Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.3 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 45%.

[0070] In some specific embodiments, the raw material composition comprises components in the following contents:

[0071] Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.1 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 45%.

[0072] In the present invention, the flake is generally obtained by casting the product obtained by melting each raw material on a copper roller. Among them, the surface of the flake in contact with the copper roller is the roller-contact surface, and the surface away from the copper roller is the free surface. Those skilled in the art can understand its specific meaning.

[0073] In some embodiments, in step S1, the columnar crystals in the flake penetrate the roller-contact surface and the free surface.

[0074] In some embodiments, in step S1, the average thickness of the flake is 0.2 mm - 0.33 mm, such as 0.27 mm or 0.28 mm.

[0075] In some embodiments, in step S2, the X50 particle size of the powder is 2.7 - 3.3 μm, such as 2.8 μm, 2.9 μm, 3.0 μm, 3.1 μm or 3.2 μm.

[0076] In the present invention, in step S2, the powder making can be carried out by conventional operations in the art; preferably, the powder making includes hydrogenation dehydrogenation and jet milling carried out in sequence.

[0077] Among them, the hydrogen breaking preferably includes a hydrogen absorption step, and optionally, a dehydrogenation step may be included after the hydrogen absorption; the pressure of the hydrogen absorption is preferably 70-100 kPa; the temperature of the dehydrogenation is preferably 550-600 °C, such as 580 °C.

[0078] Among them, the hydrogen breaking is preferably carried out in a hydrogen breaking furnace.

[0079] Among them, the jet mill is preferably carried out in an inert atmosphere; the inert atmosphere is, for example, nitrogen or argon.

[0080] Among them, the pressure of the jet mill is preferably 0.5-1 MPa, such as 0.6 MPa.

[0081] In some specific embodiments, in step S2, after the hydrogen breaking and the jet mill steps, each independently further includes a step of mixing the obtained product and an additive.

[0082] Among them, the additive can be conventional in the art, for example, it includes a lubricant; for the present invention, after adding the lubricant, it can play a lubricating role and further reduce the nitrogen content in the obtained neodymium iron boron magnet material.

[0083] In some specific embodiments, the lubricant is, for example, tributyl borate and petroleum ether, and the dosage ratio of tributyl borate and petroleum ether is, for example, 1:1.

[0084] Preferably, after the hydrogen breaking, the dosage of the lubricant is 0.5%-2%, and the percentage refers to the mass percentage of the product obtained by hydrogen breaking.

[0085] Preferably, after the jet mill, the dosage of the lubricant is 0-1.5%, and the percentage refers to the mass percentage of the product obtained by the jet mill.

[0086] In the present invention, in step S3, both the pressing and sintering can be carried out by conventional operations in the art.

[0087] In some embodiments, in step S3, the pressing is carried out by an oriented pressing method.

[0088] In some embodiments, in step S3, the magnetic field strength of the pressing is 1.5 T-2.0 T, such as 1.8 T.

[0089] In some embodiments, in step S4, the sintering is carried out under vacuum conditions.

[0090] In some embodiments, in step S4, the sintering temperature is 1050-1090 °C, such as 1055 °C or 1063 °C.

[0091] In some embodiments, in step S4, the sintering time is 4 - 10 h, such as 8 h.

[0092] In some embodiments, in step S4, after sintering, two - stage tempering treatment is further included.

[0093] The first stage: the temperature is 850 - 940 °C, such as 900 °C; the time is 1 - 10 h, such as 2 h.

[0094] The second stage: the temperature is 440 - 505 °C, such as 465 °C or 470 °C; the time is 1 - 10 h, such as 3 h.

[0095] In some specific embodiments, in step S4, the sintering and two - stage tempering treatment satisfy one of the following conditions:

[0096] The sintering temperature is 1055 °C, the first - stage tempering treatment temperature is 900 °C, and the second - stage tempering treatment temperature is 470 °C;

[0097] Or, the sintering temperature is 1063 °C, the first - stage tempering treatment temperature is 900 °C, and the second - stage tempering treatment temperature is 470 °C.

[0098] The present invention also provides a neodymium - iron - boron magnet material, and the neodymium - iron - boron magnet material is prepared by the preparation method of the neodymium - iron - boron magnet material as described above.

[0099] In some embodiments, in the neodymium - iron - boron magnet material, the volume ratio of grains with a particle size of 2 - 8 μm to the total grains is not less than 99%.

[0100] In some embodiments, in the neodymium - iron - boron magnet material, the volume ratio of grains with a particle size of 4 - 6 μm to the total grains is not less than 90%.

[0101] In some embodiments, in the neodymium - iron - boron magnet material, the oxygen content is lower than 800 ppm, such as 418 ppm, 425 ppm, 484 ppm, 503 ppm, 515 ppm, 518 ppm, 519 ppm, 521 ppm, 530 ppm, 532 ppm, 545 ppm, 569 ppm, 579 ppm, 592 ppm, 603 ppm or 780 ppm.

[0102] In some embodiments, in the neodymium - iron - boron magnet material, the nitrogen content is lower than 500 ppm, such as 123 ppm, 235 ppm, 242 ppm, 261 ppm, 278 ppm, 281 ppm, 289 ppm, 292 ppm, 297 ppm, 298 ppm, 301 ppm, 305 ppm, 345 ppm, 439 ppm or 475 ppm.

[0103] In some embodiments, in the neodymium iron boron magnet material, the carbon content is less than 800 ppm, such as 523 ppm, 525 ppm, 528 ppm, 529 ppm, 537 ppm, 542 ppm, 544 ppm, 551 ppm, 552 ppm, 553 ppm, 563 ppm, 566 ppm, 575 ppm, 581 ppm, 593 ppm or 598 ppm.

[0104] The present invention also provides an application of the neodymium iron boron magnet material as described above as a magnetic component.

[0105] In some embodiments, the neodymium iron boron magnet material is applied as a magnetic device in many fields such as rail transit, military equipment, wind power generation, low-altitude flight, artificial intelligence, aerospace, medical devices, precision manufacturing, etc.

[0106] In the present invention, each element symbol has its conventional meaning in the art. Specifically: "Pr" is praseodymium, "Nd" is neodymium, "Al" is aluminum, "Cu" is copper, "Ga" is gallium, "Co" is cobalt, "Ti" is titanium, "Zr" is zirconium, "Nb" is niobium, "Fe" is iron, and "B" is boron.

[0107] In the present invention, unless otherwise specified, an element appearing alone refers to the elemental substance of that element.

[0108] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0109] The reagents and raw materials used in the present invention are all commercially available.

[0110] The positive and progressive effects of the present invention are as follows:

[0111] The present invention prepares a neodymium iron boron magnet material without heavy rare earths through formula design and process parameter design. Among them, mainly through the regulation of the proportion of Pr in the light rare earth elements in the formula, combined with the control of the amounts of elements such as Cu, Zr, B, Ga, and Co, and further combined with the regulation of the columnar crystals formed by spin casting and the powder size obtained by powder making in the process, a neodymium iron boron magnet material with fine grains is obtained. The particle size of the vast majority of grains in this neodymium iron boron magnet material is between 2 - 8 μm, and the contents of impurity elements such as carbon, oxygen, and nitrogen are significantly reduced. It has excellent magnetic properties and can have both ultra-high remanence, high intrinsic coercivity, and high magnetic energy product. Specifically: in the case of no heavy rare earth elements, the remanence can still be guaranteed to be above 13.90 kGs, the intrinsic coercivity is above 18.6 kOe, the magnetic energy product is above 46.80 MGOe, and the squareness is above 91%. BRIEF DESCRIPTION OF THE DRAWINGS

[0112] Figure 1This is the metallographic diagram corresponding to the flake casting during the preparation of the neodymium-iron-boron permanent magnet in Example 1 of the present invention.

[0113] Figure 2 This is the metallographic diagram of the neodymium-iron-boron permanent magnet obtained in Example 1 of the present invention.

[0114] Figure 3 This is the metallographic diagram corresponding to the flake casting during the preparation of the neodymium-iron-boron permanent magnet obtained in Comparative Example 1 of the present invention.

[0115] Figure 4 This is the metallographic diagram of the neodymium-iron-boron permanent magnet obtained in Comparative Example 1 of the present invention. Detailed implementation manners

[0116] The present invention will be further illustrated by the following examples, but the present invention is not limited to the scope of the examples described herein. For the experimental methods without specific conditions noted in the following examples, they are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0117] The sources of the instruments used in the following examples and comparative examples are shown in Table 1:

[0118] Table 1

[0119] Instrument Model / Specification Manufacturer Carbon and Sulfur Analyzer CS-3000 GangYen NCS Oxygen, Nitrogen and Hydrogen Analyzer ONH836 Shanghai Yuzhong Industrial Co., Ltd.

[0120] Example 1

[0121] According to the formula in Table 2 and the process parameters in Table 3, the neodymium-iron-boron magnet material of this example was prepared by the following steps:

[0122] S1. Melting and casting

[0123] Weigh each raw material component according to Table 2 and mix them. Then melt them in a melting furnace at 1500 °C and cast them on a copper roller (the rotation speed of the copper roller is 1.3 m / s). After cooling to room temperature, take them out of the furnace to obtain the flake casting, and the columnar crystals in the flake casting penetrate the roller contact surface and the free surface. Specifically, the thickness of the flake casting and the width of the columnar crystals are shown in Table 3. Among them, the proportion of columnar crystals with a size of 2 - 4 μm in the flake casting is calculated by the area in the metallographic diagram.

[0124] S2. Powder making

[0125] (1) Subject the flake casting obtained in step S1 to hydrogen breaking treatment in a hydrogen breaking furnace. Carry out hydrogen absorption treatment under a reaction pressure of 70 - 100 kPa, and then carry out dehydrogenation treatment at 580 °C. After cooling to room temperature, take them out of the furnace in a fully sealed state to obtain the coarse powder;

[0126] (2) Add a lubricant (tributyl borate: petroleum ether = 1:1 mixture) to the obtained coarse powder at a ratio of 1.5% (by mass percentage), shake well, and use a nitrogen gas jet mill to obtain a fine powder with an X50 particle size of 3.0 μm under a grinding pressure of 0.6 MPa. Subsequently, add the obtained fine powder to a lubricant (tributyl borate: petroleum ether = 1:1 mixture) at a ratio of 0.7% (by mass percentage), and shake well to obtain a mixed fine powder.

[0127] S3. Compression

[0128] Use a fully electric floating press and a combined die to perform orientation pressing on the mixed fine powder obtained in step S2 at a magnetic field strength of 1.8 T to obtain a green body.

[0129] S4. Sintering and tempering treatment

[0130] Sinter the green body obtained in step S3 in a vacuum sintering furnace at 1055 °C for 8 h, and then perform tempering treatment at 900 °C for 2 h and tempering treatment at 470 °C for 3 h in sequence.

[0131] Examples 2 - 16 and Comparative Examples 1 - 16

[0132] Referring to the steps in Example 1, prepare the NdFeB magnet materials of Examples 2 - 17 and Comparative Examples 1 - 16 according to the formulations in Table 2 and the process parameters in Table 3.

[0133] Table 2

[0134]

[0135]

[0136] Table 3

[0137]

[0138]

[0139] Effect Example

[0140] 1. Chip throwing and magnet morphology characterization;

[0141] Perform microstructure characterization on the chips thrown in Example 1 and Comparative Example 1 and the finally obtained magnet materials. Among them, for the chips thrown, after embedding, sample preparation, grinding, and polishing, take microscopic photos using a metallurgical microscope, analyze the width of columnar crystals by roughly dividing the area with the naked eye, and calculate the corresponding proportion; during the grinding process of the powder particle size, use a new Patak laser particle size tester; in the microstructure of the obtained magnet, take photos with a metallurgical microscope, analyze and process to obtain the grain volume fraction in the sample.

[0142] The results are shown in Figures 1-4 and Table 4 respectively.

[0143] It can be seen from Figure 1 (Example 1) that most of the columnar crystals in the spin casting of the present invention grow uniformly, have regular shapes, and have small differences in columnar crystal sizes, penetrate the entire thickness direction, and have few transverse dendrites; while Figure 3 (Comparative Example 1) shows that most of the columnar crystals grow unevenly, have irregular shapes, have large differences in columnar crystal sizes, penetrate the entire thickness direction, and have many transverse dendrites. Further, it can be seen from the comparison between Figure 2 (Example 1) and Figure 4 (Comparative Example 1) that the grains in the magnet material obtained by the present invention are more uniform and finer.

[0144] Table 4

[0145]

[0146]

[0147] Wherein:

[0148] In the preparation process of Comparative Example 6, the lattice structure of the spin-cast α-Fe was serious and the microstructure of the spin casting was poor, so no subsequent relevant tests were carried out.

[0149] The stability of the neodymium iron boron magnet material obtained in Comparative Example 10 was significantly poor, so no subsequent relevant tests were carried out.

[0150] In the preparation process of Comparative Example 11, the material could not be sintered solid during sintering, so no subsequent relevant tests were carried out.

[0151] In the preparation process of Comparative Example 12, the grains of the obtained neodymium iron boron magnet material grew significantly, so no subsequent relevant tests were carried out.

[0152] In the preparation process of Comparative Example 16, the discharge rate could not be guaranteed during grinding, so no subsequent relevant tests were carried out.

[0153] 2. Characterization of oxygen content, carbon content, and nitrogen content;

[0154] The neodymium iron boron magnet materials prepared in Examples 1-16 and Comparative Examples 1-5, 7-9, and 13-15 were knocked into small particles, and carbon and oxygen / nitrogen tests were respectively carried out using a carbon-sulfur analyzer CS-3000 and an oxygen-nitrogen-hydrogen analyzer ONH836. The test data are shown in Table 5.

[0155] Table 5

[0156]

[0157]

[0158] As can be seen from Table 5, the contents of impurity elements carbon, oxygen, and nitrogen in the NdFeB magnet material prepared in the embodiments of the present invention are significantly reduced, which is also one of the important factors for the substantial improvement of magnetic properties.

[0159] 3. Characterization of magnetic properties (remanent magnetization, intrinsic coercivity, maximum energy product, squareness ratio);

[0160] The NdFeB magnet materials prepared in Examples 1-16 and Comparative Examples 1-5, 7-9, and 13-15 were respectively processed into standard sample columns, and magnetic property tests were carried out using NIM62000 in an environment with a constant temperature of 20 °C. The test data are shown in Table 6.

[0161] Table 6

[0162] Br / kGs Hcj / kOe Magnetic Energy Product / MGOe Q / ％ Example 1 14.23 19.2 48.73 97.1 Example 2 14.27 19.34 48.91 97.7 Example 3 14.16 19.68 48.36 97.5 Example 4 14.04 19.26 47.58 98.2 Example 5 14.1 20.34 48.16 96.5 Example 6 14.03 20.55 47.68 98.1 Example 7 14.43 19.07 50.41 93 Example 8 14.16 20.74 48.57 96.3 Example 9 14.28 19.14 49.40 97.2 Example 10 14.04 20.05 47.76 97.4 Example 11 14.16 19.8 48.56 97.2 Example 12 14.06 20.35 47.92 96.7 Example 13 14.05 20.13 47.85 96.8 Example 14 14.14 20.2 48.44 96.8 Example 15 14.18 18.72 48.71 97.2 Example 16 13.90 18.6 46.80 91 Comparative Example 1 14.3 19.1 49.2 97 Comparative Example 2 14.16 20.6 48.39 97.9 Comparative Example 3 14.22 19.9 48.61 97.6 Comparative Example 4 13.84 24.20 46.39 97.3 Comparative Example 5 13.61 21.81 44.88 97.6 Comparative Example 7 13.98 21.14 47.34 97.2 Comparative Example 8 14.34 18.74 49.81 97.1 Comparative Example 9 14.01 19.84 47.56 96.8 Comparative Example 13 13.95 20.10 47.15 97.3 Comparative Example 14 14.14 19.80 48.44 97.5 Comparative Example 15 14.18 18.54 48.71 97.2

[0163] In Table 6, Br represents the remanent magnetization; Hcj represents the intrinsic coercivity; Q represents the squareness ratio, which reflects the rectangularity of the demagnetization curve. The closer its value is to 100%, the stronger the irreversibility of the magnetization reversal of the magnet under the action of the reverse magnetic field, the more stable the magnetic domains are before the knee point (Hk), and the better the demagnetization resistance ability.

[0164] As can be seen from Table 6, the remanent magnetization of the NdFeB magnet material prepared in the embodiments of the present invention can reach above 13.90 kGs, the intrinsic coercivity can reach above 18.6 kOe, the maximum energy product can reach above 46.80 MGOe, and the squareness ratio can reach above 91%. It is equivalent to the overall effect of Comparative Examples 1-3 with the addition of heavy rare earth elements.

[0165] In contrast, on the basis of the existing Example 5, when and only when the content of Re in the formula (the proportion of Pr in Re remains unchanged), the content of B, the content of Zr, the content of Cu, or the proportion of Pr in Re is changed so that it is not within the scope protected by the present application (Comparative Examples 1-5, 7-9, and 13-14), at least one of the above aspects of the magnetic properties of the obtained NdFeB magnet material will be significantly deteriorated, especially the intrinsic coercivity and the maximum energy product.

[0166] In contrast, on the basis of the existing Example 5, when and only when the powder particle size obtained by powder making is changed so that it is not within the scope protected by the present application (Comparative Example 15), the intrinsic coercivity of the obtained NdFeB magnet material is significantly deteriorated.

[0167] In addition, in the present invention, the cost comparison of the NdFeB magnet materials corresponding to Examples 1-5 and Comparative Examples 1-3 is shown in Table 7 below:

[0168] Table 7

[0169] Price (yuan / kg) Example 1 188.5 Example 2 186.5 Example 3 192.2 Example 4 193 Example 5 198 Comparative Example 1 228 Comparative Example 2 238 Comparative Example 3 205.3

[0170] Among them, the unit prices of the main raw materials are as follows: PrNd is 510 yuan / kg, pure Pr is 568 yuan / kg, and DyFe is 2030 yuan / kg; in the existing diffusion process, the processing fee is usually 15 yuan / kg, the cost corresponding to adding 0.8 wt% Dy is 20 yuan / kg, and the relative substrate increases by approximately 35 yuan / kg. Finally, it is calculated that when using the heavy rare earth Dy element, it is approximately 25 yuan / kg more than when there is no heavy rare earth.

[0171] It can be seen that the NdFeB magnet material of the present invention can maintain excellent magnetic properties under the condition of no heavy rare earth to control lower costs.

[0172] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only an example, and the protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A method for preparing a neodymium iron boron magnet material, characterized in that, The preparation method of the neodymium iron boron magnet material comprises the following steps: S1. Melting and casting the raw material composition to obtain a flake; S2. Pulverizing the flake to obtain powder; S3. Pressing the powder to obtain a green body; S4. Sintering the green body to prepare the neodymium iron boron magnet material; Wherein, The raw material composition does not include heavy rare earth elements and includes the following components in mass percentage: Re: 28.8 - 30.7 wt%, wherein Re is a light rare earth element, and Re includes Pr and Nd; the mass proportion of Pr in Re is 30 - 50 wt%; M: 0.1 - 0.3 wt%, wherein M includes Cu and / or Al; X: 0.35 - 0.5 wt%, wherein X includes one or more of Zr, Ti, and Nb; B: 0.88 - 0.96 wt%; Ga: 0.25 - 0.5 wt%; Co: 0 - 2 wt%; And the balance of Fe and inevitable impurities; wt% represents the mass percentage of the total mass of the raw material composition; The flake includes a first columnar crystal, the width of the first columnar crystal is 2 - 4 μm, and the proportion of the first columnar crystal in all columnar crystals is not less than 60%; The X50 particle size of the powder is 2.0 - 3.7 μm.

2. The preparation method of the neodymium iron boron magnet material according to claim 1, characterized in that, The raw material composition satisfies one or more of the following conditions: (1) The content of Re is 28.8 - 30.2 wt%, such as 29.9 wt%; (2) The mass proportion of Pr in Re is 30 - 45 wt%, such as 34%; (3) The content of M is 0.1 - 0.2 wt%; (4) The content of X is 0.35 - 0.4 wt%; (5) The content of B is 0.88 - 0.92 wt%.

3. The preparation method of the neodymium iron boron magnet material according to claim 1, characterized in that, The raw material composition satisfies one or more of the following conditions: (1) The content of Pr is 8 - 15 wt%, such as 8.97 wt%, 10.4 wt%, 12.96 wt%, 13.45 wt%, 13.59 wt% or 14.95 wt%; (2) The content of Nd is 14 - 21 wt%, such as 14.95 wt%, 15.84 wt%, 16.45 wt%, 16.61 wt%, 20.3 wt% or 20.93 wt%; (3) M is Cu, and the content of Cu is 0.1 - 0.3 wt%, such as 0.2 wt%; (4) X is Zr, and the content of Zr is 0.35 - 0.5 wt%, such as 0.4 wt%; (5) The content of Ga is 0.3 - 0.5 wt%, such as 0.35 wt% or 0.45 wt%; (6) The content of Co is 0 - 1 wt% and not 0, such as 0.5 wt%.

4. The preparation method of the neodymium iron boron magnet material according to claim 1, characterized in that, The raw material composition includes the following components in mass percentage: Pr: 8 - 15 wt%; Nd: 14 - 21 wt%; M: 0.1 - 0.3 wt%, wherein M includes Cu and / or Al; X: 0.35 - 0.5 wt%, wherein X includes one or more of Zr, Ti, and Nb; B: 0.88 - 0.96 wt%; Ga: 0.25 - 0.5 wt%; Co: 0 - 2 wt%; and the balance of Fe and inevitable impurities; Preferably, the raw material composition comprises components with the following contents: Pr: 10.4 wt%; Nd: 20.3 wt%; Cu: 0.2 wt%; Zr: 0.35 wt%; B: 0.92 wt%; Ga: 0.35 wt%; Co: 0.5 wt%; and the balance of Fe; the proportion of Pr in the Re is 34%; Or, Pr: 10.4 wt%; Nd: 20.3 wt%; Cu: 0.2 wt%; Zr: 0.35 wt%; B: 0.92 wt%; Ga: 0.35 wt%; Co: 0.1 wt%; and the balance of Fe; the proportion of Pr in the Re is 34%; Or, Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance of Fe; the proportion of Pr in the Re is 45%; Or, Pr: 13.59 wt%; Nd: 16.61 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.35 wt%; Co: 0.5 wt%; and the balance of Fe; the proportion of Pr in the Re is 45%; Or, Pr: 12.96 wt%; Nd: 15.84 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.35 wt%; Co: 0.5 wt%; and the balance of Fe; the proportion of Pr in the Re is 45%; Or, Pr: 14.95 wt%; Nd: 14.95 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance of Fe; the proportion of Pr in the Re is 50%; Or, Pr: 8.97 wt%; Nd: 20.93 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance of Fe; the proportion of Pr in the Re is 30%; Or, Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.96 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance of Fe; the proportion of Pr in the Re is 45%; Or, Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.2 wt%; Zr: 0.4 wt%; B: 0.88 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance of Fe; the proportion of Pr in the Re is 45%; Alternatively, Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.2 wt%; Zr: 0.5 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 45%; Alternatively, Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.3 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 45%; Alternatively, Pr: 13.45 wt%; Nd: 16.45 wt%; Cu: 0.1 wt%; Zr: 0.4 wt%; B: 0.92 wt%; Ga: 0.45 wt%; Co: 0.5 wt%; and the balance Fe; the proportion of Pr in the Re is 45%.

5. The preparation method of the neodymium iron boron magnet material according to claim 1, wherein The preparation method of the Nd-Fe-B permanent magnet material satisfies one or more of the following conditions: (1) In step S1, the columnar crystals in the sputtering slice penetrate the roller-attached surface and the free surface; (2) In step S1, the average thickness of the sputtering slice is 0.2 mm - 0.33 mm, such as 0.27 mm or 0.28 mm; (3) In step S2, the X50 particle size of the powder is 2.7 - 3.3 μm, such as 2.8 μm, 2.9 μm, 3.0 μm, 3.1 μm or 3.2 μm.

6. The preparation method of the neodymium iron boron magnet material according to claim 1, wherein The preparation method of the Nd-Fe-B permanent magnet material satisfies one or more of the following conditions: (1) In step S2, the powder making includes hydrogen breaking and jet milling carried out in sequence; Among them, the hydrogen breaking preferably includes a hydrogen absorption step, and optionally further includes a dehydrogenation step after hydrogen absorption; the pressure of the hydrogen absorption is preferably 70 - 100 kPa; the temperature of the dehydrogenation is preferably 550 - 600 °C, such as 580 °C; Among them, the pressure of the jet milling is preferably 0.5 - 1 MPa, such as 0.6 MPa; (2) In step S3, the pressing is carried out in an orientation pressing manner; (3) In step S3, the magnetic field strength of the pressing is 1.5 T - 2.0 T, such as 1.8 T.

7. The preparation method of the neodymium iron boron magnet material according to claim 1, characterized in that, The preparation method of the Nd-Fe-B permanent magnet material satisfies one or more of the following conditions: (1) In step S4, the sintering is carried out under vacuum conditions; (2) In step S4, the temperature of the sintering is 1050 - 1090 °C, such as 1055 °C or 1063 °C; (3) In step S4, the time of the sintering is 4 - 10 h, such as 8 h; (4) After the sintering in step S4, it further includes two-stage tempering treatment; The first stage: the temperature is 850 - 940 °C, such as 900 °C; the time is 1 - 10 h, such as 2 h; The second stage: the temperature is 440 - 505 °C, such as 465 °C or 470 °C; the time is 1 - 10 h, such as 3 h.

8. A neodymium iron boron magnet material, characterized in that, The Nd-Fe-B magnet material is obtained by the preparation method of the Nd-Fe-B magnet material according to any one of claims 1 - 7.

9. The neodymium iron boron magnet material according to claim 8, characterized in that, The Nd-Fe-B magnet material satisfies one or more of the following conditions: (1) In the NdFeB magnet material, the volume ratio of the grains with a particle size of 2 - 8 μm to the total grains is not less than 99%; and / or, the volume ratio of the grains with a particle size of 4 - 6 μm to the total grains is not less than 90%; (2) The oxygen content is less than 800 ppm, such as 418 ppm, 425 ppm, 484 ppm, 503 ppm, 515 ppm, 518 ppm, 519 ppm, 521 ppm, 530 ppm, 532 ppm, 545 ppm, 569 ppm, 579 ppm, 592 ppm, 603 ppm or 780 ppm; (3) The nitrogen content is less than 500 ppm, such as 123 ppm, 235 ppm, 242 ppm, 261 ppm, 278 ppm, 281 ppm, 289 ppm, 292 ppm, 297 ppm, 298 ppm, 301 ppm, 305 ppm, 345 ppm, 439 ppm or 475 ppm; (4) The carbon content is less than 800 ppm, such as 523 ppm, 525 ppm, 528 ppm, 529 ppm, 537 ppm, 542 ppm, 544 ppm, 551 ppm, 552 ppm, 553 ppm, 563 ppm, 566 ppm, 575 ppm, 581 ppm, 593 ppm or 598 ppm.

10. Use of the NdFeB magnet material as claimed in claim 8 or 9 as a magnetic component.

Images