Regenerated sintered neodymium-iron-boron permanent magnet and preparation method thereof

Abstract

The invention discloses a regenerated sintered neodymium-iron-boron permanent magnet and a preparation method thereof, and belongs to the technical field of magnetic materials, the preparation method comprises the following steps: S1, performing crushing treatment on neodymium-iron-boron permanent magnet waste, and then performing a jet milling process to obtain waste fine powder; the method comprises the following steps: smelting a rare earth alloy, performing hydrogen decrepitation non-dehydrogenation treatment to obtain a rare earth alloy hydride, and then performing a jet milling process to obtain rare earth alloy hydride fine powder; and S2, the waste fine powder and the rare earth alloy hydride fine powder are mixed, fully stirred, sieved, subjected to magnetic field forming, sintered and subjected to tempering heat treatment, and the regenerated sintered neodymium-iron-boron permanent magnet is obtained. The preparation method provided by the invention is simple, the neodymium iron boron waste can be effectively recycled, meanwhile, the utilization rate of the waste is increased, resources are saved, and the cost is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic materials, and in particular relates to a regenerated sintered NdFeB permanent magnet and a preparation method thereof. Background Art

[0002] Neodymium iron boron magnetic material, known as the "king of magnets" due to its excellent magnetic properties, is widely used in electronics, power machinery, medical equipment, toys, packaging, hardware machinery, aerospace and other fields.

[0003] However, since NdFeB products will inevitably produce about 25%-30% of scraps and defective products during the production and processing, and as time goes by, some mechanical equipment and motors using NdFeB permanent magnets will produce a large number of scrapped NdFeB waste magnets due to failures, expiration of service life, etc. Due to the high cost of raw materials for NdFeB permanent magnet materials, the industry has been researching and developing methods for recycling rare earth permanent magnet defectives, scraps, and waste NdFeB magnets and other rare earth permanent magnet wastes to reduce the raw material cost of rare earth permanent magnet materials and save existing natural resources. Therefore, it is of great significance to study how to recycle NdFeB waste materials in a green, high-value and efficient manner to regenerate sintered NdFeB permanent magnets. Summary of the invention

[0004] Aiming at the recycling of existing sintered NdFeB product waste, the present invention provides a regenerated sintered NdFeB permanent magnet and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a regenerated sintered NdFeB permanent magnet comprises the following steps:

[0007] S1, crushing the NdFeB permanent magnet waste, and then performing a jet milling process to obtain waste fine powder; smelting the rare earth alloy, performing hydrogen crushing without dehydrogenation treatment to obtain rare earth alloy hydride, and then performing a jet milling process to obtain rare earth alloy hydride fine powder;

[0008] S2. Mix the waste fine powder and the rare earth alloy hydride fine powder, fully stir, sieve, form in a magnetic field, sinter, and perform tempering heat treatment to obtain a regenerated sintered NdFeB permanent magnet.

[0009] Furthermore, the crushing process in S1 is: mechanical crushing and hydrogen crushing in sequence.

[0010] Furthermore, the average particle size of the waste fine powder in S1 is 4.5-5.5 μm. Grain refinement is achieved by reducing the size of the waste particles before sintering, thereby improving the coercivity.

[0011] Furthermore, the rare earth alloy is Tb 70 Cu 30 , Pr 52.5 Tb 17.5 Cu 30 , Pr 60 Tb 10 Al 20 , Pr 60 Tb 10 Cu 15 Al 15 At least one of the following. The rare earth alloy is subjected to hydrogen crushing without dehydrogenation treatment to obtain the hydride of the rare earth alloy. The rare earth alloy hydride releases highly reducing hydrogen during the sintering process, which can reduce the oxidized components in the waste powder and protect the magnet from oxidation; the dehydrogenated rare earth alloy can also optimize the grain boundary structure and enhance the demagnetization coupling effect, thereby improving the coercive force of the magnet and making the regenerated sintered NdFeB permanent magnet have good consistency.

[0012] Furthermore, the average particle size of the rare earth alloy hydride fine powder in S1 is 3-5 μm.

[0013] Furthermore, the mass ratio of the waste fine powder and the rare earth alloy hydride fine powder in S2 is (95:5)-(97:3).

[0014] Furthermore, in the sintering process in S2, the sintering temperature is 1060-1100° C., and the sintering time is 3-8 hours.

[0015] Furthermore, the tempering heat treatment in S2 adopts a two-stage tempering heat treatment process, wherein the first-stage tempering temperature is 850-900°C, and the tempering time is 1.8-2h; the second-stage tempering temperature is 500-550°C, and the tempering time is 2.5-3h.

[0016] A regenerated sintered NdFeB permanent magnet is prepared by the above steps.

[0017] Beneficial effects of the present invention:

[0018] The present invention uses NdFeB waste to prepare regenerated sintered NdFeB permanent magnets, which relieves the rare earth supply pressure. The national standard of magnetic properties of regenerated sintered NdFeB is basically consistent with that of sintered NdFeB, but there are still slight differences: the magnetic energy product and coercive force of regenerated sintered NdFeB are relatively low. Therefore, the present invention adds rare earth alloys during the preparation process, adopts double alloy technology and mixes with NdFeB waste to prepare regenerated sintered NdFeB permanent magnets with high magnetic energy product and high coercive force. The addition of rare earth alloys can improve the coercive force of the magnet. On the one hand, it forms a dual main phase structure and improves the magnetocrystalline anisotropy field of the main phase grains as a whole; on the other hand, it increases the content of rare earth phases in the grain boundaries, improves the anti-demagnetization ability of the epitaxial layer of the main phase grains, and thus can significantly improve the coercive force of the regenerated sintered NdFeB permanent magnets.

[0019] The invention provides a regenerated sintered NdFeB permanent magnet and a preparation method thereof. The preparation method is simple and can effectively recycle and reuse NdFeB waste, while improving the utilization rate of the waste, saving resources and greatly reducing costs. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1

[0022] This embodiment provides a method for preparing a regenerated sintered NdFeB permanent magnet, comprising the following steps:

[0023] S1, subjecting NdFeB permanent magnet waste to mechanical crushing and hydrogen crushing treatment in sequence, and then to a jet milling process to obtain waste fine powder, wherein the average particle size of the waste fine powder is 4.5 μm;

[0024] Tb 70 Cu 30 After the rare earth alloy is smelted, hydrogen crushing without dehydrogenation treatment is performed to obtain rare earth alloy hydride, and then a jet milling process is performed to obtain rare earth alloy hydride fine powder, wherein the average particle size of the rare earth alloy hydride fine powder is 3 μm;

[0025] S2. Mix 95g of waste fine powder and 5g of rare earth alloy hydride fine powder, stir them fully, sieve them, form them in a magnetic field, and sinter them, wherein the sintering temperature is 1060°C and the sintering time is 4.5h. Then, perform tempering heat treatment, wherein the tempering heat treatment adopts a two-stage tempering heat treatment process, wherein the first stage tempering temperature is 850°C and the tempering time is 1.8h; the second stage tempering temperature is 500°C and the tempering time is 3h, to obtain a regenerated sintered NdFeB permanent magnet.

[0026] The regenerated sintered NdFeB permanent magnet is prepared by the above steps.

[0027] Example 2

[0028] This embodiment provides a method for preparing a regenerated sintered NdFeB permanent magnet, comprising the following steps:

[0029] S1, subjecting NdFeB permanent magnet waste to mechanical crushing and hydrogen crushing treatment in sequence, and then to a jet milling process to obtain waste fine powder, wherein the average particle size of the waste fine powder is 4.5 μm;

[0030] Pr 52.5 Tb 17.5 Cu 30 After the rare earth alloy is smelted, hydrogen crushing without dehydrogenation treatment is performed to obtain rare earth alloy hydride, and then a jet milling process is performed to obtain rare earth alloy hydride fine powder, wherein the average particle size of the rare earth alloy hydride fine powder is 3 μm;

[0031] S2. Mix 95g of waste fine powder and 5g of rare earth alloy hydride fine powder, stir them fully, sieve them, form them in a magnetic field, and sinter them, wherein the sintering temperature is 1060°C and the sintering time is 4.5h. Then, perform tempering heat treatment, wherein the tempering heat treatment adopts a two-stage tempering heat treatment process, wherein the first stage tempering temperature is 850°C and the tempering time is 1.8h; the second stage tempering temperature is 500°C and the tempering time is 3h, to obtain a regenerated sintered NdFeB permanent magnet.

[0032] The regenerated sintered NdFeB permanent magnet is prepared by the above steps.

[0033] Example 3

[0034] This embodiment provides a method for preparing a regenerated sintered NdFeB permanent magnet, comprising the following steps:

[0035] S1, subjecting NdFeB permanent magnet waste to mechanical crushing and hydrogen crushing treatment in sequence, and then to a jet milling process to obtain waste fine powder, wherein the average particle size of the waste fine powder is 4.5 μm;

[0036] Pr 60 Tb 10 Cu 15 Al 15 After the rare earth alloy is smelted, hydrogen crushing without dehydrogenation treatment is performed to obtain rare earth alloy hydride, and then a jet milling process is performed to obtain rare earth alloy hydride fine powder, wherein the average particle size of the rare earth alloy hydride fine powder is 3 μm;

[0037] S2. Mix 95g of waste fine powder and 5g of rare earth alloy hydride fine powder, stir them fully, sieve them, form them in a magnetic field, and sinter them, wherein the sintering temperature is 1060°C and the sintering time is 4.5h. Then, perform tempering heat treatment, wherein the tempering heat treatment adopts a two-stage tempering heat treatment process, wherein the first stage tempering temperature is 850°C and the tempering time is 1.8h; the second stage tempering temperature is 500°C and the tempering time is 3h, to obtain a regenerated sintered NdFeB permanent magnet.

[0038] The regenerated sintered NdFeB permanent magnet is prepared by the above steps.

[0039] Example 4

[0040] This embodiment provides a method for preparing a regenerated sintered NdFeB permanent magnet, comprising the following steps:

[0041] S1. The NdFeB permanent magnet waste is subjected to mechanical crushing and hydrogen crushing treatment in sequence, and then subjected to a jet milling process to obtain waste fine powder, wherein the average particle size of the waste fine powder is 5.5 μm;

[0042] Tb 70 Cu 30 After the rare earth alloy is smelted, hydrogen crushing without dehydrogenation treatment is performed to obtain rare earth alloy hydride, and then a jet milling process is performed to obtain rare earth alloy hydride fine powder, wherein the average particle size of the rare earth alloy hydride fine powder is 5 μm;

[0043] S2. Mix 97g of waste fine powder and 3g of rare earth alloy hydride fine powder, stir them fully, sieve them, form them in a magnetic field, and sinter them, wherein the sintering temperature is 1100°C and the sintering time is 4h. Then, perform tempering heat treatment, wherein the tempering heat treatment adopts a two-stage tempering heat treatment process, wherein the first stage tempering temperature is 900°C and the tempering time is 1.8h; the second stage tempering temperature is 550°C and the tempering time is 2.5h, to obtain a regenerated sintered NdFeB permanent magnet.

[0044] The regenerated sintered NdFeB permanent magnet is prepared by the above steps.

[0045] Example 5

[0046] This embodiment provides a method for preparing a regenerated sintered NdFeB permanent magnet, comprising the following steps:

[0047] S1, subjecting NdFeB permanent magnet waste to mechanical crushing and hydrogen crushing treatment in sequence, and then to a jet milling process to obtain waste fine powder, wherein the average particle size of the waste fine powder is 5 μm;

[0048] Tb 70 Cu 30 After the rare earth alloy is smelted, hydrogen crushing without dehydrogenation treatment is performed to obtain rare earth alloy hydride, and then a jet milling process is performed to obtain rare earth alloy hydride fine powder, wherein the average particle size of the rare earth alloy hydride fine powder is 3 μm;

[0049] S2. Mix 96g of waste fine powder and 4g of rare earth alloy hydride fine powder, stir them fully, sieve them, form them in a magnetic field, and sinter them, wherein the sintering temperature is 1080°C and the sintering time is 6h. Then, perform tempering heat treatment, wherein the tempering heat treatment adopts a two-stage tempering heat treatment process, wherein the first-stage tempering temperature is 860°C and the tempering time is 1.8h; the second-stage tempering temperature is 530°C and the tempering time is 2.8h, to obtain a regenerated sintered NdFeB permanent magnet.

[0050] The regenerated sintered NdFeB permanent magnet is prepared by the above steps.

[0051] Example 6

[0052] This embodiment provides a method for preparing a regenerated sintered NdFeB permanent magnet, comprising the following steps:

[0053] S1, subjecting NdFeB permanent magnet waste to mechanical crushing and hydrogen crushing treatment in sequence, and then to a jet milling process to obtain waste fine powder, wherein the average particle size of the waste fine powder is 5 μm;

[0054] Pr 60 Tb 10 Al 20 After the rare earth alloy is smelted, hydrogen crushing without dehydrogenation treatment is performed to obtain rare earth alloy hydride, and then a jet milling process is performed to obtain rare earth alloy hydride fine powder, wherein the average particle size of the rare earth alloy hydride fine powder is 3 μm;

[0055] S2. Mix 95g of waste fine powder and 5g of rare earth alloy hydride fine powder, stir them fully, sieve them, form them in a magnetic field, and sinter them, wherein the sintering temperature is 1060°C and the sintering time is 5h. Then, perform tempering heat treatment, wherein the tempering heat treatment adopts a two-stage tempering heat treatment process, wherein the first stage tempering temperature is 880°C and the tempering time is 2h; the second stage tempering temperature is 540°C and the tempering time is 2.8h, to obtain a regenerated sintered NdFeB permanent magnet.

[0056] The regenerated sintered NdFeB permanent magnet is prepared by the above steps.

[0057] Comparative Example 1

[0058] This comparative example provides a method for preparing a regenerated sintered NdFeB permanent magnet, comprising the following steps:

[0059] S1, subjecting NdFeB permanent magnet waste to mechanical crushing and hydrogen crushing treatment in sequence, and then to a jet milling process to obtain waste fine powder, wherein the average particle size of the waste fine powder is 4.5 μm;

[0060] S2. Fully stir 95g of waste fine powder, sieve, form in a magnetic field, and sinter, wherein the sintering temperature is 1060°C, the sintering time is 4.5h, and tempering heat treatment is performed, wherein the tempering heat treatment adopts a two-stage tempering heat treatment process, wherein the first stage tempering temperature is 850°C, and the tempering time is 1.8h; the second stage tempering temperature is 500°C, and the tempering time is 3h, to obtain a regenerated sintered NdFeB permanent magnet.

[0061] Comparative Example 2

[0062] The only difference from Example 1 is that:

[0063] S1, subjecting NdFeB permanent magnet waste to mechanical crushing and hydrogen crushing treatment in sequence, and then to a jet milling process to obtain waste fine powder, wherein the average particle size of the waste fine powder is 8 μm;

[0064] Tb 70 Cu 30 After the rare earth alloy is smelted, hydrogen crushing without dehydrogenation treatment is performed to obtain rare earth alloy hydride, and then a jet milling process is performed to obtain rare earth alloy hydride fine powder, wherein the average particle size of the rare earth alloy hydride fine powder is 8 μm;

[0065] Comparative Example 3

[0066] The only difference from Example 1 is that:

[0067] S2. Mix 90g of waste fine powder and 10g of rare earth alloy hydride fine powder, stir them fully, sieve them, form them in a magnetic field, and sinter them, wherein the sintering temperature is 1060°C and the sintering time is 4.5h. Then, perform tempering heat treatment, wherein the tempering heat treatment adopts a two-stage tempering heat treatment process, wherein the first stage tempering temperature is 850°C and the tempering time is 1.8h; the second stage tempering temperature is 500°C and the tempering time is 3h, to obtain a regenerated sintered NdFeB permanent magnet.

[0068] Comparative Example 4

[0069] The only difference from Example 1 is that:

[0070] S2. Mix 95g of waste fine powder and 5g of rare earth alloy hydride fine powder, stir them fully, sieve them, form them in a magnetic field, sinter them, wherein the sintering temperature is 1060°C and the sintering time is 4.5h, and perform tempering heat treatment, wherein the tempering temperature is 500°C and the tempering time is 4.8h, to obtain a regenerated sintered NdFeB permanent magnet.

[0071] The performance tests of Examples 1 to 5 and Comparative Examples 1 to 4 were carried out. The residual magnetic induction intensity B was tested at room temperature using a permanent magnetic material measurement system according to the method specified in GB / T 3217-2013. r , intrinsic coercivity H cj And squareness Q, the specific test results are shown in Table 1:

[0072] Table 1

[0073]

[0074] It can be seen from Table 1 that the residual magnetic induction intensity, intrinsic coercive force and squareness of the regenerated sintered NdFeB permanent magnets prepared in Examples 1-5 are higher than those in Comparative Examples 1-4. It can be seen that the preparation method of the regenerated sintered NdFeB permanent magnets provided by the present invention improves the utilization value of NdFeB waste, and prepares regenerated sintered NdFeB permanent magnets with stable performance, high magnetic energy product and high coercive force. The preparation method is simple and suitable for large-scale production.

[0075] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0076] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a regenerated sintered NdFeB permanent magnet, characterized in that: The following steps are involved: S1, crushing the NdFeB permanent magnet waste, and then performing a jet milling process to obtain waste fine powder; smelting the rare earth alloy, performing hydrogen crushing without dehydrogenation treatment to obtain rare earth alloy hydride, and then performing a jet milling process to obtain rare earth alloy hydride fine powder; S2. Mix the waste fine powder and the rare earth alloy hydride fine powder, fully stir, sieve, form in a magnetic field, sinter, and perform tempering heat treatment to obtain a regenerated sintered NdFeB permanent magnet.

2. The method for preparing a regenerated sintered NdFeB permanent magnet according to claim 1, characterized in that: The crushing process in S1 is: mechanical crushing and hydrogen crushing in sequence.

3. The method for preparing a regenerated sintered NdFeB permanent magnet according to claim 1, characterized in that: The average particle size of the waste fine powder in S1 is 4.5-5.5 μm.

4. The method for preparing a regenerated sintered NdFeB permanent magnet according to claim 1, characterized in that: The rare earth alloy is Tb 70 Cu 30 , Pr 52.5 Tb 17.5 Cu 30 , Pr 60 Tb 10 Al 20 , Pr 60 Tb 10 Cu 15 Al 15 At least one of .

5. The method for preparing a regenerated sintered NdFeB permanent magnet according to claim 1, characterized in that: The average particle size of the rare earth alloy hydride fine powder in S1 is 3-5 μm.

6. The method for preparing a regenerated sintered NdFeB permanent magnet according to claim 1, characterized in that: The mass ratio of the waste fine powder and the rare earth alloy hydride fine powder in S2 is (95:5)-(97:3).

7. The method for preparing a regenerated sintered NdFeB permanent magnet according to claim 1, characterized in that: In the sintering treatment in S2, the sintering temperature is 1060-1100°C and the sintering time is 3-8h.

8. The method for preparing a regenerated sintered NdFeB permanent magnet according to claim 1, characterized in that: The tempering heat treatment in S2 adopts a two-stage tempering heat treatment process, wherein the first-stage tempering temperature is 850-900°C, and the tempering time is 1.8-2h; the second-stage tempering temperature is 500-550°C, and the tempering time is 2.5-3h.

9. A regenerated sintered NdFeB permanent magnet, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

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