CN-116092810-B - Agglomeration-avoiding anisotropic sintered magnetic powder, preparation method thereof and magnet containing same

Abstract

The invention relates to the technical field of magnetic materials, in particular to agglomeration-avoiding anisotropic sintered magnetic powder, a preparation method thereof and a magnet containing the same, wherein the agglomeration-avoiding anisotropic sintered magnetic powder consists of UiO-66 and SmFeN, the preparation method is to take high-purity samarium blocks and iron blocks as raw materials, alloy and crush the high-purity samarium blocks into powder, nitriding, mixing and ball milling, wherein the magnet comprises the anisotropic sintered magnetic powder capable of avoiding caking, is obtained through hole breaking, embryo making and sintering, the UiO-66 in the anisotropic sintered magnetic powder for avoiding agglomeration can absorb moisture, prevent liquid phase bridges from forming between the magnetic powder, and further avoid agglomeration between the magnetic powder.

Inventors

• ZHANG PENGJIE
• SUN WEI
• CAO YUJIE
• WANG JIQUAN

Assignees

• 北矿磁材（阜阳）有限公司

Dates

Publication Date

20260508

Application Date

20221210

Claims (10)

1. 1. The preparation method of the anisotropic sintered magnetic powder capable of avoiding caking is characterized by comprising the following steps of: alloying, namely repeatedly smelting samarium blocks and iron blocks serving as raw materials in a vacuum arc smelting furnace for 4-6 times to prepare alloy blocks, and then performing heat treatment on the alloy blocks for 10-16 hours at 1000-1100 ℃ to obtain Sm 2 Fe 17 alloy; Crushing into powder, namely carrying out melt rapid quenching and melt spinning on Sm 2 Fe 17 alloy under the protection of argon, wherein the melt spinning speed is 15-25m/s, obtaining Sm 2 Fe 17 strip, then carrying out ball milling and crushing on Sm 2 Fe 17 strip into powder by a stainless steel ball mill, carrying out ball milling for 4-6h at 150-180r/min, and obtaining Sm 2 Fe 17 powder with a ball material ratio of 1:4-6; (3) Nitriding, namely placing Sm 2 Fe 17 powder into a tube furnace for nitriding to obtain SmFeN powder; (4) Mixing and ball milling, namely adding UiO-66 and SmFeN powder into a stainless steel ball mill, and ball milling for 1-3 hours at the speed of 200-240r/min, wherein the ball-to-material ratio is 1:4-6, so as to obtain the anisotropic sintered magnetic powder avoiding caking.
2. 2. The method for preparing agglomeration-free anisotropic sintered magnetic powder according to claim 1, wherein the purity of samarium and iron in the step (1) is 99.9% or more, and the atomic ratio of Sm to Fe is 2.2-2.5:17.
3. 3. The method for preparing anisotropic sintered magnetic powder for preventing agglomeration according to claim 1, wherein the operating current of the vacuum arc melting furnace in the step (1) is 130-150A, and the operating atmosphere is argon.
4. 4. A method for preparing a bonded sintered magnetic powder of anisotropic property avoiding agglomeration according to claim 1, wherein the nitriding condition in the step (3) is calcination at 490-550 ℃ for 5-8 hours in nitrogen atmosphere.
5. 5. A method for producing a lump avoidance anisotropic sintered magnetic powder as claimed in claim 1, wherein the UiO-66 in the step (4) has an average particle diameter of 50 to 100nm and an average pore diameter of 0.8 to 1nm.
6. 6. A method for preparing agglomeration-free anisotropic sintered magnetic powder according to claim 1, wherein the mass ratio of SmFeN to UiO-66 in step (4) is 10:1-3.
7. 7. A caking-avoiding anisotropic sintered magnetic powder, characterized in that the caking-avoiding anisotropic sintered magnetic powder is prepared by the preparation method according to any one of claims 1 to 6.
8. 8. A magnet comprising the agglomeration-avoiding anisotropic sintered magnetic powder of claim 7.
9. 9. A magnet according to claim 8, wherein the magnet is prepared by the following method: (1) Hole breaking, namely adding the agglomeration-avoiding anisotropic sintered magnetic powder in the N, N-dimethylformamide, breaking holes, filtering the obtained mixture under vacuum, and drying to obtain the anisotropic sintered magnetic powder; (2) Embryo preparation, namely carrying out oriented profiling on the hole-breaking anisotropic sintered magnetic powder to obtain an embryo body; (3) And (3) sintering, namely sequentially performing primary sintering and secondary sintering on the blank body obtained in the step (2) in an argon atmosphere, and finally obtaining the magnet.
10. 10. The magnet according to claim 9, wherein the mass ratio of the anisotropic sintered magnetic powder to the N, N-dimethylformamide which are prevented from caking in the step (1) is 10:50-80, the condition of pore breaking in the step (1) is that the pore breaking is performed at 150-155 ℃ for 24-36 hours, the orientation pressing in the step (2) is performed in a magnetic field with a magnetic field strength of 1.5-2T, the condition of primary sintering in the step (3) is that the sintering is performed at 300-400 ℃ for 2-4 hours, and the condition of secondary sintering is that the sintering is performed at 400-600 ℃ for 1-3 hours.

Description

Agglomeration-avoiding anisotropic sintered magnetic powder, preparation method thereof and magnet containing same Technical Field The invention relates to the technical field of magnetic materials, in particular to a pressed sintered magnetic powder capable of avoiding caking, a preparation method thereof and a magnet containing the pressed sintered magnetic powder. Background Permanent magnetic materials are key materials required for the healthy and steady development of various high and new technical fields at present. The existing NdFeB rare earth permanent magnet material has high magnetic performance, but the NdFeB rare earth permanent magnet material consumes a large amount of Nd, pr, dy, tb and other rare earth elements, so that the use of rare earth strategic elements is unbalanced, and even the waste of the rare earth elements is caused. Therefore, research on developing rare earth permanent magnet materials with low rare earth or high abundance is a research hotspot in the field of rare earth permanent magnet materials. The pressed sintered SmFeN permanent magnetic material has the advantages of high Curie temperature, high cost performance, high magnetocrystalline anisotropy and corrosion resistance, and has been widely paid attention for a long time. The pressed sintered SmFeN permanent magnetic material is obtained by performing embryo preparation and sintering on magnetic powder, however, the embryo is cracked due to agglomeration of the magnetic powder, the molding qualification rate is low, and the orientation degree of the magnetic powder is poor. Eventually leading to poor mechanical and magnetic properties of the sintered body. Agglomeration is a phenomenon commonly existing in anisotropic sintered magnetic powder, large-area agglomeration can affect orientation compression in the preparation process of the anisotropic sintered magnetic powder, larger air holes are reserved in a ligand after compression due to irregularity of the agglomerated magnetic powder, the agglomerated magnetic powder can affect sintering behavior of the magnetic powder, the sintering degree of the magnetic powder in the agglomerated magnetic powder is higher than that between the agglomerated magnetic powder, the required sintering temperature is increased, overburning is extremely easy to cause, crystal grains are excessively increased, so that a required nano crystal grain structure is damaged, a nano magnetic body is difficult to obtain, and the agglomeration is mainly caused by the fact that moisture in the anisotropic sintered magnetic powder tightly adheres magnetic powder particles together through a liquid phase bridge under the action of hydrogen bonds. UiO-66 is used as a three-dimensional porous zirconium-based MOF, and is composed of a1, 4-phthalic acid connector and a cationic Zr 6O4 (OH)4 node, has octahedron and tetrahedron cavities, and has the advantages of excellent heat stability, water stability, acid stability, easiness in synthesis and the like, so that great attention is paid to the advantages of excellent heat stability, easiness in synthesis and the like, and due to capillary benefits, the porous pore channels of the UiO-66 have an adsorption effect on water in the environment. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a anisotropic sintered magnetic powder capable of avoiding caking, a preparation method thereof and a magnet containing the anisotropic sintered magnetic powder, and aims to solve the problem of caking of the magnetic powder in the process of preparing the anisotropic sintered magnetic powder. In order to solve the problems, the technical scheme of the invention is as follows: In a first aspect, the invention provides a method for preparing anisotropic sintered magnetic powder without caking, which comprises the following specific steps: And alloying, namely repeatedly smelting the samarium blocks and the iron blocks serving as raw materials in a vacuum arc smelting furnace for 4-6 times to prepare alloy blocks, and then carrying out heat treatment on the alloy blocks to obtain the Sm 2Fe17 alloy. Crushing into powder, namely carrying out melt rapid quenching and melt spinning on Sm 2Fe17 alloy under the protection of argon to obtain Sm 2Fe17 strip, and then carrying out ball milling and crushing on the Sm2Fe17 strip into powder by using a stainless steel ball mill to obtain Sm 2Fe17 powder. Nitriding, namely placing Sm 2Fe17 powder into a tube furnace for nitriding to obtain SmFeN powder. Mixing and ball milling, namely adding UiO-66 and SmFeN powder into a stainless steel ball mill for ball milling to obtain the anisotropic sintered magnetic powder without caking. Preferably, the purity of the samarium blocks and the iron blocks in the step (1) is more than 99.9%, and the atomic ratio of Sm to Fe is 2.2-2.5:17. Preferably, the working current of the vacuum arc melting furnace in the step (1) is 130-150A, and the working atmosp