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A method for improving the coercive force of NdFeB sintered permanent magnets

A permanent magnet and NdFeB technology, which is applied in the manufacture of magnetic objects, magnetic materials, inductors/transformers/magnets, etc., can solve the problems of difficult control of coating thickness, easy volatilization, difficult modulation, etc., and achieve precise control consistency, Strong antioxidant capacity and good binding effect

Active Publication Date: 2021-08-06
YANTAI DONGXING MAGNETIC MATERIALS INC
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this method has the following problems: 1. Since the organic solvent is volatile, the ratio of rare earth in the suspension will continue to change, causing the coating thickness to be difficult to control; Uncontrollable factors such as powder reaction; 3. Composite metal coatings generally require at least two coating processes, and double-layer coatings lead to worse bonding, falling off, and frequent inconsistencies; 4. The coating curing process is easy to oxidize and fall off , leading to insufficient diffusion; 5. The mixed metal powder is easy to precipitate and agglomerate, resulting in stratification of the coating solution and cannot be stored for a long time
[0006] Chinese patents CN107578912A, CN104112580A, CN107026003A, CN107492430A, and CN105761861A propose to coat the suspension made of alcohols, gasoline, paint, etc. on the surface of the magnet, and then carry out diffusion treatment. Mass production is extremely difficult due to poor controllability
In the Chinese patent CN107578912A, a binder can be added, but the composition is complicated, the controllability is poor, and it is easy to be volatile.
In Chinese patent CN109390145A, in order to prevent oxidation of the heavy rare earth coating, the surface layer is coated with an inorganic coating, which increases the production process and increases the cost
Chinese patent CN108039259 A deposits three layers of metal layers by vapor phase, including metal coating, heavy rare earth layer or heavy rare earth alloy layer and non-rare earth metal layer or non-rare earth alloy layer. This method has complicated process, many parameter controls and high cost.

Method used

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  • A method for improving the coercive force of NdFeB sintered permanent magnets
  • A method for improving the coercive force of NdFeB sintered permanent magnets
  • A method for improving the coercive force of NdFeB sintered permanent magnets

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Experimental program
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Effect test

Embodiment 1

[0043] see Figure 1-3 , take a mixed slurry with a density of 4.1g / cm3, the powder used for the large particle 2 is PrAl powder with a particle size of 6 μm, and the powder used for the small particle 3 is Dy powder with a particle size of 3 μm.

[0044] Coat the 20*20*5T NdFeB sintered permanent magnet with a viscous liquid film layer, and ensure that the surface perpendicular to the magnetization direction is in close contact with the viscous liquid film layer, the thickness is about 30 μm, and the vertical vibration frequency is 35HZ After vibrating for 1 minute, dry at 120°C to form a composite film layer. The surface of the NdFeB sintered permanent magnet is a metal film layer, and the metal film layer is a heavy rare earth film layer. On the other side of the NdFeB sintered permanent magnet 5 The surface perpendicular to the magnetization direction is also covered with a layer of viscous liquid film with a thickness of about 30 μm, a vertical vibration frequency of 35 H...

Embodiment 2

[0051] Get density is 3.5g / cm3, the powder that big particle 2 adopts is NdCu powder, and particle size is 8 μm, and the powder that small particle 3 adopts is TbCu, and the slurry that particle size is made of 2 μm;

[0052] Coat a 20*20*3T NdFeB sintered permanent magnet with a viscous liquid film layer, and ensure that the surface perpendicular to the magnetization direction is in close contact with the viscous liquid film layer, with a thickness of about 26 μm and a vertical vibration frequency of 35HZ. After 1 minute, carry out UV drying. On the other surface of the NdFeB sintered permanent magnet 5 perpendicular to the magnetization direction, a layer of viscous liquid film layer is also covered. The vertical vibration frequency is 35HZ. After 1 minute of vibration, UV drying is carried out. The thickness is about 26 μm.

[0053] Send the NdFeB sintered permanent magnet covered with the composite film diffusion source into the sintering furnace for 880°C*30h diffusion tr...

Embodiment 3

[0059] Get density is 4.5g / cm3, the powder that big particle 2 adopts is LaCu alloy powder, particle size is 20 μ m, the powder DyAlCu that small particle 3 adopts, particle size 1 μ m make slurry;

[0060] Coat a 20*20*6T NdFeB sintered permanent magnet with a viscous liquid film layer, and ensure that the surface perpendicular to the magnetization direction is in close contact with the viscous liquid film layer, with a thickness of about 40 μm and a vertical vibration frequency of 20HZ. After 80 seconds, carry out UV drying. On the surface of the other perpendicular magnetization direction of the NdFeB sintered permanent magnet 5, a layer of viscous liquid film layer is also covered, the thickness is about 40 μm, and the vertical vibration frequency is 20HZ. After 80 seconds of vibration Perform UV drying.

[0061] Send the NdFeB sintered permanent magnet covered with the composite film diffusion source into the sintering furnace for 850℃*48h diffusion treatment, then cool t...

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Abstract

The invention discloses a method for improving the coercive force of a sintered NdFeB permanent magnet. A viscous liquid film layer is coated on the surface of the sintered NdFeB permanent magnet. The film layer contains large particles formed by metal particles or metal alloy particles. , small particles formed by heavy rare earth alloy particles or heavy rare earth particles or non-metallic particles, through the osmotic pressure gradient in the evaporation process of the static viscous liquid film or through the vertical vibration of the viscous liquid film, the surface of the sintered NdFeB permanent magnet is separated The layer forms a large particle layer and a small particle layer, and forms a composite film layer of particles covering a layered structure by low-temperature curing or UV curing. Then, the large particles are opened to the grain boundary by low-temperature diffusion, and the small particles enter the grain boundary or stay on the surface of the magnet through high-temperature heat treatment. Forming an anti-corrosion layer followed by aging treatment can effectively improve the coercive force of NdFeB. The invention has good oxidation resistance, can be stored in an oxygen environment for 336 hours, has a binding force as high as 15MPa, greatly improves magnetic properties, has good magnet consistency, reduces production procedures, improves material utilization, and reduces costs.

Description

technical field [0001] The invention belongs to the technical field of NdFeB magnets, and in particular relates to a method for improving the coercive force of NdFeB sintered permanent magnets. Background technique [0002] NdFeB sintered permanent magnet, known as "Magnetic King", has been widely used by people since its birth, and has been deeply rooted in modern society. It is widely used in high-tech fields such as electronic information, medical equipment, new energy vehicles, household appliances, and robots. With the rapid development of informatization and industrialization, high-performance magnets have become a current research hotspot. [0003] In 2005, Nakamura reported a simple and rapid method of increasing the coercive force by using heavy rare earth oxide and fluoride powders, that is, "grain boundary diffusion technology". With the development of diffusion technology, two diffusion mechanisms are formed, that is, through the diffusion hardening of Nd2Fe14B...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F41/02
CPCH01F41/0293H01F41/0253H01F1/0577
Inventor 王传申杨昆昆彭众杰贾道宁丁开鸿
Owner YANTAI DONGXING MAGNETIC MATERIALS INC