Preparation method of NdFeB magnet with high coercivity

A high coercivity, NdFeB technology, used in magnetic objects, inductor/transformer/magnet manufacturing, magnetic materials, etc. The problem of high activity, etc., can improve the coercivity of the magnet, the manufacturing process is simple, and the fluorine chemical stability is high.

Inactive Publication Date: 2018-01-12
YANTAI ZHENGHAI MAGNETIC MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to achieve a high coercive force improvement effect, it is necessary to repeatedly coat the slurry, which is complicated to operate, and a large amount of Tb or Dy powder adheres to the surface of the magnetic sheet after treatment, which needs to be machined or cleaned to remove it. The process is complicated and causes waste; coating The slurry covering the surface of the magnet is still powdery after drying and is easy to fall off, and the coercive force of the magnet cannot be greatly improved after treatment
The disadvantage of the metal alloy-only method is that it is difficult to coat the surface of the magnet with a large and uniform coat weight of the metal alloy
[0005] In addition, the neodymium in the magnet has high chemical activity, is easily oxidized, and has poor corrosion resistance. In a humid environment, a corrosive micro-battery is formed on the surface of the magnet, which increases the corrosion rate. The existing anti-corrosion ability of the NdFeB surface increases Technologies include electroplating, organic coatings and composite coatings, etc., all working to improve the electrochemical characteristics of magnets
However, the above-mentioned method of improving the coercive force and remanence of NdFeB magnets by using the grain boundary diffusion process of heavy rare earth oxides and fluorides does not play a favorable role in the surface treatment of magnets.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] 1) Preparation of sintered magnets: Nd-23.8%, Pr-5%, Dy-0.6%, Tb -0.4%, Co-0.5%, Cu-0.13%, Ga-0.1%, Al-0.1%, Zr-0.12%, B-1%, the balance is iron and unavoidable impurities, in an inert gas environment The pouring is completed in the vacuum melting furnace under the furnace, the pouring temperature is 1450°C, the speed of the quenching roll is 60r / min, and the cooling water is passed through the quenching roll, and the thickness of the obtained scales is about 0.36mm; then, the scales are made by HD powder milling and jet milling. Magnetic powder with an average particle size of 3.4 μm; Orientation pressing is carried out at room temperature and in an environment with a magnetic field strength of 2T orientation field to make a compact; put the compact into a sintering furnace under an Ar atmosphere, and sinter at 1100°C for 5 hours to obtain a green compact. The green body was aged at 500° C. for 5 hours to obtain a sintered green body. The sintered blank is machined in...

Embodiment 2

[0042] 1) The weight ratio of neodymium, dysprosium, terbium, cobalt, copper, aluminum, boron: Nd-30.1%, Dy-0.5%, Co-0.8%, Cu-0.13%, Al-0.2%, B-1% Ratio, the balance is Fe and unavoidable impurities. The pouring is completed in a vacuum melting furnace under an inert gas environment. The pouring temperature is 1450°C, the speed of the quenching roll is 65r / min, and cooling water is passed through the quenching roll. The thickness of the obtained scales is about 0.32mm; then, the scales are made into magnetic powder with an average particle size of 3.2μm after HD powder milling and jet milling; orientation pressing is carried out at room temperature and an environment with a magnetic field strength of 2T orientation field to make compacts; put the compacts into In a sintering furnace under an Ar atmosphere, sinter at 1060° C. for 6 hours to obtain a green compact, and age the green compact at a temperature of 510° C. for 4 hours to obtain a sintered blank. The sintered blank is...

Embodiment 3

[0056] 1) The weight ratio of neodymium, dysprosium, terbium, cobalt, copper, aluminum, boron: Nd-30.5%, Tb-0.5%, Co-1.1%, Cu-0.16%, Al-0.4%, B-1.02% Ratio, the balance is Fe and unavoidable impurities. The pouring is completed in a vacuum melting furnace under an inert gas environment. The pouring temperature is 1460°C, the speed of the quenching roll is 70r / min, and cooling water is passed through the quenching roll. The thickness of the obtained scales is about 0.3mm; then the scales are made into magnetic powder with an average particle size of 3.0μm through HD powder milling and jet milling; orientation pressing is carried out at room temperature and the magnetic field strength is 2T orientation field, and made into compacts; then aging treatment at 530°C , the aging time is 4.0h, and the sintered blank is obtained. The sintered blank is processed into a magnet with a size of 40mm*20mm*4mm by machining, and after degreasing, pickling, activation, and deionized water washi...

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Abstract

The invention relates to a preparation method of an NdFeB magnet with high coercivity. The method includes the following steps that heavy rare earth powder is mixed with an anti-oxidizing agent, a binder and an organic solvent to prepare uniform slurry, wherein the heavy rare earth powder refers to one or a mixture of Dy, hydrogenated dysprosium, Tb and terbium hydride, the mass ratio of the heavyrare earth powder in the slurry is 40-80%, the mass ratio of the anti-oxidizing agent is 5-20%, the mass ratio of the binder is 2-10% and the balance organic solvent, and the anti-oxidizing agent refers to the anti-oxidizing agent containing fluorine; after the slurry covers the surface of a sintered magnet, the thickness of the slurry is controlled to 20-100 micrometers, and drying is then conducted; the dried magnet is then sintered, and aging treatment is conducted. The method can reduce the use amount of heavy rare earth powder such as Dy and Tb, meanwhile, the requirement of the grain boundary diffusion technology for the size of a product is met, the problem that fluoride and oxide coating powder is easy to fall off is solved, and the manufacturing process is simple.

Description

technical field [0001] The invention relates to a method for preparing an NdFeB magnet, in particular to a method for preparing an NdFeB magnet with high coercive force, and belongs to the technical field of magnet preparation technology. Background technique [0002] Nd-Fe-B magnets are widely used due to their superior performance, especially due to the demand for energy-saving motors in automotive and electronic applications, the market application of sintered NdFeB will be further expanded. The improvement of remanence and coercive force of NdFeB material is conducive to its rapid growth in the motor market, but the improvement of coercive force in the traditional process is always at the expense of remanence, and in order to improve the coercivity must use a larger The specific gravity of the heavy rare earth element Dy / Tb causes a sharp increase in the cost of the magnet. [0003] The method (K.Machida, H.Kawasaki, T.Suzuki, M.Ito and T.Horikawa, "GrainBoundary Tailor...

Claims

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Application Information

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IPC IPC(8): H01F41/02H01F1/057B22F1/00B22F3/10
Inventor 于永江魏蕊刘磊
Owner YANTAI ZHENGHAI MAGNETIC MATERIAL
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