Do you know what is heavy rare earth NdFeB magnet pure metal non-contact direct infiltration method and heavy rare earth NdFeB permanent alloy contact direct infiltration method?

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Do you know what is heavy rare earth NdFeB magnet pure metal non-contact direct infiltration method and heavy rare earth NdFeB permanent alloy contact direct infiltration method?

Sep 30,2022

Pure metal non-contact direct infiltration method for heavy rare earth NdFeB magnets

In fact, using the principle of vapor pressure and vacuum evaporation technology, pure metal is directly infiltrated into rare earth NdFeB magnets. The evaporation method avoids the difficulty of coating and can increase the thickness of rare earth NdFeB magnets to 7mm, but it brings the following problems:

①The equipment investment is large, and the equipment with a daily output of 300 kg is 6-10 million;

②The evaporated heavy rare earth particles not only accumulate on the surface of the magnet, but also accumulate a lot on the inner wall of the evaporation equipment, which will gradually cause serious contamination to the equipment. The worse it is, the vacuum cannot be achieved even after several years of use; that is why the heavy rare earth utilization rate of the evaporation method is only 80%, and the cost is high.

③ The evaporated heavy rare earth particles can only be upwards (it is a bit like smoked chicken in the image), in order to achieve uniform infiltration on all surfaces of the rare earth NdFeB magnet, the requirements for the placement of the workpiece are very high. If the workpiece is placed If the method is inappropriate, there will be areas that have not penetrated; the contact part between the workpiece and the pallet is blocked by the grid, so the film cannot be formed in this area, which affects the uniformity of the final diffusion layer, and the product still has the hidden danger of poor consistency

Contact direct infiltration method of heavy rare earth NdFeB permanent alloy

In order to solve the problem of material swing in the non-contact evaporation method, the rolling contact type was developed. Direct infiltration into the equipment, the daily output is 500 kg, and the equipment investment is 5 million, which is slightly lower than the evaporation method.

Because the production of dysprosium-iron and terbium-iron alloy particles can be industrialized compared to the pure metal powder for dysprosium-terbium production, the alloy form is selected for the infiltration material. The thickness of the contact type can achieve ≤6mm penetration, but this method will collide with each other because the magnets keep shaking during the production process. To prevent the edge from falling off, the single weight of the magnet is limited. For square rare earth NdFeB permanent magnets It is only suitable for sizes within 36mm×26mm, and the specifications are limited.

At the same time, the infiltration process of the heavy rare earth alloy method requires continuous addition of foil materials. In addition to infiltrating the rare earth NdFeB permanent magnets, some rare earths will be coated on the foil materials. On the other hand, after the repeated use of dysprosium iron and terbium iron alloy In the remaining dysprosium iron or terbium iron, the content of dysprosium or terbium is not uniform, and it is difficult to use, thus causing a great waste of Dy and Tb resources, which is not conducive to the reduction of mass production costs.

Compared with the evaporation method, the contact type has a worse control accuracy for the infiltration amount. In order to ensure the infiltration amount, the interference control is conservatively used for production, which will also lead to fluctuations in the consistency of the remanence.

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