NdFeB magnet grain boundary diffusion method

Abstract

The invention belongs to the technical field of neodymium-iron-boron magnets, and particularly discloses a neodymium-iron-boron magnet grain boundary diffusion method which comprises the steps that a neodymium-iron-boron blank is subjected to cleaning and activation pretreatment; sequentially depositing a heavy rare earth element film layer, a non-rare earth element film layer and a high-temperature-resistant inorganic film layer on the surface of the pretreated diffusion substrate; and sequentially carrying out thermal diffusion and tempering treatment on the multi-layer thin film diffusion substrate to obtain the sintered neodymium-iron-boron magnet. The heavy rare earth element-non-rare earth element-heat-resistant inorganic film is deposited on the surface of the magnet through the magnetron sputtering method, then the non-rare earth element permeates into the heavy rare earth element film layer through the thermal diffusion permeation technology, multi-element heavy rare earth alloy is formed, the melting point of a heavy rare earth compound is reduced, the infiltration capacity of the heavy rare earth element is enhanced, and the magnetic hardening layer is formed; non-rare earth elements refine grains, irreversible magnetic loss is reduced, an inorganic film forms a protective layer, element oxidation is avoided, adhesion caused by contact between magnets during grain boundary diffusion is prevented, and the charging amount of a material box is increased.

Description

technical field [0001] The application belongs to the technical field of neodymium iron boron magnets, and in particular relates to a method for diffusing grain boundaries of neodymium iron boron magnets. Background technique [0002] As an important functional material, sintered NdFeB magnets are widely used in new energy vehicles, wind power generation, consumer electronics, medical equipment and aerospace industries. Among them, high coercivity sintered NdFeB magnets are key materials for new energy vehicles and rare earth permanent magnet motors for wind power generation. The traditional method of preparing high-coercivity sintered NdFeB magnets is to add heavy rare earths during the smelting process to form a uniform (Nd, Dy / Tb) 2Fe14B phase and improve the magnetocrystalline anisotropy field. However, due to the reverse coupling of the magnetic moments of the heavy rare earth elements Dy / Tb and Fe atoms, adding a large amount of Dy / Tb will greatly reduce the remanence...

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Problems solved by technology

Its shortcomings are also obvious, mainly because the actual production process can easily lead to the destruction of the surface state of the magnet. During the diffusion process, a large concentration difference is formed in the direct contact part with the heavy rare earth element, and the heavy rare earth element enters the main phase, resulting in residual magnetism. The magnetism is reduced, and the magnets cannot be in direct contact with each other during the heat treatment process. If there is contact, the problem of adhesion will occur. Therefore, it is necessary to add a partition between the magnets or spread high-temperature resistant powder, which takes up a lot of space and leads to a large increase in the amount of material. reduce

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