Neodymium iron boron rare-earth permanent magnet heavy rare-earth thermal diffusion coating liquid and preparation method and application thereof

Abstract

The invention relates to neodymium iron boron rare-earth permanent magnet heavy rare-earth thermal diffusion coating liquid and a preparation method and application thereof, and belongs to the technical field of rare-earth permanent magnet surface treatment. The neodymium iron boron rare-earth permanent magnet heavy rare-earth thermal diffusion coating liquid is prepared from the components: 25-50% of heavy rare-earth powder, 0-5% of a penetration-promoting agent, 2-15% of a binder, 1-3% of a surfactant, 1-3% of a dispersing agent and the balance of a diluent. The preparation method comprisesthe steps of mixing the heavy rare-earth powder, the penetration-prompting agent and the diluent, and adding residual raw materials. The method is applied to a neodymium iron boron rare-earth permanent magnet heavy rare-earth thermal diffusion process, and the process comprises the specific steps that surface cleaning treatment is carried out on the neodymium iron boron rare-earth permanent magnet, surface coating treatment is carried out by centrifugal immersion or spraying, and then thermal expansion is carried out. According to the neodymium iron boron rare-earth permanent magnet heavy rare-earth thermal diffusion coating liquid, the coercive force can be greatly improved after the thermal diffusion, meanwhile, the coating efficiency is improved, the waste of the heavy rare-earth powderis reduced, and a bottleneck of the prior coating art is broken.

Description

technical field [0001] The invention belongs to the technical field of rare earth permanent magnet surface treatment, and in particular relates to a heavy rare earth thermal expansion and infiltration coating liquid for neodymium-iron-boron rare earth permanent magnets and a preparation method and application thereof. Background technique [0002] NdFeB sintered magnets are permanent magnet materials with the highest magnetic properties so far, and are key functional materials in many fields. They have been widely used in industrial automation, energy-saving motors, medical care, electronic information, motors for hybrid vehicles, and wind turbines. and other fields. [0003] The service temperature of NdFeB rare earth permanent magnets is closely related to its coercive force, and high coercive force magnets can be used in relatively high temperature environments. In order to obtain high coercive force, it is necessary to add heavy rare earth elements, such as Dy, Tb, etc....

AI Technical Summary

Problems solved by technology

However, the existing methods have defects. The solid mixing method makes Dy into Dy balls or Dy plates, which are mixed with rare earth permanent magnet sheets, which is expensive; the sputtering method deposits a layer on the surface of rare earth permanent magnet sheets by magnetron sputtering. For heavy rare earth films, it is difficult to remove the film after thermal diffusion, which will affect the subsequent electroplating process and easily cause magnet HAST and other tests to fail; the current mainstream technology of thermal diffusion is the coating method, mainly using DyF 3 , TbF 3 、Dy 2 o 3 Mix the powder with alcohol, and then immerse the magnetic sheet in the mixture to make a layer of powder adhere to the surface of the magnetic sheet. After drying, put it into a heat treatment furnace for thermal expansion and infiltration treatment. However, this method has poor powder adhesion and is easy to fall off during movement. As a result, there is no powder coating on the surface of the magnet, and the coating uniformity is poor. In addition, the powder is very easy to precipitate in alcohol, and it is difficult to obtain a uniform heavy rare earth powder coating layer, which affects the consistency and uniformity of thermal diffusion and penetration. The process lacks stability. Inefficient use leads to increased costs

Therefore, these shortcomings limit the wide application of rare earth permanent magnet thermal diffusion technology. How to obtain an economical, practical and efficient thermal diffusion method has always been a bottleneck problem in this field.

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