Preparation method of high-corrosion-resistance sintered neodymium-iron-boron magnet

Abstract

The invention discloses a preparation method of a high-corrosion-resistance sintered neodymium-iron-boron magnet, and the methodcomprises the following steps: preparing a neodymium-iron-boron alloy cast sheet containing trace metal, and standing in dry air for 10-30 days to enable a neodymium-rich phase to fully absorb oxygen; performing hydrogen decrepitation, performingcooling to 35 DEG C afterdehydrogenation is finished; stoppingcooling, and standing for 30 to 120 minutes; introducing 20 to 100 ppm of pure oxygen into a hydrogen decrepitation reaction device;when the oxygen content is reduced to 10 ppm or below, performingcooling again, taking out the coarse powder, performing mixing, adding a lubricating agent and an antioxidant, not supplementing oxygen during jet milling, preparingfine powder, performing cold storage treatment on the fine powder, performing orientation forming, increasing the temperature to be less than or equal to 2 DEG C in the forming process, performing 180-300MPa cold isostatic pressing, and finally sintering, aging and tempering to obtain the high-corrosion-resistance neodymium-iron-boron magnet. According to the method, on the premise that the magnetic performance of the magnet is not reduced, the stability and corrosion resistance of the neodymium-rich phase of the sintered neodymium-iron-boron magnet are improved.

Description

technical field [0001] The invention belongs to the technical field of rare earth permanent magnet materials, and in particular relates to a preparation method of a highly corrosion-resistant sintered NdFeB magnet. Background technique [0002] In 1983, Japan's Sumitomo Metal Corporation invented NdFeB permanent magnets for the first time. Because of its high remanence, high coercive force and high magnetic energy product, and good dynamic recovery characteristics, it has been widely used in high-tech industries. Applications. At present, the application of NdFeB permanent magnets has been involved in various fields of the national economy, and has become the core functional material in the fields of electric power, new energy vehicles, and biomedicine. And other fields have achieved very large application breakthroughs. [0003] Although sintered NdFeB has many advantages, but because rare earth elements are very active, the metal activity is second only to alkali metals,...

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Problems solved by technology

[0003] Although sintered NdFeB has many advantages, but because rare earth elements are very active, the activity of metals is second only to alkali metals, so all NdFeB products need to be protected by electroplating or coating. If there is no electroplating or coating, the material Corrosion resistance is very poor, easy to oxidize

[0004] However, although there is electroplating or coating protection, it will inevitably cause certain damage to the electroplating or coating during the installation or use of the motor, and even if the electroplating or coating is not damaged, the electroplating and coating itself There is also a life span and certain pores. If the corrosion resistance of sintered NdFeB magnets cannot be improved, the reliability of motors used in harsh outdoor conditions for 10-20 years is self-evident and difficult to obtain. Assure

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