A kind of preparation method of high corrosion resistance sintered NdFeB magnet

Abstract

The invention discloses a preparation method of a highly corrosion-resistant sintered NdFeB magnet, which comprises the following steps: preparing a NdFeB alloy cast piece containing a trace amount of metal, and placing it in dry air for 10-30 days to make the NdFeB-rich phase Fully absorb oxygen; then perform hydrogen crushing, cool to 35°C after dehydrogenation, turn off the cooling, and let it stand for 30-120 minutes, introduce 20-100ppm pure oxygen into the hydrogen crushing reaction device, and wait until the oxygen content is reduced to 10ppm When the time is below, cool again, take out the coarse powder and mix it, add lubricant and antioxidant at the same time, do not supplement oxygen during jet milling, and make fine powder, which is oriented and formed after refrigerated treatment, and the temperature rise in the forming process is ≤ 2 ° C 180‑300MPa cold isostatic pressing, final sintering, aging and tempering to obtain high corrosion resistance NdFeB magnets. The method of the invention improves the stability and corrosion resistance of the neodymium-rich phase of the sintered NdFeB magnet without causing the magnetic performance of the magnet to decline.

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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