High-performance sintered neodymium-iron-boron magnet and preparation method thereof

Abstract

The invention discloses a preparation method of a high-performance sintered neodymium-iron-boron magnet. The method comprises the following steps: respectively smelting a main phase alloy and a grainboundary phase alloy, respectively pulverizing, mixing, molding, carrying out grain boundary diffusion, sintering, and carrying out tempering heat treatment to finally obtain the sintered neodymium-iron-boron magnet. Heavy rare earth Dy or Tb, corrosion-resistant metals Co, Cu, Al and Zn and carbon nanotubes with excellent strength and flexibility are added during grain boundary phase alloy smelting, the added heavy rare earth Dy or Tb can improve the coercive force of the magnet, the added corrosion-resistant metals Co, Cu, Al and Zn can improve the potential of a grain boundary phase and reduce the chemical activity of the grain boundary phase, and the added high-melting-point carbon nanotubes do not change the nano form when the grain boundary phase is smelted, so that the mechanical property of the magnet is improved. Therefore, according to the sintered neodymium-iron-boron magnet prepared by the method, the corrosion resistance and the toughness of the magnet are remarkably improved on the basis of ensuring relatively high magnetic performance.

Description

technical field [0001] The invention belongs to the field of rare earth permanent magnet materials, and in particular relates to a high-performance sintered NdFeB magnet and a preparation method thereof. Background technique [0002] As an important basic magnetic functional material, permanent magnet materials have a wide range of applications, covering almost all industrial sectors, living areas, science and technology, aerospace and military, etc. Among them, sintered NdFeB magnets occupy "half of the country" of permanent magnet materials due to their excellent magnetic properties and higher cost performance, and are known as the contemporary "Magnetic King". The sintered NdFeB magnet prepared by powder metallurgy has a multi-phase structure, and the potential difference between the phases is relatively large, especially the electrochemical activity of the grain boundary phase is the highest, and it is easy to corrode in an electrochemical environment. As the anode, the...

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Problems solved by technology

The sintered NdFeB magnet prepared by powder metallurgy has a multi-phase structure, and the potential difference between the phases is relatively large, especially the electrochemical activity of the grain boundary phase is the highest, and it is easy to corrode in an electrochemical environment. As the anode, the grain boundary phase bears a large amount of corrosion current, which accelerates the corrosion of the grain boundary phase of the magnet, and causes the powdering phenomenon between the main phase grains due to the loss of adhesion, which seriously affects the chemical stability of the magnet.

[0003] In addition, as a brittle material, sintered NdFeB magnets have poor mechanical properties

Poor strength and toughness make the magnet prone to defects such as slag, missing corners, and cracks during machining

Greatly reduces the yield and processing accuracy of magnets, increases the processing cost of magnets, and limits the application of magnets in the field of high-precision instruments and meters

At the same time, the poor strength and toughness of sintered NdFeB magnets leads to poor shock resistance and impact resistance, which limits the application of magnets in occasions that require high shock resistance and shock resistance, such as high-speed motors and aviation instruments.

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