A method for improving the magnetic properties of sintered NdFeB permanent magnets

Abstract

Provided is a method for improving the magnetic performance of a sintered neodymium-iron-boron permanent magnet. According to the method, a sintered magnet undergoes inductive eddy current heating to turn a neodymium-rich phase thereof into a liquid phase, thus on the one hand, under the effect of an induced electromagnetic field, the flow of the neodymium-rich liquid phase can be intensified through electromagnetic stirring of induced eddy currents, so as to optimize the microstructure of the magnet; and on the other hand, main phase grains are more prone to rotate along the magnetic field direction of an induction coil, further increasing the degree of orientation of the magnet. Experiments prove that the coercive force of the sintered neodymium-iron-boron permanent magnet is somewhat improved, so does the squareness thereof. And meanwhile, both the remanence and the maximum magnetic energy product of the permanent magnet are also boosted. In addition, the method has the advantages of cleanliness without any pollution, high energy efficiency, great simplicity and practicability and so forth, and accordingly is highly promising in application.

Description

technical field [0001] The invention relates to the technical field of NdFeB permanent magnets, and relates to a method for improving the magnetic properties of sintered NdFeB permanent magnets. Background technique [0002] Rare earth permanent magnet materials, as a functional material with important influence, have been widely used in energy, transportation, communication, machinery, medical, computer, home appliances, and national defense technology and other fields, and have penetrated into all aspects of the national economy and people's livelihood. The dosage has become one of the important symbols to measure the country's comprehensive national strength and the level of national economic development. At present, my country has become the world's largest production base of rare earth permanent magnets, and it is also an important application market. [0003] In the 1980s, the intermetallic compound Nd 2 Fe 14 The third generation of permanent magnet materials based...

AI Technical Summary

Problems solved by technology

However, there are two problems with this method: (1) the addition of heavy rare earths will reduce the remanence of permanent magnets; (2) the resources of heavy rare earths are scarce and the production cost is high

However, after the existing heat treatment technology, there are still problems such as sharp corners and defects in the main phase grains in the magnet, and the Nd-rich phase thin layer wrapped outside the main phase grains is not uniform and continuous, resulting in the failure of the Nd-rich phase to form. Very good magnetic isolation, so the magnet coercive force is low

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