Preparation method of high-performance NdFeB magnet

Abstract

The invention discloses a preparation method of a high-performance NdFeB magnet. The preparation method comprises the following steps of 1) performing vacuum melting on an NdFeB alloy raw material with a positive ratio being 2:14:1 to obtain NdFeB alloy ingot; 2) performing powder processing on the ingot obtained in the step 1) to obtain NdFeB alloy powder; 3) performing magnetic-field orientationpressing on the NdFeB alloy powder obtained in the step 2), and performing isostatic cool pressing to obtain a press blank; 4) pre-sintering the press blank obtained in the step 3) to obtain a sintered blank with compactness being 80-90%; 5) preparing a fused salt from a dysprosium or terbium compound and 1-methyl-3-ehtyl imidazoline onium chloride (MEIC), taking the fused salt as a plating liquid, and performing electroplating by taking the sintered blank obtained in the step 4) as a negative electrode and dysprosium or terbium metal as a positive electrode so that a dysprosium or terbium metal atomic layer is attached onto the sintered blank; and 6) sintering the sintered blank in the step 5) again after electroplating, and performing tempering and thermal processing to obtain a final Dy / Tb permeated magnet. The magnet has the advantages of a few amount of Dy / Tb, high Dy-permeated and Tb-permeated efficiency and short production time.

Description

technical field [0001] The invention relates to the technical field of rare earth permanent magnet materials, more specifically, it relates to a preparation method of a high-performance NdFeB magnet. Background technique [0002] In 1983, on the basis of extensive research on RE-Fe-X ternary alloys, Sagawa Masato and others in Japan prepared a magnetic energy product as high as 290kJ / m by powder metallurgy. 3 The advanced neodymium iron boron (Nd-Fe-B) sintered magnets created the third generation of rare earth permanent magnet materials. Sintered Nd-Fe-B is widely used in military equipment, electroacoustic devices, motors, generators, computer hard disk drives (HDD), voice coil motors (VCM), human magnetic resonance imaging (MRI), microwave communication technology, controllers , instruments, magnetic separation equipment, magnetic chucks and other devices and equipment that require permanent magnetic fields. [0003] Sintered NdFeB magnets are based on Nd 2 Fe 14 Comp...

AI Technical Summary

Problems solved by technology

Although the coercive force has been improved to a certain extent, there is still a big gap compared with its theoretical value of 5600kA / m. The level that can be achieved at present is about 1 / 10 of its theoretical value of coercive force. 1 / 3

This greatly limits the application of NdFeB magnets in high working temperature environments

[0004] In order to solve this problem, scientific workers have engaged in a lot of research. Studies have shown that infiltrating Dy or Tb in NdFeB magnets can improve the coercive force of the magnets. The existing technical means mainly include heavy rare earth alloying or Nd replacement. Dy / Tb oxide / fluoride, but there are more or less problems in these technologies. For example, due to the diamagnetic coupling between heavy rare earth atoms and iron atoms in the former, the remanence and maximum energy product of the magnet will be greatly reduced. The Nd on the grain edge of the main phase directly replaces the oxide or fluoride of Dy or Tb, and the replacement speed is very slow, so that the efficiency of Dy and Tb infiltration is very low, and the production time is long

And the amount of dysprosium / terbium used in the above method is large and the cost is high