Method for preparing bulk sintered Nd-Fe-B permanent magnet material

Abstract

The invention discloses a method for preparing a bulk sintered Nd-Fe-B permanent magnet material. The method comprises the following steps of: preparing fine powder with the average particle size of 2.9 to 3.3 micrometers from raw materials which are prepared according to a required formula; adding the fine powder into a metal die cavity of a molding pressing machine; and arranging a molding magnetic field to ensure that the fine powder is prepared into a patch raw blank in a compression molding way under an electromagnetic induction oriented magnetic field. The method is characterized by comprising the following steps of: selecting at least two patch raw blanks; selecting the joint surfaces of the patch raw blanks on the premise of ensuring the consistent orientation of all patch raw blanks; clearing Nd-Fe-B attached powder on the joint surfaces of all the patch raw blanks; performing butt joint on all the patch raw blanks; putting the butt-jointed raw blanks into a die box made of rubber; performing vacuum encapsulation on the die box; keeping the pressure of an encapsulation body under the isostatic pressure of 180 to 220MPa for 8 to 13 seconds; taking the butt-jointed raw blank combination body out; transferring into a sintering basin; and sintering in a vacuum furnace to form a compact bulk Nd-Fe-B blank body. The invention has the advantages that: the bulk sintered Nd-Fe-B permanent magnet material can be produced by the conventional universal equipment, and has high precision, stable magnetic performance and low preparation cost.

Description

technical field [0001] The invention relates to a preparation method of a sintered NdFeB permanent magnet material, in particular to a preparation method of a bulk sintered NdFeB permanent magnet material. Background technique [0002] Sintered NdFeB permanent magnet material is currently the strongest magnetic material, widely used in electromagnetics, electroacoustics, magnetism, nuclear magnetism and electron accelerated luminescence and other disciplines, such as various motors, speakers, magnetic coupling devices, medical camera equipment and free electron oscillators and other instruments and devices. [0003] Usually to make sintered NdFeB, the raw materials are melted and cast into ingots or quick-setting tablets in a vacuum electromagnetic induction furnace, and then the ingots are mechanically crushed or the quick-setting tablets are hydrogen-crushed to make coarse powder, and the coarse powder is accelerated by high-pressure gas and interacted with each other. co...

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is to overcome the disadvantages of poor dimensional accuracy, easy dislocation and high cost in the production of large sintered NdFeB permanent magnet materials by viscose process in the prior art, and provide a kind of high dimensional accuracy, stable process and high performance. Method for preparing consistent bulk sintered NdFeB permanent magnet materials

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