A kind of NdFeB permanent magnet material and its preparation method and magnetic field assisted direct casting device

Abstract

The invention discloses a neodymium-iron-boron permanent magnet material, a preparation method and a magnetic field auxiliary direct casting device. A main magnet of the device is a circular-ring-shaped magnet which is magnetized in a radial mode. A first disc-shaped repulsion magnet with the magnetic field direction being axially upward is arranged below the center of the main magnet, and a second disc-shaped repulsion magnet which is magnetized in a radial mode is arranged on the periphery of the first repulsion magnet. A regulating magnet is arranged at the upper end of the main magnet, second soft iron is arranged on the upper portion of the regulating magnet, first soft iron is arranged outside the regulating magnet, and a circular-ring-shaped magnet guide magnet which is magnetized downwards in the axial direction is arranged outside the main magnet. The chemical general formula of the neodymium-iron-boron permanent magnet material is [Nd (85-x-y) CoxFeyAlzB (15-z)] (100-a) Ma, wherein in the formula, x+y is larger than or equal to 30 and smaller than or equal to 70, z is larger than or equal to 0 and smaller than or equal to 10, and a is smaller than and equal to 4. Compared with a material prepared without adding magnetic fields, the performance of the neodymium-iron-boron permanent magnet material is greatly improved, the preparation process is simple, cost is low, products are dense, and the neodymium-iron-boron permanent magnet material is suitable for industrial production.

Description

technical field [0001] The invention relates to an NdFeB magnetic field assisted direct casting device, in particular to a preparation method for directly casting NdFeB under the auxiliary magnetic field system. Background technique [0002] Neodymium-iron-boron (NdFeB)-based alloys (including rare earth-iron / cobalt-boron alloys of different compositions), as rare earth permanent magnet materials with the best comprehensive magnetic properties at room temperature, are widely used in various electromechanical products, and their market value is close to that of permanent magnets. One-half of magnetic materials and rising year by year. At present, the preparation of NdFeB magnets mainly adopts powder metallurgy route. Firstly, magnetic powder is obtained by different methods, and then sintered magnets, bonded magnets and thermally deformed magnets are obtained by sintering, bonding or thermal deformation (die forging). The preparation process of magnets is complicated and the...

AI Technical Summary

Problems solved by technology

[0004] However, due to the difference in the cooling rate between the core and the surface of the casting during the casting process, the outer surface of the copper mold that first contacts the copper mold has a faster cooling rate, and the greater degree of undercooling makes it skip the crystallization process and obtain an amorphous phase or grain Smaller nanocrystals, while in the core of the casting, due to the existence of the temperature gradient, the cooling rate is much lower than that of the surface, and the grains are easy to nucleate and grow

This leads to uneven overall structure of the casting, which has a great impact on the improvement of the comprehensive magnetic properties of the magnet and the design of subsequent heat treatment, and limits the application of the copper mold casting method in actual production.

Images