Core-shell structure NdFeB magnetic powder high in electrical resistivity and magnetic performance and application

A high-resistivity, core-shell structure technology, applied to magnetic materials, magnetic objects, circuits, etc., can solve the problems of low performance and low resistivity of high-resistivity magnets, achieve stable magnetic properties, improve corrosion resistance, Effect of reducing eddy current loss

Active Publication Date: 2015-10-07
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The object of the present invention is to overcome the deficiency that the resistivity of common NdFeB magnets is not high at present, and the performance of hig

Method used

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  • Core-shell structure NdFeB magnetic powder high in electrical resistivity and magnetic performance and application
  • Core-shell structure NdFeB magnetic powder high in electrical resistivity and magnetic performance and application

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Put the above-mentioned magnetic powder into a tube furnace, firstly evacuate the tube furnace, then feed ammonia gas with a flow rate of 100mL / min, with 10 o C / min heating rate to 300 o C and keep warm for 5 minutes, then cool with the furnace, continue to feed ammonia gas during heat preservation and cool with the furnace, wait until the temperature drops to room temperature, take out the magnetic powder for XRD test, and then prepare it by sintering, bonding or hot pressing magnet. When preparing magnets by bonding, select high-purity epoxy resin as the binder, silane as the coupling agent, and polyamide as the curing agent as the mixed polymer, and then mix the magnetic powder with the above polymer into alcohol , and then stir it with a mixer for 1h, the stirring speed of the mixer is 300~1500r / min, take it out and wait for it to dry and put it under 80 o The temperature field and the magnetic field are formed under the orientation field of 2T, and the molding pr...

Embodiment 2

[0018] Put the above-mentioned magnetic powder into a tube furnace, firstly evacuate the tube furnace, then feed ammonia gas with a flow rate of 100mL / min, with 10 o C / min heating rate to 300 o C and keep it warm for 10 minutes, then cool it with the furnace, continue to feed ammonia gas during the heat preservation and cooling with the furnace, wait for the temperature to drop to room temperature, take out the magnetic powder for XRD test. like figure 2 As shown, the overall XRD peak after chemical heat treatment shifted to the left, indicating that the crystal lattice expanded, which was due to the expansion of the lattice due to nitrogen atoms as interstitial atoms. It is then sintered, bonded and hot pressed to make a magnet. When preparing magnets by bonding, select high-purity epoxy resin as the binder, silane as the coupling agent, and polyamide as the curing agent as the mixed polymer, and then mix the magnetic powder with the above polymer into alcohol , and then ...

Embodiment 3

[0020] Put the above-mentioned magnetic powder into a tube furnace, firstly evacuate the tube furnace, then feed ammonia gas with a flow rate of 100mL / min, with 10 o C / min heating rate to 300 o C and keep it warm for 30min, then cool with the furnace, continue to feed ammonia gas during the heat preservation and cool with the furnace, wait until the temperature drops to room temperature, take out the magnetic powder for XRD test, and then prepare it by sintering, bonding and hot pressing magnet. When preparing magnets by bonding, select high-purity epoxy resin as the binder, silane as the coupling agent, and polyamide as the curing agent as the mixed polymer, and then mix the magnetic powder with the above polymer into alcohol , and then stir it with a mixer for 1h, the stirring speed of the mixer is 300~1500r / min, take it out and wait for it to dry and put it under 80 o C The temperature field and the magnetic field are formed under the orientation field of 2T, and the mold...

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Abstract

The invention discloses core-shell structure NdFeB magnetic powder high in electrical resistivity and magnetic performance. Firstly, a prepared raw material is subjected to induction melting to form Nd2Fe14B strip-casting flakes, wherein the average thickness of the strip-casting flakes is 0.1-0.5 mm; the strip-casting flakes are subjected to formed hydrogen decrepitation, and coarsely crushed magnetic powder is obtained after dehydrogenation; secondly, air flow grinding is performed under the inert gas protection atmosphere to obtain magnetic powder with approximate particle size of 1-6 micron; finally, the magnetic powder is put into a tube furnace, ammonia gas is led into the tube furnace at the flowing speed of 50-300 mL/min, the magnetic powder is heated to be at the temperature of 300-400 DEG C, is subjected to heat preservation for 5-30 minutes and then is cooled with cooling of the furnace, and the core-shell structure NdFeB magnetic powder can be obtained by continuously leading the ammonia gas during heat preservation and cooling performed with cooling of the furnace. Due to the insulation effect of a nitration layer, the core-shell structure NdFeB magnetic powder has the advantages of being high in electrical resistivity, high in corrosion resistance, good in demagnetizing-coupling effect, high in magnetic performance, controllable in nitration layer thickness, even in nitration layer coating and the like.

Description

technical field [0001] The invention belongs to the technical field of magnetic material preparation, and in particular relates to a preparation method of high-resistivity core-shell structure NdFeB magnetic powder. Background technique [0002] NdFeB magnets are currently widely used in traditional motors, medical equipment, high-speed rail, magnetic disks, and intelligent high-tech equipment. However, in some high-frequency alternating electromagnetic field environments and high-speed motors, NdFeB magnets will produce obvious eddy current losses, resulting in abnormal temperature rises, which will reduce the performance of the magnets or even lose their magnetism, and the magnets will be used for a long time Working at high temperatures will also significantly reduce its service life. Therefore, reducing the eddy current loss while maintaining the performance of the magnet is very critical for the application of the magnet in high frequency, AC, high speed and other fiel...

Claims

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Application Information

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IPC IPC(8): B22F9/02H01F1/057
Inventor 邹君鼎丁文洋严密
Owner ZHEJIANG UNIV
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