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Method for grain boundary adulterated by oxide or nitride to improve the NdFeB permanent magnetic material performance

A technology of permanent magnet materials and oxides, which is applied in the manufacture of magnetic materials, magnetic objects, inductors/transformers/magnets, etc., can solve the problems of magnet coercive force reduction, achieve increased remanence, small corrosion current density, and increased resistance The effect of action

Inactive Publication Date: 2007-10-17
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage is that although the thermal stability of Co-containing magnets is improved, the Nd-(FeCo) formed at the grain boundary is enriched. 2 Soft magnetic phase, resulting in a rapid decrease in the coercive force of the magnet

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] (1) NdFeB ingot alloy is made by ingot casting process, and its composition is Nd 13 Fe 余 B 6 (Dy 0.5 Al 0.4 Nb 0.2 ) (at%), the alloy is first coarsely crushed in a jaw crusher, then crushed to 80-100 mesh in a secondary crusher, and finally made into a powder with an average particle diameter of 4-5 μm by jet milling.

[0027] (2) Adding dispersed titanium nitride powder with a particle size of about 1 μm by means of ball milling and powder mixing, the mass of which accounts for 0.1% of the NdFeB powder. The mixing time of ball milling is 40min, and the mixing medium is petroleum ether.

[0028] (3) The mixed powder is pressed and formed in a magnetic field orientation forming press, and the forming orientation magnetic field is 1.5T. After orientation pressing, the blank is subjected to cold isostatic pressing to increase the density of the blank, and the isostatic pressing pressure is 150 MPa.

[0029] (4) Put the blank into a high-vacuum sintering furnace, s...

Embodiment 2

[0033] (1) NdFeB ingot alloy is made by quick-setting sheet technology, the speed of copper roller is 2m / s, and its composition is Nd 18 Fe 余 B 5.5 Al 0.4 Dy 0.5 Ga 0.3 (at%). The alloy is first coarsely crushed in a jaw crusher, then crushed to 80-100 mesh in a secondary crusher, and finally made into a powder with an average particle diameter of 4-5 μm by jet milling.

[0034] (2) Adding dispersed zinc oxide powder with a particle size of about 1 μm in the form of ball milling, whose mass accounts for 2% of the NdFeB powder. The mixing time of the ball mill is 20 minutes, and the mixing medium is petroleum ether.

[0035] (3) The mixed powder is pressed and formed in a magnetic field orientation forming press, and the forming orientation magnetic field is 1.8T. After orientation pressing, the blank is subjected to cold isostatic pressing to increase the density of the blank, and the isostatic pressing pressure is 200 MPa.

[0036] (4) Put the blank into a high vacuum...

Embodiment 3

[0039] (1) NdFeB ingot alloy is made by quick-setting sheet technology, the speed of copper roller is 2m / s, and its composition is Nd 24 Fe 余 B 5.5 Al 0.4 Dy 0.5 Ga0.3 (at%). The alloy is first coarsely crushed in a jaw crusher, then crushed to 80-100 mesh in a secondary crusher, and finally made into a powder with an average particle diameter of 4-5 μm by jet milling.

[0040] (2) Dysprosium nitride powder with a particle size of about 1 μm and dispersed treatment is added by ball milling, and its mass accounts for 5% of the NdFeB powder. The mixing time of ball milling is 90min, and the mixing medium is petroleum ether.

[0041] (3) The mixed powder is pressed and formed in a magnetic field orientation forming press, and the forming orientation magnetic field is 2.0T. After orientation pressing, the blank is subjected to cold isostatic pressing to increase the density of the blank, and the isostatic pressing pressure is 250 MPa.

[0042] (4) Put the blank into a high ...

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Abstract

The invention relates to a method of a rare earth material technic field for adding an oxide in a grain boundary or increasing an Nd-Fe-B permanent magnetic material performance by a nitride, the method comprises: (1) preparing an Nd-Fe-B ingot casting alloy by an ingot casting process or preparing an Nd-Fe-B alloy rapid hardening thin sheet by a rapid hardening thin sheet process, (2) performing rough-cracking on the alloy and grinding the alloy to powder by an air flow; (3) adding oxide or nitride powder and evenly mixing; (4) directional press-forming the mixed power in a magnetic field, isostatic cool pressing a blank after being directional press-forming; (5) putting the blank into a high vacuum fritting furnace, producing a magnet by fritting and tempering. The Nd-Fe-B permanent magnetic material has a chemical formula of NdaFe100-a-b-cBbMc, atom percents are: 12<=a<=24, 5.5<=b<=7, 0<=c<=7; M is one or more of elements Dy, Tb, Co, Ga, Al, Cu. The fritted Nd-Fe-B prepared in the invention has better magnetic performance and corrosion resistance than the magnet produced without adding the oxide or the nitride.

Description

technical field [0001] The invention relates to a method in the technical field of rare earth materials, in particular to a method for improving the magnetic properties, thermal stability and corrosion resistance of NdFeB permanent magnet materials by adding oxides or nitrides at grain boundaries to improve NdFeB permanent magnets. approach to material properties. Background technique [0002] Sintered NdFeB magnets have high remanence, coercive force and maximum magnetic energy product. Since their inception, they have been widely used in many fields such as national defense, household appliances, medical machinery, electronic information and automobile industries, especially in recent years. The popularity of computers, electronic communications and other equipment and the rapid development of low-energy automotive motors have broadened its application prospects. However, the low thermal stability and corrosion resistance of NdFeB permanent magnet materials greatly reduce...

Claims

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Application Information

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IPC IPC(8): H01F1/057H01F41/02C22C1/04B22F3/10
Inventor 莫文剑张澜庭刘琼珍单爱党曹力军吴建生
Owner SHANGHAI JIAO TONG UNIV
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