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Degassing method for Nd-Fe-B permanent magnet before sintered

A permanent magnet and NdFeB technology, which is applied in the degassing field of NdFeB permanent magnets before sintering, can solve the problems of permanent magnets such as reduced magnetic and mechanical properties, unqualified, easy to produce microcracks, etc., to reduce microcracks The probability of improving the pass rate and maintaining the effect of magnetic properties

Active Publication Date: 2011-09-28
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In the above-mentioned prior art, due to degassing under high vacuum, the gas pressure inside the NdFeB billet is significantly higher than the pressure in the sintering furnace cavity, and the escape of hydrogen from the NdFeB billet during degassing is relatively violent, thus making the final NdFeB permanent magnet products are prone to microcracks, and the magnetic and mechanical properties of permanent magnets with microcracks will be reduced, so products with microcracks are usually substandard products

Method used

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  • Degassing method for Nd-Fe-B permanent magnet before sintered

Examples

Experimental program
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Effect test

Embodiment 1

[0017] Put the first 50 NdFeB permanent magnet blanks into the sintering furnace, and evacuate the sintering furnace until the vacuum degree of the cavity is 2×10 -2 Pa, heated to the primary degassing temperature of 600°C, and at the same time, a certain amount of argon gas with a purity of 99.9% was introduced into the sintering furnace cavity to make the pressure in the sintering furnace cavity 10 Pa, and the temperature was kept at this temperature for 1 hour. First level degassing.

[0018] Vacuum the sintering furnace again until the vacuum degree of the cavity is 2×10 -2 Pa, continue to heat to the secondary degassing temperature of 820 ° C, and at the same time pass a certain amount of argon gas with a purity of 99.9% into the cavity, so that the pressure in the cavity of the sintering furnace is 10 Pa, keep it at this temperature for 1 hour, and carry out Secondary degassing.

[0019] Then, continue heating to 1070°C for sintering, and keep it warm for 3 hours, then...

Embodiment 2

[0021] Put the second 50 NdFeB permanent magnet blanks into the sintering furnace, and vacuum the sintering furnace until the vacuum degree of the cavity is 2×10 -2 Pa, heated to the primary degassing temperature of 600 °C, and at the same time, a certain amount of argon gas with a purity of 99.99% was introduced into the sintering furnace cavity to make the pressure in the sintering furnace cavity 500 Pa, and the temperature was kept at this temperature for 1 hour. First level degassing.

[0022] Vacuum the sintering furnace again until the vacuum degree of the cavity is 2×10 -2 Pa, continue to heat to the secondary degassing temperature of 820 ° C, and at the same time pass a certain amount of argon gas with a purity of 99.99% into the cavity to make the pressure in the cavity of the sintering furnace 500 Pa, keep it warm at this temperature for 1 hour, and carry out the secondary degassing process. level degassing.

[0023] Carry out sintering and tempering according to t...

Embodiment 3

[0025] Put the third part of 50 NdFeB permanent magnet blanks into the sintering furnace, and vacuum the sintering furnace until the vacuum degree of the cavity is 2×10 -2 Pa, heated to the primary degassing temperature of 600 °C, and at the same time, a certain amount of argon gas with a purity of 99.99% was introduced into the sintering furnace cavity to make the pressure in the sintering furnace cavity 1000 Pa, and the temperature was kept at this temperature for 1 hour. First level degassing.

[0026] Vacuum the sintering furnace again until the vacuum degree of the cavity is 2×10 -2 Pa, continue to heat to the secondary degassing temperature of 820 ° C, and at the same time pass a certain amount of argon gas with a purity of 99.99% into the cavity to make the pressure in the cavity of the sintering furnace 1000 Pa, keep the temperature at this temperature for 1 hour, and carry out Secondary degassing.

[0027] Carry out sintering and tempering according to the sintering...

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Abstract

The invention relates to a NdFeB permanent magnet desaeration method before sintering. The method includes primary and secondary steps of deaerating the NdFeB permanent magnet inside the cavity of a sintering furnace respectively under a primary desaeration temperature and a secondary desaeration temperature. The primary and secondary steps of deaeration are carried out under the existence of inert gases. The desaeration method described in the invention can reduce the probability of microcracks on the NdFeB permanent magne, thus improving the qualification rate of the product.

Description

technical field [0001] The invention relates to a method for degassing an NdFeB permanent magnet before sintering. Background technique [0002] NdFeB permanent magnet materials have the advantages of high magnetic energy product and high coercive force, so they have been widely used in many fields such as automobiles, computers, electronics, machinery, energy, and medical equipment. Sintering is a commonly used method in the manufacture of NdFeB permanent magnets. [0003] When using the usual powder metallurgy process to sinter NdFeB permanent magnets, the NdFeB alloy ingots or strips obtained by different methods must first be roughly crushed, and then crushed into alloy particles with a size of about 200-400 microns, and finally It is ground into alloy powder with a size of about 3-5 microns by ball milling or jet milling, and then sintered. When the hydrogen explosion process is used for the middle crushing, after the hydrogen absorption and dehydrogenation process, s...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F1/057H01F41/02C04B35/64
Inventor 杜鑫程晓峰张法亮宫清
Owner BYD CO LTD
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