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Preparation method of anti-oxidation neodymium-iron-boron magnet

A neodymium iron boron, anti-oxidation technology, used in magnetic objects, inductor/transformer/magnet manufacturing, magnetic materials, etc. Intrinsic coercivity, the effect of avoiding liquid phase shrinkage differences

Active Publication Date: 2018-09-07
廊坊京磁精密材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Generally speaking, the stages of powder making, magnetic field orientation, and pressing are the most severely oxidized. If the oxygen that enters cannot be discharged before sintering and heating, it will cause oxidative deformation of the magnet, which will seriously affect the comprehensive performance of the magnet, such as magnetic properties, and cause magnet failure. scrapped
[0003] Under normal circumstances, the process of oxygen intake is strictly controlled, such as powder making, powder storage, pressing, cutting, sintering into the furnace, etc., are protected by nitrogen, but because oxygen is easy to adsorb on the powder and compact, and water vapor will be released during heating. Oxygen is decomposed, which will cause secondary oxidation
However, in the current process, strict control of oxygen before heating and vacuum exhaust during heating have not fundamentally solved the adsorption of oxygen and water vapor on the magnet.

Method used

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Examples

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Effect test

Embodiment 1

[0032] A preparation method of an anti-oxidation NdFeB magnet, comprising the following steps:

[0033] The raw materials are melted in a vacuum melting furnace to obtain NdFeB alloys, and then the NdFeB alloys are placed in a hydrogen breaking furnace and injected with hydrogen to be broken into loose powders of 30-300 μm, and then dehydrogenated at a temperature of 500 ° C for 8 hours Finally, the NdFeB alloy powder is obtained by air mill flow; then the NdFeB alloy powder is mixed with a small amount of antioxidant and pressed in a magnetic orientation machine to a density of 4.6g / cm 3 Obtain the NdFeB magnet green body; place the NdFeB magnet green body in a vacuum sintering furnace, evacuate until the vacuum degree is below 0.3Pa, fill the furnace with argon until the pressure in the furnace is 95KPa, and turn on the fan in the furnace to wash the furnace for 30 minutes; Then evacuate again to below 0.3Pa, sinter at a temperature of 1050°C for 600min, turn off the heater ...

Embodiment 2

[0035] A preparation method of an anti-oxidation NdFeB magnet, comprising the following steps:

[0036] Put the raw materials in a vacuum melting furnace to smelt the NdFeB alloy, then put the NdFeB alloy in a hydrogen breaking furnace and pass in hydrogen gas, break it into a loose powder of 30-300 μm, and then dehydrogenate it at a temperature of 580 ° C for 6 hours Finally, the NdFeB alloy powder is obtained by air mill flow; then the NdFeB alloy powder is mixed with a small amount of antioxidant and pressed in a magnetic orientation machine to a density of 4.6g / cm 3 Obtain the NdFeB magnet green body; place the NdFeB magnet green body in a vacuum sintering furnace, evacuate until the vacuum degree is below 0.3Pa, fill the furnace with argon until the pressure in the furnace is 100KPa, and turn on the fan in the furnace to wash the furnace for 20 minutes; Then evacuate again to below 0.3Pa, sinter at a temperature of 1050°C for 360min, turn off the heater of the sintering f...

Embodiment 3

[0038] A preparation method of an anti-oxidation NdFeB magnet, comprising the following steps:

[0039] Put the raw materials in a vacuum melting furnace to smelt the NdFeB alloy, then put the NdFeB alloy in a hydrogen breaking furnace and pass in hydrogen gas, break it into a loose powder of 30-300 μm, and then dehydrogenate it at a temperature of 520 ° C for 4 hours Finally, the NdFeB alloy powder is obtained by air mill flow; then the NdFeB alloy powder is mixed with a small amount of antioxidant and pressed in a magnetic orientation machine to a density of 4.4g / cm 3 Obtain the NdFeB magnet green body; place the NdFeB magnet green body in a vacuum sintering furnace, evacuate until the vacuum degree is below 0.3Pa, fill the furnace with argon until the pressure in the furnace is 85KPa, and turn on the fan in the furnace to wash the furnace for 15 minutes; Then evacuate again to below 0.3Pa, sinter at a temperature of 1020°C for 180min, turn off the heater of the sintering fu...

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Abstract

The invention discloses a preparation method of an anti-oxidation neodymium-iron-boron magnet. The method comprises the following steps of putting a green body of a neodymium-iron-boron magnet into asintering furnace, pumping the sintering furnace to vacuum and then introducing an argon gas until the pressure in the sintering furnace is 85-100Kpa; and opening a fan in the sintering furnace to rotate for 15-30min, carrying out vacuumizing again and carrying out sintering and tempering to obtain the neodymium-iron-boron magnet. According to the preparation method of the anti-oxidation neodymium-iron-boron magnet disclosed by the invention, the sintering furnace is vacuumized, the argon gas is introduced into the sintering furnace, and then the fan in the sintering furnace is opened to rotate to wash the furnace, so that oxygen and water vapor adsorbed in the sintering furnace are discharged, equivalently the problem of the oxygen is fundamentally solved, reaction of rare earth in the green body of the neodymium-iron-boron magnet and the oxygen is prevented and oxidation and deformation caused by a liquid shrinkage difference during sintering are avoided.

Description

technical field [0001] The invention relates to the technical field of preparation methods of NdFeB magnets, in particular to a preparation method of anti-oxidation NdFeB magnets. Background technique [0002] In the process of manufacturing sintered NdFeB permanent magnet materials, oxygen inevitably enters the magnet from the atmosphere. Generally speaking, the stages of powder making, magnetic field orientation, and pressing are the most severely oxidized. If the oxygen that enters cannot be discharged before sintering and heating, it will cause oxidative deformation of the magnet, which will seriously affect the comprehensive performance of the magnet, such as magnetic properties, and cause magnet failure. scrapped. [0003] Under normal circumstances, the process of oxygen intake is strictly controlled, such as powder making, powder storage, pressing, cutting, sintering into the furnace, etc., are protected by nitrogen, but because oxygen is easy to adsorb on the powde...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F41/02H01F1/057B22F9/04B22F3/10B22F1/00B22F3/24
CPCB22F1/0003B22F3/1007B22F3/24B22F9/023B22F9/04B22F2003/248B22F2009/044H01F1/0577H01F41/0293
Inventor 刘润海刘月玲
Owner 廊坊京磁精密材料有限公司
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