Method for preparing rare-earth permanent magnets by infiltration process and graphite box utilized in method

A technology of rare earth permanent magnet and infiltration method, which is applied in the field of graphite box, can solve the problems of magnet coercive force drop and damage structure, and achieve the effects of reducing usage, simple process operation and reducing production cost

Inactive Publication Date: 2012-07-11
BAOTOU TIANHE MAGNETICS TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the actual sintering process, the diffusion rate of heavy rare earth elements RH increases, and these elements will diffuse to the center of the grain, destroying the ideal structure and causing a decrease in the coercive for

Method used

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  • Method for preparing rare-earth permanent magnets by infiltration process and graphite box utilized in method
  • Method for preparing rare-earth permanent magnets by infiltration process and graphite box utilized in method
  • Method for preparing rare-earth permanent magnets by infiltration process and graphite box utilized in method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Produce according to the steps of the example:

[0030] (1) The raw materials of the following atomic percentages: Nd: 13.78%; Al: 0.3%; Nb: 0.2%; B: 5.9% and Fe of the remaining content and impurities introduced by the raw materials are mixed together for batching;

[0031] (2) Put the raw material prepared in step (1) into a vacuum intermediate frequency quick-setting induction furnace, vacuumize to less than 1Pa, fill it with Ar gas protection for heating and melting, and pour the NdFeB alloy liquid into the rotating furnace after refining On the cooling copper roll, the alloy casting sheet with a thickness of 0.25-0.35mm is prepared, and then the hydrogenated NdFeB alloy casting sheet is carried out in the hydrogen crushing furnace, and the hydrogenated alloy casting sheet is ground in the jet mill to have an average particle size of 3.0 -5.0μm material powder, orientated in a magnetic field with a magnetic field strength of 1.8T and pressed to form a green body, th...

Embodiment 2

[0038] Produce according to the steps of the example:

[0039] (1) The production method of the magnet base material (substrate) is as in Example 1. The magnet block material prepared by the above method is cut to make a Nd-Fe-B rare earth magnet with a length of 30 mm, a width of 10 mm, and a thickness of 2 mm;

[0040] (2) Put the prepared samples into the attached figure 2 On the bracket 3 with holes in the special graphite box shown, the bottom of the graphite box is placed white powder uranium fluoride (TbF 3 ) and a small amount of metal calcium particles, put the device in a vacuum sintering furnace; vacuumize to less than 5.0×10 -3 At Pa, start heating to 600°C, keep it warm for 1.5 hours, the purpose is to remove the oxide layer on the surface of the magnet; then adjust the temperature to 950°C, fill it with Ar gas at an atmospheric pressure after holding it for 3 hours, cool it to 60°C, and then in high vacuum Aging treatment in the furnace: the aging temperature ...

Embodiment 3

[0043] Produce according to the steps of the example:

[0044] (1) The production method of the magnet base material (substrate) is as in Example 1. The magnet block material prepared by the above method is cut to make a Nd-Fe-B rare earth magnet with a length of 30 mm, a width of 10 mm, and a thickness of 2 mm;

[0045] (2) Put the prepared samples into the attached figure 2 On the special graphite box with hole bracket 3 shown, white powdered holmium fluoride (HoF 3 ) and a small amount of metal calcium particles, put the device in a vacuum sintering furnace; vacuumize to less than 5.0×10 -3 At Pa, start heating to 600°C, keep it warm for 1.5 hours, the purpose is to remove the oxide layer on the surface of the magnet; then adjust the temperature to 950°C, fill it with Ar gas at an atmospheric pressure after holding it for 3 hours, cool it to 60°C, and then in high vacuum Aging treatment in the furnace: the aging temperature is 480°C, after 4.5 hours of heat preservation,...

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Abstract

Disclosed are a method for preparing rare-earth permanent magnets by the infiltration process and a graphite box utilized in the method. The method includes: preparing base materials of R (rare earth)-Fe (ferrum)-B (boron) rear earth magnets by prepared raw materials which are subjected to smelting, hydrogen decrepitation, magnetic field forming, sintering and the like; cutting the base material into slices with the thickness ranging from 2mm to 10mm; placing the slices into a specially-made graphite box and placing heavy rare earth type metal fluoride and a few of metal calcium particles into the bottom of the graphite box; sintering the graphite box in a sintering furnace, inflating air into the sintering furnace to cool the temperature to be lower than 60 DEG C, finally ageing magnets, then inflating Ar gas into the sintering furnace to cool the temperature to be lower than 60 DEG C after ageing, and finally obtaining the rare-earth permanent magnets. Elements including Dy (dysprosium), Tb (terbium), Ho (holmium) and the like are infiltrated into the crystal boundary of the R-Fe-B to prepare high-coercivity rare-earth permanent magnets by means of infiltration process, usage of heavy rare earth metal can be greatly reduced, and production cost of magnets can be effectively reduced. Additionally, the method for preparing rare-earth permanent magnets by the infiltration process is simple in operation and suitable for batch production.

Description

technical field [0001] The invention relates to a method for preparing a rare earth permanent magnet by an infiltration method and a graphite box used in the method, belonging to the technical field of magnetic materials. Background technique [0002] Take Nd 2 Fe 14 R-Fe-B rare earth sintered magnets with B-type compounds as the main phase are widely used in many fields such as electronics, automobiles, computers, energy, machinery, and medical equipment. When sintered magnets are used in various devices such as motors, the magnets are required to have good heat resistance and high coercive force characteristics in order to adapt to the use conditions at high temperatures. At present, the coercive force of the magnet is mainly increased by adding heavy rare earth metals Dy, Tb, Ho or their compounds in the smelting process to replace Nd in the main phase. During the process, the heavy rare earth elements cannot be evenly distributed in the grain boundary phase of the mag...

Claims

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Application Information

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IPC IPC(8): H01F41/02H01F7/02H01F1/053C23C10/06
Inventor 袁文杰刁树林袁易刘刚赵永刚张文旺武志敏
Owner BAOTOU TIANHE MAGNETICS TECH CO LTD
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