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Method for decreasing harmful gases in process of sintering sintered neodymium iron boron (NdFeB) magnet

A sintering process and harmful gas technology, applied in the direction of magnetic objects, magnetic materials, electrical components, etc., can solve problems such as magnet blank cracks, affecting product qualification rate, surface coating blistering, etc., to reduce cracks and improve oxidation resistance , the effect of vacuum degree improvement

Active Publication Date: 2014-09-17
SANVAC BEIJING MAGNETICS +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If the hydrogen element remains in the magnet blank, it will cause cracks inside the magnet blank and blisters on the surface coating of the finished magnet, which will affect the qualified rate of the product

Method used

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  • Method for decreasing harmful gases in process of sintering sintered neodymium iron boron (NdFeB) magnet

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] The alloy with the composition of 9.7Pr-19Nd-4Dy-0.5Al-0.1Cu-1.2Co-1.0B-remainder Fe is smelted in a vacuum induction furnace to obtain a NdFeB alloy, which is subjected to hydrogen explosion treatment after coarse and medium crushing. Jet milling powder to obtain 3.7 ~ 4.0μm NdFeB alloy powder. The green compact size is D20×28. Place the dehydrogenation device in the sintering furnace, and place it inside the furnace body of the sintering furnace. Wherein, the dehydrogenation device is an airtight stainless steel box, in which is placed broken into 10 × 10 × 10mm 3 A small piece of LaNi5 hydrogen storage alloy activated by 99.99% high-purity hydrogen, and the device has a mechanical transmission to control the opening and closing of the box, wherein the hydrogen storage alloy occupies 1 / 3 of the volume of the box, and the top of the box to The distance between the molybdenum belts in the sintering furnace is 15cm. Put the green body into the sintering furnace for si...

Embodiment 2

[0027] The alloy with the composition of 10.3Pr-20Nd-4Dy-0.5Tb-0.2Gd-0.5Al-0.1Cu-1.2Co-1.2B-the balance of Fe is smelted in a vacuum induction furnace to obtain NdFeB alloy, after coarse and medium crushing The hydrogen explosion treatment is carried out, and the powder is obtained by jet milling to obtain 3.7-4.0 μm neodymium-iron-boron alloy powder. The green compact size is D20×28. Place the dehydrogenation device in the sintering furnace, and place it inside the furnace body of the sintering furnace. Wherein, the dehydrogenation device is an airtight stainless steel box, in which is placed broken into 10 × 10 × 10mm 3 A small piece of LaCeNi5 hydrogen storage alloy activated by 99.99% high-purity hydrogen, and the device has a mechanical transmission to control the opening and closing of the box, wherein the hydrogen storage alloy occupies 1 / 3 of the volume of the box, and the top of the box to The distance between the molybdenum belts in the sintering furnace is 15cm. ...

Embodiment 3

[0029] The alloy with the composition of 25.6Nd-2.4Dy-0.1Ga-0.9B-the balance of Fe is processed into thin strips by the thin strip process, and then hydrogen explosion treatment is carried out, and the powder is obtained by jet milling to obtain 3.7~4.0μm NdFeB alloy powder . The green compact size is D20×28. Place the dehydrogenation device in the sintering furnace, and place it inside the furnace body of the sintering furnace. Wherein, the dehydrogenation device is an airtight stainless steel box, in which is placed broken into 10 × 10 × 10mm 3 A small piece of LaCePrNi5 hydrogen storage alloy activated by 99.99% high-purity hydrogen, and the device has a mechanical transmission to control the opening and closing of the box, wherein the hydrogen storage alloy occupies 1 / 3 of the volume of the box, and the top of the box to The distance between the molybdenum belts in the sintering furnace is 15cm. Put the green body into a sintering furnace for sintering and aging. The si...

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Abstract

The invention provides a method for decreasing harmful gases in the process of sintering a sintered neodymium iron boron (NdFeB) magnet, which comprises the following steps: crushing a hydrogen storage alloy into a plurality of small hydrogen storage alloy blocks, and putting the small hydrogen storage alloy blocks into a dehydrogenation unit after activating the small hydrogen storage metal blocks by using high-purity hydrogen, wherein the dehydrogenation unit is an airtight stainless box and provided with a mechanical driving device for controlling opening and closing; fixing the box on the furnace body inner wall of a sintering furnace, and connecting the mechanical driving device with the box so as to control the opening and closing of the box; at the heat preservation and breathing stage of rising the temperature of sintering a blank to 800-1000 DEG C, opening the box by the mechanical driving device so as to cause the small hydrogen storage alloy blocks to be exposed in the sintering atmosphere when a vacuum pump vacuumizes to 10Pa or below 10Pa; and closing the box after the vacuum degree reaches 10-2Pa. The method provided by the invention can be used to obviously improve oxidation resistance of the manufactured magnet in an external environment, and after the magnet blank is subject to plate surface treatment, bubbling and cracks are greatly reduced.

Description

technical field [0001] The invention relates to an environment-friendly sintering method of an NdFeB magnet, in particular to a method for reducing harmful gas in the sintering process of the sintered NdFeB magnet. Background technique [0002] In the existing sintered NdFeB magnet production process, a large number of hydrogen explosion processes are used to improve the magnetic properties of the rough magnet, so hydrogen gas (H 2 ). In addition, the volatile substances such as lubricants added when the magnet green powder is mixed, and the oil vapor caused by the return oil of the diffusion pump will volatilize methane (CH 4 ) gas, if the methane cannot be extracted in time, the methane will interact with the adsorbed water vapor (H 2 O) reaction, the reaction formula is: CH 4 +2H 2 O→CO 2 +4H 2 , also releases hydrogen gas H 2 . In a sealed sintering furnace system, when the vacuum is poor, there will be a lot of air in the furnace, and the air contains 78% nitrog...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22F3/10H01F41/02H01F7/02H01F1/057
Inventor 王浩颉赵玉刚张瑾徐滨王志伟
Owner SANVAC BEIJING MAGNETICS
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