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Manufacturing method for improving squareness of sintered NdFeB magnet and product

A NdFeB, squareness technology, applied in the direction of magnetic objects, inductance/transformer/magnet manufacturing, magnetic materials, etc., can solve the problem of coercive force drop, etc., to reduce the reverse magnetization center, improve the squareness, reduce the grain boundary The effect of defects

Inactive Publication Date: 2015-10-07
宁波永久磁业有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, they are all based on a substantial increase in cost, especially the partial replacement of Fe by the strategic element Co. Although the remanence and maximum energy product of the magnet have been improved to a certain extent, it will lead to a decrease in the coercive force.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] (1) Take NdFeB alloy, the NdFeB alloy is a quick-setting thin strip made by the quick-setting stripping process, and then crush the ingot by hydrogen crushing and jet milling to make the average particle size preferably 2.8μm Alloy particle powder, the alloy by mass ratio, the composition is: Pr 7 Nd 21.3 Dy 1.0 Tb 0.5 Fe bal Cu 0.25 Ga 0.2 co 2.0 Nb 0.4 Al 0.15 B 0.99 .

[0029] (2) The alloy powder is oriented and pressed under a magnetic field of 1.8T; the pressed compact is subjected to 200MPa cold isostatic pressing;

[0030] (3) In a vacuum sintering furnace, sinter the pressed green body at 1050°C for 3.5 hours, and then undergo primary tempering at 890°C for 2 hours and secondary tempering at 490°C for 3 hours to obtain a sintered NdFeB magnet;

[0031] (4) The sintered NdFeB magnets are cut into small pieces of 10mm×10mm×5mm, the surface is simply degreased, dried, and then magnetized with a magnetization intensity of 3.5 T until it reaches full ...

Embodiment 2

[0038] Steps (1) to (4) are the same as in Example 1.

[0039] (5) Directly measure the magnetic properties of the magnetized small piece of magnet: Br=1.405T, Hcj=1450.2kA / m, squareness is 0.892, as the initial magnet measurement results.

[0040] Demagnetize the magnetized small piece of magnet in a constant temperature drying oven at 400°C for 20 minutes, then quench it with ice water, and measure the magnetic properties: Br=1.403T, Hcj=1495.2kA / m, and the squareness is 0.955.

[0041] Demagnetize the magnetized small piece of magnet in a constant temperature drying oven at 450°C for 20 minutes, and then quench it with ice water. The magnetic properties are measured: Br=1.400T, Hcj=1485.7kA / m, and the squareness is 0.949.

[0042] Through test comparison, at the same cooling rate, it is found that the thermal demagnetization temperature is 420°C, and the squareness of the magnet is the best.

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Abstract

Provided is a manufacturing method for improving the squareness of a sintered NdFeB magnet. The method includes the steps that 1, NdFeB alloy is taken and manufactured into NdFeB alloy powder, wherein the NdFeB alloy is a rapid-hardening ribbon manufactured through a rapid hardening melt spinning process and comprises, by mass, 28.3% of Pr+Nd, 1.5% of Dy+Tb, 3.0% of Febal(Cu+Ga+Co+Nb+Al) and 0.99% of B; 2, orientated compression is performed on the NdFeB alloy powder under a 1.8 T magnetic field, and 200 MPa cold isostatic pressing treatment is performed on a compressed blank obtained after compression so that the compressed blank can be compressed into a green blank; 3, the green blank is sintered, primary annealing and secondary annealing are performed, and then the sintered NdFeB magnet is obtained; 4, the sintered NdFeB magnet is machined into small magnets, the small magnets are dried after oil removal treatment is performed on the surfaces, and the small magnets are magnetized under a magnetic field, wherein for small magnets of which the coercivity is 1500 kA / m, a 3T magnetizing external magnetic field can be adopted; 5, the magnetized small magnets are demagnetized and then cooled.

Description

technical field [0001] The invention belongs to the technical field of permanent magnet materials, and in particular relates to a preparation method for improving the squareness of a sintered NdFeB magnet, and also relates to a product prepared by the above preparation method. Background technique [0002] In 1983, on the basis of extensive research on RE-Fe-X ternary alloys, Sagawa Masato and others in Japan prepared a magnetic energy product as high as 290kJ / m by powder metallurgy. 3 The advanced Nd-Fe-B (Nd-Fe-B) sintered Nd-Fe-B magnets created the third generation of rare earth permanent magnet materials. Sintered Nd-Fe-B is widely used in military equipment, electroacoustic devices, motors, generators, computer hard disk drives (HDD), voice coil motors (VCM), human magnetic resonance imaging (MRI), microwave communication technology, controllers , instruments, magnetic separation equipment, magnetic chucks and other devices and equipment that require permanent magneti...

Claims

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Application Information

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IPC IPC(8): H01F41/02H01F1/057H01F1/08B22F3/16
Inventor 金伟洋唐国才周鸿波任春德金东杰李建忠
Owner 宁波永久磁业有限公司
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