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ndfeb sintered magnet

Active Publication Date: 2016-08-17
DAIDO STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In contrast, since the main phase particles are still solid, the diffusion rate from the grain boundary into the main phase particles is slow

Method used

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Embodiment

[0044] For the method of manufacturing the NdFeB system sintered magnets of the present embodiment and comparative example, use figure 1 and figure 2 The flow chart is described.

[0045] Such as figure 1 As shown, the manufacturing method of the NdFeB-based sintered magnet of this embodiment includes the following steps: Hydrogen crushing step (step A1): hydrogen is stored in the NdFeB-based alloy prepared in advance by the strip casting (Strip Casting) method. Coarse crushing; fine crushing process (step A2): 0.05 to 0.1 wt% of a lubricant such as methyl octanoate is mixed with the NdFeB-based alloy that has undergone hydrogen crushing in the hydrogen crushing process and has not been heated for dehydrogenation, and uses a jet mill The device is finely pulverized in a nitrogen gas flow, so that the median value (D50) of the particle size distribution measured by the laser diffraction method is below 3.2 μm; the filling process (step A3): mix 0.05 to 0.15 wt in the finel...

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Abstract

The present invention provides a NdFeB sintered magnet, which is a NdFeB sintered magnet produced by a grain boundary diffusion method, has high coercive force and squareness ratio, and has little decrease in maximum energy product. The NdFeB sintered magnet of the present invention is characterized in that Dy and / or Tb (hereinafter, "Dy and / or Tb" will be referred to as "RH") adhering to the surface of the base material is diffused to the surface by grain boundary diffusion treatment. In a sintered NdFeB magnet with a grain boundary inside a substrate produced by orienting and sintering NdFeB alloy powder, the concentration of RH in the grain boundary within a range from the surface to which RH is attached to a depth of 3mm The difference Cgx-Cx between Cgx (wt %) and the RH concentration Cx (wt %) in the particles constituting the substrate, that is, the main phase particles at the same depth, is 3 wt % or more.

Description

technical field [0001] The present invention relates to a NdFeB-based sintered magnet produced by grain boundary diffusion treatment. Background technique [0002] NdFeB-based sintered magnets were discovered by Sagawa (one of the inventors) in 1982. It has characteristics significantly surpassing those of permanent magnets at that time. It can be composed of Nd (a kind of rare earth), iron and boron. Advantages of cheap raw materials to manufacture. Therefore, NdFeB-based sintered magnets are used in driving motors for hybrid vehicles or electric vehicles, motors for electrically-assisted vehicles, industrial motors, voice coil motors such as hard disks, high-end speakers, earphones, and permanent magnet magnetic resonance diagnostic devices. and other products. NdFeB-based sintered magnets used in these applications are required to have high coercive force H cJ , High maximum energy product (BH) max and high rectangular ratio sq. The squareness ratio SQ here is define...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F1/08B22F1/00B22F3/00C22C33/02H01F1/057H01F41/02
CPCH01F1/0571C22C33/0278C22C38/00C22C38/005C22C38/06C22C38/10C22C38/16C22C2202/02H01F1/0577H01F41/0293H01F1/057H01F1/08
Inventor 佐川真人沟口彻彦
Owner DAIDO STEEL CO LTD