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R-T-B based permanent magnet

A permanent magnet, R-T-B technology, applied in the direction of magnetic objects, magnetic materials, inorganic materials, etc., can solve problems such as influence

Active Publication Date: 2006-07-05
TDK CORPARATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

What is required is the size of the magnet with the protective film, but there is no doubt that the size of the magnet substrate also has a great influence on this size

Method used

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  • R-T-B based permanent magnet
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Embodiment Construction

[0041] Embodiments of the present invention will be described below.

[0042]

[0043] First, the hydrogen-rich layer which is the characteristic of the present invention will be described.

[0044] As shown in FIG. 1 , the R-T-B permanent magnet 1 of the present invention includes a magnet base 2 and a protective film 3 coated on the surface of the magnet base 2 . In addition, a hydrogen-rich layer 21 having a higher hydrogen concentration than the inside of the magnet base 2 exists on the surface portion of the magnet base 2 . Here, the hydrogen-rich layer means that the hydrogen concentration in the surface layer is higher than that in the magnet base 2 .

[0045] The hydrogen-rich layer 21 of the first aspect contains 300 ppm or more of hydrogen, and particularly the hydrogen-rich layer 21 of the 1-1 aspect contains 1000 ppm or more of hydrogen. The corrosion resistance is improved due to the presence of the hydrogen-rich layer 21 , but when the thickness of the layer ...

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PUM

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Abstract

An R-T-B based permanent magnet (1) which comprises a magnet body (2) comprising a sintered product comprising a main phase comprising R2T14B crystal grains (wherein R represents one or more of rare earth elements, and T represents one or more transition metals comprising Fe or Fe and Co) and a grain boundary phase containing R in an amount more than that in the main phase and, formed in the surface layer portion thereof, a hydrogen-rich layer (21) having a hydrogen concentration of 300 ppm or more and having a thickness of 300 mum or less (exclusive of zero), and a protective coating film (3) covering the surface of the magnet body (2). The R-T-B based permanent magnet (1) exhibits the corrosion resistance being improved by the protective coating film (3) without the deterioration of magnetic characteristics, and the protective coating film (3) may be formed by electrolytic plating. The R-T-B based permanent magnet (1) can secure the satisfactory corrosion resistance, which is the object of the formation of the protective coating film (3), with little reduction of the efficiency in the production, and also is reduced in the partial disintegration (falling of grains) in the surface thereof and thus exhibits high dimensional precision.

Description

technical field [0001] The invention relates to the improvement of the corrosion resistance of R-T-B permanent magnets. Background technique [0002] by R 2 T 14 The crystal grain that B type intermetallic compound forms (the present invention is referred to as R 2 T 14 B grain) R-T-B system permanent magnet (R is one, two or more kinds of rare earth elements, T is Fe or Fe and Co) as the main phase. Due to its excellent magnetic properties, Nd as the main component It is abundant and relatively cheap, so it is used in various electrical equipment. [0003] In R-T-B permanent magnets with excellent magnetic properties, there are also several technical issues that must be solved. One is corrosion resistance, that is, R and Fe, which are the main constituent elements of R-T-B permanent magnets, are easily oxidized elements, so the corrosion resistance is poor. For this reason, a protective film for preventing corrosion is formed on the surface of the magnet. As the prot...

Claims

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Application Information

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IPC IPC(8): H01F1/04H01F1/08H01F41/02C22C38/00H01F1/053
Inventor 日高彻也冈田宏成坂元一也坂本健中山靖之山本智实
Owner TDK CORPARATION
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