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Method of mfg. P-Fe-B bond magnets of high corrosion resistance

A technology of bonded magnets and high corrosion resistance, applied in a field of body, can solve problems such as high cost, difficulty in uniform resin coating, and polishing problems

Inactive Publication Date: 2004-05-05
SUMITOMO SPECIAL METAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0016] However, the above two methods are undesirable because the use of various resins to seal the pores in the magnet material inevitably leads to excessively long processing steps of resin coating (dip coating), curing and smoothing treatment, and thus These methods inherently involve the possibility of high costs from an industrial perspective
[0017] With the method of coating (dipping) the magnet material with resin, it is difficult to uniformly apply the resin to the surface of the material, and it is difficult to obtain a product exhibiting excellent dimensional accuracy even with barrel polishing in a subsequent processing step. very difficult
Polishing in wet processing is also problematic due to corrosion resistance

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] 2 wt.% epoxy resin was added to the alloy powder obtained by the rapid quenching method with an average particle size of 150 μm and a composition of 12 at.% Nd, 77 at.% Fe, 6 at.% B and 5 at.% Co. Stir and at 7 tons / cm 2 Compression molding was performed under a pressure of 150 °C, followed by heat treatment at 150° C. for 1 hour to produce a ring-shaped bonded magnet with an outer diameter of 20 mm, an inner diameter of 18 mm, and a height of 3 mm.

[0051] The average magnetic properties of the bonded magnet thus obtained are Br=0.69T, (BH)max=74.8kJ / m 3 , iHc=756kA / m, Hk=279kA / m and density=5.90g / cm 3 . The surfaces of 100 magnets thus obtained were dry-polished for 120 minutes with Al 2 o 3 The spherical rolling stone fills a 20-liter volume vibrating drum to 40% of the drum volume, and then introduces 40% of its surface made of walnut shells with a diameter of about 1mm. 2 o 3 Plant media for powder trimming.

[0052] The porosity of the magnet after surface...

Embodiment 2

[0057] A ring-shaped bonded magnet obtained in the same manner as in Example 1 was used in Example 1 except that plant matter with a diameter of about 1 mm consisting only of walnut shells was used instead of having the trimmed surface used in Example 1. The vegetable matter is polished and plated under the same conditions.

Embodiment 3

[0059] The ring-shaped bonded magnet obtained in the same manner as in Example 1 was surface-polished and rinsed with water for 2-3 minutes in the same manner as in Example 1, and electroless nickel plating was performed. The plating film thickness is 4 μm on both the inner side and the outer side. Electroless nickel plating condition is that solution temperature is 68 ℃, electroplating time is 60 minutes, pH value=9 and electroplating solution composition is the nickel sulfate of 20g / l, the sodium hypophosphite of 15g / l, the sodium citrate of 30g / l and 30 g / l of ammonium chloride. Electrolytic nickel plating was performed in the same manner as in Example 1.

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Abstract

A method of manufacturing R-Fe-B bond magnets, capable of forming various corrosion resisting films on a R-Fe-B bond magnet uniformly with a very high bond strength so as to attain such a very high corrosion resistance thereof that prevents the bond magnet from being rusted even in a long-period high-temperature high-humidity test; comprising barrel-polishing a porous R-Fe-B bond magnet by a dry method using as media an abrasive stone formed by sintering inorganic powder of Al2O3, SiC, ZrO and MgO, or a mixture of an abrasive for metal balls and vegetable media, such as vegetable skin chips, sawdust, rind of a fruit and a core of corn, or a mixture of vegetable media the surfaces of which are modified by the above-mentioned abrasive and the above-mentioned inorganic pulverized bodies, so as to enable a surface of the magnet to be smoothed and sealed; or immersing a magnet material in a neutral or alkali bath so as to enable a layer of electroless plating to be formed thereon; or subjecting a magnet material to electrolytic plating so as to enable a film of markedly high bond strength and dimensional accuracy to be formed thereon, whereby an object R-Fe-B bond magnet of a high dimensional accuracy and a high corrosion resistance is obtained.

Description

technical field [0001] The present invention relates to an improved method of manufacturing R-Fe-B bonded magnets, and more particularly to an improved method of manufacturing highly corrosion-resistant R-Fe-B bonded magnets exhibiting excellent corrosion resistance and bonding characteristics. A method of bonding magnets in which, using dry barrel polishing, powders of polishing materials are placed and sealed in the pores of magnets together with scraps of bonded magnets or those inorganic powders, and surface smoothing is performed for improvement, in After the non-electrolytic electroplating layer is directly formed on the surface of the magnetic material, a uniform conductive layer is formed as the bottom layer, and a layer of electrolytic electroplating layer with high corrosion resistance can be formed with high production efficiency. At the same time, the electroplating solution is not used Limited to electrolytic nickel plating solutions, etc. Background technique ...

Claims

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Application Information

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IPC IPC(8): B24B31/14H01F41/02
CPCB24B31/14H01F41/026H01F41/02
Inventor 吉村公志菊井文秋西内武司
Owner SUMITOMO SPECIAL METAL CO LTD