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Method for producing R-Fe-B permanent magnet, and lubricating agent and release agent for use in shaping same

A technology of molding and lubricants, applied in the direction of magnetic objects, metal processing equipment, magnetic materials, etc., can solve the problems of poor productivity, difficult to remove binders and molding strength, reduction of magnet performance, etc.

Inactive Publication Date: 2005-04-06
HITACHI METALS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the method using the above-mentioned lubricant faces problems in that it is difficult to remove the binder and the strength of the molded product is poor, resulting in poor productivity
[0012] Moreover, in order to improve the moldability, it is recommended to add a binder with excellent adhesion such as PVA (polyvinyl alcohol) etc. during the granulation of the magnet powder, however, the removal of the binder during the sintering process encounters various problems. This kind of problem, but also the following problem: Special handling such as in H 2 Sintering in a reducing atmosphere, etc. will be necessary, as the amount of C remaining in the sintered body increases, the magnet performance will decrease, etc.

Method used

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  • Method for producing R-Fe-B permanent magnet, and lubricating agent and release agent for use in shaping same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0064] Electrolytic iron with a purity of 99.9%, an iron-boron alloy containing 19.8% by weight of B, and Nd and Dy with a purity of 99.7% or higher are used as starting alloys. They are mixed at high frequency and then melted. They were cast into a mold with a water-cooled casting mold to obtain a billet with a composition of 14.5at%Nd-0.5at%Dy-78.8at%Fe-6.2at%B.

[0065] Then the above-mentioned billet was crushed by a hammer mill, and further crushed under the protection of a hydrogen atmosphere to obtain crushed powder with an average particle size of 40 μm. The obtained crushed powder passes at 6kG / mm 2 Under the condition of gas pressure and using inert gas (nitrogen), it is pulverized by a jet mill to obtain fine powder with an average particle diameter of 3 μm.

[0066] Methyl caproate lubricant (boiling point: 150°C, effective ingredient: 10%, Paresu Kagaku Co., Ltd., Magrupu PS-A-21) and methyl caprylate lubricant (boiling point: 150°C, effective ingredient: 10%, Paresu ...

Embodiment 2

[0074] Electrolytic iron with a purity of 99.9%, an iron-boron alloy containing 19.89% by weight of B, and Nd and Dy with a purity of 99.7% or higher are used as starting alloys. They are mixed and melted at high frequency, and then they are cast into a mold with a water-cooled casting mold to obtain a composition of 13.4at%Nd-2.6at%Dy-77.8at%Fe-6.2at%B Blank.

[0075] Then the above-mentioned billet was crushed by a hammer mill, and further dissociated under the protection of a hydrogen atmosphere to obtain crushed powder with an average particle size of 40 μm. The obtained crushed powder passes at 6kg / mm 2 Under the condition of gas pressure and using inert gas (nitrogen), it is pulverized by a jet mill to obtain fine powder with an average particle diameter of 3 μm.

[0076] As a depolymerized polymer, a copolymer with a molecular weight of 550 composed of isobutylene and n-butene, and a low-viscosity mineral oil with a dynamic viscosity of 5 mm at 40°C 2 / s pure paraffinic min...

Embodiment 3

[0095] Electrolytic iron with a purity of 99.9%, an iron-boron alloy containing 19.8% by weight of B, and Nd and Dy with a purity of 99.7% or higher are used as starting alloys. They are mixed and melted under high frequency, and then cast into a mold with a water-cooled casting mold to obtain a billet with a composition of 13.4at%Nd-2.6at%Dy-77.8at%Fe-6.2at%B.

[0096] Then the above-mentioned billet was crushed with a hammer mill, and further crushed under the protection of a hydrogen atmosphere to obtain crushed powder with an average particle size of 40 μm. The obtained crushed powder passes at 6kg / mm 2 Under the condition of gas pressure and using nitrogen as an inert gas, it is pulverized by a jet mill to obtain a fine powder with an average particle size of 3 μm.

[0097] A mixture of various lubricants 1, 2 was added to the obtained fine R-Fe-B crushed powder and mixed, as shown in Table 10. Methyl caproate and methyl caprylate or Ti coupling agent (boiling point: 200°C or...

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Abstract

A method for producing a R-Fe-B permanent magnet, characterized in that it comprises shaping and sintering a fine powder of R-Fe-B alloy in a magnetic field with a lubricating agent for shaping a magnet containing methyl caproate and / or methyl caprate, which imparts high degree of crystal orientation to the powder, and / or a depolymerized polymer, which improves the mechanical strength of the resultant shaped product, in specific respective amounts, or a lubricating agent containing the aforementioned agent and a Ti coupling agent, which is added for enhancing the degree of crystal orientation. Each particle of the resultant fine powder is highly oriented to the direction of a magnetic field, and the resultant shaped product has a markedly improved mechanical strength so that both productivity and yield are increased. In a sintering step, since the lubricating agent has no reactivity with a magnet powder used in the present process and is discharged as a gas, the amount of a carbon residue in a sintered product is suppressed to a low level, which results in producing a R-Fe-B permanent magnet having a high Br and iHc characteristic.

Description

Technical field [0001] The present invention relates to a method for producing R-Fe-B permanent magnets. With this method, high crystal orientation can be obtained and the molded product has high strength, so the productivity is excellent. The present invention relates to a method for producing R-Fe-B magnets, in which high crystal orientation is obtained, the strength of molded products is significantly improved, and R-Fe-B magnets with high Br can be mass-produced with good yield. Yes: by adding and mixing a lubricant for molding and processing magnets, it is characterized by adding a specific amount of methyl caproate and / or methyl octoate (with which high crystal orientation can be obtained), and containing for improving the strength of the molded product The lubricant of the depolymerized polymer is added to the R-Fe-B alloy fine powder individually or as a combination, or is added and mixed with the lubricant for the molding process of the magnet, which is characterized by t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22F1/10H01F1/057
CPCH01F1/0577B22F1/0059B22F1/10
Inventor 金子裕治马场顺一郎田中和雄森静男
Owner HITACHI METALS LTD
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