Claims
- 1. A process of producing a magnetic powder for use in a plastic or rubber magnet wherein said powder is filled in a plastic or rubber matrix and magnetically oriented comprising:
- (a) firing a starting composition capable of forming when fired a ferrite selected from the group consisting of barium ferrite, strontium ferrite and lead plumbite ferrite at a temperature above 1200.degree. C. to produce a sintered body of magnetic material;
- (b) coarse-crushing said sintered body to obtain coarse particles;
- (c) pulverizing said coarse particles together with about 0.1% by weight of about 10% by weight based on the weight of said coarse particles of a lower alcohol having three or less carbon atoms until a fine powder is obtained, said fine powder having an average particle size in the range between about 1.00.mu. and about 1.50.mu. measured with a Fisher Sub-Sieve Sizer and having a compressed density in the range of about 3.30 g/cm.sup.3 and about 3.55 g/cm.sup.3 when compressed under a pressure of 1 ton/cm.sup.2 ; and
- (d) annealing said fine powder at an elevated temperature.
- 2. A process according to claim 1 wherein said ferrite is barium ferrite.
- 3. A process according to claim 1 wherein said coarse particles are pulverized in a ball mill.
- 4. A process according to claim 1 wherein said coarse particles are pulverized in a vibration mill.
- 5. A process according to claim 1 wherein said alcohol is selected from the group consisting of methanol, ethanol, propanol, ispropanol, mixtures thereof, and ethanol denatured with methanol.
- 6. A magnetic powder for use in a plastic or rubber magnet wherein said powder is filled in a plastic or rubber matrix and magnetically oriented, said powder being made according to the following steps:
- (a) firing a starting composition capable of forming when fired a ferrite selected from the group consisting of barium ferrite, strontium ferrite and lead plumbite ferrite at a temperature above 1200.degree. C. to produce a sintered body of magnetic material;
- (b) coarse-crushing said sintered body to obtain coarse particles;
- (c) pulverizing said coarse particles together with about 0.1% by weight to about 10% by weight based on the weight of said coarse particles of a lower alcohol having three or less carbon atoms until a fine powder is obtained, said fine powder having an average particle size in the range between 1.00.mu. and 1.50.mu. measured with a Fisher Sub-Sieve Sizer having a compressed density in the range of about 3.30 g/cm.sup.3 and about 3.55 g/cm.sup.3 when compressed under a pressure of 1 ton/cm.sup.2 ; and
- (d) annealing said fine powder at an elevated temperature.
- 7. A magnetic powder according to claim 6 wherein said ferrite is barium ferrite.
- 8. A magnetic powder according to claim 6 wherein said powder is comprised predominantly of single crystal particles.
- 9. A plastic or rubber magnet comprising a magnetic powder uniformly dispersed in a plastic or rubber matrix, said powder being magnetically or mechanically oriented in said matrix, said powder being made according to the following steps:
- (a) firing a starting composition capable of forming when fired a ferrite selected from the group consisting of barium ferrite, strontium ferrite and lead plumbite ferrite at a temperature above 1200.degree. C. to produce a sintered body of magnetic material;
- (b) coarse-crushing said sintered body to obtain coarse particles;
- (c) pulverizing said coarse particles together with about 0.1% by weight to about 10% by weight based on the weight of said coarse particles of a lower alcohol having three or less carbon atoms until a fine powder is obtained, said fine powder having an average particle size in the range between about 1.00.mu. and about 1.50.mu. measured with a Fisher Sub-Sieve Sizer and having a compressed density in the range of about 3.30 g/cm.sup.3 and about 3.55 g/cm.sup.3 when compressed under a pressure of 1 ton/cm.sup.2 ; and
- (d) annealing said fine powder at an elevated temperature.
- 10. A magnet according to claim 9 wherein said ferrite is barium ferrite.
- 11. A magnet according to claim 9 wherein said plastic matrix is selected from the group consisting of thermoplastic materials and thermosetting materials.
Priority Claims (1)
Number |
Date |
Country |
Kind |
51-140177 |
Nov 1976 |
JPX |
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CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of our copending U.S. Patent application Ser. No. 801,000, filed May 26, 1977 now abandoned, entitled Rubber or Plastic Magnet and Magnetic Powder for Making the Same, which application is now abandoned.
US Referenced Citations (9)
Foreign Referenced Citations (4)
Number |
Date |
Country |
1571622 |
Jan 1971 |
DEX |
1323095 |
Feb 1963 |
FRX |
2089928 |
Jan 1972 |
FRX |
46-24834 |
Jul 1971 |
JPX |
Non-Patent Literature Citations (1)
Entry |
Hackh's Chemical Dictionary by Grant 3rd Ed., p. 667, Blakiston, Philadelphia (1944). |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
801000 |
May 1977 |
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