Claims
- 1. A process for making a permanent magnet having a high corrosion resistance which comprises forming a magnet from a magnetic material containing at least 50 atom % of iron, and coating the surface of said magnet with a polycondensation product of tannic acid, phenols and aldehydes.
- 2. A process as set forth in claim 4, wherein said material is a Nd-Fe-D alloy, and said magnet is a sintered product.
- 3. A process as set forth in claim 1, wherein said material is a Nd-Fe-B alloy, and said magnet is a bonded magnet.
- 4. A process for making a bonded magnet having a high corrosion resistance which comprises coating particles of a powder of a magnetic material containing at least 50 atom % of iron with a polycondensation product of tannic acid, phenols and aldehydes, and bonding said particles with a synthetic resin.
- 5. A process as set forth in claim 4, wherein said material is a Nd-Fe-B alloy.
- 6. A process as set forth in claim 4, further including coating the surface of said magnet with said polycondensation product.
- 7. A process as set forth in claim 5, further including coating the surface of said magnet with said polycondensation product.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2-249090 |
Sep 1990 |
JPX |
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Parent Case Info
This is a division of application Ser. No. 07/759,369 filed Sep. 13, 1991, now U.S. Pat. No. 5,234,771.
US Referenced Citations (15)
Divisions (1)
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Number |
Date |
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Parent |
759369 |
Sep 1991 |
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