Preparation of rare earth permanent magnets
US6746545B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 30, 2001 |
| Grant date | Jun 8, 2004 |
| Priority date | — |
| Expiry date | May 30, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01F41/026
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An R—Fe—B permanent magnet wherein R is Nd or a combination of Nd with a rare earth element is prepared by casting an R—Fe—B alloy, crushing the alloy in an oxygen-free atmosphere of argon, nitrogen or vacuum, effecting comminution, compaction, sintering, aging, and cutting and/or polishing the magnet to give a finished surface. The magnet is then heat treated in an argon, nitrogen or low-pressure vacuum atmosphere having a limited oxygen partial pressure, obtaining a highly oil resistant sintered permanent magnet having corrosion resistance and hydrogen barrier property even in a high pressure hot environment of refrigerant and/or lubricant as encountered in compressors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.