Fabrication methods for R-Fe-B permanent magnets
US5666635A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 6, 1995 |
| Grant date | Sep 9, 1997 |
| Priority date | — |
| Expiry date | Sep 6, 2015 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB22F2999/00
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
This invention, using finely ground powders obtained by either a ingot grinding method, a Ca reduction diffusion method or a strip casting method, proposes a fabrication method for high-performance R--Fe--B permanent magnets with excellent press packing characteristics, a high degree of orientation of the magnetization direction of each crystallite and a total sum of A, (BH)max (MGOe) and B, iHc (kOe), A+B greater than 59.5. Here, cast alloys or ground alloys are coarse ground by mechanical grinding or by a H.sub.2 absorption and decomposition method, and then fine ground by either mechanical grinding or by a jet mill grinding process to yield R--Fe--B fine powders with an average particle size of 1.0 .mu.m.about.10 .mu.m. These powders are then packed into a mold at a packing density of 1.4.about.3.5 g/cm.sup.3, a pulsed magnetic field with a field intensity greater than 10 kOe is applied so as to repeatedly invert the magnetization direction, and finally cold isostatic pressing is performed in a static magnetic field.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.