Hexagonal ferrite magnetic powder, method for producing the same and magnetic recording medium
US7381482B2 · kind B2 · utility
13Cited by
2References
3Claims
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Key dates
| Filing date | Jun 20, 2005 |
| Grant date | Jun 3, 2008 |
| Priority date | — |
| Expiry date | Feb 8, 2026 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2982
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A hexagonal ferrite magnetic powder having an average tabular diameter of from 15 to 28 nm, a coercive force (Hc) of from 2,000 to 5,000 Oe (from 160 to 400 kA/m), a switching field distribution (SFD) of from 0.3 to 0.7 and a D70/D50 of from 1.05 to 1.25. This magnetic powder can be obtained by melting and quenching starting materials to obtain an amorphous product, and thermally treating the product, which comprises increasing a temperature at a rate of 300 to 500° C./hr in a temperature range of 550 to 600° C. in the thermal treatment before the temperature reaches the thermally treating temperature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.