Invention Grant
- Patent Title: Magnetic metal powder suitable for use in magnetic recording media and method of manufacturing the powder
- Patent Title (中): 适用于磁记录介质的磁性金属粉末及其制造方法
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Application No.: US12952273Application Date: 2010-11-23
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Publication No.: US08357222B2Publication Date: 2013-01-22
- Inventor: Takayuki Yoshida , Masatoshi Nakayama , Ryota Igarashi
- Applicant: Takayuki Yoshida , Masatoshi Nakayama , Ryota Igarashi
- Applicant Address: JP Tokyo
- Assignee: DOWA Electronics Materials Co., Ltd.
- Current Assignee: DOWA Electronics Materials Co., Ltd.
- Current Assignee Address: JP Tokyo
- Agency: Clark & Brody
- Priority: JP2006-086906 20060328; JP2006-261531 20060926
- Main IPC: B22F9/16
- IPC: B22F9/16 ; H01F1/14

Abstract:
A metal magnetic powder for a magnetic recording medium is provided whose particles have a metal magnetic phase, composed mainly of Fe or Fe plus Co, and an oxide layer, wherein the average major axis length of the powder particles is 10-50 nm, the average particle volume including the oxide layer is 5,000 nm3 or less, the atomic ratio (R+Al+Si)/(Fe+Co) calculated using the content values (at. %) of the elements contained in the powder particles is 20% or less, where R is rare earth element (Y being treated as a rare earth element). The metal magnetic powder is obtained by using a complexing agent and a reducing agent to elute nonmagnetic constituents after firing. The metal magnetic powder exhibits a large saturation magnetization as for its particle volume while maintaining weatherability comparable to the conventional level and is suitable for a coated-type magnetic recording medium.
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