FERROMAGNETIC IRON ALLOY POWDER FOR MAGNETIC RECORDING MEDIUM AND METHOD FOR MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To simultaneously improve an oxidation resistance and coercive force of ferromagnetic iron alloy powder consisting of superfine particulates of≤80 nm in mean major axis diameter required as a high recording density medium of the next generation. SOLUTION: The ferromagnetic iron alloy powder for magnetic recording media consists of acicular particles essentially consisting of iron and having the mean major axis diameter (X) of≥20 to≤80 nm, in which the oxygen content is≥17 wt.% and the coercive force (Hc) is≥0.0036X3-1.1X2+110X-1390 (Oe) (X denotes the mean major axis diameter: unit nm). The ferromagnetic iron alloy powder is obtained by reacting the metal powder consisting of the acicular particles essentially consisting of the iron and having the mean major axis diameter of≥20 to≤80 nm with pure water under conditions under which oxygen does not substantially exist to form metal oxide films on the particle surfaces and reacting the metal powder with a weak oxidizing gas by a wet or dry process when needed. COPYRIGHT: (C)2003,JPO