METHOD FOR MANUFACTURING METALLIC MAGNETIC POWDER FOR MAGNETIC RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To obtain metallic magnetic powder which increases σs (saturated magnetization) without reducing BET (specific surface area of ferromagnetic fine metallic particle). SOLUTION: In manufacturing metallic magnetic powder for a magnetic recording media by heat reducing iron oxide or iron oxyhydroxide in needles with pure hydrogen gas, the treatment temperature in early stage of the reduction from the start of reduction during a predetermined time is made lower than that in the later stage up to the end of reduction. The treatment temperature in the early stage is set to 300 deg.C or more and that in the later stage is set to less than 500 deg.C.