PURPOSE: To improve the dispersibility and electromagnetic transducing characteristics of magnetic powder by treating a suspension of needlelike iron oxyhydroxide having a stuck silicon compound with sulfate and by converting the iron oxyhydroxide into metallic iron or γ-iron oxide by oxidation or reduction.
CONSTITUTION: A suspension of needlelike iron oxyhydroxide is mixed with a water soluble aluminum compound to improve the dispersibility. A water soluble silicon compound is added to the mixture to inhibit the coagulation of the iron oxyhydroxide particles and to stick the silicon compound to the particles. The iron oxyhydroxide having the stuck silicon compound is then treated with sulfate and higher fatty acid, and it is converted into metallic iron by dehydration and reduction or into γ-iron oxide by dehydration, reduction and oxidation. Thus, magnetic powder having high dispersibility and superior electromagnetic transducing characteristics is obtd.
ISHICHI KOUJI
KURATOU TOSHIO
