| 摘要 |
PURPOSE:To obtain a ferrite magnetic powder excellent in magnetic characteristics, needle shape, and particle size distribution by conducting the firing while coating the surface with a compound composed of metal ions from a part or the entirety of ferrite composition when the material of needle-like hexagonal system ferrite magnetic powder, i.e., a needle-like iron oxyhydroxide or an iron oxide. CONSTITUTION:In the process for mixing an aqueous solution of iron(j) salt and an alkaline aqueous solution and injecting an oxidative gas to produce a needle-like iron oxyhydroxide, a part of compound of one or more kind of element (A) selected from Ba, Sr and Pb with a mole rate of Fe:(A):(M<1>):(M<2>) =12-2X: a:X:X(a is 0.8-1.2, X is 0.1-1.0), a compound of one or more kind of bivalent metal (M<1>) selected from Co, Mn, Ni, Cu or Zn, and a compound of one or more kind of quadrivalent metal (M<2>) selected from Ti, Sn and Zr are added entirely or partially to produce a needle-like iron oxyhydroxide or an iron oxide which is subjected to surface treatment with the remaining compound and then fired at 700-1200 deg.C. |
