| 摘要 |
PURPOSE:To obtain the excellent magnetic powder by a method wherein the surfaces of particles are coated with dispersant and the particles are kneaded and a mechanical shearing force is provided to them before drying when nuclear crystals of iron oxide magnetic powder are coated with a cobalt compound and are washed with water and are filtered and dried. CONSTITUTION:A suspension that contains needlelike gamma-Fe2O3 magnetic powder, cobalt sulfate, ferrous sulfate and caustic soda or the like is heated at the boiling point of 100 deg.C for about 6hr, and the nuclear crystals of iron oxide magnetic powder are coated with a cobalt compound. Next it is filtered, polyoxyethylene alkyl acid ester as a dispersant is added to the cake of 35% moisture content by weight and the mixture is kneaded by means of a kneader for about 1hr to provide a mechanical shearing force to the particles. After this, it is heated at temperature of 130 deg.C for about 3hr and is dried to obtain a magnetic powder for the magnetic recording. In this way, a powder with excellent characteristics on dispersion, orientation and packing can be obtained. |
