| 摘要 |
PURPOSE:To eliminate the deterioration of dispersibility of magnetic iron powder to paint with uniform particle diameter distribution even if the powder is finely pulverized by specifying a mean long axis diameter and axis ratio. CONSTITUTION:An aqueous ferrous iron solution is added to an aqueous ammonium carbonate solution, oxygen-containing gas is diffused to produce goethite, which is coated with silicide and/or aluminum compound, reduced at 300-500 deg.C in a hydrogen gas stream to obtain spindle-like magnetic iron powder having 0.03-0.5mum of mean long axis diameter and 3-9 of axis ratio. Silicide such as water glass, silicic soda or colloidal silica and aluminum compound such as aluminic soda, aluminum nitrate or aluminum phosphate are used solely or in combination as surface treating agents for preventing the powder from sintering and controlling the magnetic property at reducing time. Thus, the collapse of the shape of the powder and flocculation among the powder particles are eliminated to improve the dispersibility in paint. |
