| 摘要 |
PURPOSE:To prevent particles from sintering and getting out of shape when heating and reducing and provide the particles having excellent magnetic characteristics, by coating the powder particles of oxy ferric hydroxide or ferric oxide with the two components of Al and Si to heat and reduce the particles. CONSTITUTION:The powder mainly comprising oxy ferric hydroxide or ferric oxide such as alpha-FeOOH or alpha-Fe2O3 is dispersed in the aqueous solution of an Al compound such as e.g. Al2(SO4)3 and then neutralized by CO2 blowing or the addition of an acid to coat the particle surfaces with Al(OH)3. When the particles are heated at a temperature of 150 deg.C or higher, the Al component is converted into a water- containing oxide and an oxide in low and high temperature regions, respectively, and provides a form in which the Al component is not chited into an alkaline solution, thereby forming a very compact coating. The particles are, further, dispersed in the solution or dispersion of an inorganic or organic silicon compound in water or an organic solvent, and, as in the above-mentioned process, the silicon compound is neutralized to coat the particle surfaces with silic acid sol. Finally the particles are heated and reduced in a gaseous phase to provide the powder mainly comprising metallic iron. |
