| 摘要 |
PURPOSE:To manufacture metal magnetic powder, which is available for magnetic recording element by adding the specific quantity of alkali carbonate to ferric ion- contained water solution, bringing it into reaction, executing water heat treatment to it after causing oxygen-contained gas to flow through and executing heating- reduction to the reacted product. CONSTITUTION:The alkali carbonate (Na2CO3, etc.) having equivalent or more to the ferric metal ion is added to the ferric ion-contained water solution and brought into reaction to make the water solution containing FeCO3. The oxygen-contained gas is caused to flow into this water solution and oxidizing-reaction is executed at <=30 deg.C, and after producing alpha-FeOOH having fusiform particle shape, further, the water heat treatment is executed in the temp. range of 120 - 250 deg.C and this is changed to the acicular alpha-FeOOH having small particle size and uniform particle distribution and low axial ratio. Successively, this alpha-FeOOH is washed with water and filtrated and after drying, the heating-reduction is executed under hydrogen gas flow in the temp. range of about 300 - 600 deg.C, to produce the acicular metal magnetic powder containing iron as essential component, having small particle size of about 0.08 - 0.15mu average long axis and uniform particle distribution and ordinarily about 4 - 6 average axial ratio. |
