| 摘要 |
PURPOSE:To give high coercive force to a surface of a metal compound by covering the surface of the metal compound with a compound of amphoteric oxides composed primarily of Sn<4+>, heating it after moreover covering it with silicate gel, and reducing it by hydrogen to enhance the above effect sufficiently under low temperature heating. CONSTITUTION:Strong alkali suspension of metal compound powder composed primarily of reduced oxy-iron hydroxide or iron oxide is added with alkaline solution composed primarily of Sn<4+>. Acid is added to it to adjust it into light alkaline and then the surface of acicular powder is covered with hydroxide composed primarily of Sn(OH)4. Next, this supension is added with water-soluble silicate aqueous salt water to adjust pH using acid. By this, the surface of acicular powder is doubly coated with hydroxide composed primarily of Sn(OH)4 and silicate gel. After the obtained metal compound powder is heated at 500- 800 deg.C, it is reduced by hydrogen at 400-600 deg.C to obtain magnetic powder having strong coercive force. |
