| 摘要 |
PURPOSE:To prepare a metal cobalt magnetic powder having good magnetic characteristics and suitable as a magnetic recording medium suitable for high density recording, by coating the surface of a plate shaped cobalt hydroxide powder with a sintering preventing agent while reducing the coated powder under heating in a reductive atmosphere. CONSTITUTION:A plate shaped cobalt hydroxide powder is added and dispersed in an aqueous alkali solution in which a known sintering preventing agent is dissolved and, thereafter, CO2 gas is blown into said solution or an acid is added thereto to neutralize said solution. Whereby, the surface of the cobalt hydroxide powder is coated with a crystalline or amorphous sintering preventing coating. Because the shape of the plate shaped cobalt hydroxide powder particle is effectively held and the sintering between the particles is effectively suppressed, heating reduction is performed sufficiently well and reducing reaction is also uniformized. As a result, the plate shaped metal cobalt magnetic powder having high coercive force and high magnetic saturation susceptibility is obtained. |
