| 摘要 |
PURPOSE:To obtain magnetic material suitable for a high-density magnetic recording medium superior in the squareness ratio, orientation and electromagnetic conversion property by a method wherein a silica-alumina coprecipitate is deposited on the surface of magnetic iron oxide powder to improve dispersity into a resin bonding agent. CONSTITUTION:A circular gamma-Fe2O3 is dispersed into a NaOH aqueous solution to obtain slurry, and cobalt sulfate aqueous solution and ferrous sulfate aqueous solution are added thereto while blowing N2 gas. After sufficient agitation at the room temperature, the slurry is filtered and washed to obtain a wet cake of magnetized iron oxide containing cobalt which is then dispersed into water. Subsequently, the slurry is heated up to 45 deg.C while blowing N2 gas, and then sodium aluminate aqueous solution and ortho-sodium slicate aqueous solution are added thereto under agitation. Next, dilute sulfic acid is added thereto to neutralize the pH value to 7.5 and it then undergoes maturation while agitating. In this way, high dispersity is applied to the magnetic powder, thereby resulting in powder suitable for a magnetic recording medium material. |
