| 摘要 |
PURPOSE:To obtain an enhanced coercive force and its sharp distribution by depositing a cobalt compound and a silicic acid compound on the surface of an acicular magnetic oxide particulates. CONSTITUTION:Acicular iron oxide particulates, a cobalt salt, and a silicic acid compound are dispered in an alkali solution, heat-treated, washed with water, dehydrated, and then dried. More preferably, the silicic acid compound is added into a mixture of the acicular iron oxide particulates and cobalt salt which are being dispersed into alkaline solution under heating, and then washed with water, dehydrated, and dried. This allows the cobalt salt and silicate salt to be deposited on the surface of the acicular iron oxide particulates. If the silicic acid compound is not used in the process of heating, a long period of heating causes the deposited cobalt to be partly decomposed by the alkali, resulting in a reduced coercive force. A magnetic material using such silicic acid compound provides a magnetic tape having a more enhanced coercive force with a sharper distribution than those given by a material not using such silicic acid compound. |
