| 摘要 |
PURPOSE:To make an initial magnetizing rate large, to make a magnetizing value sufficiently large and to achieve the saturated value of the magnetization quickly with the increase in magnetic field, by dispersing two or more kinds of magnetic particles which are coated with a surface active agent and have the different magnetic saturation values in base oil. CONSTITUTION:Magnetic metal, e.g., cobalt particle, is coated with a surface active agent, e.g., polybutenyl succinimidetetraethylenepentamine (molecular weight of polybutenyl group is about 1,000). Magnetic metal oxide, e.g., a magnetite particle, is coated sequentially with surface active agent of oleic acid and polybutenylsuccinimidetetraethylenepentamine. Said particles are dispersed in base oil, e.g., eicosylnaphalene, and magnetic fluid is obtained. The magnetic fluid has a larger initial magnetizing rate in comparison with the magnetizing characteristic curve of conventional oxide magnetic fluid as shown with a dotted line, and the magnetization quickly approaches the saturation value. |
