抄録
Ultra-fine grinding and simultaneous surface treatment of magnetite particles were examined by a high-speed media agitating mill using zirconia balls of about 0.6mm diameter in decane. Oleic acid was used as the surface treatment agent.
Well-dispersed ultra-fine particles were obtained. More than 10mol% of oleic acid was necessary to produce Ultra-Fine Magnetite Particles (UFMP). Hematite ultra-fine. particles were produced if oleic acid was less than 5mol%. The weight in percent of the ultra-fine particles produced increased with the increase in grinding time up to 10hr and became almost constant above 10hr.
The magnetic fluid made up of the obtained UFMP had almost the same magnetic susceptibility as that of UFMP produced by other methods, such as chemical synthesis.
