Abstract
Cobalt magnetic fluid was prepared by vacuum evaporation method. The colloidal fluid obtained was heated up to 150, 200, 250 and 280°C for 20min in Ar atmosphere. The effects of concentration of surfactant and heat treatment temperature on particle size and its distribution were studied by torsion magnetometer and TEM. As a result, the particle size was controlled by varying the relative concentration of the particles to surfactant and heat treatment temperature. It was difficult to redisperse the cobalt particles flocculation. so it is suggested to use the oil substrate with the high concentration of surfactant. The saturation magnetization of the fluid was improved by heat treatment.
