Study on the Stability of Nanosized Fe3O4 Magnetic Fluids

The effect of interaction（attraction effect and repulsion effect）between magnetic particles on the stability of nanometer magnetic fluids was analyzed theoretically. It was pointed that the size and concentration of magnetic particles and the coating of surfactant were important factors affecting the stability of magnetic fluids. Nanosized Fe3O4 magnetic fluids were prepared by the chemical co-precipitation method. Characterized by means of TEM，zeta potential and so on，the magnetic fluids had the mean size of 10 nm and exellent stability. The stability of magnetic fluids was researched experimentally as to the factors such as the method of adding starting materials，the speed of stirring，dispersion effect，surfactants coating occasion，coating time and adding amount，and pH. The affecting mechanism of these factors was analyzed further.