Investigation On Preparation And Viscosity Of Magnetic Fluids

Aqueous magnetic fluids are prepared by the physical and chemical means, and the influence of the crafts of the preparation on the magnetic fluid characters is discussed. The capillary tube viscometer is used to measure the viscosity of the magnetic fluids in a magnetic field. The effects of the shear rate of the magnetic fluid, the volume fraction of the suspended magnetic particles, concentration of surfactants and the external magnetic field strength as well as the orientation on the viscosity of the magnetic fluid are analyzed. The experimental results show that the magnetic fluids with the low volume fraction of the suspended magnetic particles are the Newton fluids, and the viscosity of the sample magnetic fluids increases with the rise of the percentages of the suspended magnetic particles and the surfactants. The viscosity drops with the rise of the temperature of the magnetic fluid. The viscosity increases with the magnetic field firstly and approaches a constant as the magnetization arrives at a saturation state finally. For the same magnetic fluid, the viscosity in the perpendicular field is higher than that in the parallel field under the same magnetic field. The increase of the concentration of surfactants and the rise of the temperature of the magnetic fluid will weaken the influence of the magnetic field on the viscosity.