Research On Suspension Properties Of Nano-magnetic Fluid

Magnetic fluid combines the magnetic property of solid materials and fluidity of liquid. It is a kind of new liquid functional material which sensitive to magnetic field, has the function of damping, heat transfer and targeting when subject to a magnetic field. Its applications range from the fundamental area, like aero-space, mechanical seal and damping, to the high-gradehigh-precision, advanced area as photoelectronic device and biomedicine.When applied to a magnetic field, the nano-magnetic particles in magnetic fluid change their uniform distribution, thus their magnetic moments shift order to disorder. The magnetic particles arrange themselves along the magnetic induction line, align like spherical cluster chain. When increase the magnetic field, the space between particles become smaller. If in a nonuniform magnetic field, the different layer's particles concentrate differently, leading to a change in density. From a macro point of view, the magnetic fluid shows suspend ability.The forces of nano-magnetic particles in magnetic fluid is analyzed either there is or no magnetic field. The modified Bernoulli equation is derived from magnetic fluid's kinetic equations;theoretical formula of magnetic fluid's apparent density is also derived in different attribution magnetic field.The apparent density is measured in different magnetic strength, magnetic field gradient and layers by magnetic fluid apparent density measuring device and self-produced smart magnetic fluid particles space distribution apparatus. It is found that the apparent density is an important measurement of ferrofluid's suspending ability. It shows that suspension properties of magnetic fluid relates to magnetic strength, magnetic field gradient and magnetic circuit. The change of apparent density and inner state of magnetic fluid in extra magnetic field is also explained by magnetic fluid interfacial instability.The influence factor of magnetic fluid's suspend ability is analyzed by magnetic float and sink instrument, which shows the magnetic fluid in a strong magnetic field can float non-magnetic body with different density, such as aluminum body, copper body, lead body. Also, the temperature distribution of magnetic fluid in nonuniform magnetic field gradient is also measured by the magnetic float and sink instrument, showing that magnetic fluid has thermo-magnetic ability in nonuniform magnetic field gradient. The suspend ability of magnetic fluid not also can make the separation of objects come true, but can apply to sewage treatment area. The objective of this paper is urging the development and application of magnetic fluid products by improving the basic theory of magnetic fluid in separation and sewage treatment field.