The Study On The Preparation And The Characteristic Of Magneto-Optical Transmission Of Tunable Viscous CoFe₂O₄ Ionic Magnetic Fluid

This paper reviews the history on the progress of magnetic fluid, classifies all kinds of magnetic fluid from three different perspectives, and briefs the application of magnetic fluid and the principle.On the base of chemical coprecipitated method, we prepare CoFe2O4 ionic magnetic fluid by coprecipitated and acid erode method. We get six kinds of magnetic fluid through changing two important parameters, which are mass percent S of basicliquid and magnetic particulate volume ratiov. In order to get magnetic fluid of highquality, we carefully weigh the needed material by the analytical balance and keep in mind the points for attention of the experimental operation during the course of experiment.Utilizing the Transmitted Electronic Microscope (TEM), we can observe that particles disperse uniformly and some of them congregate. Using the structure of diffused electric doublet layer based on DLVO theory, we analyze the factors which influence the CoFe2O4 ionic magnetic fluid's stability, and they include magneticparticles' diameter D, magnetic fluid's Q, magnetic particulate volume ratio v, and the viscous layer on the surface of particles.We respectively measure some different magnetic fluid's viscosity by theviscometer in the magnetic field and not in the magnetic field, and discuss what result in it. Using Smoluchowsky and Mooney's rheology theory we analyze that withoutmagnetic field 77 will increase as S andv increase; using the Rosensweig's formula and hydromechanical theory, we can illustrate that in the magnetic field and the outside temperature being certain, 77 will increase as the magnetic field increase,when the magnetic fluid's S and v are determined.We design a set of devices that can test magneto-optical effects-transmitted laser's intensity using quits method. And we test how the laser's intensity changes with time through six kinds of CoFe2O4 ionic magnetic fluid when laser has the same direction as the magnetic field (be perpendicular to the magnetic fluid film). The whole test course takes 500s. Without magnetic field, transmitivity T equals 1; At the moment of 50s, when the magnetic field is added, T increases rapidly, then decreases gradually, and increases again when it is minimum, later reaches a stable value slowly; At the time of 350s, when the magnetic field is got rid of, T decreases instantaneously and increases by inches until it is a stable value. In order to explain how the factors influence the magnetic fluid's transmissivity, we use discuss the following three cases in detail: (1)v and S are same, while B is different; (2) v and B are same, while S isdifferent; (3) S and B are same, while v is different.We describe how magnetic fluid's inner structure transforms with the time under all kinds of conditions using magnetic dipole model and magnetic chain model. And using effect field theory we analyze the mechanisms of the magnetic particles being chains, change of the chains and reciprocity in chains. So we can make out that the transmissivity varies with the magnetic fluid's inner structure.