The Preparation Of Magnetic Fluid By Chemical Co-Precipitation Method

Magnetic fluid is a kind of stable colloidal solution formed from magnetic nanoparticles,regularly scattering in the carrier, coverd by surfactant. It has both magnetism and fluidity. Itis apply in the domain of space, electron, chemical industry, mechanism, energy, metallurgy,instrument, environmental protection, medical treatment.In the paper, Fe₃O₄ magnetic fluid and CoFe₂O₄ magnetic fluid were prepared by thechemical co-precipitation method. Without the protection of nitrogen, nano Fe₃O₄ particle wasprepared by co-precipitation method using ammonia as precipitator, nano CoFe₂O₄ particlewas prepared by co-precipitation method using sodium hydroxide as precipitator. Wediscussed the effect factors, which influence the magnetic particle's dimension, such asprecipitator type and quantity of precipitator, the ratio of Fe²⁺/Fe³⁺ or Co²⁺/Fe³⁺, the reactiontemperature, the reaction time, determined the optimum parameter of prepared Fe₃O₄ andCoFe₂O₄ nanoparticles.Fe₃O₄ and CoFe₂O₄ particles were cleaned with distilled water. In this course, theclearing time was reduced by magnet. When the pH was about 7, the particles modified by thesurfactant were scattered in the carrier. The magnetic fluid was prepared. The factors, whichinfluence magnetic fluid properties, such as type of surfactant, quantity of surfactant,modified temperature, modified time, pH, action of ultrasonic, centrifugal effect, werediscussed.By means of Differential Thermal Analysis (DTA), Infrared Ray spectrum (IR),Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and Vibration SampleMagnetometer (VSM), the purity, covered effect, dispersed effect, appearance, conglobation,grain size and saturation magnetization were measured. The density and the viscosity ofmagnetic fluid were also measured.In the article the total iron—Fe_[x] in the magnetic fluid was used to express the stabilityof magnetic fluid. Using SnCl₂-TiCl₃ to deoxidize Fe³⁺, K₂Cr₂O₇ titration the magnetic fluid,the total iron—Fe_[x] was measured. This method was no pollution to environment, it was easyto operate. The effects on the stability of magnetic fluid were discussed, such as the gravity,the centrifugal force, the depositing condition, then the effects on the magnetism of magneticfluid were discussed.Moreover, magnetic fluid took place special optical phenomenon-Tyndall phenomenonas colloid. Tyndall phenomenon of magnetic fluid was observed. When the particles weresmaller, the Tyndall phenomenon was more obvious.