Preparation And Characterization Of Silicon Oil Based Ferrofluid

Magnetic fiuid has been widely used in seal, sensors and shock absorbers. In order to meet the needs of shock absorbers in the space complex environment, in this paper silicon oil which has excellent viscosity-temperature characteristics at a relatively high temperature was chosen as carrier liquid and silicon fuel based magnetic fluid was prepared. And a variety of test means have been used for characterization of the structure and properties of magnetic fluid. Finally, we get the best preparation solutions.The difficulty of silicone-based magnetic fluid preparation lies in how the magnetic particles dispersed in the carrier liquid silicone oil uniformly. This involves the preparation modified and match among silicone oil, the nano-magnetic particles and the surfactant. The key factor is the coating of surfactant to the magnetic particles surface.This paper firstly Fe3O4nano-magnetic particles were prepared by the chemical precipitation method. By making experiments optional technological conditions were determined. It was that concentration of the reactors was0.6mol/L, reaction temperature was normal atmospheric temperature, reaction time was10min. Moreover, the first-step coating experiment was conducted using sodium laurate as the surface active agent to the sample which had the best performance. The reaction temperature was70℃, reaction time was10h.Then a kind of silane coupling agent was selected as the surface active agent to the sample in the second-step coating experiment. The reaction temperature was60℃, reaction time was1h. The average size of the coated particles was about9nm with a higher saturation magnetization strength of57.32emu/g.The particles prepared under this process had preferable dispersibility.Then Fe3O4nano-magnetic prepared the chemical precipitation method. By making experiments optional technological conditions were determined. It was that concentration of the reactors was0.6mol/L, reaction temperature was normal atmospheric temperature, reaction time was10min. Moreover, the first-step coating experiment was conducted using TEOS as the surface active agent to the sample which had the best performance. The reaction temperature was70℃, reaction time was6h.Then a kind of polyethoxylated siloxane was selected as the surface active agent to the sample in the second-step coating experiment. The reaction temperature was70℃, reaction time was6h. The average size of the coated particles was about9nm with a higher saturation magnetization strength of63.43emu/g.The particles prepared under this process had preferable dispersibility. Then by the disperse way of ultrasonic oscillating, silicon oil based Fe3O4magnetic fluid was prepared with the two kinds of magnetic particles mentioned above. The influence of technological condition of magnetic particles and its content in the fluid on the performance of the fluid were observed. The result shows that the silicon oil magnetic fluid with better stability were prepared by coated with TEOS and polyethoxylated siloxane at a certain temperature. The compatibility between the magnetic particles and the carrier liquid was the key factors to magnetic property and stability of the silicon oil based magnetic fluid.The performance of the silicone based magnetic fluid prepared in this paper is: saturation magnetization strength as high as51.13Gs,viscosity (at room temperature)111.2mPa·s with excellent viscosity-temperature characteristics at higher temperature, and the viscosity increased slowly with the rise of the magnetic field intensity, which makes it a good candidate for the high temperature, the weightless environment.