Optimization Of Preparative Technology Condition Of Silicon-oil-based Fe₃O₄ Magnetic Liquid

Silicon-oil-based magnetic liquid is a kind of functional material with solid magnetism and liquid fluidity.Compared with traditional water-based and kerosene-based magnetic liquid,silicon-oil-based magnetic liquid has the features of stable chemical property,good heat resistance and little change of viscosity with temperature.Silicon-oil-based magnetic liquid may be used on the occasion of higher operating ambient temperature and low change of carrier liquid viscosity with temperature,which broadens the application area of traditional magnetic liquid.The article described the procedure and result of preparing Silicon-oil -based Fe₃O₄ magnetic liquid with chemical coprecipitation method.Under the condition of the ratio of Fe²⁺to Fe³⁺and NaOH molarity constant,the effect of variation of main technological parameter such as reaction temperature,mixing speed,reaction time,pH value on Fe₃O₄ magnetic particle formation,shape and particle size was researched by the orthogonal experiment.By sieving to different surfactant,usable surfactant was determined,and transitive liquid was selected which could be soluble with surfactant and Silicon oil.The effect of the quantity of Fe₃O₄ magnetic particles,surfactant and transitive liquid on magnetism and stability of Silicon-oil -based magnetic liquid was researched by orthogonal experiment.The optimum ratio of Fe₃₄ magnetic particles, surfactant and transitive liquid was determined in accordance with different saturation magnetization and light transmittance.The effect of disperse style on the stability of magnetic liquids was surveyed.Silicon-oil-based Fe₃O₄ magnetic liquid with saturation magnetization of 897.4Gs and light transmittance of 3.2%was prepared. Topography and particle size of Fe₃O₄ magnetic particles was observed by TEM; crystalling phase structure was researched by X-ray diffraction;saturation magnetization of silicon-oil -based Fe₃O₄ magnetic liquid was tested by VSM; compatible mode of surfactant on Fe₃O₄ magnetic particles surface was tested by IR. The results show that optimum technological parameter of preparing Fe304 magnetic particles is reactive temperature 60℃,mixing speed 700r/min and reactive time 2.5h.when the reactant ratio and molarity remain constant.The appropriate particle size of Fe₃O₄ magnetic particles which are used to prepare silicon-oil -based magnetic liquid is 10.96nm,the particles' main topography is sphere and their lattice structure is tetrahedron.The optimum ratio of Fe₃O₄ magnetic particles,surfactant and transitive liquid is 8.0(g):0.6(g):9mL.The sticking mode of surfactant and Fe₃O₄ magnetic particles surface is chemical adsorption.