Research of dielectric fluid dispersing barium titanate

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Amorphous barium titanate has been prepared by hydrolysis of titanium isopropoxide in aqueous alkaline solutions in the presence of barium ions at -320K. The dielectric constant of the barium titanate is strongly dependent on the moisture content. As the average particle size was in the range 5-10nm, the particles dispersed stably in kerosene when coated with surfactant polyoxyethylene alkyl ether acetates. A glass sphere immersed in the resulting dielectric fluid with low moisture content experienced a levitation force under the influence of an electric field gradient.The viscosity change of hydrocarbon based fluid dispersing surfactant coated about 10nm barium titanate particles was investigated under DC electric field. When the dispersed particle contained moisture, the fluid became a Bingham body under adequate DC electric field intensity at room temperature and the static yield stress was influenced extremely by the moisture percentage, volume fraction of solid particles and electric field intensity.When the dispersed particle contained no water, the fluid became easily a Bingham body at temperature between 373K and 393K under adequate DC electric field intensity. The increases of volume fraction and electric field intensity are considered to produce higher static yield stress for the practical application.