Research of dielectric fluid dispersing barium titanate

在-320K温度下，用异丙醇钛在钡离子存在的碱性水溶液中水解制备了无定形钛酸钡。钛酸钡的介电常数与水分含量密切相关。表面活性剂聚氧乙烯烷基醚乙酸酯包覆后，颗粒在煤油中稳定分散，平均粒径在5 ~ 10nm之间。在电场梯度的影响下，将玻璃球浸入所产生的低含水量介电流体中，产生悬浮力。在直流电场作用下，研究了包覆10nm钛酸钡颗粒的烃基流体分散表面活性剂的粘度变化。当分散颗粒中含有水分时，在室温下足够的直流电场强度下，流体成为宾厄姆体，静态屈服应力受固体颗粒的含水量、体积分数和电场强度的影响极大。当分散的颗粒不含水时，在足够的直流电场强度下，温度在373K ~ 393K之间，流体容易形成宾厄姆体。在实际应用中，认为体积分数和电场强度的增加会产生更高的静态屈服应力。

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.