电流变液微波反射可调控性

研究了纳米二氧化钛包覆高岭土和钇掺杂钛酸钡两种电流变液的微波反射行为.实验发现，在垂直于微波传播方向电场作用下，两种电流变液微波反射系数均随电场强度的增大而增大；钇掺杂钛酸钡电流变液微波反射系数变化幅度比二氧化钛包覆高岭土电流变液宽，并且电场调节的能力随浓度的增加有减弱的趋势.对钇掺杂钛酸钡电流变液存在一个临界浓度，低于这个浓度，电场的调控能力随电场强度的增加而增大，高于这个浓度，电场的调控能力随电场的增加先增大后减小.另外，二氧化钛包覆高岭土电流变液反射回波相位随电场强度的增大出现最大值后逐渐减小趋于平关键词：电流变液微波反射相位

Modulatory character of microwave reflection behavior in electrorheological fluids

The microwave reflection behavior of electrorheological (ER) fluids containing TiO2 coated Kaolinite and Y doped BaTiO3 was investigated in the case that the direction of the TE10 module to the electrical field is vertical. We found that the reflection coefficient of TiO2 coated Kaolinite and Ydoped Ba TiO3 based ER fluids increased with the electrical field. However, the increase of reflection coefficient of Ydoped BaTiO3 based ER fluid was more significant compared with that of TiO2 coated Kaolinite. At the same time, the reflection coefficient of Y doped BaTiO3 ER fluid showed strong dependence on particle volume fraction. There was a critical volume fraction. When the volume fraction was lower than this critical value, the reflection coefficient gradually increased, otherwise the reflection coefficient initially increased and then decreased with electrical field. It was also found that the reflection wave phase of TiO2 coated Kaolinite ER fluid initially increased and reached its maximum value, then declined to a constant. The reflection wave phase of Y doped BaTiO3 ER fluid, however, steadily increased with the electrical field. We considered that the modulatory character of microwave reflection behaviors was attributed to the change in structure, electric properties of ER fluids and dispersed phase under electric field.