Investigations on Zeolite-Based ER Fluids Supported by Experimental Design

Abstract

The application of experimental design for determining the influence of various parameters on rheological properties of electrorheological (ER) fluids is demonstrated. Such statistical methods allow the quantitative determination of parameter effects even in the presence of considerable property fluctuations of the ER fluid as well as the calculation of interactions between the parameter effects. They thus provide a powerful optimization tool. Investigations have been performed on ER fluids containing particles of zeolite A in silicone oil. The influence of zeolite content, oil viscosity, particle size, cation composition and ER fluid temperature on the viscosity of ER fluids with and without electric field has been studied. In addition to the main effects of the parameters interactions between them also play a considerable role. The ratio of ER fluid viscosities with and without field, respectively, decreases with rising oil viscosity and increases with temperature. The larger value of the ratio for ER fluids with smaller particles is referred to different particle structures. Results of parameter effects on viscosity of the ER fluid in electric fields depend on the shear rate. Cation exchange of sodium to potassium has only a minor influence on ER activity. This result is compared with cation exchange with calcium, by which ER activity is drastically diminished. The loss of activity can be related to the occupation of different cation sites in zeolite A.