AMORPHOUS CERAMICS AS THE PARTICULATE PHASE IN ELECTRORHEOLOGICAL MATERIALS SYSTEMS

Several electrorheological (ER) materials systems composed of amorphou s ceramic powders dispersed in light paraffin oil were developed to de termine if relationships among ER activities, dielectric properties, c ompositions, porosities, and oxide species could be identified. The re sults of the studies suggested that trends among ER activity, dielectr ic phenomena, and alkali metal species existed. The aluminosilicate po wders developed with various alkali metals showed that the ER activity increased as the activation energy decreased. The sodium aluminosilic ate appeared to have the greatest ER activity and the lowest activatio n energy, while the cesium aluminosilicate displayed the weakest ER re sponse, but had the highest activation energy. The thermodielectric re sponses of the different oxide materials systems developed with sodium showed that the mechanisms contributing to the dielectric dispersions had similar activation energies; however, the magnitudes of the recor ded ER activities varied, and thus a direct correlation was not appare nt. In addition, studies conducted with ER materials composed of sodiu m aluminosilicate powders of varying porosities showed that ER activit ies increased with increasing porosity. Furthermore, the analysis of t he results of the thermodielectric and rheological studies of the diff erent amorphous materials ER systems suggested that these materials ma y have an optimal stimulus frequency/temperature for ER activity.