ELECTROKINETIC BEHAVIOR AND DISPERSION CHARACTERISTICS OF CERAMIC POWDERS WITH CATIONIC AND ANIONIC POLYELECTROLYTES

Three different ceramic powders, viz. alumina, zirconia and silicon ni tride were dispersed using two polyelectrolytes, one cationic (Betz 11 90) and the other anionic (Darvan-C). All powders examined during the study could be well dispersed only under conditions of polymer dosage and pH such that the working pH is at least 2 pH units away from the p H(IEP) of the powder-dispersant combination. The shift in the isoelect ric point (IEP) of the powders were determined through electro-acousti c measurements on 1% volume suspensions. Specific free energy of inter action were also computed using a model based on the electrical double layer theory of surfactant absorption.