PROBING THE MECHANISM BY WHICH CERAMIC DISPERSANTS ACT

Herein is described our efforts to better understand the mechanisms th at control the interactions between stabilised ceramic powders. To thi s end we have employed two distinct experimental techniques, rheology and atomic force microscopy (AFM). The two techniques have been used i n conjunction here for the specific task of examining the effects of D arvan C, a polyelectrolyte on the dispersability of an alumina powder. The AFM technique enables one to obtain information concerning the in teraction between alumina particles. The results showed that at a pH o f 6.0 the interactions between alumina particles are attractive, but i n the presence of Darvan C the interactions are repulsive. This gives rise to a suspension of alumina particles having a markedly lower visc osity in the presence of Darvan C. Similar effects were also found at pH values away from the isoelectric point of the alumina, where there is also a repulsive interaction between the particles.