Probing the mechanism by which ceramic dispersants act

Herein is described our efforts to better understand the mechanisms that control the interactions between stabilised ceramic powders. To this end we have employed two distinct experimental techniques, rheology and atomic force microscopy (AFM). The two techniques have been used in conjunction here for the specific task of examining the effects of Darvan C, a polyelectrolyte on the dispersability of an alumina powder. The AFM technique enables one to obtain information concerning the interaction between alumina particles. The results showed that at a pH of 6.0 the interactions between alumina particles are attractive, but in the presence of Darvan C the interactions are repulsive. This gives rise to a suspension of alumina particles having a markedly lower viscosity 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.