Application of the charge regulation model to the colloidal processing of ceramics

We implement competitive adsorption of ions in the charge regulation (CR) model to describe several aspects of the interaction and compaction behavior of ceramic particles. This model shows that there is an electrostatic origin to the experimental observation that the compaction of particles to high volume fractions can still result in a body of nontouching particles that exhibits fluidlike theological behavior. Analytical expressions based on the model describe the influence of pH and ionic strength on the pressure needed to force particles into touching contact. The model predicts a weakly attractive but nontouching particle network when sufficient salt is added, in agreement with experiments. The CR model further predicts that when salt is added to a dispersed particle network, surface dipoles of the indifferent co-ion will make up much of the surface sites; the fraction of dipoles increases slightly when opposing surfaces approach one another and eventually discharge when they touch.