Adsorption and Desorption Mechanism of Carboxylate to Alumina Particles

The particle assembling state in a slurry affects the production quality or performance in ceramic industry and so on. Generally, to control the assembling state dispersants are added However, it is difficult to control it precisely because the adsorbing mechanism of dispersants has not been clarified enough. We have tried to make clear the adsorption mechanism of dispersant mainly through the observation of desorption behavior of the adsorbed dispersant. A mono-carboxylate and a polycarboxylate were used as dispersant, and two kinds of pure alumina powder were used : one contains Mg as sintering aid and the other one doesn't. It was found that the hydrophilic carboxyl groups in dispersants adsorbs on alumina particles electrostatically. In addition it was shown that polycarboxylate strongly adsorbs on alumina powder since it has a lot of carboxyl groups in a molecule. Furthermore, when containing Mg into alumina powder, dispersants should associate to Mg on the particle surface, resulting in much stronger adsorption.