Deflocculation of Alumina Suspensions Using Polyelectrolyte Dispersants

摘要

In this paper, the dispersing abilities of three polyelectrolytes, poly (acrylic acid), poly (acrylic acid-co-acrylate), and a four-member copolymer containing various anionic functional groups were tested for aqueous Al_2O_3 suspensions. The influence of the dispersants on the surface charge of the powder was evaluated by measuring the zeta potential in dilute Al_2O_3 suspensions. It was found that all the three dispersants shifted the isoelectric point to a lower pH value. Rheological measurements showed that the four-member dispersant decreased the viscosity in the widest pH range, which should be ascribed to the synergistic effect of different functional groups. The 58vol% concentrated Al_2O_3 slurry using the four-member dispersant was further consolidated using gel casting and was fully sintered at 1600℃.