Electrophoretic Deposition Characteristics of Alumina Particles in Aqueous Media

抄録

The electrophoretic deposition characteristics of alumina particles in aqueous media were investigated under a constant current condition. The apparent deposition rate and green density of the deposits were dependent on the pH and salt concentration of the suspensions. The isoelectric point (i.e.p.) of alumina in aqueous media was pH 7.9 and no deposition of the particles was observed for the suspension prepared at the i.e.p. As the pH of the suspension slightly decreased from the i.e.p., the deposition rate rapidly increased. The maximum deposition rate was observed at pH 7.0. As the suspension became more acid, the zeta potential of alumina particles increased, however, the deposition rate decreased. At a fixed pH, the higher concentration of the salt, sodium chloride, produced a smaller amount of deposits and the higher solid concentration produced a the larger amount of deposits. The apparent transport number of the surface-charged alumina particles estimated from the total electrical current and deposit weight was low. The predominate carrier of the electric charge in the solvent was considered to be other ions, such as protons.