Electrophoretic deposition of aqueous alumina slips

Electrophoretic deposition (EPD) of aqueous alumina slips on a graphite electrode is studied The suspension is characterized in terms of viscosity, zeta potential and conductivity. The conductivity has proved to be a determining parameter for obtaining deposits. Well-dispersed slips having an adequate value of conductivity are used for constant current density experiments. Current densities of 1.6 to 12.8 mA cm(-2) are applied for 10 min. After defining the optimal slip properties for the deposition, both the process development and the final properties of the materials obtained depend on the current/time relationship. Alumina deposits obtained at different current densities are characterized. The best conditions for obtaining uniform and dense coatings are 6.4 mA cm(-2) far up to 10 min. The applied current allows cm not only to modify the properties and microstructure of the deposit, but also to increase the margin of slip conductivity assuring the success of the EPD process, that is, the working conditions. (C) 1997 Elsevier Science Limited All rights reserved.