Papers by Keyword: Nonaqueous Suspension

Abstract: We have studied the processing of lead-zirconate-titanate PbZr0.53Ti0.47O3 (denoted PZT) based thick films using an electrophoretic deposition (EPD) process in order to obtain the active film with desired thickness and porosity at low the sintering temperature. The colloidal suspensions were prepared by mixing the ceramic powder in ethanol with the controlled addition of a polyelectrolyte salt and an organic base. In order to optimise the deposition process, the stability of the PZT and Pb5Ge3O11 (denoted PGO) particles in ethanol-based suspensions was studied. The electrophoretic deposition of PZT-PGO was performed from a mixture of optimal PZT and PGO suspensions in an appropriate molar ratio. PZT and PGO acting as a sintering aid were deposited on an Al2O3/Au substrate at a constant applied current and sintered at 850 oC. The thickness of the deposit was controlled by the deposition time and the applied current. PZT-PGO thick films deposited at 1.2 mA for 60 seconds and sintered at 850oC for 8 hours exhibited a room-temperature dielectric permittivity of 1050, dielectric losses of 0.038, a remanent polarisation Pr of 29 C/cm2, a coercive field Ec of 21 kV/cm and a d33 of 97pC/N.

Abstract: In the present contribution, the electrophoretic deposition (EPD) of nanocrystalline SiC powders will be discussed. In order to avoid the electrolysis of water during deposition as well as oxygen uptake of the nanocrystalline SiC by hydrolysis reactions, nonaqueous solvents were tested including ethanol and diethyl formamide. The solvents were compared regarding their effect on particle size distributions and sedimentation tests. Auxiliary information on the surface conditions as a function of the acidity of the suspension was drawn from aqueous zeta-potential measurements. The influence of dispersants, binders and the type of powder on the suspension properties was studied, and EPD was performed. For promising solvent-dispersant systems, the film thickness, current and deposition time at a given voltage were monitored during EPD.