The influence of nanoparticle aggregation on formation of ZrO2 electrolyte thin films by electrophoretic deposition

The paper presents the results of the studies of electrically stabilized nonaqueous suspensions of ZrO2 stabilized by Y2O3 (YSZ) nanoparticles with an average diameter of 11 nm for the formation of green films of electrolyte for solid oxide fuel cells. Nanoparticles were de-aggregated to different degrees, which were provided by the ultrasonic treatment and the centrifugation, and monitored by the dynamic light scattering. YSZ green thin films were obtained by the electrophoretic deposition (EPD) on dense lanthanum strontium manganite cathodes using suspensions with the average diameter of aggregates: 107; 66; 53 nm. To investigate the possibilities of EPD we used the model drying of the same suspensions cast upon the same substrates. It was shown that the structure and the morphology of the green films obtained by EPD was different compared to the films prepared by the model drying of the suspension. The drying of the stable suspension resulted in the formation of loose aggregates on the surface. The efficient packing of electrically stabilized particles was prevented by the forces of electrostatic repulsion between them. In the case of EPD the electrocoagulation of particles near the cathode takes place with the formation of dense aggregates. As a result, uncharged spherical aggregates with an average size of about 100-200 nm settle on the surface of the cathode and pack into a uniform dense coating suitable for the subsequent sintering of a gas-tight coating for the solid YSZ electrolyte. (C) 2016 Elsevier B.V. All rights reserved.