Tahereh Talebi

Electrophoretic Deposition of YSZ Electrolyte on Porous NiO-YSZ Substrate for Solid Oxide Fuel Cells

: In this study a thin dense YSZ film has been fabricated from stable non-aqueous suspensions by Electrophoretic Deposition (EPD) method on a porous pre-sintered NiO-YSZ substrate. Thin film of YSZ and NiO-YSZ composite were used as electrolyte and anode, respectively, in SOFCs that should have certain characteristics. Process parameters like porosity, pre-sintering temperature, voltage and time of deposition have been considered and optimized for obtaining a controlled thickness. After depositing a conductive layer, EPD has been performed on NiO-YSZ composites. These layers were sintered and a crack-free dense thin film of 8 mol % YSZ was obtained on porous NiO-YSZ anode. The interface and adhesion between the two layers was investigated by Scanning Electron Microscope and microstructural observations.

Fabrication of Solid Oxide Fuel Cells (SOFCs) Electrolytes by Electrophoretic Deposition (EPD) and Optimizing the Process

Fabrication of Solid Oxide Fuel Cells (SOFCs) electrolytes by Electrophoretic Deposition (EPD) was the target of our study. For such purpose, thin layers of Yttria Stabilized Zirconia (YSZ) were electrophoritically deposited on pre-sintered NiO-YSZ pellets. A thin graphite film on each pellet was painted to make it conductive and can act as a working electrode for EPD. In this research acetylacetone-ethanol mixture (1:1 by vol.) was selected as the solvent and by applying different electrical fields (25, 50, 75, 100V/cm) in different deposition times (6, 3, 2, 1.5 min respectively), the obtained layers were examined. It was revealed that although electrical field multiplied deposition time remained constant in our experiments, the thicknesses of the deposited films were increased with increasing the applied electrical field which could not be explained easily by the Hamaker equation. For the next step, sintering of the deposited layers which prepared by applying 75 V/cm electrical field during 2 minutes was investigated. It was found that although the sintering processes were activated at 1250oC, 2 hours soaking time was not enough to produce a non-permeable layer. On the contrary, the layer which sintered at 1400oC for 2 hours was dense and crack-free. The thickness of the obtained layer was about 7μm and this layer seemed to be suitable for electrolyte of SOFCs.