The role of electrical conductivity of substrate on the YSZ film formed by EPD for solid oxide fuel cell applications

Thick YSZ (8 mol% Y2O3–ZrO2) films were coated by EPD, which was performed on non-conducting and graphite-coated NiO–YSZ composites. Weights of depositions had depended on the applied voltage linearly for both types of NiO–YSZ composites. In addition, weights of depositions were significantly higher when graphite-coated substrates were used. Uniform and dense depositions were successfully obtained by both methods. Adhesion strength was evaluated by micro hardness testing. However, it was observed that the interfacial adhesion was improved when graphite-coated substrates were used. The qualities of the deposited YSZ films were different after the subsequent sintering and cracks were developed on the surface of sintered YSZ films when non-conducting substrates were used. SEM observations showed that there were thicker YSZ films on the graphite-coated substrates than on the non-conducting ones. After the reduction process, NiO–YSZ composites were altered to Ni–YSZ cermet, which showed a good electrical conductivity all over it.