| Summary: | 碩士 === 南台科技大學 === 化學工程與材枓工程系 === 98 === In this study, we will prepare a thin and dense SDC electrolyte on porous NiO-SDC anode-supported substrate to improve the conductivity for solid oxide fuel cell(SOFC) by electrophoretic deposition(EPD), because EPD is easy to control the shape of SDC film. Exploring the effect of deposition rate and deposition structure upon deposition behavior and electric performance of SDC electrolyte by changing the voltage, deposition time and pH value.
The SDC(Samarium doped Ceria) powder is prepared by hydrothermal method and dispersed in ethanol solvent. The uncharged SDC powder will adsorb H+ protons to charge to carry out EPD successfully by the use of nitric acid to adjust pH value. To prepare a high sintering characteristic and high ionic conductivity SDC electrolyte on the porous NiO-SDC anode-supported substrate. By adding starch to improve the porosity of NiO-SDC anode-supported substrate, it has no enough porosity when the adding of starch is below 10 wt% ; but the porosity is too high when adding of starch is over 25 wt%, the best condition is 20 wt%.
The pH value of suspension has obvious effect upon surface charge of SDC particle. When pH value is below 4.0, the SDC particles have higher positive charge,.SDC thin film can’t deposit on the substrate when pH = 2.5~4.0, the suit deposition pH range is 2.5~4.0. The best deposition pH value is pH=3.0 . The thickness of SDC electrolyte film increases with increasing deposition time; in the same deposition time, it increases with increasing deposition voltage. We observed that growing rate of SDC thin film is very intense about 6 minutes ago and the thickness grow slowly in 6 minutes later. It has no any deposition of film below 10 V, the deposition rate increases with increasing deposition voltage. The result exhibited that SDC thin film could obtain denser substrate in 30V~50V.
In electric performance, impedance of SDC electrolyte film increases with increasing deposition voltage. The best electric conductivity of 0.0877Scm-1 were attained with 50V deposition condition at 800℃.
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