The Study Of Scandia Stabilized Zircoina Powder Material Preparation Process

Scandia stabilized zirconia (ScSZ) has become preferred electrolyte materials in medium temperature solid oxide fuel cell (SOFC) for its excellent oxygen ionic conduction performance. In recent years, the development of the medium temperature SOFC technology in the United States and Japan promotes the application of ScSZ powder. However, the study of the ScSZ powder preparation techniques is insufficient at home and abroad, the domestic products has many disadvantages, such as the low electrical conductivity, the unstable batch, and the commercialization ScSZ powder is mainly offered by Japan’s first rare element company. Therefore, developing high performance ScSZ powder materials preparation and studying its synthetic process mechanism is significance.This paper adopted coprecipitation method to synthesis ScSZ precursors under chloride system which was easy to industrialization. The high temperature pyrolysis method and microwave hydrothermal method were studied for ScSZ precursors respectively. The main research contents and results were as follows:(1) The influence of pH value of zirconium compounds on precipitation system were studied, the results showed that with the increasing of pH value, hard reunion phenomenon of powder gradually increased, the uniformity of a particle size increased as well. We explained the phenomenon reasonably by quoting electronic structure theory;(2) The influence of pH value of scandium compounds on precipitation system were studied, the results showed that the existence of Sc(OH)2.6Cl0.4-H20at the lower pH value which hindering the growth of precursor y-ScOOH.nH2O,with the increasing of pH value of the impact gradually weakened;(3) Based on the above research, combined with the mixed precipitation system Ksp and Zeta potential, determined the mixed system of precipitation pH between8-9.The process of coprecipitation were monitored using online particle analysis system FBRM and PVM for real-time image and particle size analysis, the reaction system mainly occurred amorphous precipitate. The crystal growth on one dimensional direction at high temperature aging process, but the crystal structure is not stable for crystal collapsed into amorphous type after drying.(4) The ScSZ precursor was studied using the microwave hydrothermal method and high temperature pyrolysis method. By different microwave hydrothermal conditions exploration, we can acquired good crystallinity and high specific surface area of powders, which D50was about6.1μm, particle size distribution (D90-D10)/2D50closed to1.0at the temperature150℃during2.5h after adding mineralizer preparation. High temperature decomposition method results showed that the calcination temperature was fixed at420℃～1000℃, cubic phase structure can be obtained. Powder’s particle size became smaller and uniform distribution, the conductivity was bigger than160ms/cm after ball grinded, the conductivity was enhanced to180.25ms/cm by secondary resintering. The particle size and conductivity of the powder by microwave hydrothermal method were inferior to the powder by pyrolysis and the ball milling, but making consideration of the energy consumption, microwave hydrothermal method in preparation of ScSZ powder material still has great development potential.(5) Compared with the commercialization ScSZ powder, the ScSZ powder,which was prepared by coprecipitation-pyrolysis process,was better than domestic powder and slightly inferior to Japan’s first rare elements on the phase structure and microstructure, the conductivity performance can meet the application requirements of SOFC under the condition of the medium temperature.