Production and characterization of YSZ tape-cast films using aqueous slurries Tomas Baquero 1, a , Vanessa Amaral de Oliveira 2,b , D. Marinha 2 , J. Frade 3 , E. Antunes 4 , J. Calado 4 , J. Escobar 1 , D. Hotza 2 1 Group of Materials and Manufacture (CIPP-CIPEM), Department of Mechanical Engineering, University of Los Andes, Cra 1 Este No. 19A-40, Bogota, Colombia 2 CERMAT: Group of Ceramic and Glass Materials, Universidade Federal de Santa Catarina, Brasil 3 CICECO: Centre for research in ceramics & composite materials, Universidade de Aveiro, Portugal 4 INNOVNANO, Vale d´Oca, Apart.102, 7601-909 Aljustrel, Portugal a tombaq88@gmail.com, b vanessa.amaoli@gmail.com Keywords: YSZ, SOFC, tape casting, aqueous, electrolytes Abstract. This work was dedicated to the preparation and characterization of 8% yttria- stabilized zirconia (YSZ) films from nanometric synthesized commercial powders. XRD showed that these precursor powders were single phase and nanocrystalline, with composition within the expected range for cubic YSZ. Grain size distribution and area specific measurements confirmed the submicrometer range. Thick (~150 μm) YSZ films were produced by aqueous tape casting to be used as electrolytes for solid oxide fuel cells (SOFC). Rheological characterization was carried out by viscosimetry, zeta-potential and pH measurements. Colloidal stability, slurry pseudoplastic behavior and flexible green tapes were obtained after adequate mixture of additives. Average grain size and porosity levels were determined from SEM imaging of sintered films. Polycrystalline cubic structured phase YSZ composition was confirmed by XRD analysis, and no second-phases were detected. A relationship between starting powders, ceramic suspensions and sintered bodies was established and tape-casting parameters adapted for optimized YSZ tapes. Introduction Solid oxide fuel cells (SOFC) are used to generate electrons from electrochemical reactions catalyzed by ceramic-based materials. Yttria-stabilized zirconia (YSZ) has been widely used as SOFC components [1-3], most commonly as electrolyte material, but also as a second-phase added to electrodes to increase ionic conductivity [1]. YSZ displays high shock-resistance and chemical stability within a wide range of temperature and oxygen partial pressures [4-9]. A current challenge to YSZ-based electrolytes is the relatively high temperatures required to reach and maintain adequate conductivity values (≥ 0.1 S.cm -1 ). YSZ achieves this value near 1000 °C both in bulk and film form. However, such temperature increase operation costs and increase chances of thermal degradation of the components in the device. Several techniques have been used to process YSZ electrolytes [1, 3, 10]. Tape-casting is a well-known method to produce films with very large surface areas. Rheological control of the slurry must be achieved in order to control the final microstructural features of the film. The use of aqueous slurries [11, 12] is preferable to using organic solvents due to the decrease in cost and evident environmental advantages. In this work, aqueous slurries were prepared using commercial YSZ powders (Innovnano, PT). Viscosimetry, zeta-potential and pH measurements were performed to determine optimum additive composition. Smooth and flexible YSZ green tapes with 20 × 20 cm were obtained by