Rheological Analysis of Concentrated Zirconia Pastes with Ethyl Cellulose for Screen Printing SOFC Electrolyte Films
Concentrated zirconia pastes require optimization before they can be used in large-scale screen-printing processes in solid oxide fuel cells (SOFC) manufacture. The present article investigates a series of terpineol-based zirconia pastes stabilized with ethyl cellulose of varying concentrations by combined rheological methods. Small additions of ethyl cellulose (up to 0.50 vol%) resulted in a significant increase in the shear viscosity, shear stress, and network strength of the pastes. In comparison with the properties of the ink vehicles, the observed elastic response of the ink pastes on the initiation of flow was attributed to the interaction of ethyl cellulose with the zirconia particles. This interaction was confirmed to be bridging flocculation by rheological methods. Start-up shear flow experiments assessed the elastic deformation of the pastes in greater detail. Application of transient network theory (TNT) to describe the properties of the pastes was confirmed by the linear dependence of the equilibrium shear modulus (G∞) with increasing ethyl cellulose concentration. TNT provides a basis for explaining the rheological effects of bridging polymers in network suspensions and assessing their interaction with other organic additives in high solids volume suspensions. This is a useful analysis for optimizing suspensions for screen-printing SOFC components among other applications.
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Document Type: Research Article
Affiliations: Risø National Laboratory for Sustainable Energy, Department of Fuel Cells and Solid State Chemistry, Technical University of Denmark, DK-4000, Roskilde, Denmark
Publication date: 01 July 2008