In the last years many efforts have been spent to develop colloidal processes that use water instead of organic solvents. The aim of this study was to develop aqueous tape casting systems to produce zirconia tapes. Different types of binder were tested. Rheological properties of the slurries were measured at room temperature. The slurries were cast on a PET carrier with/without a silicone-based coating. Interactions between the slurry and the polymeric substrate were evaluated. It was found that an acrylic binder is more appropriate for colloidal processing. The acrylic-based suspensions showed a pseudoplastic behavior and remained stable after hours. Tapes with thicknesses between 90 and 200 µm were produced. Optimized tapes showed smooth and homogeneous surfaces and adequate plasticity.
Dense electrolytes and flawless laminated YSZ electrolytes can be produce combining aqueous tape casting and constrained calendering. During calendering two or more layers are laminated continuously and the edges (entering and final) are not sealed at the same time avoiding air bubbles to trap between the layers. In this study constrained calendering laminates showed adequate adhesion between layers, and almost 20% thickness reduction after sintering as well as high green and sintered densities.
The potential of a natural Mexican zeolite from the northern state of Sonora as microfiltration membranes was evaluated. The zeolite was characterized by x-ray diffraction, scanning electron microscopy (SEM), N2 physisorption and thermal analysis. Clinoptilolite and heulandite were the main components of the zeolite. The crystallinity of this material was confirmed. Two steps made up the manufacturing process of porous membranes: pressing and sintering. It was necessary to use lubricants and agglomerants with different particle size of the zeolite. The best properties of the porous membranes were obtained using zinc stearate (4 wt%) as lubricant, boehmite (15 wt%) as agglomerant and the best particle size ranged from 63 to 300 µm. Moreover it was observed that the zeolite granule distribution improved the press of the materials by approximately 10% in the distribution proposed. The thermal treatment of the porous membranes was carried out at several temperatures (500–1000 °C). The porous membranes obtained were characterized by x-ray diffraction, scanning electron microscopy and N2 physisorption to study the global porosity, phase transformations and pore size distribution. A loss of crystallinity, decreased porosity and a lower specific surface area were found when the sintering temperature was increased. The results of pore distribution suggest that these materials are porous membranes for microfiltration.
Aqueous tape casting was used to produce yttria-stabilized zirconia films for electrolyte-supported solid oxide fuel cell (SOFC). Tape casting slurries were prepared varying the binder content between 20 and 25 wt%. A commercial acrylic emulsion served as binder. Rheological measurements of the two slurries were performed. Both slurries showed a shear-thinning behavior. Tapes with 25 wt% binder exhibited adequate flexibility and a smooth and homogeneous surface, free of cracks and other defects. Suitable conditions of lamination were found and a theoretical density of 54% in the laminates was achieved. Laminated tapes showed higher tensile strength compared to single sheets. Tape orientation has a significant influence on the mechanical properties. Tensile strength, elongation to strain, and Young’s modulus measured in samples produced in the direction of casting showed higher property values.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.