Innovative aqueous alumina mixtures using eco-friendly additives for micro-extrusion and tape casting

Reference Presenter Authors
(Institution)
Abstract
13-016 Julie Bourret Bourret, J.(IRCER, European Ceramic Center, UMR CNRS 7315, Université de Limoges); Marie, J.(IRCER, European Ceramic Center, UMR CNRS 7315, Université de Limoges); Geffroy, P.(IRCER, European Ceramic Center, UMR CNRS 7315, Université de Limoges); El Younsi, I.(IRCER, European Ceramic Center, UMR CNRS 7315, Université de Limoges); Chartier, T.(IRCER, European Ceramic Center, UMR CNRS 7315, Université de Limoges); Pateloup, V.(IRCER, European Ceramic Center, UMR CNRS 7315, Université de Limoges); Smith, A.(IRCER, European Ceramic Center, UMR CNRS 7315, Université de Limoges); Chaleix, V.(IRCER, European Ceramic Center, UMR CNRS 7315, Université de Limoges); Bienia, M.(IRCER, European Ceramic Center, UMR CNRS 7315, Université de Limoges); To be shaped, alumina must be combined with additives (solvent, binder, dispersant ...) and constitute a mixture (slip, paste or pellets) whose rheological behavior is adapted to the chosen manufacturing process. In many ceramic applications, the used additives are still often derived from petrochemicals. In order to develop processes that respect the principles of green chemistry, it is important to focus on the substitution of these additives with products of natural origin and with a low environmental impact. This substitution can have consequences on the rheological behavior of the prepared mixtures, on the feasibility of the processes and on the final structural and microstructural properties of the sintered products. These issues are presented here through two shaping processes: tape casting and micro-extrusion. Concentrated slips and pastes (respectively 40 and 50% vol) are made in an aqueous medium containing bio-sourced dispersants and / or binders, having undergone little or no chemical transformation. Their rheological properties are studied according to the composition and the age of the slips/pastes or the order of introduction of the different components. These properties are then related to the feasibility of the process as well as the structure, the microstructure and the mechanical properties of the products after their consolidation by heat treatment. Thus, cubic porous networks of alumina and natural binders were made by micro-extrusion from 400 ?m in diameter cords. In addition, green tapes having sufficient mechanical strength for handling were also prepared by tape casting from suspensions containing eco-friendly binders and dispersants. These early works show that products of various geometrical shapes can be made from innovative ceramic mixtures containing eco-friendly additives, while having satisfactory structural and mechanical properties.
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