Programming self-shaping in ceramics through bio-inspired microstructural design

Reference Presenter Authors
03-040 Rafael Libanori Libanori, R.(ETH Zurich); Bargardi, F.L.(ETH Zurich); Le Ferrand, H.(ETH Zurich); Studart, A.R.(ETH Zurich); Processing of ceramic parts with complex and intricate geometries usually requires the use of laborious and cumbersome fabrication technologies such as machining of pressed powder compacts, in situ coagulation of ceramic slurries, co-firing of cut and glued green bodies, and additive manufacturing. Inspired by the preferential alignment of cellulose fibrils of bilayer microstructures found in the plant kingdom, we demonstrate that self-shaping can be implemented in ceramic parts by preprogramming the green body’s microstructure to undergo local anisotropic shrinkage during the sintering process. Such anisotropic shrinkage is achieved by modifying the microstructure of ceramic green bodies through magnetic bi-axial alignment of functionalized micron-sized ceramic platelets that are co-suspended with ceramic nanoparticles in an aqueous slurry. The preferential alignment of the ceramic platelets is subsequently consolidated through an established in situ coagulation technique that uses an enzyme-catalyzed reaction. By fabricating ceramic green bodies exhibiting preprogrammed bilayer architectures, we obtain deliberate control over shape change during the densification process. Bending, twisting or combinations of these two basic movements can be successfully implemented to obtain a myriad of complex shapes. The simplicity and the universality of such a bottom-up shaping method makes it attractive for applications that would benefit from low-waste ceramic fabrication, temperature-resistant interlocking structures or unusual geometries not accessible using conventional top–down manufacturing.
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