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Radial-Concentric Freeze Casting Inspired by Porcupine Fish Spines

Materials Science and Engineering Program, University of California San Diego, La Jolla, CA 92093-0418, USA
Department of Structural Engineering, University of California San Diego, La Jolla, CA 92093-0085, USA
Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093-0411, USA
Author to whom correspondence should be addressed.
Both authors contributed equally to this work.
Ceramics 2019, 2(1), 161-179;
Received: 30 January 2019 / Revised: 28 February 2019 / Accepted: 1 March 2019 / Published: 6 March 2019
(This article belongs to the Special Issue Ice-Templated and Freeze-Cast Ceramics)
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Freeze casting is a technique used to manufacture porous ceramics with aligned microstructures. In conventional freeze casting, these microstructures are aligned along a single direction of freezing. However, a caveat to these ceramics has been their ensuing lack of strength and toughness due to their high porosity, especially in the direction orthogonal to the direction of alignment. In this work, a novel freezing casting method referred to as “radial-concentric freeze casting” is presented, which takes its inspiration from the radially and concentrically aligned structure of the defensive spines of the porcupine fish. The method builds off the radial freeze casting method, in which the microstructure is aligned radially, and imposes a concentric alignment. Axial compression and Brazilian tests were performed to obtain axial compressive strengths, axial compressive moduli, and splitting tensile strengths of freeze cast samples with and without epoxy infiltration. Notably, radial-concentric freeze cast samples had the greatest improvements in axial compressive modulus and splitting tensile strength with infiltration, when compared against the changes in mechanical properties of conventional and radial freeze cast ceramics with infiltration. These results provide further evidence for the importance of structure in multiphase materials and the possibility of enhancing mechanical properties through the controlled alignment of microstructures. View Full-Text
Keywords: freeze casting; bioinspired materials; porous ceramics freeze casting; bioinspired materials; porous ceramics

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Su, F.Y.; Mok, J.R.; McKittrick, J. Radial-Concentric Freeze Casting Inspired by Porcupine Fish Spines. Ceramics 2019, 2, 161-179.

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