Conch-Shell-Inspired Tough Ceramic

Biological structural materials realize outstanding mechanical properties by assembling hard and soft components into complex hierarchical structures, which provide abundant inspirations for synthetic materials. Specifically, conch shell exhibits around ten times higher toughness than widely-explored nacre due to its cross-lamellar architecture at nano- to macroscopic scales. Previously, conch-shell-inspired materials are realized by 3D-printing. However, it remains challenging to translate the properties of conch shell into synthetic materials because of the limited approaches to duplicating complex architecture with high ceramic contents. Here, a surface-pattern-induced ice-templating strategy is reported to fabricate conch-shell-inspired composites with a cross-lamellar structure across a 10 7 -fold range of length. This is realized by directional freezing on a grooved surface, which has previously been confirmed to induce preferential ice growth. These composites have a flexural strength of 165 MPa and a work of fracture of 8.2 kJ m –2 , which are 2.5 and 2 times, respectively, higher than those of conch shell. Such conch-shell-inspired structure yields a toughness twice that of nacre-mimetic structure due to multiple crack deflections. Additionally, the impact resistance of these composites is comparable to those of aluminum alloys. The research provides a feasible approach to fabricating bioinspired materials with complex architectures and multifunctionality.