Modern industry requires multi-dimensional performance design for protective structural materials. Many organisms in nature maintain the mechanical strength required for defense while also achieving camouflage effects. Among these, nacre (mother-of-pearl), thanks to its sophisticated multi-level microstructure, exhibits fracture toughness far beyond that of its constituent components. How to effectively apply this structural design to engineered material systems, however, remains a challenge.
Modern industry requires multidimensional performance design of protective structural materials. In nature, many organisms achieve camouflage effects while maintaining the mechanical strength necessary for defense. Among these, nacre, owing to its sophisticated multi-level microstructure, exhibits fracture toughness far exceeding that of its constituent components. How to effectively apply this structural design to engineered material systems remains a challenge.
In a study published in Advanced Materials, a research team led by Academician YU Shuhong from the University of Science and Technology of China (USTC), affiliated with the Chinese Academy of Sciences, reported an integrated structure-function design for nacre-mimetic alumina (Al₂O₃)-based (NMA) composites. This NMA composite material, alongside unique color tunability and excellent electromagnetic wave transmittance, also combines lightweight, high strength, high toughness and superior impact resistance properties.
The researchers proposed a dual-oxide interfacial design strategy. By creating mineral bridge structures between alumina microplates (MPs), mechanical strength and toughness were significantly enhanced. The chemical composition of the MP interface was controlled through solid-phase reactions to achieve controlled coloration.
Additionally, the researchers prepared a new type of NMA composite through self-assembly and high-temperature sintering. The fracture toughness of this biomimetic composite was found to exceed that of commercial alumina ceramics by more than three times, while the absorbed impact energy reached more than four times that of commercial alumina ceramics.
Considering the favorable structural conditions of NMA composites for electromagnetic (EM) wave transmission, a new design was proposed for EM wave transmission. Through micron-scale wave transmission channels formed by a layered ceramic skeleton and a polymer with low dielectric constant, as well as the perpendicular alignment of the optical axis of single-crystalline aluminum oxide MPs, wave transmission became more efficient.
This study achieves simultaneous enhancement of mechanical properties and EM transmission performance, providing a platform for future applications in aerospace, navigation and electronics fields.
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