State Key Laboratory of High Performance Ceramics & Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.
Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.
ACS Nano. 2023 Jul 11;17(13):12673-12683. doi: 10.1021/acsnano.3c03332. Epub 2023 Jun 28.
The custom design of lightweight cellular materials is widely concerned due to effectively improved mechanical properties and functional applications. However, the strength attenuation and brittleness behavior hinder honeycomb structure design for the ceramic monolith. Herein, the ceramic matrix composite metamaterial (CCM) with a negative Poisson's ratio and high specific strength, exhibiting superelasticity, stability, and high compressive strength, is customized by combining centripetal freeze-casting and hierarchical structures. CCM maintains a negative Poisson's ratio response under compression with the lowest value reaching -0.16, and the relationship between CCM's specific modulus and density is ∼ ρ, which indicates the mechanical metamaterial characteristic of high specific strength. In addition to the extraordinary mechanical performance endowed by hierarchical structures, the CCM exhibits excellent thermal insulation and electromagnetic interference shielding properties, in which the thermal conductivity is 30.62 mW·m·K and the electromagnetic interference (EMI) shielding efficiency (SE) reaches 40 dB at room temperature. The specific EMI shielding efficiency divided by thickness (SSE/) of CCM can reach 9416 dB·cm·g at 700 °C due to its stability at elevated temperatures, which is 100 times higher than that of traditional ceramic matrix composites. Moreover, the designed hierarchical structure and metamaterial properties provide a potential scheme to implement cellular materials with collaborative optimization in structure and function.
由于能够有效提高机械性能和功能应用，因此定制轻量化多孔材料受到了广泛关注。然而，陶瓷整体式蜂窝结构的强度衰减和脆性行为阻碍了其设计。本文通过离心冷冻铸造和分级结构相结合，定制了具有负泊松比和高比强度的陶瓷基复合材料超材料（CCM），具有超弹性、稳定性和高抗压强度。CCM 在压缩下保持负泊松比响应，最低值达到-0.16，CCM 的比模量与密度的关系为∼ρ，这表明了其具有高比强度的力学超材料特性。除了分级结构赋予的非凡机械性能外，CCM 还表现出优异的隔热和电磁干扰屏蔽性能，其热导率为 30.62 mW·m·K，室温下电磁干扰（EMI）屏蔽效率（SE）达到 40 dB。由于其在高温下的稳定性，CCM 的特定 EMI 屏蔽效率与厚度之比（SSE/）在 700°C 时可达到 9416 dB·cm·g，是传统陶瓷基复合材料的 100 倍。此外，设计的分级结构和超材料特性为实现协同优化结构和功能的多孔材料提供了潜在方案。
