Elastic ceramics Aerogels hold promise as lightweight replacements for thermal insulation. However, poor mechanical stability has hampered progress in moving toward commercialization. Xu et al. designed a mechanical metamaterial that pinches in a small amount when you compress it (see the Perspective by Chhowalla and Jariwala). This is characteristic of materials with a negative Poisson's ratio and dramatically improves mechanical stability. The trick was using three-dimensional graphene structures to template the ceramic aerogels, thus producing a superinsulating material endowed with excellent mechanical properties. Science, this issue p. 723; see also p. 694 Ultralow-density ceramic aerogels have excellent mechanical stability that makes them attractive superinsulating materials. Ceramic aerogels are attractive for thermal insulation but plagued by poor mechanical stability and degradation under thermal shock. In this study, we designed and synthesized hyperbolic architectured ceramic aerogels with nanolayered double-pane walls with a negative Poisson’s ratio (−0.25) and a negative linear thermal expansion coefficient (−1.8 × 10−6 per °C). Our aerogels display robust mechanical and thermal stability and feature ultralow densities down to ~0.1 milligram per cubic centimeter, superelasticity up to 95%, and near-zero strength loss after sharp thermal shocks (275°C per second) or intense thermal stress at 1400°C, as well as ultralow thermal conductivity in vacuum [~2.4 milliwatts per meter-kelvin (mW/m·K)] and in air (~20 mW/m·K). This robust material system is ideal for thermal superinsulation under extreme conditions, such as those encountered by spacecraft.
Double-negative-index ceramic aerogels for thermal superinsulation
Xiang Xu,Qiangqiang Zhang,Menglong Hao,Yuan Hu,Zhaoyang Lin,Lele Peng,Tao Wang,Xuexin Ren,Chen Wang,Zipeng Zhao,Chengzhang Wan,H. Fei,Lei Wang,Jian Zhu,Hongtao Sun,Wenli Chen,T. Du,B. Deng,G. Cheng,I. Shakir,C. Dames,T. Fisher,Xiang Zhang,Hui Li,Yu Huang,X. Duan
Published 2019 in Science
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- Publication year
2019
- Venue
Science
- Publication date
2019-02-14
- Fields of study
Medicine, Materials Science, Engineering
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Semantic Scholar, PubMed
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