Carbon aerogel is a kind of materials that can maintain mechanical stability in extremely high temperature (above 2000℃). It can be used in such as defense, energy and intelligent sensing. But, its brittleness limits its further applications. In recent years, researchers have successively developed aerogels with compressive resilience by using flexible nanostructures such as graphene, carbon nanofibers and carbon nanotubes as the basic constituent units. However, its compression strength is generally low (a few to hundreds of kPa) and the load bearing is insufficient. Usually, improving the load bearing of a aerogel is often accompanied by the decrease of its deformation capacity. Therefore, how to solve the contradiction between high bearing capacity and resilience, and thus further improve the comprehensive mechanical properties of carbon aerogels, is still a huge challenge.
Recently, the team of prof. Wang Hongjie from the School of Materials of Xi'an Jiaotong University took the silicon-based ceramic aerogel as raw material, and used chemical vapor deposition to develop a highly cross-linked, lamellar carbon aerogel composed of sp2-sp3 hybrid carbon tubes. The interlocking three-dimensional network structure of the aerogel facilitate the deformation of elastic struts, which can effectively avoid the structural damage caused by the local stress concentration during compression. In addition, the local sp3 bond in the carbon tubes can suppress the relative slippage caused by the weak van der Waals bond between the walls to some extent, thus improving the stability and stiffness of the tubes. Therefore, the aerogel (with a density of only ~12-40 m g/cm3) not only demonstrates excellent compressive resilience (completely recoverable strain up to 99%), but also exhibits high bearing capacity (maximum compressive stress above 20MPa) and fatigue resistance (less than 1.5% permanent degradation after1000cycles at 99% strain). Moreover, it is thermally stable up to 2500 °C in an Ar atmosphere. These properties make it valuable in extreme environments.
The work has been published online in Nature Communications under the title "highly cross-linked carbon tube aerogels with enhanced elasticity and fatigue resistance". Lei Zhuang from the School of Materials, Xi'an Jiaotong University, is the first author of the paper, and Hongjie Wang is the corresponding author. This work was supported by the National Natural Science Foundation of China (92263204, 52102077, and 52072294).
Link: https://doi.org/10.1038/s41467-023-38664-6
