Insulating and Robust Ceramic Nanorod Aerogels with High-Temperature Resistance over 1400 °C

Abstract

Ceramic aerogels, which present a unique combination of low thermal conductivity and excellent high-temperature stability, are attractive for thermal insulation under extreme conditions. However, most ceramic aerogels are constructed by oxide ceramic nanoparticles and thus are usually plagued by their brittleness and structural collapse at elevated temperatures (less than 1000 °C). Despite great progress achieved in this regard recently, it still remains a big challenge to design and fabricate intriguing ceramic aerogels with enhanced mechanical strength and remarkable thermal stability at ultrahigh temperature up to 1400 °C. To this end, we herein report a facile and scalable strategy to manufacture ceramic nanorod aerogels (CNRAs) with hierarchically macroporous and mesoporous structures by the controllable assembly of Al2O3 nanorods and SiO2 nanoparticles. Subsequently, the high-temperature annealing treatment of CNRAs significantly maximizes mechanical strength and promotes thermal tolerance. The obtained CNRAs demonstrate the integrated properties of super-strong heat resistance (up to 1400 °C), low thermal conductivity (0.026 W/m·K at 25 °C and 0.089 W/m·K at 1200 °C), high mechanical robustness (compressive strength 1.5 MPa), and low density (0.146 g/cm3). We envision that this novel nanorod-assembled ceramic aerogels offer considerable advantages than most of the state-of-the-art ceramic aerogels for thermal superinsulation upon exposure to extremely harsh environments.

Hypocrystalline ceramic aerogels for thermal insulation at extreme conditions

“…Studies so far have shown that the mechanical properties of ceramic aerogels can be considerably enhanced through elaborate structural engineering 1,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] . For example, ceramic aerogels constructed from one-dimensional fibres can form a flexible porous framework by physical twining or chemical bonding, which can result in not only compression elasticity but also, more importantly, additional stretchability and bendability 21,22 .…”

Design, Synthesis, and Use of High Temperature Resistant Aerogels Exceeding 800 oC

“…For ceramic aerogel, the thermal conductivity of polycrystalline structure is lower than that of single crystal structure, because in polycrystalline, the crystal grain size is small, there are many grain boundaries and defects. [71,72] The thermal conduction phonons are easy to scatter so the thermal conductivity is lower. As temperature rises, the difference becomes more pronounced.…”

Versatile Thermal‐Solidifying Direct‐Write Assembly towards Heat‐Resistant 3D‐Printed Ceramic Aerogels for Thermal Insulation

“…[1][2][3][4] These exceptional performances make ceramic aerogels attractive candidates for multi-applications such as thermal insulation, catalysis, filtration, environmental remediation, energy storage, etc. [5][6][7][8][9][10] However, conventional ceramic aerogels appear intrinsic brittleness in the process of shaping and machining, which is mainly due to the narrow neck connection of interparticle resorcinol-formaldehyde inks, in which a hydrochloric acid solution was applied to help inks to realize solidification. Yuan et al [25] fabricated 3D carbon aerogel micro-lattices via the fast freeze of deposited graphene oxide/polymer inks in a liquid nitrogen atmosphere.…”

“…[ 1–4 ] These exceptional performances make ceramic aerogels attractive candidates for multi‐applications such as thermal insulation, catalysis, filtration, environmental remediation, energy storage, etc. [ 5–10 ] However, conventional ceramic aerogels appear intrinsic brittleness in the process of shaping and machining, which is mainly due to the narrow neck connection of interparticle in the pearl‐chain‐like networks. Thus, it remains challenging to obtain the custom‐designed architectures and geometries of ceramic aerogels based on subtractive manufacturing.…”