All-Ceramic and Elastic Aerogels with Nanofibrous-Granular Binary Synergistic Structure for Thermal Superinsulation

Abstract

High-performance thermally insulating ceramic materials with robust mechanical properties, high-temperature resistance, and excellent thermal insulation characteristics are highly desirable for thermal management systems under extreme conditions. However, the large-scale application of traditional ceramic granular aerogels is still limited by their brittleness and stiff nature, while ceramic fibrous aerogels often display high thermal conductivity. To meet the above requirements, in this study, ceramic nanofibrous-granular composite aerogels with lamellar multiarch cellular structure and leaf-like fibrous-granular binary networks are designed and fabricated. The resulting composite aerogels possess ultralow weight, superelasticity with recoverable compression strain up to 80%, and large mechanical strength. Furthermore, excellent fatigue resistance with 1.2% plastic deformation after 1000 cyclic compressions, temperature-invariant dynamic mechanical stability from −100 to 500 °C, and an operational temperature range from −196 to 1100 °C are successfully achieved in the proposed composites. The nanosized silica granular aerogels are assembled into a leaf-like shape and wrapped around the fibrous cell walls, endowing low thermal conductivity (0.024 W m–1 K–1) as well as favorable high-temperature thermal superinsulation properties. Benefiting from the favorable compatibility, the present strategy for nanofiber-granular composite ceramic aerogels provides a dominant route to produce thermally insulated and mechanically robust composite cellular materials for use in harsh environments.

From 1D Nanofibers to 3D Nanofibrous Aerogels: A Marvellous Evolution of Electrospun SiO2 Nanofibers for Emerging Applications

“…However, the micron-sized pores between the nanofibers in these aerogels did not mitigate the heat transfer of the air, so the insulation performance was not as good as expected. Therefore, Zhang and colleagues further impregnated ZrO 2 -SiO 2 nanofibrous membranes into SiO 2 sol containing SiO 2 nanoparticle aerogels and then obtained the ceramic nanofibers–nanoparticles composite aerogels through the ultrasound-assisted ice-template shaping process [ 171 ]. Benefiting from the lamellar, multi-arched, and leaf-like nanofibrous-granular binary networks of the novel nanofibrous aerogels, the thermal conductivity of ZrO 2 -SiO 2 nanofibrous aerogels was significantly reduced to 0.024 W m −1 k −1 .…”

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Fig. 9 a SEM image of ZrO 2 -SiO 2 nanofibrous aerogel showing its hierarchical structure [ 171 ]. b Schematic demonstration of factors contributing to thermal conductivity of the ZrO 2 -SiO 2 nanofibrous aerogel [ 171 ].

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“…9 a SEM image of ZrO 2 -SiO 2 nanofibrous aerogel showing its hierarchical structure [ 171 ]. b Schematic demonstration of factors contributing to thermal conductivity of the ZrO 2 -SiO 2 nanofibrous aerogel [ 171 ]. c Optical and infrared thermal images showing temperature distributions of the aerogel jetted by a butane flame [ 171 ].…”

“…b Schematic demonstration of factors contributing to thermal conductivity of the ZrO 2 -SiO 2 nanofibrous aerogel [ 171 ]. c Optical and infrared thermal images showing temperature distributions of the aerogel jetted by a butane flame [ 171 ]. Copyright 2022, American Chemical Society.…”

Bubble Templated Flexible Ceramic Nanofiber Aerogels with Cascaded Resonant Cavities for High-Temperature Noise Absorption

“…As high-performance fiber materials, electrospun ceramic nanofibers with the advantages of small fiber diameter (<500 nm), high channel tortuosity, and good temperature resistance (usually >1000 °C) have exhibited great application potential in high-temperature noise absorption. − Unfortunately, electrospun ceramic nanofibers are usually assembled into randomly distributed two-dimensional thin fibrous membranes (thickness <50 μm) caused by their direct deposition characteristics, greatly reducing dissipation paths of acoustic energy. , More recently, newly developed ceramic nanofibrous aerogels, for the advantages of stable inorganic microstructure, superhigh porosity, interlinked porous structure, and tunable density/thickness, have caused extensive concern in the aerospace field . Simultaneously, these comprehensive superiorities also make ceramic nanofibrous aerogels a promising advanced noise-absorbing material, with high sound incidence, large acoustic contact areas, high-temperature resistance, corrosion resistance, and ease of operation .…”