Resilient Si₃N₄ Nanobelt Aerogel as Fire-Resistant and Electromagnetic Wave-Transparent Thermal Insulator

Abstract

With the prevailing energy challenges and the rapid development of aerospace engineering, high-performance thermal insulators with various functions are attracting more and more attention. Ceramic aerogels are promising candidates for thermal insulators to be applied in harsh environments because of their low thermal conductivity and simultaneously excellent thermal and chemical stabilities. In general, the effective properties of this class of materials depend on both their microstructures and the intrinsic properties of their building blocks. Herein, to enrich the family and broaden the application fields of this class of materials, we prepared ultralight α-Si 3 N 4 nanobelt aerogels (NBAs) with tunable densities ranging from 1.8 to 9.6 mg cm −3 . The α-Si 3 N 4 NBA realized resilient compressibility (with a recoverable strain of 40−80%), fire resistance (1200 °C butane blow torch), thermal insulation (0.029 W m −1 K −1 ), and electronic wave transparency (a dielectric constant of 1−1.04 and a dielectric loss of 0.001−0.004) in one material, which makes it a promising candidate for mechanical energy dissipative, fire-resistant, and electronic wavetransparent thermal insulator to be applied in extreme conditions. The successful preparation of such resilient and multifunctional α-Si 3 N 4 NBAs will open up a new world for the development and widespread applications of ceramic aerogels.

Interweaved Cellular Structured Ceramic Nanofibrous Aerogels with Superior Bendability and Compressibility

“…[ 3 ] Recently, a wealth of research on 3D ceramic materials constructing by using 1D fibrous structures as building block has turned up. Thus far, ceramic aerogels with improved structural integrity and compressibility have been developed using SiC nanowires, [ 4 ] Si 3 N 4 nanobelts, [ 5 ] Al 2 O 3 nanotubes, [ 6 ] boron nitride (BN) nanoribbons, [ 7 ] and ceramic oxide (TiO 2 , ZrO 2, SiO 2 ‐Al 2 O 3 , and BaTiO 3 ) nanofibers. [ 8 ] The 3D self‐supportive structure consisting of continuous basic units would enhance the inherent mechanical properties of materials.…”

Facile and Green Strategy for Designing Ultralight, Flexible, and Multifunctional PVA Nanofiber‐Based Aerogels

“…Aerogels are solid, lightweight, open‐celled, porous materials. In view of their low density, high porosity, large specific surface area, low dielectric constant, and high thermal resistance,[1,2] they have been widely applied in thermal,[3–6] catalytic,[7–10] electrical,[11] environmental,[1,12–14] and energy applications. [15–17] Since SiO 2 aerogels were first produced in the 1930s,[18] the development of superinsulating and ultralight materials based on inorganic aerogels—such as boron nitride,[2,19] silicon carbide,[20,21] boehmite,[22] and titanium dioxide[23]—has received significant attention.…”

Stretchable and Compressible Si3N4 Nanofiber Sponge with Aligned Microstructure for Highly Efficient Particulate Matter Filtration under High‐Velocity Airflow

“…Considering all of these factors, we developed an ultralight, stretchable, compressible, and thermally stable Si 3 N 4 nanofiber sponge (Si 3 N 4 NFS) for high-performance filtration media via a chemical vapor deposition (CVD) method (Figure 1c). [27] The Si 3 N 4 NFS showed a highly porous 3D microstructure that was made of ultralong and highly aligned Si 3 N 4 nanofibers. It exhibits a temperature-invariant reversible stretchability at a tensile strain of 10%, the largest stretchability at 28%, and reversible compressibility at a compressive strain of 50%.…”