Resilient Si 3N 4@SiO 2 nanowire aerogel for high-temperature electromagnetic wave transparency and thermal insulation
Journal of Advanced Ceramics(2023)
摘要
With the development of aerospace technology, the Mach number of aircraft continues to increase, which puts forward higher performance requirements for high-temperature wave-transparent materials. Silicon nitride has excellent mechanical properties, high-temperature stability, and oxidation resistance, but its brittleness and high dielectric constant impede its practical applications. Herein, by employing a template-assisted precursor pyrolysis method, we prepared a class of Si3N4@SiO2 nanowires aerogels (Si3N4@SiO2 NWAGs) that are assembled by Si3N4@SiO2 nanowires with diameters ranging from 386 nm to 631 nm. The Si3N4@SiO2 NWAGs have low densities (12-31 mg·cm-3), a specific surface aerogel of 4.13 m2g-1, and an average pore size of 68.9 μm. Mechanical properties characterization shows that the aerogels exhibit reversible compressibility from 60% compressive strain and good fatigue resistance even when being compressed for 100 times at a set strain of 20%. The aerogels also show good thermal insulation performance (0.032 W·m-1K-1 at room temperature), ablation resistance (butane blow torch), and high-temperature stability (maximum service temperature in the air over 1200 °C). The dielectric constant and loss of the aerogels are 1.02-1.06 and 4.3× 10-5-1.4×10-3 at room temperature, respectively. The combination of the good mechanical, thermal, and dielectric properties makes Si3N4@SiO2 NWAG a promising ultralight wave-transparent and thermally insulating material for application at high temperatures.
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关键词
nanowire aerogel,thermal insulation,electromagnetic wave transparency,resilient,high-temperature
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