Thermal stable, fire-resistant and high strength SiBNO fiber/SiO2 aerogel composites with excellent thermal insulation and wave-transparent performances

Abstract

The radome and antenna windows of aerospace aircrafts highly require multifunctional materials that are thermal stable, capable of wave-transparent and have excellent thermal insulation performance. Due to the SiO2 aerogel with high thermal stability, low dielectric constant and ultralow thermal conductivity, they are considered as promising high-temperature thermal insulating and wave-transparent materials. In this work, the SiBNO fibers with good wave-transparent performance were used as reinforcements to prepare SiO2 aerogel composites (SiBNOf/SiO2 ACs) by sol-gel impregnating and supercritical drying method. The prepared SiBNOf/SiO2 ACs exhibit integrated performances of excellent fire resistance, high-temperature stability (1100 °C in Air), high mechanical properties (compressive strength is 1.89 ± 0.14 MPa at 40 % strain and bending strength is 1.93 ± 0.03 MPa), ultralow thermal conductivity (0.029 W m−1 K−1 at 25 °C and 0.051 W m−1 K−1 at 1100 °C) and good wave-transparent property (dielectric constant<1.45, loss tangent<0.01 in 4–18 GHz). All of these characteristics are related to the unique nanoporous structure of SiO2 aerogel and intrinsic nature of SiBNO fibers and SiO2 aerogel. The prepared multifunctional SiBNOf/SiO2 ACs have great potential to be used in harsh environment for thermal insulation and wave-transparent.