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

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 SiO 2 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 SiO 2 aerogel composites (SiBNO f /SiO 2 ACs) by sol-gel impregnating and supercritical drying method. The prepared SiBNO f /SiO 2 ACs exhibit integrated performances of excellent fire resistance, high-temperature stability (1100 ºC 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 ºC and 0.051 W m -1 ·K -1 at 1100 ºC) 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 SiO 2 aerogel and intrinsic nature of SiBNO fibers and SiO 2 aerogel. The prepared multifunctional SiBNO f /SiO 2 ACs have great potential to be used in harsh environment for thermal insulation and wave-transparent. The prepared SiBNO f /SiO 2 aerogel composites exhibit excellent integrated properties of high mechanical properties, outstanding thermal stability, ultralow thermal conductivity and good wave-transparent property.