Functionalized boron nitride nanosheets composite SiNO fibers with enhanced high-temperature stability and wave-transparent properties

The increasing operational temperatures of aircraft antenna windows caused by aerodynamic heating in high-speed flight systems necessitate microwave window materials with exceptional thermal stability. In this study, functionalized boron nitride nanosheets (F-BNNS) modified SiNO (F-BNNS/SiNO) fibers are obtained through melt spinning, air-curing, decarburization, and sintering process. The F-BNNS/SiNO fibers exhibit superior high-temperature stability, retaining 60% of initial tensile strength at 1600 °C, outperforming pristine SiNO fibers (19% at 1400 °C) and electron beam irradiation crosslinked Si 3 N 4 fibers (43% at 1450 °C). The composition and structure evolution of F-BNNS/SiNO fibers at 1400~1700 ℃ were investigated, and in combination with molecular dynamics simulations, it was revealed F-BNNS effectively mitigating the structural degradation at high-temperatures through interfacial bonding. Furthermore, F-BNNS enhances microwave transparency of SiNO fibers by reducing dielectric constant and loss. This work establishes a pathway for developing high-performance ceramic fibers with integrated thermomechanical stability and electromagnetic functionality, advancing aerospace material design.