Coaxial Electrospinning-Derived Hollow SiBCN Ceramic Fibers with Multiscale Heat-Transfer Suppression for High-Temperature Thermal Insulation

<title>Abstract</title> <p> Ceramic fiber aerogels are widely regarded as promising materials for high-temperature thermal insulation. However, conventional ceramic fiber aerogels often suffer from limited temperature resistance and insufficient mechanical strength, which restrict their application in the extreme thermal environments encountered in aerospace systems. In this work, continuous hollow SiBCN ceramic fibers were prepared by coaxial electrospinning and precursor conversion, using polyborosilazane as the shell precursor and polymethyl methacrylate as a sacrificial core template. The hollow structure reduces solid-state heat-transfer pathways, while the dense, disordered amorphous SiBCN network suppresses grain growth and phase separation at elevated temperatures, thereby enhancing phonon scattering. This structural and compositional synergy provides low thermal conductivity and high-temperature stability. The prepared hollow SiBCN fibers exhibited a room-temperature thermal conductivity as low as 0.0359 W·m ^− 1 ·K ^− 1 . After pyrolysis at 1400°C, the fibers retained good flexibility and mechanical integrity, showed no detectable mass loss above 800°C, and demonstrated excellent thermal stability. When a hollow fiber membrane was exposed to 1000°C for 60 s, the temperature difference between the hot and cold surfaces reached 740°C, confirming its outstanding thermal-insulation performance. These results demonstrate that hollow SiBCN fibers are promising lightweight materials for thermal insulation and structural applications in aerospace and other high-temperature environments. </p>