Low-dielectric continuous ceramic fibers with thermal and load-bearing functions serve as critical raw materials for accident-tolerant ceramic composites in aerospace shuttles. Silicon oxynitride ceramics exhibit a temperature resistance exceeding 1700 °C, which holds potential applications in extreme thermal protection materials. According to the attractive potential properties of silicon oxynitride ceramics, this study develops continuous silicon oxynitride (sinoite) fibers with a near-stoichiometric Si₂N₂O ratio and a tensile strength of 1.53 GPa via the precursor conversion method. The research investigates the relationships between composition and microstructure, demonstrating mechanical properties and high-temperature evolution. Sinoite fibers retain 65% of their strength at 1600 °C in a nitrogen atmosphere. After 1700 °C treatment, Si₂N₂O crystallization formed on the surface layer, elucidating the mosaic-shell formation mechanism in high-temperature evolution. Despite extremely low porosity, the strength retention rate remained up to 51%. To the best of our knowledge, this study provides a novel sinoite fiber with outstanding heat resistance up to 1700 °C for the first time. The sinoite fibers exhibit excellent properties compared with alumina, silicon nitride, and mullite fibers, offering promising reinforcement for thermal protection systems and electromagnetic components served in extreme environments.

Efficient and environmentally friendly production of high-quality continuous fiber coatings using current preparation methods is highly challenging due to issues such as scale and batch processing restrictions, low deposition rate, high energy consumption, and utilization of multiple environmentally hazardous steps. To address these challenges, we propose a stable and efficient wet chemical deposition coating method for high-throughput online continuous preparation of boron nitride (BN) coatings on ceramic fibers under an ambient environment. Our process involves surface modification, in-situ wet chemical deposition, and heat treatment, and all seamlessly connecting with the ceramic fiber preparation process through continuous stretching. Hydrophilic groups were introduced via surface modification enhancing wettability of the fiber surface with impregnating solution. An in-situ reaction and atom migration improve uniformity and binding of the coating. As a result, outstanding impregnation and adhesion properties are achieved. A comprehensive analysis to evaluate the impact of the BN coatings was conducted, which demonstrates that the BN-coated fibers exhibit a remarkable 36% increase in tensile strength, a 133% increase in fracture toughness, and enhanced temperature resistance of up to 1600 ℃. It provides a secure and efficient platform for cost-effective production of functional and high-quality coatings through targeted surface modification and rapid stretching impregnation.

Ceramic nanofibers with robust mechanical properties, high-temperature resistance, and superior thermal insulation performance are promising thermal insulators used under extreme conditions. However, developing of ceramic fibers with both low solid thermal conductivity (λ_s) and low infrared radiation thermal conductivity (λ_r) is still a great challenge. Herein, according to the Ioffe–Regel limit theory, we report a novel SiZrNOC nanofiber membrane (NFM) with a typically amorphous structure by combining the electrospinning method and high-temperature pyrolysis technique in a NH₃ atmosphere. The prepared SiZrNOC NFM has a high tensile strength (1.98±0.09 MPa), excellent thermal stability (1100 ℃ in air), and superior thermal insulation performance. The thermal conductivity of SiZrNOC NFM was 0.112 W·m⁻¹·K⁻¹ at 1000 ℃, which is obviously lower than that of the traditional ceramic fiber membranes (> 0.2 W·m⁻¹·K⁻¹ at 1000 ℃). In addition, the prepared SiZrNOC NFM-reinforced SiO₂ aerogel composites (SiZrNOC_f/SiO₂ ACs) exhibited ultralow thermal conductivity of 0.044 W·m⁻¹·K⁻¹ at 1000 ℃, which was the lowest value for SiO₂-based aerogel composites ever reported. Such superior thermal insulation performance of SiZrNOC NFMs was mainly due to significant decreasing of solid heat conduction and thermal radiation by the fancy amorphous microstructure and high infrared shielding compositions. This work not only provides a promising high-temperature thermal insulator, but also offers a novel route to develop other high-performance thermal insulating materials.