Fabrication and investigations on Si3N4/PAN/SiZrOCN ceramic aerogel composites with high-temperature wave permeability.

Novel Si₃N₄/PAN/SiZrOCN ceramic aerogel composites, which have excellent wave transmission functions, were prepared through electrospinning, freeze-drying, and high-temperature pyrolysis. Polyvinyl alcohol was used as the aerogel carbon skeleton, polystyrene served as the pore-forming substance, Si₃N₄/PAN fiber was used as the reinforcement material. The pore size distribution and dielectric properties of the composites were systematically studied at different pyrolysis temperatures. An increase in pyrolysis temperatures led to a decrease in the specific surface area and dielectric constant. Fourier infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction were employed to investigate the polymerization mechanism and ceramic process of the precursor. The Brunauer–Emmett–Teller test revealed that the maximum specific surface area of Si₃N₄/PAN/SiZrOCN ceramic aerogel composites was 109.261 m²/g, and the average pore size was 4.56 nm when sintered at 600 °C. The dielectric properties test results showed a dielectric constant ranging between 3.1 and 3.7 and a dielectric loss tangent value between 2.6 × 10^–3 and 1.6 × 10^–2 for the sample. Si₃N₄/PAN/SiZrOCN ceramic aerogel composites exhibited excellent dielectric properties at room temperature and demonstrated exceptional dielectric stability across different frequency bands (1.8–18.0 GHz), making them a potential high-temperature wave-transmittance material. [ABSTRACT FROM AUTHOR]