Preparation of BN@SiO2 nanofiber ceramic aerogel with ultralight, wave-transparent and heat-insulating for microwave sintering furnace

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Thermal insulation devices play an extremely important role in enhancing microwave heating efficiency. However, existing wave-transparent insulation materials often exhibit high heat storage, low microwave transmittance at high temperatures, and poor oxidation and thermal shock resistance, hindering high-temperature applications for microwave sintering. To address this issue, we developed an ultralight and wave-transparent BN@SiO2 aerogel, which was fabricated through the in situ growth of SiO2 on the surfaces of BN fibers. The resulting composite aerogel demonstrated excellent high-temperature oxidation resistance and an impressively low density of 0.07 g/cm3. Furthermore, the dielectric constant of the BN@SiO2 aerogel ranged from 2.58 to 2.80, and its dielectric loss tangent was as low as 5.13 × 10−3–7.98 × 10−3 within the 2–10 GHz frequency range. The successful synthesis of BN@SiO2 aerogel provides new progress and research ideas for the development of wave transparent and thermal insulation materials.