原位制备磁性碳纳米纤维复合气凝胶及其吸波性能研究

In situ preparation and wave absorption performance of magnetic carbon nanofiber composite aerogels

以聚丙烯腈(PAN)为碳源,在PAN纺丝液中引入磁性材料乙酰丙酮铁,通过静电纺丝制备复合纳米纤维膜,再通过预氧化、高温碳化制备磁性碳纳米纤维(FeCNF);然后用水性聚氨酯和可溶性淀粉作为黏结剂,采用冷冻干燥和高温热解法制备碳纳米纤维复合气凝胶(FeCNFA);研究了FeCNF的化学结构、FeCNFA的微观形貌和吸波性能,并探讨了FeCNFA的吸波机理。结果表明:通过静电纺丝法成功在FeCNF中引入了磁性材料,纤维内部的磁性成分主要是四氧化三铁及铁碳合金;FeCNFA内部呈现三维多孔结构;随着热解温度的升高,FeCNFA的吸波性能逐渐变弱,热处理温度为400℃时FeCNFA表现出良好的吸波性能,在匹配厚度为3.0 mm时FeCNFA的反射损耗为-40.27 dB,且有效吸收带宽(EAB)可达5.28 GHz,在匹配厚度为2.6 mm时EAB可拓宽到5.68 GHz;FeCNFA的吸波机理以介电损耗为主要机制,磁损耗中主要以涡流损耗为主。

A composite nanofiber membrane was prepared by using polyacrylonitrile(PAN)as carbon source and introducing magnetic material acetylacetone iron into PAN spinning solution via electrospinning and was produced into magnetic carbon nanofibers(FeCNF)by pre-oxidation and high-temperature carbonization.Carbon nanofiber composite aerogels(FeCNFA)were prepared by freeze-drying and high-temperature pyrolysis using waterborne polyurethane and soluble starch as binders.The chemical structure of FeCNF and the micromorphology and wave absorption performance of FeCNFA were studied,and the wave absorption mechanism of FeCNFA was explored.The results showed that magnetic materials were successfully introduced into FeCNF by electrospinning,and the magnetic components in the fiber were mainly ferric oxide and iron carbon alloy;the interior of FeCNFA exhibited a three-dimensional porous structure;the wave absorption performance of FeCNFA was gradually weakened with the increase of pyrolysis temperature,and FeCNFA demonstrated excellent wave absorption performance when the heat treatment temperature was 400℃,the reflection loss and effective absorption bandwidth(EAB)of FeCNFA could reach-40.27 dB and 5.28 GHz,respectively,when the matching thickness was 3.0 mm,and the EAB could be widened to 5.68 GHz when the matching thickness was 2.6 mm;and the wave absorption mechanism of FeCNFA was based on dielectric loss,supplemented by magnetic loss,especially eddy current loss.