碳纤维表面羰基铁的原位生长及吸波性能

以Fe(CO)5为前驱体,通过金属有机化学气相沉积(MOCVD),在碳纤维(CF)表面构筑厚度为纳米级的羰基铁(CI)壳层,通过改变沉积温度,调控核壳粉体的形貌结构和吸波性能。用X射线衍射仪、扫描电子显微镜和矢量网络分析仪对粉末的结构及电磁性能进行表征并对其吸波性能进行研究。结果表明:随着沉积温度升高(210~240℃),沉积到CF表面的羰基铁颗粒互相“吞并-融合”,此时CF-CI形成了完整的薄膜包覆型核壳结构;沉积温度太高时(270℃)会造成CF表面羰基铁壳层形貌的恶化。通过调节沉积温度,在纳米尺度上可以有效调控CI壳层的形貌,从而调节CF-CI核壳粒子的电磁性能。以核壳形貌及吸波性能为考察指标,最终确定最佳的沉积温度为240℃。以沉积温度为240℃时所获样品的电磁参数,模拟计算出涂层厚度为0.9 mm时,小于-10 dB的吸波带宽最大为4.6 GHz(13.4~18 GHz);涂层厚度为2.0 mm时,反射率达到最小值为-21.5 dB;厚度为0.9~3.9 mm时,在2~18 GHz均能实现吸波强度低于-10 dB。

In-Situ Growth and Microwave Absorption Properties of Carbonyl Iron on Carbon Fiber Surface

Fe(CO)5 was used as precursor to construct nano-sized carbonyl iron(CI)shell on carbon fiber(CF)surface by metal organic chemical vapor deposition(MOCVD).The morphology and microwave absorption properties of core-shell powders were controlled by changing deposition temperature.The structure and electromagnetic properties of the powders were characterized by X-ray diffractometer,scanning electron microscopy and vector network analyzer.The results show that the carbonyl iron particles deposited on the surface of CF“merge and fuse”with the increase of deposition temperature(210~240℃).At this time,CF-CI forms a complete core-shell structure with thin film coating.When the deposition temperature is too high(270℃),the morphology of carbonyl iron shell on the surface of CF will deteriorate.The thickness of CI shell on CF surface can be effectively controlled by adjusting deposition temperature at nanoscale,thus the electromagnetic properties of CF-CI core-shell particles can be adjusted.The core-shell morphology and microwave absorption properties were taken as indexes to determine the optimum deposition temperature of 240℃.With the electromagnetic parameters of the samples obtained at 240℃,the maximum absorbing bandwidth is 4.6 GHz(13.4~18 GHz)when the thickness of the coating is 0.9 mm,the minimum reflectivity is-21.5 dB when the thickness of the coating is 2.0 mm,and the absorption intensity is less than-10 dB among the whole 2?18 GHz when the thickness of the coating is 0.9?3.9 mm.