Fe-Co-Ni合金纳米粒子镶嵌的碳纳米纤维的简单制备及其吸波性能

通过在氩气中碳化含有乙酰丙酮金属盐的电纺聚丙烯腈纳米纤维合成了镶嵌(Fe1-xCox)0.8Ni0.2(x=0.25,0.50,0.75)合金纳米粒子的碳纳米纤维,用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、振动样品磁强计(VSM)和矢量网络分析仪(VNA)等对其物相、形貌、微观结构、静磁及电磁特性进行表征和分析,并根据传输线理论模拟计算了2~18 GHz频率范围内的微波吸收性能。结果表明:所制备的复合纳米纤维具有典型的铁磁特征,由无定形碳、石墨和面心立方结构Fe-Co-Ni合金三相组成,原位形成的合金纳米粒子沿纤维轴向均匀分布,且被有序石墨层所包覆。磁损耗和介电损耗间的协同作用及特殊的核/壳微观结构使仅含5%(w/w)的(Fe1-xCox)0.8Ni0.2/C复合纳米纤维的硅胶基吸波涂层表现出优异的微波吸收性能。当涂层厚度为1.1~5.0 mm时,x=0.25、0.50和0.75的样品最小反射损耗分别达到-78.5、-80.2和-63.4 d B,反射损耗在-20 d B以下的吸收带宽分别为14.9、14.8和14.5 GHz,几乎覆盖整个S波段至Ku波段。通过调节合金的组成可对材料的电磁特性及微波吸收性能进行一定程度的控制。

Facile Preparation and Microwave Absorption Properties of Fe-Co-Ni Alloy Nanoparticle Embedded-Carbon Nanofibers

Carbon nanofibers embedded with (Fe_1-xCo_x)_0.8Ni_0.2(x=0.25, 0.50 and 0.75) alloy nanoparticles were synthesized by carbonizing electrospun polyacrylonitrile nanofibers containing metallic acetylacetonate salts in argon atmosphere. The phase composition, morphology, microstructure, static magnetic properties and electromagnetic characteristics of them were characterized and analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA), and their microwave absorption performances in the frequency range of 2~18 GHz were calculated according to transmission line theory. The results indicate that the as-prepared composite nanofibers have a typical ferromagnetic characteristics and are composed of amorphous carbon, graphite and face-centered cubic structured Fe-Co-Ni alloy. The in situ formed alloy nanoparticles are uniformly dispersed along carbon-based nanofibers and encapsulated by ordered graphite layers. The silicone-based absorbing coatings with only 5%(w/w) of (Fe_1-xCo_x)_0.8Ni_0.2/C composite nanofibers as absorbers exhibit excellent microwave absorption properties, which are attributed to the synergistic effect between the magnetic loss and dielectric loss and the special particle/graphite core/shell microstructures in the nanofibers. The minimum reflection loss reaches -78.5, -80.2 and -63.4 dB for the x=0.25, 0.50 and 0.75 samples, respectively, and the absorption bandwidth of reflection loss under -20 dB is respectively up to 14.9, 14.8 and 14.5 GHz for an absorber thickness of 1.1~5.0 mm, almost covering the entire C-band to Ku-band. Furthermore, the electromagnetic characteristics and microwave absorption performances can be tuned to some extent by adjusting the composition of Fe-Co-Ni alloy.