【作者】 陈利阳；

【导师】 刘顺华；

【作者基本信息】 大连理工大学 ， 材料表面工程， 2010， 硕士

【摘要】 本文主要通过扫描电镜,透射电镜和矢量网络分析仪等手段对羰基铁(CIP)、羰基铁纤维(CIF)、Fe-Si磁性金属微粉和炭黑(CB)等吸收剂的结构和电磁特性进行了分析,并研究了各种吸波剂的吸波机理,进而制备具有优良吸波性能的环氧树脂(ER)基吸波涂层,研究结果表明：CIP和CIF既有磁损耗又有介电损耗,但都以磁损耗为主,其特有的频散效应能够拓宽有效带宽。其中CIF的长径比可达到30～100,能够增强对吸波体内电磁波的散射和吸收,提高吸波性能。Fe-Si也是以磁损耗为主,但其介电常数较低,有利于减少对电磁波的反射。CB作为电阻型吸收剂,具有较大的介电常数,并且可以通过电偶极子振动衰减电磁波,但其阻抗匹配性相对较差。以CIP、CIF、Fe-Si和CB分别为吸波剂制备的环氧树脂基吸波涂层的吸波性能,均随着吸收剂含量的增加,涂层的吸收峰向低频移动,但当吸收剂含量达到一定值之后,涂层的阻抗匹配性下降,涂层的吸波性能降低。通过不同吸波剂之间的复合,利用其不同的损耗机理可以提高复合涂层的吸波性能。CIP与CIF复合使涂层的低频性能得到显著改善,当CIP:CIF:ER质量比为4：0.05：1时,涂层在2.3 GHz反射损耗(RL)达到-22.6 dB；CIP/Fe-Si/ER复合涂层的阻抗匹配性较好,在低频和高频均有所改善；CIP与CB复合,利用其不同的损耗类型提高涂层的吸波性能,当CIP:CB:ER质量比为1：0.3：1时,涂层的有效带宽(RL<-4dB)达到6 GHz。以单层吸波材料吸波性能的研究为基础,制备了具有阻抗渐变结构(匹配层+吸收层)的双层吸波材料,通过调整匹配层羰基铁的含量和透波剂SiO2的含量来调整其电磁参数,从而达到改善涂层与空气的阻抗匹配,减少涂层表面对电磁波的反射,提高吸收效率,增强吸波性能。涂层的吸波性能随着SiO2在匹配层中含量的增加而增强,当SiO2含量(SiO2:CI:ER)为2：5：1时,双层复合涂层的吸收峰值达到-17.3dB,频宽(RL<-4dB)为5.7 GHz,涂层的吸波性能最好。更多还原

【Abstract】 In this paper, the structures and performances of carbonyl iron powder (CIP), carbonyl iron fibers (CIF), Fe-Si powders and carbon black (CB) were characterized by Scanning Electron Microscope, Transmission Electron Microscope and Vector Network Analyzer etc. ER based absorbing coatings were prepared with these absorbents.The findings showed that CIP and CIF were not only magnetic loss materials but also dielectric loss materials. The aspect ratio of CIF reached 30～100, which could enhance the scattering of electromagnetic (EM) wave in the absorbers and improve the absorption properties. Fe-Si could reduce the reflection of EM on the surface of the absorber with the low permittivity. The CB powders considered as dipoles in the process of damped vibration attenuated the electromagnetic wave effectively. But the impendence matching of CB was not very good.ER based absorbing coatings were prepared with CIP, CIF, Fe-Si, and CB, respectively. The absorption peaks of the coatings moved toward the low-frequency region with the increase of absorbents weight concentrations. The impedance matching became poor when the mass fraction of the absorbents exceeded the threshold value. The absorption properties of the coatings could be improved through mixing different absorbents. When the weight concentration (CIP:CIF:ER) was 4:0.05:1, the RL of the coating reached-22.6 dB at 2.3 GHz. The good absorption properties of the CIP/Fe-Si/ER appeared not only in low frequency region but also in high frequency region. When the weight concentration (CIP:CB:ER) was 1:0.3:1, the bandwidth (RL<-4 dB) of the CIP/CB/ER coating reached 6 GHz.On the base of monolayer composites, double-layer absorbing coatings with resistance gradual changing structure (absorbing layer + matching layer) were prepared. The electromagnetic parameter was controlled by the amount of the absorbent and SiO2 which was transparent to EM in the matching layer to achieve the impendence matching between the surface of the double-layer coating and the air. The good impendence matching reduced the reflection of EM wave at the coating surface and enhanced the absorption properties. The SiO2 could improve the matching impendence and had great influence on the absorbing performance of the composite coating. With increasing SiO2 content in the matching layer, the wave loss was enhanced. When the SiO2 weight concentration (CI:SiO2:ER) got to 2:5:1, the optimal RL reached-17.3 dB and the effectual absorption band (better than -4 dB) was 5.7 GHz.更多还原