双壁碳纳米管薄膜的制备及其电磁屏蔽性能研究

发布时间：2018-05-11 09:55

本文选题：碳纳米管薄膜 + 二茂铁　；参考：《江西理工大学》2015年硕士论文

【摘要】：传统金属电磁屏蔽材料由于其自身密度高的特点,限制了其发展。当前,电磁屏蔽材料研究最为热点的是以碳纳米管(CNTs)填充轻质高分子材料的导电复合材料,但其性能在目前阶段还难以得到很大提高,维持在20 d B左右。究其原因在于CNTs的分散性能差,导致复合材料中的CNTs含量低、分布不均匀,导电率差。而CNTs因其管长,相互缠绕和成束,使得其均匀分散难以解决。解决含碳类屏蔽材料的关键在于增加基体中碳的含量。基于以上原因,本文开展了CNTs电磁屏蔽薄膜的研究,制备超轻、高效的CNTs屏蔽薄膜,具体包括以下内容:采用浮动催化的化学气相沉积法(CVD),以正己烷为碳源,二茂铁为金属催化剂,噻吩为催化剂,甲醇为生长调节剂,生长出双壁碳纳米管(DWCNTs)和少量多壁碳纳米管(MWCNTs),通过自沉积技术得到低密度,较好柔韧性和易操作的薄膜。通过在导磁填充法和电镀法在CNTs中填充磁性材料,微观上可观察到管壁上附着有大量的Fe颗粒。通过导磁填充法在CNTs薄膜中填充二茂铁/乙醇溶液,制备出中间体二茂铁/CNTs复合材料。通过热分解法,二茂铁受热分解出Fe颗粒,则制备出具有磁性能的Fe/CNTs屏蔽薄膜。通过差热/热重分析,导磁填充相比原始薄膜,Fe含量从之前的21%增加到了35%。磁滞回线中饱和磁化强度由35.43 emu g-1提升到47.35 emu g-1,屏蔽效能在6-9和12-15 GHz的范围内有了很大的提高。通过导磁填充法在CNTs薄膜中填充二茂铁/甲醇制备CNTs薄膜屏蔽材料。甲醇既可以降低碳源的浓度,从而控制反应过程中碳原子的供应量与碳源的分解速度;另一方面,还可以增加了金属催化剂二茂铁的溶解量,使生成的CNTs管壁表面附着更多的Fe原子,提升薄膜的屏蔽效能。本实验通过增加一根石英毛细管通入二茂铁/甲醇溶液,直接制备出高性能的屏蔽薄膜。通过差热/热重分析,填充二茂铁/甲醇溶液相比原始样品,Fe含量从21%增加到了31.5%。磁滞回线中的饱和磁化强度也由原始的35.43 emu g-1增加到了57.3 emu g-1,屏蔽效能得到很大的提升,在5和19 GHz附近屏蔽效能达到了60-65 d B。探索研究了电镀制备CNTs薄膜屏蔽材料。以硫酸亚铁为渡液的主盐,硫酸为渡液缓蚀剂。调节渡液的PH值为2-3,电流为0.1-0.2A。采用纯铁作为阳极材料,CNTs薄膜作为阴极材料,在薄膜表面覆盖一层纳米铁。通过差热/热重分析,电镀法相比原始薄膜,Fe含量从21%增加到了22.4%。由于Fe颗粒长时间处于湿润环境中,磁滞回线中的饱和磁化强度由原始的35.45 emu g-1增加到了38.35 emu g-1,屏蔽效能在小频段内有提升。导磁填充法在常温下填充二茂铁/乙醇溶液,在高温下填充二茂铁/甲醇溶液,屏蔽薄膜中Fe含量、铁磁性以及薄膜的屏蔽效能都有了很大的提升。电镀作为本实验探索制备高屏蔽薄膜的一种新方法,屏蔽性也有一定的提升。
[Abstract]:The development of traditional metal electromagnetic shielding materials is limited because of their high density. At present, conductive composites filled with carbon nanotubes (CNTs) are the most popular electromagnetic shielding materials. However, the properties of the composites are difficult to be improved at present and maintained at about 20 dB. The reason lies in the poor dispersion property of CNTs, which leads to low CNTs content, uneven distribution and poor conductivity. Because of its tube length, intertwining and bunching, it is difficult to solve the problem of uniform dispersion of CNTs. The key to solve the problem of carbon-containing shielding materials is to increase the content of carbon in the matrix. For the above reasons, the study of CNTs electromagnetic shielding thin films was carried out, and the ultra-light and high efficiency CNTs shielding films were prepared, including the following contents: using floating catalytic chemical vapor deposition method, using n-hexane as carbon source, Ferrocene was used as metal catalyst, thiophene as catalyst and methanol as growth regulator. DWCNTsand a few multi-walled carbon nanotubes (MWCNTs) were grown. Low density, good flexibility and easy to operate thin films were obtained by self-deposition. By filling magnetic materials in CNTs by magnetic-conductive filling and electroplating, a large number of Fe particles can be observed on the tube wall microscopically. The intermediate ferrocene / CNTs composite was prepared by magnetic conductivity filling method in ferrocene / ethanol solution. Fe particles were decomposed by thermal decomposition of ferrocene, and Fe/CNTs shielding films with magnetic properties were prepared. By differential thermal / thermogravimetric analysis (DTA), the Fe content of the original film was increased from 21% to 35%. The saturation magnetization in the hysteresis loop is increased from 35.43 emu g ~ (-1) to 47.35 emu g ~ (-1), and the shielding efficiency is greatly improved in the range of 6-9 and 12-15 GHz. Ferrocene / methanol was filled into CNTs thin film by magnetic conductivity filling method. The shielding material of CNTs thin film was prepared. Methanol can not only reduce the concentration of carbon source, so as to control the supply of carbon atoms and the decomposition rate of carbon source during the reaction, on the other hand, it can also increase the dissolution of ferrocene in the metal catalyst. More Fe atoms are attached to the surface of the CNTs tube wall, and the shielding efficiency of the film is improved. In this experiment, high performance shielding films were prepared by adding a quartz capillary through ferrocene / methanol solution. By differential thermogravimetric analysis, the Fe content of ferrocene / methanol solution was increased from 21% to 31.5% compared with the original sample. The saturation magnetization in hysteresis loop also increased from 35.43 emu g ~ (-1) to 57.3 emu g ~ (-1), and the shielding efficiency increased greatly, and the shielding efficiency reached 60-65 dB near 5 and 19 GHz. The shielding material of CNTs thin film prepared by electroplating was studied. Ferrous sulfate was used as the main salt and sulfuric acid as corrosion inhibitor. The pH value of the regulating solution is 2-3 and the current is 0. 1-0. 2 A. Pure iron was used as anode material and CNTs film was used as cathode material, and a layer of nanometer iron was coated on the surface of the film. By differential thermal / thermogravimetric analysis (DTA), the Fe content increased from 21% to 22.4% by electroplating compared with the original film. The saturation magnetization of Fe particles in hysteresis loop increases from 35.45 emu g ~ (-1) to 38.35 emu g ~ (-1) for a long time in wet environment, and the shielding efficiency is improved in small frequency range. The magnetic conductivity filling method filled ferrocene / ethanol solution at room temperature and ferrocene / methanol solution at high temperature. The Fe content, ferromagnetism and shielding efficiency of the film were greatly improved. Electroplating is a new method to fabricate high shielding films in this experiment.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.2;TQ127.11

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