【作者】 於留芳；

【导师】 王淀佐； 朱红；

【作者基本信息】 北京交通大学 ， 应用化学， 2006， 硕士

【摘要】 本论文主要研究的是一种具有吸波性能的复合材料,在实验过程中,使用碳纳米管、活性炭为化学镀的基体,对其进行一系列改性处理,然后对其进行化学镀,旨在制备出一种吸波性能优异、吸收频带宽、密度小、质量轻的新型吸波材料。实验中,对碳纳米管、活性炭的纯化处理、氧化处理及敏化、活化处理进行了大量的实验,从而找出了一种比较理想的预处理方法:即先对碳纳米管进行研磨,接着在NaOH溶液中进行纯化,在浓硝酸溶液、Fenton试剂中进行氧化,最后采用敏化活化一步法完成化学镀前的预处理。在选择镀液组成时,采用了单因素实验方法进行了一系列的实验,找出了较好的化学镀液配方:CoSO4·7H₂O,25～30 g/L;NaH₂PO₂·H₂O,25～30 g/L;Na₃C₆H₅O₇·2H₂O,45～55 g/L;NH₄Cl,25～30 g/L;NH₄·H₂O、CH₃COOH,适量;阴离子表面活性剂,痕量;具体的施镀条件为:温度80±2℃;搅拌速度为中速;pH值为9.80±0.50。从TEM图中看出:碳纳米管、活性炭的表面已镀覆上较为均匀的金属镀层。从红外光谱图中看出:在镀前的预处理以及镀后的热处理过程中碳纳米管的结构并没有发生变化。对样品的电磁参数及吸波性能的研究表明:碳纳米管的匹配厚度经计算为3.5mm,在整个频率范围内反射损耗呈现出减小的趋势,吸收峰出现在17GHz左右,最大反射损耗为-11.28dB。化学镀钴碳纳米管的吸波性能随着匹配厚度的增大,吸收峰向低频方向移动,在匹配厚度d_m=9mm时,样品最大反射损耗达-30.92dB,对应的匹配频率f_m=10.99GHz,R <-5 dB的频宽为2.7 GHz,R<-10 dB的频宽为1.4GHz。化学镀镍碳纳米管的吸波性能随着匹配厚度的增大,吸收峰并没有发生移动,在匹配厚度d_m=0.2mm时,样品最大反射损耗达-11.40dB,对应的匹配频率f_m=15.6GHz,而且在整个频率范围内,反射损耗均小于-10.5dB,反射损耗在所测试的样品中最大。随着匹配厚度的增大,样品的吸收峰没有发生移动,但反射损耗有所减小。在匹配厚度d_m=0.2mm时,样品最大反射损耗达-5.23dB,对应的匹配频率f_m=10.59GHz。更多还原

【Abstract】 In this paper, the composite materials with microwave absorbing property are studied. In the experiment, carbon nanotubes and active carbon are the substrate for electroless plating, and a series of modified processing are carried in order to produce new absorbing materials with the property of outstanding absorption performance, band absorption width, light density and quality.A series of experiments are carried on carbon nanotubes and active carbon, such as purification, oxidation, sensitization, and activation,etc. As a result, one quite ideal pretreatment method is discovered. Firstly, carbon nanotubes is grinded in a mortar. Secondly, carbon nanotubes is purified in the sodium hydroxide solution, and oxidized in the thick nitric acid solution and the Fenton reagent. The single factor experimental method is used to discover the better composition of the electroless plating solution. The composition is listed below: CoSO4·7H₂O, 25～30g/L; NaH₂PO₂·H₂O, 25～30g/L; Na₃C₆H₅O₇·2H₂O, 45⁵5g/L; NH₄Cl,25～30g/L; NH₄·H₂O,CH₃COOH, anion surface active agent, trace amount. The plating condition is: temperature: 80±2℃; the mixing speed: medium speed; the pH value: 9.80±0.50.etc.By electroless plating, cobalt/nickel is deposited respectively on the surface of carbon nanotubes and active carbon by transmission electron microscopy. The structure of carbon nanotubes doesn’t change after electroless plating by infrared spectrum picture. And the complex relative permittivity （εr=ε’ -jε’’） and permeability （μr =μ’- jμ’’） of the absorber were measured in a frequency range from 2 GHz to 18 GHz. The reflection loss （R.L.）, matching thickness （d_m） and matching frequency （f_m） were calculated by the theory of the absorbing wall. When the matching thickness of canbon nanotubes is 3.5mm, the maximum reflection coefficient is about -11.28dB , the corresponding matching frequency is 17GHz. With the increase of the frequency, the value of the reflection loss transfers to lower value. When the matching thickness of canbon nanotubes with Co coating is 9mm, the maximum reflection coefficient is about ?30.92dB, the corresponding matching frequency is 10.99GHz. The bandwidth corresponding to the reflection loss below ?5 dB is more than 2.7GHz, and the reflection loss below ?10dB is more than1.4GHz. When the matching thickness of canbon nanotubes with Ni coating is 0.2mm, the maximum reflection coefficient is about ?11.40dB, the corresponding matching frequency is 15.6GHz. The reflection loss更多还原