本文選題：電磁屏蔽　切入點(diǎn)：石墨烯　出處：《山東大學(xué)》2017年碩士論文

【摘要】：電磁屏蔽材料對(duì)電磁波的屏蔽作用機(jī)理分為吸收和反射。本文所研究的材料為碳納米材料及其與鐵氧體材料的復(fù)合材料,碳材料屬于良好的電阻型吸收劑,鐵氧體屬于磁介質(zhì)型吸收劑,兩者復(fù)合能更大的符合現(xiàn)代新型吸波劑向著頻帶寬,密度低,吸收高的性能發(fā)展要求。碳納米材料包括碳納米管和石墨烯表現(xiàn)出的巨大優(yōu)異性質(zhì),能夠結(jié)合傳統(tǒng)碳材料頻帶寬,質(zhì)量輕的特點(diǎn),又能將納米材料比表面積大,導(dǎo)電率好等優(yōu)勢(shì)發(fā)揮出來,但吸波能力較弱,限制了其應(yīng)用。而相比較CNT和石墨烯材料,Fe_3O_4的吸波能力更強(qiáng),但吸波頻帶較窄,將其與碳材料復(fù)合,發(fā)揮兩類材料的特點(diǎn),具有重要的意義。本文中主要討論了 CNT,石墨烯,Fe_3O_4及其復(fù)合材料的制備,優(yōu)化制備參數(shù),并利用TEM、SEM、XRD、Raman、TGA等對(duì)材料的形貌,結(jié)構(gòu),成分進(jìn)行分析。利用VSM、VAN測(cè)試材料的磁學(xué)性能及吸波性能。主要內(nèi)容如下:1)利用Hummers法制備高比表面積的氧化石墨烯(GO),改進(jìn)洗滌工藝,縮短了實(shí)驗(yàn)過程,利用冷凍干燥法制得GO粉末。采用浮動(dòng)催化法制備了 CNT,探究不同碳源、催化劑、氣體流量、進(jìn)液速度對(duì)CNT質(zhì)量的影響,確定了批量制備CNT的優(yōu)化參數(shù)。利用二甲苯為碳源,可以得到較高質(zhì)量的CNT,但二甲苯有一定的毒性,且制備的CNT容易粘在石英管壁上不利于成膜;利用酒精為碳源,可制得高質(zhì)量CNT,克服了二甲苯粘度大的缺點(diǎn),成膜性能較好。確定了催化劑中二茂鐵和噻吩的比例范圍3.5/1～2.5/1,確定氣流量比例Ar氣流量為5L/min,H2為2L/min,進(jìn)液速度為0.08ml/min。此法制得單壁CNT,管徑為20nm。2)以聚乙二醇(PEG)為分散劑,以乙二醇為還原劑,在醋酸鈉提供的堿性環(huán)境下,采用水熱法將氯化鐵還原制備Fe_3O_4納米球,得到均勻?qū)嵭那蝮w。在反應(yīng)溶液中添加GO的方式,制得了 Fe_3O_4納米球/GO復(fù)合物,Fe_3O_4納米球均勻的負(fù)載在GO片的表面,GO對(duì)Fe_3O_4納米球的生長(zhǎng)大小沒有影響,只是提供形核場(chǎng)所。磁性能測(cè)試發(fā)現(xiàn)Fe_3O_4納米球/GO復(fù)合物的磁飽和強(qiáng)度為28.7emu/g,磁滯回線較窄,為軟磁材料。對(duì)Fe_3O_4納米球/GO復(fù)合物的在2～18GHz的吸波特性進(jìn)行表征,發(fā)現(xiàn)復(fù)合物在石蠟中含量為20%時(shí)在13.5GHz頻率下最高反射損耗為-13dB,30%含量的復(fù)合物反射損耗在8.5GHz時(shí)最高為-19dB。將復(fù)合材料分散在環(huán)氧樹脂中,利用刷涂法制備Fe_3O_4/GO@CNT@碳纖維布的四元材料,測(cè)試其在10MHz～2GHz內(nèi)的吸波特性進(jìn)行表征,在280MHz頻率的電磁損耗達(dá)到峰值-45dB。對(duì)比不加入Fe_3O_4/GO復(fù)合物和單純的碳纖維布的反射損耗-37dB和-32dB,發(fā)現(xiàn)Fe_3O_4/GO復(fù)合物能夠提高電磁損耗,但相比于純碳材料,其損耗峰值位置發(fā)生變化。3)以硫代硫酸鈉為氧化劑,在氫氧化鈉提供的堿性環(huán)境中,利用PEG400為模板劑,采用水熱法制備Fe_3O_4納米線,得到直徑為100nm的均勻線體。不添加PEG400,僅以水溶液作為反應(yīng)劑,得到的是晶粒尺寸為200nm的八面體結(jié)構(gòu)的Fe_3O_4。在水溶劑中添加一定量的GO代替PEG400,同樣得到納米線結(jié)構(gòu)的Fe_3O_4,證明GO具有類似于PEG400作為模板劑的作用,同時(shí)得到了Fe_3O_4納米線/GO復(fù)合材料。GO在合成Fe_3O_4納米線主要起兩個(gè)作用,一是GO的片層結(jié)構(gòu)均勻分散在水溶液中,降低了離子的結(jié)合速度,第二是GO表面的-OH等官能團(tuán)對(duì)Fe_3O_4納米線的不同晶面的生長(zhǎng)有不同的影響。對(duì)Fe_3O_4納米線/GO復(fù)合物的磁性能測(cè)試發(fā)現(xiàn)其磁飽和強(qiáng)度為37emu/g,磁滯回線較Fe_3O_4納米球/GO復(fù)合物寬,但同為軟磁材料。對(duì)Fe_3O_4納米線/GO復(fù)合物的在2～18GHz的吸波特性進(jìn)行表征,發(fā)現(xiàn)復(fù)合物在石蠟中含量為20%、30%時(shí),他們的最高反射損耗分別為-9dB和-7dB,40%含量的復(fù)合物反射損耗在6.8GHz時(shí)最高為-17dB。
[Abstract]:The shielding mechanism of electromagnetic shielding material for electromagnetic wave absorption and reflection. This paper is divided into the composite material of carbon nano material and ferrite material, carbon material is a kind of good resistance type absorbent, ferrite magnetic medium absorbent belongs to the type, two more in line with modern composite energy absorbing model agent to frequency bandwidth, low density, high absorption performance requirements. The development of carbon nano materials including large excellent properties of carbon nanotubes and graphene exhibits, can be combined with traditional carbon materials with wide frequency band, light quality characteristics, and the nano material is bigger than the surface area, good conductivity and other advantages to play out, but the absorption wave ability is weak, which limits its application. Compared with CNT materials and graphene, absorbing ability of Fe_3O_4, but the absorption band is narrow, and the carbon composite, exert the characteristics of two kinds of materials, has important significance. This paper mainly discusses CNT, graphene, Fe_3O_4 and preparation of composite materials, optimization of preparation parameters, and the use of TEM, SEM, XRD, Raman, TGA and other materials on morphology, structure and composition analysis. Using VSM, magnetic properties and microwave absorption properties of VAN test materials. The main contents are as follows: 1) preparation of graphene oxide with high specific surface area by Hummers method (GO), to improve the washing process, shorten the process, using freeze drying method. Using CNT GO powder prepared by the floating catalyst method, explore the different carbon source, catalyst, gas flow, liquid inlet velocity effect on the quality of CNT, to determine the volume system parameter optimization of preparation of CNT. Using xylene as carbon source, can get higher quality of CNT, but the xylene has a certain toxicity, and the preparation of the CNT easy to stick in the quartz tube wall is not conducive to the film; using alcohol as carbon source, can be made of high quality CNT, overcome the viscosity of xylene The disadvantage of large, good film-forming properties. The two ferrocene and thiophene catalyst ratio in the range of 3.5/1 ~ 2.5/1, determine the gas flow ratio of Ar gas flow rate is 5L/min, H2 is 2L/min, the rate of the liquid is 0.08ml/min. this method of single wall CNT, diameter 20nm.2) with polyethylene glycol (PEG) as dispersant. Ethylene glycol as the reducing agent in alkaline environment of sodium acetate, via hydrothermal method preparation of Fe_3O_4 nanoparticles by homogeneous reduction of ferric chloride, solid sphere. The addition of GO in the reaction solution, prepared Fe_3O_4 nanoparticles /GO complexes, Fe_3O_4 nanoparticles uniformly loaded on the surface of GO film. The size of GO did not affect the growth of the Fe_3O_4 nanospheres, only provide nucleation sites. Magnetic test shows that Fe_3O_4 nanoparticles /GO complex magnetic saturation intensity is 28.7emu/g, the hysteresis loop is narrow, as soft magnetic materials. The Fe_3O_4 nanoparticles of /GO complex in 2~1 The microwave absorbing properties of 8GHz were characterized and found complex content in paraffin at 20% 13.5GHz under the highest frequency reflection loss is -13dB, the complex reflection loss of 30% content in 8.5GHz is the highest of -19dB. composite materials dispersed in epoxy resin, four yuan Fe_3O_4/ GO@CNT@ carbon fiber cloth material prepared by brush coating method. In the test, 10MHz ~ 2GHz wave absorbing properties were studied, and -45dB. reached the peak in contrast to add carbon fiber cloth Fe_3O_4/GO composite and pure reflection loss of -37dB and -32dB in the electromagnetic loss frequency of 280MHz, found that Fe_3O_4/GO complexes can improve the electromagnetic loss, but compared to pure carbon materials, the loss peak position the change of.3) on sodium thiosulfate as oxidant, sodium hydroxide in the alkaline environment in the use of PEG400 as template, Fe_3O_4 nanowires prepared by hydrothermal method, get the uniform diameter of 100nm Line body. Do not add PEG400, only with aqueous solution as reaction agent, the grain size is eight of 200nm structure Fe_3O_4. is added in the water solvent instead of GO PEG400, also obtained nanowires Fe_3O_4, proved that GO has similar to PEG400 as the template, obtained at the same time Fe_3O_4 /GO nanowires composite.GO mainly has two roles in the synthesis of Fe_3O_4 nanowires is a lamellar structure of GO dispersed in aqueous solution, the ion binding rate is second, the surface of GO -OH functional groups on Fe_3O_4 nanowires with different crystal surface growth have different effects on magnetic properties of Fe_3O_4. /GO nanowires composite test shows that the magnetic saturation intensity is 37emu/g, the hysteresis loop of Fe_3O_4 nanospheres /GO complex is wide, but the same as soft magnetic materials. The Fe_3O_4 nanowires of /GO complex in 2 ~ 18GHz absorption into Potter Row characterization showed that the maximum reflection loss of the composite was 20% and 30% in paraffin, respectively. Their highest reflection loss was -9dB and -7dB respectively, and the compound loss reflected by 40% was the highest when 6.8GHz was -17dB..

【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB383.1;TB33

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本文編號(hào)：1730085