碳纳米管的化学镀Au研究

采用化学镀法首次在碳纳米管表面包覆了贵金属Au,研究了工艺过程对包覆层质量的影响,并利用高分辨透射电镜(HRTEM)及纳米束EDS能谱对包覆的碳纳米管进行了表征.所得包覆层完整、均匀、金属颗粒密度高,可望作为高性能准一维纳米导线得到应用.     

镀钴碳纳米管的制备及其电磁特性

在碳纳米管表面镀覆磁性金属粒子,可获得电磁性能优异的复合材料.对碳纳米管进行预处理,再用化学镀法在其表面包覆钴金属制备碳纳米管-维复合材料.用透射电子显微镜(TEM)、能谱仪、振动样品磁强计、矢量网络分析仪分析了复合材料的形貌、成分及电磁性能,并研究了化学镀工艺对镀层沉积速率的影响.结果表明:镀覆后碳管表面包覆了一层钴...     

碳纳米管的表面改性与羟基磷灰石的包覆

通过TEM、FTIR及XRD等检测手段对原位合成法制备羟基磷灰石/碳纳米管复合材料过程中碳管的表面改性及影响羟基磷灰石包覆的因素进行了系统探讨. 研究表明, 浓酸处理后, 碳纳米管表面产生大量官能团; 阴离子表面活性剂十二烷基磺酸钠(SDS)的加入提高了碳纳米管与水的相容性; 实验中随着(NH₄)₂HPO₄溶液的加入, 羟基磷灰石原位沉积并形成包覆层. 结果发现: 碳纳米管的表面改性、适当的pH值和陈化温度是得到羟基磷灰石连续包覆层的关键因素.     

氨基化二氧化硅包覆碳纳米管增强环氧树脂复合材料

本文制备了二氧化硅包覆的碳纳米管,并在其表面引入氨基,从而获得在环氧树脂基体中分散性良好的化学修饰的碳纳米管。首先通过强碱醇溶液处理碳纳米管,制备羟基化碳纳米管(MWNTs-OH),然后将MWNTs-OH分散于乙醇溶液中,加入正硅酸乙酯(TEOS),通过Stber法制备了表面包覆二氧化硅的碳纳米管(MWNTs-SiO2);将MWNTs-SiO2进一步与氨丙基三乙氧基硅烷反应,得到氨基化二氧化硅包覆碳纳米管(MWNTs-SiO2-NH2)。将所制备的MWNTs-SiO2-NH2与缩水甘油醚型环氧树脂E-44复合,并以三乙醇胺为固化剂,得到氨基化碳纳米管/环氧树脂复合材料。实验结果表明,碳纳米管表面成功地引入了氨基基团;表面氨基化碳纳米管在环氧树脂基体中的分散性得到了显著的提高,同时氨基化碳纳米管能够显著地提高复合材料的冲击强度和拉伸强度。     

聚苯胺原位包覆碳纳米管材料的制备及性能

在苯胺的盐酸溶液中，用过硫酸胺((NH4)2S2O8)作氧化剂，在碳纳米管上原位生成并包覆了聚苯胺，用SEM及TEM观察了包覆前后碳纳米管的结构形态，并对这种材料表面性质及微波电磁参数进行了研究。结果表明：碳纳米管／苯胺重量比为4：1时，生成的聚苯胺可完全包覆在碳纳米管上，包覆层厚度为10nm-20nm；碳纳米管经聚苯胺包覆后表面能增大，包覆后的碳纳米管在水中及固体状态时分散性明显得到改善，微波电磁吸收系数的实部(ε’，μ’)、虚部(ε”，μ”)及电磁损耗因子(tgδe=ε”/ε’，tgδm=μ”/μ’)均得到了提高，表明聚苯胺包覆后碳纳米管有望成为一种电磁波屏蔽材料。     

多壁碳纳米管表面均匀沉淀包覆四氧化三铁及其磁性能的研究

本文用均匀沉淀的方法在多壁碳纳米管表面包覆了四氧化三铁(Fe3O4),采用场发射扫描电镜(FESEM)和场发射透射电镜(FETEM)对改性多壁碳纳米管表面形貌进行观察,采用场发射透射电镜附带的X射线能谱仪(EDX)对其表面成分进行测试,同时结合X射线衍射仪(XRD)对多壁碳纳米管表面包覆的晶体结构进行分析,最后采用振动样品磁强计(VSM)和网络矢量分析仪表征了Fe3O4包覆多壁碳纳米管的静态磁性能和动态电磁性能.结果表明,均匀沉淀Fe3O4包覆多壁碳纳米管的效果理想,相对原始多壁碳纳米管,改性后的多壁碳纳米管静态磁性能有了显著提高,比饱和磁化强度为12.15 emu/g.     

碳纳米管/聚甲基丙烯酸甲酯复合粒子的制备及表征

采用乳液聚合法制备了CNT s/PMM A复合粒子,并用TEM,SEM,FT-IR,XRD对其进行了表征。结果表明,PMM A均匀地包覆在碳纳米管表面,并且碳纳米管也参与了MM A的聚合反应。采用TG分析了经过抽提后的CNT s/PMM A复合粒子,结果表明,使用Tw een-80为乳化剂时PMM A在碳纳米管表面的包覆量为35.04%。     

锶铁氧体包覆碳纳米管吸波材料的制备及表征

采用溶胶-凝胶法制备锶铁氧体包覆碳纳米管(CNTs)的吸波材料,并考察了碳纳米管含量对包覆后样品磁性能及吸波性能的影响.经TEM、XRD验证锶铁氧体成功地包覆在碳纳米管表面;ALVSM图中可以看出6%CNTs-SrFe11.5O19的磁性能最佳,矫顽力(Hc)为5916.13Oe.而经网络分析仪测定,5% CNTs-S...     

微胶囊铜粉对铜复合浆料性能的影响

为提高铜浆料的导电性,利用微胶囊技术在铜粉表面包覆液体石蜡,增强铜粉的抗氧化性,并添加少量导电性能优异的碳纳米管作为导电增强相,制备碳纳米管-铜复合浆料.利用四探针测试仪、扫描电镜等测试方法研究了液体石蜡含量对包覆铜粉性能的影响以及微胶囊铜粉作为主导电相,碳纳米管作为导电增强相对浆料导电性能的影响.结果表明:液体石蜡包覆含量为4 wt%的微胶囊铜粉具有良好的导电性和抗氧化性,其电导率为44.32%IACS;微胶囊铜粉作为碳纳米管-铜浆料的主导电相,制备浆料膜层电阻率为22.59 mΩ·cm,相比于未包覆的铜粉为主导电相制备的浆料膜层电阻率降低了12.44%;碳纳米管作为导电增强相所制备的浆料相比于纯铜浆料,电阻率降低31.74%.     

溶液共混法制备碳纳米管/双酚A型聚碳酸酯复合物的研究

用溶液共混法成功地制备了不同碳纳米管含量的双酚A型聚碳酸酯复合材料,用TEM,SEM和XPS对碳纳米管和所制备的复合材料进行了多种表征,结果表明碳纳米管的纯化效果较好,表面含有C-O,C=O和O-C=O等极性官能团,复合材料中聚碳酸酯对碳纳米管的包覆较好,聚碳酸酯的包覆量随碳纳米管含量的增加而降低,碳纳米管在聚合物基体中分散均匀,两相界面间存在较强的作用力。     

纳米碳管的表面改性方法研究进展

概括了目前几类常用的纳米碳管(CNTs)表面改性方法的研究进展,分析了各方法的特点、原理及存在的问题,简单地描述了改性后CNTs性质的变化。权衡各方法的利弊,提出了未来CNTs改性的研究方向,即应注重多学科的交叉应用,将各改性手段有机结合,提高修饰效果。同时指出,改性后的CNTs在环境中的迁移转化及产生的环境风险尚不清楚,在今后的研究中还需充分认识改性后CNTs的理化性质,这是对其进行客观风险评价的重要前提。     

沉积条件对碳纤维表面碳纳米管生长的影响

采用化学气相沉积(CVD)法在碳纤维(CF)表面原位生长碳纳米管(CNTs)。考察了不同催化剂、沉积温度、氢气流量以及样品距进气口距离等工艺参数对CNTs-CF生长的影响。利用SEM和高分辨透射电子显微镜(HRTEM)对CNTs-CF形貌和微结构进行了表征和分析。结果表明:在CF表面原位生长的CNTs为多壁结构,其中以Ni为催化剂得到的CNTs直径小、分布均匀;在600~750℃温度范围内,随着温度的升高,CNTs直径和长度减小,产量降低;随着氢气流量的增加,CNTs直径和长度均增加;距进气口30cm,在CF表面得到的CNTs覆盖率高、直径小且分布窄,有利于制备高质量CNTs。     

Improved field emission properties of carbon nanotubes by dual layer deposition

In this paper, we tried to increase the current density of carbon nanotubes (CNTs) by depositing double layer of CNTs instead of single layer. Both the layers of CNTs are deposited by the low pressure chemical vapour deposition technique on silicon substrate with Fe catalyst. Scanning electron microscopic images show the surface morphology of single and double layer of CNTs. Dual layer deposition of CNTs is a very simple and easy method to increase the current density of CNTs based field emitters than other conventional methods. Excellent field emission properties of double layer of CNTs are exhibited with large field enhancement factor and low turn-on voltage as compared to those for single layer of CNTs. High current density of CNTs is required for field-emission-based display devices associated with field enhancement factor and number of emitting electrons. Therefore, we may say that dual layer deposition of CNTs can be utilised as an alternative approach to improve the current density for field emitters. Stability measurement of the samples was also performed for 3 h (180 min) with current at constant applied voltage, and it was found that the stability of dual layer of CNTs is remarkable than that of single layer of CNTs.     

碳纳米管增强陶瓷基复合材料研究进展

从制备方法和力学性能两方面出发,综述了碳纳米管增强陶瓷基复合材料的研究现状,针对研究中存在的问题,提出了相应的解决方法,并预测了其发展趋势.     

活化和MnO2沉积提高碳纳米管超级电容器的性能

为了提高碳纳米管( carbon nanotubes,CNTs)超级电容器的性能,分别对 CNTs进行活化处理增大其比表面积和在CNTs表面沉积MnO2 引进赝电容,并利用TEM、BET、循环伏安和恒流充放电测试对实验样品进行了分析和表征。结果表明活化和MnO2 沉积有效地提高了 CNTs 超级电容器的性能。在充放电电流密度为 5mA/cm2 时,在 CNTs 的比容为46F/g的情况下,活化 CNTs和 CNTs/MnO2 复合物的比容分别达到87和150F/g,而且基于活化CNTs和CNTs/MnO2 复合物的超级电容器具有良好的功率特性。     

Synthesis of Well-Crystalline Lattice Carbon Nanotubes via Neutralized Cooling Method

In this contribution, vertically aligned carbon nanotubes were synthesized by chemical vapor deposition (CVD). The effects of intrinsic disorders constructed by mobile surface contaminants on the structural perfection of carbon nanotubes (CNTs) were investigated. The results indicated a complete picture on the effect of the involved parameters on the lattice defects of modulated CNTs based on the cooling step. Raman scattering showed that the different cooling methods of the CVD preforms altered the bound complex defects of the structure of the CNTs. Moreover, an array of CNTs was removed from the silicon substrate by applying the neutralized cooling method on the CVD, while the vertical and parallel orientations were retained. The FESEM images, coupled with Raman spectroscopy results, confirm the morphological improvements of the growth CNTs based on the neutralized cooling method.     

Growth and characterization of bamboo-shaped carbon nanotubes using nanocluster-assembled ZnO:Co thin films as catalyst

Bamboo-shaped carbon nanotubes (CNTs) had been successfully fabricated by a plasma enhanced chemical vapor deposition method, in which nanocluster-assembled ZnO:Co thin film was used as catalyst. It was found that bamboo-shaped CNTs were generally grown in a direction perpendicularly to the substrate surface with the tops of CNTs dominated by the droplet-like catalyst covered by the carbon layer. The diameter of CNTs was ranged from 20-50 nm. High resolution of TEM image showed that the typical CNT had a multi-walled structure with an inner core presented. The ordered graphite layers were inclined to an axis of CNT about 18 degrees and the interlayer space of a CNT was about 0.35 nm. Two peaks in Raman spectrum at 1586 cm(-1) and 1372 cm(-1) were identified as G-band and D-band for graphite, respectively. The results showed that catalyst based on ZnO:Co thin films could be used for the growth of CNTs with bamboo-shaped structure.     

Synthesis of carbon nanotube-cadmium selenide luminescent nanocomposites using electrophoretic deposition technique

In this research, nanocomposites containing carbon nanotube (CNT)-cadmium selenide (CdSe) quantum dots (QDs) were synthesized and deposited using electrophoretic deposition technique for optical sensors and displays. The composite was first synthesized using silane grafted cadmium selenide and different concentrations of carbon nanotubes, and then deposited on the aluminum electrodes via electrophoresis method. Fourier transformation infrared confirmed the formation of CNT–CdSe nanocomposites. Microstructural investigations using scanning and transmission electron microscopy also showed the presence of the QDs on the surface of carbon nanotubes (CNTs), enhancing their surface roughness. Increasing the applied voltage from 120 to 240 V resulted in the variation of deposition yield in the range of 0.0005–0.0035 g.cm^?2. The deposition yield was first increased and then decreased in all the samples. Photoluminescence studies revealed that the deposited composite has a distinct emission peak in the range of 485–495 nm (green region) under 360 nm illumination depending on the concentration of CNTs. It can be concluded that the deposited composite may be used in field emission displays due to its high efficiency emission in the presence of CNTs.     

碳纳米管表面处理及其在铜基复合材料中的应用

碳纳米管因特殊结构带来的优异性能而被海内外学者广泛关注,以碳纳米管为增强相制备铜基复合材料是使铜基导体同时具有高强度和高导电性能的有效途径。然而,由于碳纳米管表面能高、表面反应活性低,碳纳米管/铜复合材料制备的过程中存在增强体分散性差和界面结合强度弱两大问题,从而阻碍了复合材料高性能的实现。在碳纳米管/铜复合材料的制备过程中,采用适当的方法对碳纳米管进行表面处理能改变碳纳米管的表面结构和反应活性,在改善碳纳米管的分散性的同时增强碳纳米管与铜基体的界面结合,从而提高碳纳米管的增强效率,保证复合材料良好的综合性能。然而,表面处理过程可能会破坏碳纳米管的结构完整性,影响碳纳米管的本征性能,进而影响其增强效果,或可能在基体中引入其他杂质,影响复合材料的导电和导热性能。因此,在进行表面处理时应综合考虑其对碳纳米管结构性能及复合材料增强作用的影响。近年来,研究者们通过优化碳纳米管表面处理工艺突破了碳纳米管/铜复合材料在制备过程的难点,在保证铜基体优异的导电、导热性能的同时,大幅提高了碳纳米管/铜复合材料的力学性能。碳纳米管表面处理工艺类型大致可分为机械球磨、化学表面改性、表面镀层和联合表面处理四类。传统的机械球磨表面处理对碳纳米管的结构破坏较大;化学表面改性又分为共价表面改性和非共价表面改性,非共价表面改性在保持碳纳米管完整的管状结构和优异性能的同时,提高了碳纳米管在溶液中的分散性,但用于复合材料制备时会给基体引入有机杂质,影响复合材料性能;共价表面改性和表面镀层是铜基复合材料制备过程中最为常用和有效的表面处理方法,其能够在提高碳纳米管在基体中的分散性能的同时改善碳纳米管表面的反应活性,从而形成碳纳米管和铜基体之间强度较高的反应结合界面,实现碳纳米管/铜复合材料高强高导的综合性能。此外,可通过综合利用各种表面处理方法,结合各表面处理工艺的优势,获得更为优异的改性效果。本文从碳纳米管表面处理工艺的基本类型以及碳纳米管表面处理对铜基复合材料结构和性能的影响两方面阐述了碳纳米管表面处理在铜基复合材料中的应用和研究进展,并对其未来的研究方向进行了展望。     

Bending fracture in carbon nanotubes

A novel approach was adopted to incur bending fracture in carbon nanotubes (CNTs). Expanded graphite (EG) was made by intercalating and exfoliating natural graphite flakes. The?EG was deposited with nickel particles, from which CNTs were grown by chemical vapor deposition. The CNTs were tip-grown, and their roots were fixed on the EG flakes. The EG flakes were compressed, and many CNTs on the surface were fragmented due to the compression-induced bending. Two major modes of the bending fracture were observed: cone-shaped and shear-cut. High-resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the crack growth within the graphene layers. The bending fracture is characterized by two-region crack growth. An opening crack first appears around the outer-tube due to the bending-induced tensile stress. The crack then branches to grow along an inclined direction toward the inner-tube due to the presence of the shear stress in between graphene layers. An inner-tube pullout with inclined side surface is formed. The onset and development of the crack in these two regions are discussed.