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Abdulkareem AS Afolabi AS Iyuke SE Vz Pienaar HC 《Journal of nanoscience and nanotechnology》2007,7(9):3233-3238
A series of developments have been made in synthesizing Carbon Nanotubes (CNTs) by Catalytic Vapour Deposition (CVD) methods since its discovery as a possible route to the large scale and high quality production of CNTs. In this study, CNTs were synthesized continuously in a swirled floating catalytic chemical vapour deposition reactor using acetylene as carbon source, ferrocene as catalyst, with argon and hydrogen as carrier gases within the temperature range of 900-1050 degrees C. The effects of pyrolysis temperature, acetylene flow rate, hydrogen flow rate, and ratio of flow of acetylene to hydrogen on the rate of production of CNTs were investigated. The CNTs produced were purified with dilute nitric acid and the nature and quality of the CNTs were analysed by TEM, Raman spectrometer, EDX, and TGA. Results obtained revealed that a mixture of single and multi wall carbon nanotubes were produced continuously with a maximum yield rate of 0.31 g/min at 1000 degrees C and a flow ratio of acetylene to hydrogen of one to five. 相似文献
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以环己烷为碳源、二茂铁为催化剂前躯,采用浮游催化法成功的在碳纤维表面生长了碳纳米管(CNT),制备了多尺度杂化材料CNTs/CF。实验重点考察了反应温度、二茂铁浓度、载气等参数对CNT在纤维表面生长的影响,通过扫描电镜(SEM)、投射电镜(TEM)研究了CNTs/CF的形貌及产物CNT的微观结构。当固定反应温度为820℃、二茂铁-环己烷浓度为2g/100mL时,随着氢气在载气中含量在0~100%范围内变化,产物CNT直径亦有86nm降低至39nm。通过单丝拉伸测试发现,相比初始碳纤维,不同长度的CNTs/CF单纤维强度下降幅度均在10%以内。 相似文献
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《Journal of Experimental Nanoscience》2013,8(4):269-277
The ferrocene catalysed decomposition of acetylene by swirled floating chemical vapour deposition method was studied in this work. Analyses of the products formed confirm the presence of carbon nanotubes and carbon nanoballs. These materials were synthesized at different production conditions; high flow rates of carbon source and carrier gases as well as low decomposition temperature were found to be responsible for the formation of CNBs. TEM images also show that both CNTs and CNBs contain low contents of iron impurities and amorphous carbons. 相似文献
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二维树状分叉碳纤维的浮动催化法制备 总被引:1,自引:0,他引:1
采用两段加热卧式浮动催化法合成了二维树状分叉碳纤维。讨论了制备条件如:催化剂(二茂铁)、催化促进剂(噻吩)以及它们在碳源溶液中的含量、苯/氢的比例、氢气的流量等对生长二维树状分叉碳纤维的影响。二维树状分叉碳纤堆的分叉纤堆相互平行排列,直径与母体纤维接近,部分分叉碳纤维与其它碳纤维交叉相连。提出了二维树状分叉碳纤维的生长机理和交叉结构可能的生长模式;二维树状分叉碳纤维的生长符合气相生长碳纤堆的生长机理,是纳米碳纤维在反应管高温区继续生长的结果。可以预测,控制一定的条件,可以用两段加热卧式浮动催化法合成二维碳纤维网状结构,在复合材料等领域有潜在的应用价值。 相似文献
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催化剂结构与形态对碳纳米管生长的影响 总被引:15,自引:11,他引:4
采用溶胶-凝胶超临界流体干燥技术制备了含铁、钴的纳米SiO2复合气凝胶催化剂,用于碳纳米管和纳米碳包覆磁性纳米粒子的合成。利用N2物理吸附、XRD、TEM、HRTEM、EDS、SAED等手段对催化剂在不同温度下处理后晶型的转变、形态的变化进行了分析,并考察了催化剂对碳纳米管形貌、结构和碳增重率的变化。结果表明:随着处理温度从600℃升高到1000℃,催化剂比表面积从312.4m2 g降低到79.6m2 g,催化剂粒子从非晶态向晶态转变,粒径从5nm增大至60nm左右,碳的增重率从254.8%下降41.5%。采用低温处理的催化剂,碳产物中以碳纳米管为主,而采用较高温度处理后的催化剂,碳产物中则以碳包覆粒子为主,且随处理温度的升高碳包覆粒子的含量逐渐增加。 相似文献
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Amanda Araújo Silva Romário Araújo Pinheiro Vladimir Jesus Trava-Airoldi Evaldo José Corat 《Fullerenes, Nanotubes and Carbon Nanostructures》2018,26(5):315-323
Multi-walled carbon nanotubes (MWCNTs) have been successfully grown by Chemical Vapor Deposition (CVD) method. Elucidating the key characteristics of catalyst sources that affect carbon nanotubes growth is of great importance for improving and control MWCNTs morphology and structure. In this work we present a systematically study of CVD parameters, such as catalyst source, substrate morphology and temperature and how it affects carbon nanotubes synthesis. The novelty of this work lies on the catalyst composition. Two specific catalyst sources were analyzed: (i) Fe2Co and (ii) Fe2Co with ferrocene. Cyclic Voltammetry results confirmed the presence of Fe2+ in the Fe2Co with ferrocene solution. X-Ray Diffraction analysis confirmed the presence of iron particles on the substrate surface after its submission to growth conditions. Raman results suggested an improvement in carbon nanotubes crystalline quality catalyzed by Fe2Co with ferrocene. For tridimensional substrates such as fibers, the Fe2Co with ferrocene provided aligned CNTs with lower defects density noticed in Raman spectra and SEM micrographs. Finally, we corroborated the Fe2+ encapsulation relation with the growth mechanism and MWCNTs formation. 相似文献
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Nikolay V. Kobernik Roman S. Mikheev Nikolay P. Aleshin 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(7):515-520
AbstractDue to their high antifriction characteristics, the Sn-Sb-Cu alloys (referred to as babbits) are widely used to coat sliding bearings. However, some limitations of the present techniques for applying such coating materials cause a decrease in their fatigue strength because of the reinforcing phase particles growth. As a technique for restricting the increasing of the reinforcing particle sizes, this paper proposes plasma surface cladding with multiwall carbon nanotubes (MWNTs) as modifiers. The dry sliding friction tests performed according to the “pin-on-disk” scheme using as a counterface a steel 100Cr6 (DIN 17230) disk have shown that adding to the coating 0.25%wt of CNTs significantly improves the friction stability (the coefficient of friction process stability decreases twice with reducing the friction coefficient and wear resistance by 5% on the average). An attempt to reveal the mechanism for the MWNT influence on the structure and performance of the babbit-based coatings was undertaken. Studies of the coatings metal structure by soft X-ray absorption spectroscopy and also by the metallographic and fractographic analysis involving electron-microscopy have shown that MWNTs remain stable during plasma cladding process and save into the coating. 相似文献
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Carbon nanotubes (CNTs) were grown using a dc arc discharge process and relevant process parameters were investigated. Unlike the usual process in which a carbon anode is filled with metal catalyst powder, CNTs were prepared using a carbon cathode on which the metal catalyst had been deposited using an electroplating system. Various transition metals were investigated. The results show that multi walled carbon nanotubes (MWNTs) and single walled carbon nanotubes (SWNTs) can both be synthesized using this technique. SWNTs are detected in the soot sample collected around the cathode, whereas the MWNTs are detected mainly in the deposit sample collected from the central area of the cathode. The CNT yield varies depending on the catalyst used and the properties of a good catalyst are discussed. 相似文献
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Double-walled boron nitride nanotubes grown by floating catalyst chemical vapor deposition 总被引:1,自引:0,他引:1
Kim MJ Chatterjee S Kim SM Stach EA Bradley MG Pender MJ Sneddon LG Maruyama B 《Nano letters》2008,8(10):3298-3302
One-dimensional nanostructures exhibit quantum confinement which leads to unique electronic properties, making them attractive as the active elements for nanoscale electronic devices. Boron nitride nanotubes are of particular interest since, unlike carbon nanotubes, all chiralities are semiconducting. Here, we report a synthesis based on the use of low pressures of the molecular precursor borazine in conjunction with a floating nickelocene catalyst that resulted in the formation of double-walled boron nitride nanotubes. As has been shown for carbon nanotube production, the floating catalyst chemical vapor deposition method has the potential for creating high quality boron nitride nanostructures with high production volumes. 相似文献
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This study demonstrates the first example of the use of a metal-free catalyst for the continuous synthesis of carbon nanotubes (CNTs) by chemical vapor deposition (CVD). In this paper silica nanoparticles produced from the thermal decomposition of PSS-(2-(trans-3,4-Cyclohexanediol)ethyl)-Heptaisobutyl substituted (POSS) were used as catalyst and ethanol was served as both the solvent and the carbon source for nanotube growth. The POSS/ethanol solution was nebulized by an ultrasonic beam. The tiny mists were continuously introduced into the CVD reactor for the growth of CNTs. The morphology and structure of the CNTs have been investigated by scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. The obtained CNTs have a multi-walled structure with diameters mainly in the size range from 13 to 16 nm. Detailed investigations on the growth conditions indicate that the growth temperature and POSS concentration are important for achieving high-quality nanotubes, and that the existing of small amount of water in ethanol is effective to remove amorphous carbon species during the formation of CNTs. The mass production of CNTs without any metal contaminant will provide a chance for investing and understanding the intrinsic properties of CNTs and applications particularly in nanoelectronics and biomedicines. 相似文献
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G. Atthipalli R. EpurP.N. Kumta B.L. AllenY. Tang A. StarJ.L. Gray 《Thin solid films》2011,519(16):5371-5375
Growth of carbon nanotubes (CNTs) on bulk copper foil substrates has been achieved by sputtering a nickel thin film on Cu substrates followed by thermal chemical vapor deposition. The characteristics of the nanotubes are strongly dependent on the Ni film thickness and reaction temperature. Specifically, a correlation between the thin film nickel catalyst thickness and the CNT diameter was found. Two hydrocarbon sources investigated were methane and acetylene to determine the best conditions for growth of CNTs on copper. These results demonstrate the effectiveness of this simple method of directly integrating CNTs with highly conductive substrates for use in applications where a conductive CNT network is desirable. 相似文献
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The scanning tunneling microscopy (STM) observation of arc-grown Y-branched carbon nanotubes and sharp nanotube bends (nano-knees) is reported. A drilled out graphite rod filled with a nickel/yttrium particle mixture was used as the anode in an arc chamber under He atmosphere of 660-mbar pressure. Straight multi-wall nanotubes, Y-branches and nano-knees were found in a sample taken from the cathodic deposit. The asymmetrical Y-branches and complex nano-knees found in this experiment may be related to the additional use of metals or/and to induced changes of the temperature distribution on the cathode side. It is suggested that complex nano-knees could be new examples for carbon quantum dots. 相似文献