Synthesis and characterization of carbon spheres prepared by chemical vapour deposition

Carbon spheres, with uniform diameters of about 1 μm, have been achieved via Chemical vapour deposition (CVD). The fabricated materials have been fully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray analysis (EDX). The results show that the spheres are 95% carbon. The formation mechanism of carbon spheres has also been discussed.     

直流碳弧法制备碳包覆铁纳米颗粒机理研究

采用直流碳弧等离子体法成功制备了碳包覆铁纳米颗粒,利用透射电子显微镜和高分辨透射电子显微镜、X射线衍射、X射线能谱仪对样品的形貌、物相结构、化学成分和粒度进行表征分析,并对碳包覆纳米金属颗粒的形成机理进行初步探讨。结果表明:直流碳弧等离子体技术制备的碳包覆纳米金属颗粒具有明显的铁核(bcc-Fe)/碳壳(石墨层片)包覆结构,颗粒大多呈球形和椭球形,粒径分布在20~60nm范围,平均粒径为44nm,铁粒子外碳层的厚度为5~8nm。碳包覆铁纳米铁颗粒是通过颗粒内部固态形式的碳自行扩散至颗粒表面和颗粒外部气态形式的碳沉积到颗粒表面形成的。     

The microstructure and electrochemical characteristics of LiFePO4/carbon-network composite

LiFePO4/carbon-network composite was synthesized by a high temperature solid-state method using the natural sawdust as carbon precursor. The microstructure of the as-synthesized sample was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), respectively. The results revealed that the LiFePO4 particles with diameters ranging from 30 to 150 nm were well connected by carbon networks. The electrochemical performance of the composite was characterized using galvanostatic charge-discharge technique. The initial discharge capacity of LiFePO4/carbon-network cathode reached 126 mAh x g(-1) with 0.2 C rate.     

Carbon nanotubes from catalytic pyrolysis of deoiled asphalt

High purity and uniform carbon nanotubes with about 35 nm in diameter were produced by pyrolysis of deoiled asphalt in the presence of ferrocene in an atmosphere of hydrogen and argon at 1000 °C. Characterization of carbon nanotubes was carried out by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray energy dispersive spectroscopy (EDS), Raman spectroscopy and X-ray diffraction (XRD). The carbon nanotubes were highly graphitized with amorphous carbons covering the outside wall. The influence of temperature on the preparation of carbon nanotubes was also discussed.     

Solvothermal synthesis of carbon nanostructure and its influence on thermal stability of poly styrene

Carbon nanostructures were synthesized via a novel solvothermal reaction between ferrocene and sulfur. Carbon nanostructures were then added to poly styrene (PS) matrix. The thermal stability behavior of PS filled with carbon nanostructures were investigated by thermogravimetric analysis (TGA). Nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, energy-dispersive X-ray (EDS) analysis and atomic force microscopy (AFM). The flame retardancy behavior of PS–carbon was studied by UL-94 analysis.     

Fabrication of high quality carbon nanotubes with a simple ethanol-assisted arc discharge process

In this paper, a simplified ethanol-assisted arc discharge method was developed for the fabrication of multi-wall carbon nanotubes in high quality. Carbon nanotubes with high purity (80-90%) were obtained through controlling the current (15-25 V, 10-25 A) and ethanol concentration (70-100%). The products were characterized using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectrometry.     

碳包裹镍核-壳结构复合纳米颗粒的制备及性能研究

采用自行研制的实验装置,通过阳极弧放电等离子体技术成功制备了碳包裹镍核-壳结构纳米复合颗粒,并采用酸洗和磁选的方法对初产物进行了纯化.利用高分辨透射电子显微镜(HRTEM)、X射线衍射(XRD)、透射电子显微镜(TEM)和X射线能量色散分析谱仪(XEDS)等测试手段对样品的化学成分、形貌、微观结构和粒度等特征进行了表征...     

双基体炭/炭复合材料的微观结构与力学性能

借助偏光显微镜、扫描电镜,透射电镜以及力学性能测试研究了微观结构对双基体炭/炭复合材料力学性能的影响.结果表明:基体炭在偏光显微镜下呈现光学各向异性,材料内部形成多层次的界面结构,热解炭呈现"皱褶状"片层结构,中间相沥青炭呈现片层条带状结构,基体炭片层的走向基本上平行于纤维轴向.材料受载破坏时裂纹通过改变扩展路径而延缓其扩展速度,在纤维-基体界面处以及基体炭片层之间引起滑移,在断口形貌上体现出锯齿状的断裂形式,材料具有韧性断裂的特征,抗弯强度最高可达223MPa.     

Preparation and characterization of magnetic carbon nanomaterials bearing APTS–silica on their surface

The formation of metal-encapsulated carbon nanomaterials by using metallic catalysts (iron, cobalt, and nickel) has been studied. Moreover, these materials were coated with silica surface modified by (3-Aminopropyl)-trimethoxysilane (APTS). Each intermediate structure was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface morphology of silica-coated carbon nanomaterials was analyzed by scanning electron microscopy (SEM). The modified, APTS–silica surface was additionally characterized by Fourier transform infrared spectroscopy (FT-IR), elemental (EA), and thermogravimetric analysis (TGA).     

Microscope studies of the morphology and structure of carbon nanotubes

We have studied the morphologies and structures of carbon nanotubes (bucky-tubes) and carbon nanoparticles (buckyonions) using scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning tunnelling microscopy (STM). By SEM the carbon nanotubes are observed with features similar to those of some fibrous whiskers grown from pyrolytic graphite. This growth feature is supported by transmission electron microscopy (TEM) observations. The TEM results show also that the graphitic sheets can be bent into curved shapes to cap the nanotubes or form the onions. In the curved graphitic sheets elastic strains induced by layer mismatches and dislocations are revealed. The STM observations on the nanotubes show a bundle-like morphology of the carbon nanotubes, and by atomic resolution images the zigzag and armchair atomic configurations may be identified. The results also show structural distortions which may be produced by folding the graphite sheets to create the nanotubes and are responsible for the lattice mismatch.     

Filling single-wall carbon nanotubes with d- and f-metal chloride and metal nanowires

Nanowires of magnetic metals (Fe, Co, Ho, Gd) have been synthesized inside the hollow interiors of single-wall carbon nanotubes (SWNTs) by filling SWNTs with precursor metal chlorides and subsequent reduction. SWNTs have been filled by either the melt-phase sealed-tube reaction or a solution-phase method. Among the metal chlorides investigated in this study, HoCl3 and GdCl3 filled the SWNTs to a significantly higher extent. The nanowires have been imaged by transmission electron microscopy (TEM), high-resolution transmission electron microscopy, and scanning transmission electron microscopy (STEM). X-ray energy dispersive spectroscopy carried out in conjunction with TEM and STEM confirmed the presence of metal chloride and metal nanowires.     

Study on the controlled growth of carbon nanospheres from de-oiled asphalt

Carbon nanospheres were synthesized from de-oiled asphalt (DOA) by chemical vapor deposition (CVD). The morphology and microstructure of the products were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM), and the influences of different parameters were disscussed. The results showed that carbon nanospheres could be synthesized from DOA, which were spherical with uniform size and amorphous structure. Such controlled growth of carbon nanospheres of DOA has never been reported; our work would offer reliable experimental data for the transformation of DOA into high-added value carbon materials.     

一维纳米材料的ECR-CVD方法制备

应用电子回旋共振微波等离子体化学气相沉积方法(ECR-CVD)进行了一维纳米材料的制备.以Fe3O4纳米粒子为催化剂,采用不同的气源,在多孔硅基底上制备出了碳纳米管、掺硼碳纳米管以及异质结构的纳米管.利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和 X射线光电子谱(XPS)对样品的形貌、结构及组分进行表征.     

Co催化热分解制备弯曲状碳纳米管的研究

用Ｃｏ催化剂催化热分解乙炔制备碳纳米管,考察了工艺参数对碳纳米管收率及其同结构的影响,得到了较好的工艺流程,同时运用ＴＥＭ、ＨＲＴＥＭ及拉曼光谱对其微观结构进行了分析,并对生长机理做了初步的探讨。     

镍/碳微球复合材料的制备和表征

碳微球与微米镍粉按一定比例混合后,经过6h机械球磨并在1600℃真空热处理,合成了微米镍/碳复合材料。通过场发射扫描电镜(FESME)、高分辨透射电镜(HRTEM)和X射线衍射仪(XRD)对产物进行表征。结果表明,产物为碳包覆镍金属颗粒,粒径200～400nm的镍颗粒被30～100nm的碳层包覆,碳层的石墨化程度较高;产物石墨化碳层的形成缘于Ni3C的形成和分解。     

MWCNTs/PVC电纺纤维及其力学性能

用静电纺技术制备了多壁碳纳米管/聚氯乙烯(MWCNTs/PVC)超细纤维,对复合纤维的形貌、结构、结晶行为及热稳定性进行了分析测试,着重研究了复合纤维膜的力学性能与MWCNTs用量的关系。结果表明,MWCNTs能有效地分散于PVC溶液中,并成功纺出MWCNTs/PVC超细纤维。随着MWCNTs含量的增加,纤维直径变细,改善了纤维的结晶性,但热稳定性变差。纤维膜的拉伸断裂强度和断裂伸长率随MWCNTs含量增加出现先增加后下降的趋势。     

Carbon Diffusion in Hot Strips of Low Carbon Steel Produced by CSP Line under Different Thermal Histories

Two experiments were carried out on the same compact strip production (CSP) line, which differs in that one of them experienced γ→α→γ* thermal history. The differences in microstructure, precipitation, misorientation etc between two experiments were investigated by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron back-scattered diffraction (EBSD) and positron annihilation technique (PAT). The carbon concentration in matrix is more inhomogeneous in the experiment than that with γ→α→γ* thermal history. The specific precipitation characteristic in the experiment without γ→α→γ* thermal history is discussed on the basis of different carbon diffusion behavior and interaction between dislocation and excess carbon.     

Study on novel poly (vinyl pyrrolidone) doped MWCNTs/polyrhodanine nanocomposites: Synthesis,characterization, and thermal performance

In this paper, poly (vinyl pyrrolidone) (PVP) doped multiwall carbon nanotubes (MWCNTs/polyrhodanine), were synthesized through one-step chemical oxidative polymerization of rhodanine monomers on the surface-modified carbon nanotubes. Characterization of MWCNTs/polyrhodanine was conducted by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and EDX spectrum analyses in which the results confirmed the successful formation of MWCNTs/polyrhodanine. In addition, to investigate the thermal properties of samples, thermogravimetric analysis (TGA) was employed, and results exhibited significant improvement in the nanocomposite thermal stability due to the addition of MWCNTs with reinforcement effect in polymer matrix.     

填充叠氮化铜的碳纳米管纳米材料的制备研究?

首先采用电化学沉积法在碳纳米管中沉积铜,再利用叠氮化反应制备填充叠氮化铜的碳纳米管纳米材料。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)和X射线能谱(EDS)对样品的微观形貌和晶体结构进行表征。结果表明,利用电化学沉积方法在定向碳纳米管中空管腔内合成了针状纳米枝晶铜,非连续的枝晶结构有利于后续的气固叠氮化反应,最终制备得到填充叠氮化铜晶体的碳纳米管纳米材料。     

Effects of the size of nano-copper catalysts and reaction temperature on the morphology of carbon fibers

In this study, carbon fibers with different morphologies, including coiled carbon nanofibers and straight carbon fibers, were obtained by the chemical vapor deposition using a Cu-catalytic pyrolysis of acetylene at 250 °C. The influences of nano-copper catalyst particle size and the reaction temperature on the morphology of carbon fibers were investigated. Under the same reaction condition, coiled carbon nanofibers generally were synthesized using nano-copper catalyst with smaller particles size, and bigger copper particles are apt to produce straight carbon fibers. With decreasing of reaction temperature to 200 °C, straight carbon fibers were obtained, instead of coiled carbon nanofibers at 250 °C. The product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD).