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采用自制的实验装置, 通过阳极弧放电等离子体技术成功制备了Ni纳米颗粒填充的碳纳米管, 利用高分辨透射电子显微镜(HRTEM)、 XRD、 TEM、 X射线能量色散分析谱仪(XEDS)和振动样品磁强计(VSM)等测试手段对样品的化学成分、 形态、 微观结构和磁性能进行了表征。实验结果表明, 采用本文中实验方法能获得大量被纳米金属颗粒填充的碳纳米管, 其内部填充物为面心立方(FCC)结构的纳米Ni颗粒, 外围薄层为石墨碳层。碳纳米管的外径为30~40 nm, 壁厚5~8 nm, 内部填充的纳米颗粒呈球形和椭球形, 粒径均匀, 在管腔内不连续分布。产物具有顺磁特性, 矫顽力是78 Oe, 饱和磁化强度是33 enu/g。 相似文献
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喷射电沉积Co-Ni纳米合金沉积层的组织和性能 总被引:4,自引:0,他引:4
用高速喷射电沉积法快速制备了块体纳米晶Co-Ni合金,研究了喷镀工艺参数(主盐浓度、电解液喷射速度和电流密度等)对沉积层成分、微观组织结构及性能的影响.结果表明:提高喷射电沉积电解液的搅拌强度能有效减小扩散层的厚度,使电沉积在较高的极限电流密度下进行,提高沉积速度.极限电流密度的增大使阴极过电位增大,从而提高合金的形核速率,使沉积层晶粒的尺寸减小、显微硬度升高.随着电解液中Co2 含量的增加,沉积层中Co含量增加,导致沉积层相结构由单相α-Co(Ni)转变为α-Co(Ni)和ε-Co(Ni)双相组织,并使表面的形貌发生明显的变化. 相似文献
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NiAl(Co)-TiC粉末的机械合金化原位制备纳米复合材料 总被引:1,自引:0,他引:1
用高能球磨机分别对四种成分的Ni50-Al50-x-Cox 10%(体积分数,下同)TiC (x=5,10,20)和Ni50-Al45-Co5 20%TiC粉末进行机械合金化,得到原位内生TiC弥散强化的NiAl(Co)纳米复合粉末.结果表明,球磨Ni50-Al45-Co5-10%TiC粉末过程中,爆炸反应机制生成NiAl(Co)和TiC化合物,其中NiAl(Co)化合物晶粒仅为10nm左右,TiC晶粒为35~50nm.但当TiC含量增加到20%时,其爆炸反应起始时间延后20min.同时随着Co含量增加,Ni50-Al40-Co10-10%TiC粉末的机械合金化的产物仍为NiAl(Co)和TiC,但NiAl(Co)化合物的生成机制转变为扩散反应机制.进一步增加Co含量(20%,原子分数)则导致了γ-Ni(Al,Co,Ti,C)过饱和固溶体的形成,反应机制仍为互扩散反应. 相似文献
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《功能材料信息》2016,(2)
正Cobalt compounds with different phase compositions and microstructure are promising in solving the energy storage and conversion problems.Herein,the graphene-likeα-Co(OH)_2,ultra-layeredα-Co(OH)_2 stacked with hexagonal nanosheets,and needle-like Co(CO_3)0.5(OH)·0.11H_2O were hydrothermally synthesized without using surfactant and templates by increasing the reaction temperature or prolonging the reaction 相似文献
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《真空》2016,(2)
采用化学气相沉积(CVD)方法在单晶高温合金基体上制备了钴铝(Co-Al)涂层,研究了900℃下涂层的高温热腐蚀行为。采用X-射线衍射(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)等方法分析了Co-Al涂层在高温热腐蚀过程中相结构、显微组织和化学成分的演变规律,结果表明:从腐蚀动力学曲线来看,表面涂覆Co-Al涂层的单晶合金的抗高温热腐蚀性能优于无涂层的合金基体;Co层可有效阻挡基体中的Cr元素向外扩散,使涂层表面形成一层连续纯净的Al2O3层,提高了涂层对合金材料的高温热腐蚀抗力;由于Al元素向外扩散,发生Co Al→α-Co相变,直至全部转变成α-Co相,涂层抗热腐蚀退化行为结束。 相似文献
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采用低压化学气相沉积(CVD)技术在MgO载体中的Fe、Co等纳米催化颗粒上制备碳纳米管(CNTs),用高分辨透射电子显微镜(HRTEM)及喇曼光谱仪(Raman)对生长的CNTs结构特性进行了分析研究,结果表明制备的样品中虽含多壁碳纳米管,但单壁碳纳米管(SWNTs)居多,直径约为0.6~2nm.分布均匀,且既包含金属型管,也包含半导体型管。低压MgO载体CVD制备技术,大大增加了等量Fe、Co等催化反应颗粒的比表面积和反应活性,制备的单壁管产额大、成本低、CNTs更易于提纯。 相似文献
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Konya Z. Vesselenyi I. Lazar K. Kiss J. Kiricsi I. 《Nanotechnology, IEEE Transactions on》2004,3(1):73-79
Characterization of iron containing alumina supported catalysts was performed by transmission electron microcopy (TEM), Mo/spl uml/ssbauer, and XPS spectroscopy during formation of multiwall carbon nanotubes from acetylene at 1000 K. TEM images showed that carbon fibers (outer diameter is around 20-40 nm) were generated on Fe/Al/sub 2/O/sub 3/ samples while on the bimetallic Fe,Co/Al/sub 2/O/sub 3/ carbon nanotubes with an average diameter of 8-12 nm were formed. XPS spectra revealed that Fe-Co alloy formed during the interaction of Fe,Co/Al/sub 2/O/sub 3/ and acetylene at 1000 K. The formation of the bimetallic alloy was proven by Mo/spl uml/ssbauer spectroscopy as well. 相似文献
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Hua-Qiang Wu Pin-Shi Yuan Hong-Yan Xu Dong-Mei Xu Bao-You Geng Xian-Wen Wei 《Journal of Materials Science》2006,41(20):6889-6894
Fe–Co alloy nanoparticles with different size were attached on the carbon nanotubes through adjusting the ratio of the metal
to carbon in the mixed solution of nitrate with Fe:Co = 1:1 (molar ratio) via wet chemistry. X-ray powder diffraction (XRD),
transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray
spectrometry (EDX) indicated that the Fe–Co alloy nanoparticles attached on the surface of carbon nanotubes has body-centered
cubic (bcc) structure, with sizes in the range of 13–25 nm and in the shape of spheroids. Magnetization measurements indicated
that both the coercivities and the saturation magnetizations altered with size changes of the Fe–Co alloy nanoparticles. The
saturation magnetization decreases with decreasing the Fe–Co alloy nanoparticles’ sizes. A decrease in coercivity with increasing
Fe–Co size together with a local maximum coercivity at size of ca. 15 nm is visible. A linear relationship between the inverse particle diameter and the coercivity was found for larger particles.
These demonstrated that the chemical method here is promising for fabricating Fe–Co alloy nanoparticles coated on carbon nanotubes
for magnetic storage applications. 相似文献
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化学气相沉积法合成碳纳米管及其导电性能研究 总被引:1,自引:0,他引:1
《材料导报》2010,24(6)
以二甲硫醚为碳源前驱体,Co/MgO为催化剂,采用化学气相沉积法生长出碳纳米管及Y形碳纳米管,此法稳定性及重现性较好.通过扫描电子显微镜、透射电子显微镜、拉曼光谱及X射线衍射对产品形态和结构进行了分析和表征,结果表明,所制备的碳纳米管形态较规整、纯度较高,具有较好的石墨微晶结构;导电性能测试结果显示,Y形碳纳米管各分支均呈现出典型的金属性导电性能. 相似文献
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Carbon dioxide was successfully used as carbon source in the synthesis of carbon nanotubes (CNTs) by chemical vapor deposition (CVD) over Fe/CaO catalyst. The product was evaluated using both transmission electron microscopy (TEM) and Raman spectroscopy. Crooked and branching structures of multi-walled carbon nanotubes (MCNTs) with diameters of around 50 nm were observed on the TEM micrographs. Raman spectrum results show that the nanotubes have small defects, which is in agreement with the results of TEM. The influence of reaction variable such as furnace temperature and types of support media was also studied and the reaction mechanism was then discussed in this paper. 相似文献
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High quality single walled carbon nanotubes (SWCNTs) and double walled carbon nanotubes (DWCNTs) were synthesized on Co/V/MgO catalysts by catalytic decomposition of CH4 in H2. Raman spectroscopy data revealed that the diameters of as-prepared SWCNTs are 1.28 and 0.73 nm. The diameter value of DWCNTs from Raman analysis also showed a narrow diameter distribution. Using field emission transmission electron microscopy (TEM), it was found that the diameter of carbon nanotubes can be controlled mainly by adjusting the molar ratio of Co–V versus the MgO support. The structure properties of catalysts were examined by X-ray diffraction (XRD). The formation of C7V8 may play an important role in preserving carbon in the catalyst particle and favoring the dissociation balance of CH4. 相似文献
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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. 相似文献
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An ethylene-air laminar diffusion flame successfully provided silicon substrates of anodic aluminum oxide (AAO) template with vertically oriented well-aligned carbon nanotubes. Field emission scanning electron microscopy (SEM) showed that open-tipped carbon nanotubes consisting of tube elements with the same length and diameter uniformly coated the template. High-resolution transmission electron microscopy (TEM) analyses revealed these nanotubes to be multiwalled carbon nanotubes, some well graphitized. It was found that cobalt catalyst particles, but not the porous aluminum templates, helped the growth of carbon nanotubes through graphitization and bonding of carbon nanotubes to the silicon substrates. 相似文献