直流电弧等离子体法制备碳包覆金属纳米颗粒的研究
发布时间：2018-11-03 11:07
【摘要】： 碳包覆金属纳米颗粒是一种新型的纳米碳／金属复合材料,它呈现胶囊状的碳壳包覆金属纳米颗粒的壳／核结构,包覆壳层为无定形碳结构或多层石墨层结构,内核为金属纳米颗粒。这种独特的结构不仅可以防止金属纳米颗粒氧化和环境降解,而且能够有效抑制金属纳米颗粒的团聚,解决了金属纳米颗粒在空气中不能稳定存放的问题。碳包覆金属纳米颗粒具有一些独特的电学、光学、磁学性等能,在磁记录材料、铁磁流体、磁共振成像、催化剂、新能源和生物医学等许多领域有着广泛的应用前景,成为材料科学研究的热门课题。 本文首先综述了碳包覆金属纳米颗粒的制备方法及其应用。并对直流电弧等离子体制备金属纳米粉体技术进行了探讨,等离子体具有热效率高、温度高、能量集中、电弧稳定、气氛可控和便于急冷等特点,为纳米材料的形成与生长提供了理想的物理化学环境。我们采用已有的直流电弧等离子体实验装置成功制备出铁纳米粉体,并采用X射线衍射仪、透射电子显微镜、选区电子衍射、比表面积和孔隙分析仪、振动试样磁强计等多种手段对纳米铁粉体的晶体结构、形貌、粒度及其分布和磁性等进行了表征。 本文同时对现有的直流电弧等离子体实验装置进行改进,成功的制备出碳包覆铁纳米颗粒,采用X射线衍射仪、高分辨透射电子显微镜、拉曼光谱等对试样的形态和形貌、粒度及其分布、碳壳的石墨化程度、晶体结构等特征进行表征。采用振动试样磁强计、X射线能量色散分析谱仪、热重-差热分析仪等对制备的碳包覆铁纳米颗粒的化学成分、磁性和抗氧化性能进行研究,研究矫顽力和饱和磁化强度随粒度的变化关系。研究结果表明平均粒度为27nm的碳包覆铁纳米颗粒具有超顺磁性。碳包覆铁纳米颗粒比表面经过钝化处理后的铁纳米粉体有更好的抗氧化性能。 最后研究了工艺参数对生成的碳包覆铁纳米颗粒形貌的影响规律,建立了直流电弧等离子体法制备碳包覆铁纳米颗粒的形成机理模型,并用热力学、动力学和铁碳相图分析了碳包覆铁纳米颗粒的形成机理。
[Abstract]:Carbon-coated metal nanoparticles are a new type of nano-carbon / metal composite material, which presents the shell / core structure of encapsulated carbon shell coated with metal nanoparticles, and the coating shell is amorphous carbon structure or multi-layer graphite structure. The core is metal nanoparticles. This unique structure can not only prevent the oxidation of metal nanoparticles and environmental degradation, but also effectively inhibit the agglomeration of metal nanoparticles, and solve the problem that metal nanoparticles can not be stored stably in the air. Carbon coated metal nanoparticles have some unique electrical, optical and magnetic properties, and have a wide range of applications in many fields, such as magnetic recording materials, ferrofluids, magnetic resonance imaging, catalysts, new energy sources and biomedicine. It has become a hot topic in material science research. In this paper, the preparation and application of carbon coated metal nanoparticles are reviewed. The preparation technology of metal nanocrystalline powder by DC arc plasma is discussed. The plasma has the characteristics of high thermal efficiency, high temperature, concentrated energy, stable arc, controllable atmosphere and convenient for rapid cooling. It provides an ideal physical and chemical environment for the formation and growth of nanomaterials. We successfully prepared the iron nanoparticles by using the existing DC arc plasma experimental device, and used X-ray diffractometer, transmission electron microscope, selected area electron diffraction, specific surface area and pore analyzer. The crystal structure, morphology, particle size and distribution and magnetic properties of nano-iron powders were characterized by vibrating sample magnetometer. At the same time, the existing DC arc plasma experimental device was improved to successfully prepare carbon coated iron nanoparticles. The morphology and morphology of the samples were investigated by X-ray diffractometer, high resolution transmission electron microscope, Raman spectroscopy, etc. The particle size and its distribution, graphitization degree of carbon shell and crystal structure were characterized. The chemical composition, magnetic properties and oxidation resistance of carbon coated iron nanoparticles were studied by means of vibrating sample magnetometer, X-ray energy dispersive spectrometer and thermogravimetric differential thermal analyzer. The relationship between coercivity and saturation magnetization with particle size was studied. The results show that the carbon coated iron nanoparticles with average particle size of 27nm have superparamagnetic properties. Carbon coated iron nanoparticles have better oxidation resistance than surface passivated iron nanoparticles. Finally, the influence of process parameters on the morphology of carbon coated iron nanoparticles was studied. The formation mechanism model of carbon coated iron nanoparticles by DC arc plasma method was established and thermodynamics was used. The formation mechanism of carbon coated iron nanoparticles was analyzed by kinetics and phase diagram.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TB383.1
[Abstract]:Carbon-coated metal nanoparticles are a new type of nano-carbon / metal composite material, which presents the shell / core structure of encapsulated carbon shell coated with metal nanoparticles, and the coating shell is amorphous carbon structure or multi-layer graphite structure. The core is metal nanoparticles. This unique structure can not only prevent the oxidation of metal nanoparticles and environmental degradation, but also effectively inhibit the agglomeration of metal nanoparticles, and solve the problem that metal nanoparticles can not be stored stably in the air. Carbon coated metal nanoparticles have some unique electrical, optical and magnetic properties, and have a wide range of applications in many fields, such as magnetic recording materials, ferrofluids, magnetic resonance imaging, catalysts, new energy sources and biomedicine. It has become a hot topic in material science research. In this paper, the preparation and application of carbon coated metal nanoparticles are reviewed. The preparation technology of metal nanocrystalline powder by DC arc plasma is discussed. The plasma has the characteristics of high thermal efficiency, high temperature, concentrated energy, stable arc, controllable atmosphere and convenient for rapid cooling. It provides an ideal physical and chemical environment for the formation and growth of nanomaterials. We successfully prepared the iron nanoparticles by using the existing DC arc plasma experimental device, and used X-ray diffractometer, transmission electron microscope, selected area electron diffraction, specific surface area and pore analyzer. The crystal structure, morphology, particle size and distribution and magnetic properties of nano-iron powders were characterized by vibrating sample magnetometer. At the same time, the existing DC arc plasma experimental device was improved to successfully prepare carbon coated iron nanoparticles. The morphology and morphology of the samples were investigated by X-ray diffractometer, high resolution transmission electron microscope, Raman spectroscopy, etc. The particle size and its distribution, graphitization degree of carbon shell and crystal structure were characterized. The chemical composition, magnetic properties and oxidation resistance of carbon coated iron nanoparticles were studied by means of vibrating sample magnetometer, X-ray energy dispersive spectrometer and thermogravimetric differential thermal analyzer. The relationship between coercivity and saturation magnetization with particle size was studied. The results show that the carbon coated iron nanoparticles with average particle size of 27nm have superparamagnetic properties. Carbon coated iron nanoparticles have better oxidation resistance than surface passivated iron nanoparticles. Finally, the influence of process parameters on the morphology of carbon coated iron nanoparticles was studied. The formation mechanism model of carbon coated iron nanoparticles by DC arc plasma method was established and thermodynamics was used. The formation mechanism of carbon coated iron nanoparticles was analyzed by kinetics and phase diagram.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TB383.1
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