乙醇中锆丝电爆炸法制备碳包覆ZrC纳米颗粒（英文）

采用在有机液体中进行金属丝电爆炸的方法制备了碳包覆纳米颗粒。以无水乙醇为介质,对高纯度锆丝施加高压脉冲电流,锆丝在高密度电流下迅速熔化、气化、膨胀并爆炸,伴随着高温、高压下乙醇中碳的析出和碳与锆反应及包覆过程,制备出碳包覆ZrC纳米粉体颗粒。对电爆炸过程中的能量、电流、电压对产物的影响进行了分析,通过XRD、TEM、HRTEM等分析了产物特征。结果表明:产物为球状碳包覆碳化锆纳米颗粒,粒径分布在10~150 nm之间;在4、8、12 kV电压下,产物平均粒径分别为24.9、41.1、43.9 nm。最后,对碳包覆ZrC纳米颗粒的形成机理进行了初步的探讨。     

丝电爆制备金属纳米颗粒的研究

开发了金属丝电爆制备纳米颗粒的设备,适用于细金属丝连续电爆制备纳米颗粒,并用高压触发管来控制爆炸位置。利用该装置将0.2mm及0.1mm丝径的镍丝、钼丝、钨丝制备成相应的纳米颗粒,结合纳米颗粒形貌、颗粒粒度分布以及爆炸过程的电流电压波形进行分析。结果表明:在爆炸位置不受控制的情况下,钼丝电爆时受大电流气体放电作用,制备的纳米颗粒粒径大且不均匀,平均粒径在40～60nm之间;而镍丝制备的纳米颗粒品质较好,平均粒径在20～30nm之间。爆炸位置受控时,可以将钨丝制成平均粒径为20.5nm的颗粒。。     

锆丝电爆炸法制备氧化锆纳米颗粒及其特征

在空气中采用锆丝点爆炸法合成了纳米二氧化锆颗粒,根据实测电流、电压和由此计算得到的能量沉积波形分析了电爆炸和纳米颗粒形成过程。发现锆丝气化后在锆丝蒸汽和空气中形成电击穿现象诱发电爆炸并截断锆丝中的能量沉积。通过扫描电镜和透射电镜对产物进行了分析,发现纳米二氧化锆颗粒形貌呈近球形,粒度分布在30.6-69.4纳米之间。X射线衍射分析表明产物由单斜晶型(m- ZrO2)和四方晶型(t- ZrO2)二氧化锆组成,随着充电电压的提高,四方晶型二氧化锆含量增加而单斜晶型含量变小,二者粒度都呈变大趋势。     

碳包覆氧化镍纳米颗粒制备与电化学性能研究

采用直流电弧放电等离子体技术制备了核壳结构碳包覆氧化镍纳米颗粒,并采用X射线衍射、高分辨透射电子显微镜、X射线能量色散分析谱仪和表面物理吸附仪等测试技术对样品的微观结构进行研究。并利用循环伏安法、恒电流充放电以及交流阻抗等技术研究其作为超级电容器电极材料的电化学性能。结果表明:直流电弧等离子体技术制备的碳包覆氧化镍纳米颗粒具有典型的核壳结构,内核为面心立方结构的氧化镍纳米颗粒,外壳为碳层。颗粒形貌主要为立方体结构,粒度均匀,分散性良好,粒径分布在30～70 nm范围,平均粒径为50 nm,外壳碳层的厚度为5 nm。碳包覆氧化镍纳米颗粒具有较高的比容量和良好的电化学活性。     

亲油纳米铜粉制备新方法的研究

在电爆法制备纳米粉基础上,开发了一种新的电爆制备亲油纳米粉体法,它能使金属丝在爆炸的瞬间,浸润到液体油中,减少纳米粉体的团聚.研究表明,油浸润条件下所制得的纳米粉的分散性优于传统电爆法所制的纳米粉;制备的纳米铜粉平均粒径为30～50 nm,随电极电压升高,粒径有减小趋势.     

初始充电电压对电爆产物尺度分布的影响

在丝电爆过程中,初始充电电压对最终的纳米粉尺度分布有重要影响。在气体放电式丝电爆装置上进行系列试验,通过分析爆炸产物尺度分布及其形成原因,认识初始充电电压的影响。结果表明,在初始充电电压较低时,纳米粉中纳米级颗粒的平均粒径、微米级大颗粒比例随初始充电电压升高而逐渐减小,而初始充电电压过高时,纳米级颗粒平均粒径、微米级大颗粒比例反而会随初始充电电压的升高而增大。分析可知,在初始充电电压过高时,丝表面发生沿面放电现象,会阻碍能量向金属丝沉积。     

约束弧等离子体制备碳包覆铁纳米颗粒的性能

采用约束弧等离子体技术制备碳包覆铁纳米颗粒,利用X射线衍射、透射电子显微镜、高分辨透射电子显微镜、X射线能量色散分析谱仪和N2吸附等测试手段对样品的化学成分、形貌、微观结构、比表面积和粒度等特征进行表征分析。结果表明：采用约束弧等离子体技术制备的碳包覆纳米金属颗粒具有明显的核？壳结构,内核金属为体心立方结构的铁,外壳为无定形碳。颗粒大多呈球形和椭球形,粒径分布在15～40nm范围内,平均粒径为30nm,内核粒径为18nm,外层碳的厚度为6～8nm,比表面积为24m2/g。     

气相爆轰法合成超细碳包铁纳米颗粒

以气化五羰基铁为铁源,采用乙炔为可燃气氛,用气相爆轰法成功合成了超细碳包铁纳米颗粒。利用TEM和XRD对合成产物进行分析表明,爆轰产物是由碳壳层、α-Fe和γ-Fe组成的球状包覆型结构,产物分散性好,颗粒大小均匀、形态规则的球形超细纳米碳包铁颗粒,铁核的平均粒径为4.5 nm; Raman光谱分析也证实该纳米粒子表面由为石墨和无定型碳构成包覆。进一步将该纳米碳包铁颗粒在低真空温度673 K下进行热处理发现,铁核颗粒尺寸略有长大,XRD谱线上γ-Fe相消失,转化为α-Fe相,热处理后磁饱和强度提高1倍以上。     

碳包覆铜纳米颗粒的比表面积和孔结构

采用直流电弧放电等离子体技术制备碳包覆铜纳米颗粒,并对样品的形貌、晶体结构、粒度、比表面积和孔结构采用高分辨透射电子显微镜(HRTEM)、X射线衍射仪(XRD)和N_2吸-脱附等测试手段进行分析。结果表明:直流电弧等离子体技术制备的碳包覆铜纳米颗粒具有典型的核壳型结构,内核为面心立方的金属铜,外壳为石墨碳层。颗粒主要呈球形或椭球形,粒度相对比较均匀,分散性良好,粒径分布在20~100 nm范围内,平均粒径为50 nm,外壳碳层的厚度为10 nm。碳包覆铜纳米颗粒的等温吸附曲线属Ⅳ型,晶粒之间的孔隙以介孔为主,样品的BET比表面积为33 m~2/g,当量粒径为45 nm,与TEM和XRD测得的结果基本一致。BJH吸附累积总孔孔容与BJH吸附平均孔径分别为0.112 cm~3/g和13 nm。     

碳包覆纳米铜粒子的制备及抗氧化性能

以碳粉和铜粉为原料,碳粉和铜粉的质量比分别为4:1、3:2、2:3、1:4时,采用碳弧法制备4种碳包覆纳米铜粒子;采用X射线衍射(XRD)、透射电子显微镜(TEM)、热重分析(TGA)和差示扫描量热法(DSC)对样品的物相结构组成、形貌、尺寸、相组成以及抗氧化性能进行研究;并对影响碳包覆纳米铜粒子粒径以及制备速率的因素进行研究。结果表明:碳包覆纳米铜粒子具有典型的核壳型结构,内核为面心立方的金属铜,外壳为石墨碳层;碳包覆铜纳米颗粒的粒径为20~60nm,粒径随着样品电极中的金属铜含量、放电电流、反应气压的增加而增大;随着样品电极中金属铜含量的增加以及放电电流的增大,碳包覆纳米铜粒子的制备速率加快,而反应气压对制备速率没有明显的影响;随着铜含量的增加,内部铜核具有进一步晶化的趋向,铜对外层碳层的石墨化具有催化作用,铜含量越高碳的石墨化程度越明显;外面的碳层能有效阻止内核的纳米铜粒子的氧化,碳包覆纳米铜粒子比纯铜粉末表现出更好的抗氧化性能。     

镍纳米颗粒填充碳纳米管的制备和表征

采用阳极弧放电等离子体技术制备了Ni纳米颗粒填充的碳纳米管,并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)、拉曼光谱(Raman)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、形态和物相结构等特征进行了表征。结果表明,采用本实验的方法能获得大量的被纳米金属颗粒填充的碳纳米管,内部填充物为fcc结构的Ni纳米颗粒,外围薄层为石墨碳层。碳纳米管的外径在30~40nm范围内,壁厚5~8nm,内部填充的纳米颗粒呈球形和椭球形,粒径均匀。     

Synthesis of Carbon-Encapsulated Iron Nanoparticles by Gaseous Detonation of Hydrogen and Oxygen at Different Temperatures within Detonation Tube

以二茂铁为前驱体,氢氧混合气体为爆源,在爆轰管内对碳包覆铁纳米颗粒进行合成。研究了初始反应温度及热处理对产物粒子的影响。通过XRD、TEM及VSM对爆轰产物进行了检验。结果表明,碳包覆纳米颗粒呈球形或椭球形。随着反应温度的升高,碳包覆纳米铁的晶粒尺寸为30~50 nm并且趋于均匀化,说明初始反应温度的高低直接影响生成颗粒的大小。通过不同温度热处理后爆轰产物的磁滞回线分析,饱和磁化强度（Ms）随着热处理温度的升高而降低,磁滞回线为比较“瘦”的形状,但仍然具有较高的磁矫顽力,表明合成的碳包覆纳米材料呈现出硬磁性和顺磁性双重性质。     

直流电弧等离子体制备NiO包覆Ni纳米颗粒

采用直流电弧等离子体技术制备NiO包覆Ni纳米颗粒,对初产物经过钝化处理得到有氧化膜保护的NiO包覆Ni纳米颗粒.采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)、选区电子衍射(SAED)、热重和差示扫描量热分析仪(TGA/DSC)以及傅里叶变换红外光谱 (FTIR)等手段对试样的成分、表面组成、形貌、晶体结构、粒度、红外吸收性能和氧化特性进行了分析.结果表明:经过表面钝化处理的NiO包覆Ni纳米颗粒具有明显的核-壳结构,内核为纳米Ni,外壳为NiO氧化物;颗粒呈球形,粒度均匀,分散性良好,粒径分布在20～70 nm范围,平均粒径为44 nm,壳层氧化膜的厚度为5～8 nm;壳核结构可防止纳米Ni颗粒的进一步氧化和团聚,且使红外吸收峰发生蓝移.     

Research into nanoparticles obtained by electric explosion of conductive materials

One of the primary nanoparticles production methods is electric explosion of wire (further — EEW) which is known as a physical phenomenon since 1771. Limitation of EEW as a method of nanoparticles production lies in a great dispersion of particle diameters — a spectrum of nano- and micrometric diameters (10³ and higher differences in diameters are likely). Due to great differences in nanoparticles diameters formed by explosion (in aerosol conditioned by explosion), a continuous separation of nanoparticles from aerosol flows is essential. Dispersion of conductor explosion products is mostly affected by a diameter of wire, density of comparative energy, duration of the energy input. Objective of this research is to investigate the vista of producing nanoparticles by EEW at low voltage and high energy surplus using the wire of an enlarged diameter. Analyses have been made by exploding the iron wire of 60 mm length and 0.31 and 0.45 mm diameter and the copper wire of 0.375 and 0.49 mm diameter. Purity of the wire material was 99.5% of iron and 99.9% of copper. To separate nanoparticles from aerosol a separation device was used which consists of a precipitator and three stages centrifugal cyclone. SEM analysis of Fe nanoparticles using SEM showed the mean diameter of particles about 69 nm (for wire Ø0.45 mm). Cu nanoparticles was 97 nm in diameter (for wire Ø0.49 mm). XRD spectra of iron and copper nanoparticles indicated a high oxidation level of Fe and Cu (oxides of different crystollagraphic axes are formed such as Fe₃O₄, Fe₂O₃, CuO, Cu₂O). A moderate quantity of pure Fe and Cu metals (Fe(110), Fe(211), C(l 11), Cu(200)).     

Microwave-assisted synthesis and magnetic properties of size-controlled CoNi/MWCNT nanocomposites

Size-controlled CoNi alloy nanoparticles with average diameters in the range of 15-48 nm attached on the multi-walled carbon nanotubes (MWCNTs) were prepared to form CoNi/MWCNT nanocomposites by microwave-assisted method. The size of CoNi alloy nanoparticles can be controlled through adjusting the atomic ratios of metals to carbon nanotubes in the mixed acetate solution. The as-prepared nanocomposites have been characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), energy-disperse X-ray spectroscopy (EDS) and vibrating sample magnetometer (VSM). The results show that CoNi alloy nanoparticles are face-centered cubic structure, quasi-spherical and disperse uniformly on the surface of MWCNTs. Magnetic measurement shows that both the coercivity and the saturation magnetization of the samples increase with the increase of the particle size from 15 to 37 nm, and decrease from 37 to 48 nm.     

Double glow plasma carburization on zirconium to improve surface hardness and wear resistance

Though some important progress in the excellent mechanical properties of zirconium alloys have been reported,their high surface hardness and good wear properties need to be explored further.In this work,a carburized layer was formed on the surface of commercially pure zirconium by a double glow plasma hydrogen-free carburizing technique.Commercial high-purity graphite was used as the carbon source material.X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),Vickers hardness test,friction and wear test were used to characterize the samples carburized.The carburized layer could be clearly observed under a microscope.XRD patterns indicate that the zirconium carbide phase is formed in the carburized layer.The surface hardness of the sample increases significantly after carburization.Friction and wear tests results show that wear resistance and friction coefficient of zirconium are improved considerably after carburization.Surface plastic deformation is arrested to a low extent in contrast with pure zirconium because of the presence of ZrC phases during the wear test.The results may provide new insight into methods for surface strengthening of zirconium alloys.     

Large-scale synthesis of onion-like carbon nanoparticles by carbonization of phenolic resin

Onion-like carbon nanoparticles have been synthesized on a large scale by carbonization of phenolic-formaldehyde resin at 1000 °C with the aid of ferric nitrate (FN). The effects of FN loading content on the yield, morphology and structure of carbonized products were investigated using transmission electron microscopy (TEM), high-resolution TEM and X-ray diffraction. It was found that the onion-like carbon nanoparticles, which had a narrow size distribution ranging from 30 to 50 nm, were composed mainly of quasi-spherically concentric shells of well-aligned graphene layers with interlayer spacing of 0.336 nm. Based on the results of the investigation, the formation mechanism of onion-like carbon nanoparticles was also discussed.