纳米氧化铈颗粒的粒度分析研究

针对自制的纳米CeO2进行了一系列粒度分析研究,包括XRD、SEM、TEM、动态光散射法、比表面分析法、X射线衍射法和X射线小角度散射法(SAXS).不同的研究手段得到的纳米CeO2的粒径不尽相同,并阐述了各种研究手段的优缺点及适用范围.     

超细镍粉的化学还原制备及其分散剂的作用

采用溶液还原法，以硫酸镍为原料，水合肼为还原剂制备了超细和纳米镍粉。研究了不同分散剂对镍粉粒度和粒度分布的影响。X射线衍射结果表明，所得粉末为纯Ni相，晶粒尺寸约13nm；激光粒度分布测试结果表明，Ni粉粒度分布较窄，中位径集中在0．7～0．8μm，最大粒径不超过2．0μm。透射电镜照片显示粉末近球形，一次颗粒粒径在50～100nm之间，有轻微团聚。改变分散剂种类（PVP、PEG1500、PEG20000、CTAC）和用量可使超细镍粉的比表面积在3．24～57．88m^2／g间变化。     

纳米粒度测量方法浅析

本文介绍了多种纳米颗粒粒度的测量方法。主要讨论了X射线小角散射法、光子相关谱法和透射电镜-图像分析法的原理、适用范围及其优缺点。     

纳米钨粉和超细钨粉的粒度分布表征

采用X射线小角散射法测试了纳米钨粉和超细钨粉的粒度分布.结果表明,采用X射线小角散射法测试出的纳米钨粉和超细钨粉的粒度分布与透射电镜观察和比表面法测试结果吻合,能较为准确地表征纳米钨粉和超细钨粉的一次颗粒的粒度分布.但为了得到可信的结果,X射线衍射仪的最小可测试角必须根据实际情况进行选择.     

SiO_2包覆Fe-Ni15%合金纳米颗粒的制备及性能研究

采用电弧放电法,在55%Ar+25%H2+20%SiH_4的混合气氛中制备了SiO_2包覆Fe-Ni15%合金纳米颗粒,用X射线衍射仪、透射电子显微镜、X射线光电子能谱、红外光谱、氧含量分析和振动样品磁强计研究了制备的SiO_2包覆的Fe-Ni15%合金纳米颗粒的相结构、形貌、粒度、表面组成、抗氧化性能和磁性。     

电化学法和沉淀法制备的纳米结构CeO2的微观结构比较

利用X射线衍射、X射线小角散射、扫描电子显微镜、透射电子显微镜等分析手段对电化学法、沉淀法制备的纳米结构的C eO2的微观结构进行了比较，发现电化学法制备CeO2是由分散的纳米颗粒组成，而沉淀法制备的Coeh则是由粗大片状颗粒组成，而该片状颗粒具有纳米的结构。电化学法的CeO2比沉淀法CeO2具有更细的纳米结构。     

Cu纳米颗粒的晶格畸变研究

采用阳极弧放电等离子体技术成功地制备了Cu纳米颗粒,利用X射线衍射(XRD)、透射电子显微镜(TEM)和相应选区电子衍射(SAED)、BET氮吸附等测试手段对样品的晶体结构、形貌、比表面积和粒度等特征进行了表征分析,并计算了其不同晶面的晶格参数.结果表明:Cu纳米颗粒为fcc晶态结构,晶格畸变表现为晶格收缩.     

羰基法生产纳米镍粉

本文介绍了羰基法生产纳米镍粉的主要工艺过程 ,纳米镍粉的性能。分析了羰基镍蒸气浓度、热解温度、稀释比、离解所需热量供给方式对纳米镍粉的粒度等性能的影响。并对发展我国纳米镍粉提出了讨论意见     

催化热解聚丙烯塑料制备纳米碳管

以聚丙烯母粒为原料,纳米镍粉为催化剂,催化热分解法制备了碳纳米管。应用X—射线衍射、透射电镜对制备的纳米碳管进行了粒度测定、形貌观察。纳米碳管为丝状缠绕在一起,直径在20~30 nm之间,纳米碳管的d002值为0.338,具有较高的可石墨化度。应用热重分析方法准确测定了纳米碳管和无定形碳等碳杂质分离的煅烧温度。本实验得到的纳米碳管在600~730℃区间相对稳定,氧化温度大于730℃,则纳米碳管被氧化。     

冷冻干燥法制备超细镍粉的研究

以NiSO4、NaOH为原料,以液氮为冷冻介质,采用冷冻干燥法制备了粒度小于100 nm的超细镍粉;并采用X射线衍射、扫描电镜对冻干前驱体、还原粉末的中间状态和末状态的物相及转变过程进行了分析。研究结果表明:冷冻干燥前驱体呈非晶态,为棒条状,表面光滑。从冻干前驱体到超细镍粉的转变过程是,首先从非晶棒条前驱体的尖端、棱等比表面能较大的地方开始,并逐步还原吞噬前驱体,生成了球形超细镍粉。在本研究中,冻干前驱体的形貌对最终产物的粒度影响不大。     

表面改性剂在溶胶-凝胶法制备纳米氧化锌中的应用

以草酸与二水合醋酸锌为原料,采用溶胶-凝胶法制备纳米氧化锌。探讨了不同表面改性剂及其用量对氧化锌粉体的粒度、形貌及分散性的影响。利用SEM、TG、IR、XRD对氧化锌粉体进行了表征。结果表明十二烷基硫酸钠和聚乙二醇6000能有效地分散颗粒和控制颗粒的团聚。制得粒径在80 nm左右、纯度高、晶型良好、分散性好的纳米氧化锌。     

高能球磨制备Zr-V纳米粉末

将初始Zr粉和V粉按一定比例混合 ,用高能球磨设备制备Zr V纳米粉末 ,利用XRD和SEM及TEM研究研磨过程中粉末的物相及粒度变化。结果表明 ,粉末的晶粒尺寸随研磨时间的增加而减少 ,适当增加转速 ,可以缩短晶粒细化时间 ;通过高能球磨可以制备出粉末晶粒尺寸在 10nm左右 ,粉末颗粒尺寸在 6nm左右的Zr V混合粉末     

Production of nickel and iron nanopowders by hydrogen reduction from salts

The formation of nickel and iron nanoparticles produced by a chemical??metallurgical method and steels made of composite iron powders with nanosized nickel additions is studied. A procedure is developed for calculating the nanopowder particle size and the activation energy of sintering. The results obtained make it possible to decrease the temperature of the process of powder production, to decrease the energy consumed for powder sintering, and to predict the powder nanoparticle size.     

Fluctuation melting and the initial stage of nanopowder sintering

The initial stage of nanopowder sintering at low temperatures has been theoretically studied. Analytical expressions are obtained to control the nanopowder shrinkage at this stage. They also indicate that the nanopowder densification and the increase in the nanoparticle size at the initial stage of sintering are determined by a nondiffusion mechanism and that they can be calculated with a fluctuational sintering model. The effect of the granulometric composition of nanoparticles on sintering has been studied. It is shown that the shrinkage and the increase in the average particle size in the cases of sintering a nanopowder with a normal size distribution of particles and a nanopowder consisting of the same particles are the same.     

化学镀法制备镍包石墨复合粉末

采用化学镀法在石墨粉末表面镀镍制备Ni/石墨复合粉末,采用激光衍射粒度分析、扫描电镜等对Ni/石墨复合粉末的粒度和表面形貌进行表征,研究镀液中主盐硫酸镍、还原剂联氨及活化剂氯化钯的浓度对该复合粉末表面形貌的影响,并对Ni镀层在石墨表面的生长机理进行探讨.结果表明:硫酸镍质量浓度为20 g/L、联氨体积分数为2％时,化学...     

金属Ni、Al纳米材料的制备及其表征

用爆炸法制备金属镍、铝纳米粉,对其纳米颗粒的形貌特征、成分、晶体结构等进行了实际测定,结果表明:Al的粒度分布比较窄,一般在30~80 nm,镍的粒度分布约30~100 nm。     

Dispersion characteristics of a nickel nanopowder

Electron microscopy, X-ray diffraction analysis, and low-temperature nitrogen absorption are used to study the size characteristics of a nickel nanopowder. An interrelation between the size parameters of the nanomaterial (aggregates, particles, and crystallites) is found to exist. All these characteristics are shown to be true and to have a physical and technological meaning.     

Technological and strength properties of silumin modified by silicon dioxide nanoparticles

The eutectic silumin modified by SiO₂ nanoparticles is fabricated and studied. The sizes of particles and their concentration in the melt are varied. The strength of the silumin is found to complexly depend on the SiO₂ nanopowder particle size. The noticeable increase in the hardness during heat treatment of the nanomodified silumin is mainly related to Guinier–Preston zones, and the contribution of grain refinement (precipitation hardening) is insignificant.     

Synthesis and Spectral Properties of Nd3+:Gd3Ga5O12 Nanopowder for Transparent Laser Ceramics

Nd3 :Gd3Ga5O12 (Nd:GGG) nanopowder for transparent laser ceramics was synthesized using sol-gel method. XRD, SEM, and fluorescence spectrum were used to study the properties of Nd3 :Gd3Ga5O12 nanopowder. XRD patterns of samples show that it has a cubic structure. Meanwhile, pure Nd:GGG crystals were obtained at 1000 ℃ for 12 h. SEM photographs show that dispersed, uniform, ball-like Nd:GGG nanopowder is obtained. Both XRD and SEM results show that the crystallization degree and the grain size increase with the increase in calcining temperature. Analysis of fluorescence spectrum shows that fluorescence emission occurs at 1062.7 nm, which is the result of Nd3 (4F3/2→4I11/2) transition. Homogenous Nd:GGG nanopowder with a small grain size synthesized using the sol-gel method is favorable for sintering the transparent ceramic, which proves that the nanopowder obtained is suitable as a precursor for preparing GGG transparent ceramics.     

超细铁粉的制备及其对硝酸盐的降解

分别采用液相还原改性法和微乳液法制备超细铁颗粒,用乙醇-水体系制备镍包覆铁颗粒的Fe/Ni双金属颗粒,用来进行硝酸盐的降解实验,并用扫描电镜(SEM)和X射线衍射(XRD)分析超细粉末的物相结构及形貌.结果表明:通过液相还原改性法制备的超细铁粉,颗粒形状不规则,颗粒大小在0.2～0.3 μm之间;而用乙醇-水体系制备的铁/镍粉颗粒为等轴晶粒,颗粒大小也在0.2～0.3 μm之间;加入PEG-6000可改善液相改性法和醇-水法制备的铁粉的分散性.微乳液法制备的铁粉为球形颗粒,存在较明显的团聚现象,颗粒大小在0.5～ 1μm之间.在相同条件下,不同方法制备的超细铁粉降解硝酸盐的能力由高到低依次为:微乳液法制备的铁粉＞乙醇-水体系法制备的Fe/Ni双金属粉＞液相还原改性制备的铁粉＞不加PEG的乙醇-水体系制备的铁粉.