High-Performance Ceramics III

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Authors: Rui Long Zong, Ji Zhou, Long Tu Li
Abstract: The stability of porous alumina template has been investigated when the template acts as cathode and reacts in different pH electrolytes. The cathodic reaction can be separated into four stages. In particular, there exists an autocatalyse reaction, which causes the erosion of the porous template for the local high pH solution. Hence, the template is relatively stable in lower pH electrolyte. After electrochemical reaction, long and radial distributed nanowires are got at the surface of cathode for the etching of the fluid high pH solution.
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Authors: Ming Fu, Ji Zhou, Rui Long Zong, Bo Li, Long Tu Li
Abstract: Wide band-gap semiconductor ZnO film with ordered face-centered cubic (FCC) structure air holes was prepared by electrochemical process. The porous ZnO film was prepared in zinc nitrate aqueous solution, using the indium tin oxide (ITO) substrate covered with synthetic opals as cathode by potentiostatic method. In order to improve the filling ratio of ZnO in the opal interstices, various potentials were applied to control the deposition speeds. The porous ZnO film was characterized by X-ray diffraction and Scanning Electron Microscope and a photonic band gap at about 568nm was observed by micro-region reflection spectrometer in ZnO inverse opals.
569
Authors: Ya Ming Ji, Dan Yu Jiang, Yi Kun Liao, Jian Lin Shi
577
Authors: Xiao Long Cui, Li Shan Cui
Abstract: A novel process for synthesizing nano-ceramics powders, named Mechanical & Thermal Activation Processing, is discussed in the present paper. Dissimilar with the tradition processing of mechanical activation or mechanochemistry, the processing is based on thermal activation in liquid phase (molten salt) after mechanical activation. The synthesizing of nanometer sized TiC particles by the method was investigated. The end product has been analyzed by X-ray diffraction (XRD),transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersion X-ray (EDX). The results show that nano-meter sized particles were formed, and the lattice parameter of TiC is close to the value of non-oxygen TiC. Compared with usually methods, the whole processing time needed is shortened; moreover, the synthesis temperature could be reduced 500°C. The mechanism for mechanical & yhermal activation is discussed.
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Authors: Xiao Lin Jia, Xiang Chong Zhong
Abstract: MgAl2O4 nanopowder is synthesized by homogeneous precipitation method, using MgCl2,AlCl3 and ammonium bicarbonate as starting materials. The influences of the concentration of metallic salt solution, pH value and type and concentration of surface-active agents on agglomeration have been discussed. The results show that with addition of suitable amount of anion surface-activeagent, MgAl2O4 nanopowder with particle size of less than 12nm and secondary particle diameter of less than 170nm can be obtained by heated precursor at 850°C for 1h.
587
Authors: Jun Yan, Jian Zheng Yi, Hai Ping Cui, Xin Kang Du, Jian Jiang Wang
Abstract: This research focus on the technology of copper chemical plating on Al-CuO agglomerated powders with the size of 150-200µm. Orthogonal design is employed to gain the optimized formula, and the quality of the cladding was analyzed by means of SEM and EPMA. The results show that the cladding is uniform and the Al-CuO powders are primarily coated by copper.
591
Authors: S.M. Fan, Guo Sheng Gai, Yu Fen Yang, Shao Yun Fu, He Zhuo Miao
Abstract: The calcium carbonate composite particles with nanostructured surface were prepared by heterogeneous nucleation. The calcium carbonate composite particles consisted of a core of groundcalcium carbonate particle and a shell of nanometer calcium carbonate particles. The thickness of theshell of composite calcium carbonate was observed by TEM. The bond intensity between the core and the shell was measured by means of ultrasonic comminution and stirred ball milling. It was found that the composite calcium carbonate had a compact structure. The linkage between the core and shell was so strong that it must be chemical bond instead of physical adsorption.
593
Authors: Yun Hua Li, Yun Han Ling, Xin De Bai
Abstract: A series of ammonium titanium phosphate nanocrystals were prepared by hydrothermal synthesis method, and characterized by XRD, IR, XPS, SEM and DTA/TG. The results showed that themicrostructures of the materials could be rod- or sphere-like nanocrystals with aqueous pH values changing from 0 to 5, and could be flake like nanocrystals when a certainty of oxalic acid was added to the hydrothermal systems. The hydrothermal duration and temperature were not the main factors influencing the morphology of the products, but longer time and higher temperature would make the material more highly crystalline. The hydrothermal synthesizing mechanism on different experimental conditions was also discussed.
597
Authors: Jia Guo Yu, Jimmy C. Yu
Abstract: Calcium carbonate particles with different morphologies were fabricated by the precipitation reaction of sodium carbonate with calcium chloride in the absence and presence of the copolymer poly(styrene-alt-maleic acid) (PSMA) at 80oC, respectively. The as-prepared products were characterizedwith SEM, XRD, Infrared and BET surface areas. The results showed that the pH of solution and the concentration of PSMA and CaCO3 significantly influenced the morphologies of CaCO3 particles. Various crystal morphologies of calcium carbonate, such as plates, rhombohedras, rods, ellipsoids, dumbbells, peanuts, spheres etc., could be obtained depending on the experimental conditions.
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