Papers by Keyword: Precursor

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Authors: Ping Lan, Li Hong Lan, Tao Xie, An Ping Liao
Abstract: In the preparation of hydrogen, the bio-oil from pyrolysis of biomass must be further upgraded (catalytic steam reforming)SO as to improve its quality.However the catalyst used in the steam reforming reaction is easy to lose its activity due to being coked' SO that it is important to study the coke formation and its efects on the catalyst activity in the steam reforming process.Fourier Transform Infrared Spectroscopy were used to analyze the precursor of coke on the catalyst Ni/MgO-La2O3-Al2O3 used in steam reforming reaction and the mechanism of coking Was also discussed based on it.The results indicate that precursors of coke deposited inside the pore of the molecular sieve are mainly paraffin, alcohols, aldehydes and ketones, and aromatic compounds.
Authors: Anghel Ioncea, Carmen Novac, Dorel Radu, Carmen Florea, Ovidiu Dumitrescu, Dragos Ionescu
Authors: Jin Long Wang, Yan Zi Gou, Wu Rong Ren, Ke Jian, Hao Wang
Abstract: Polycarborane, as a kind of boron carbide polymeric precursor, was synthesized by hydroboration reaction with styrene, divinylbenzene as the carbon resource and borane as the boron resource in this work. The polymer precursor which had good solubility and film-forming ability was soluble in most organic solvents. Furthermore, polycarborane was used to fabricate hollow polymer microspheres by emulsion technique. The compact boron carbide ceramic hollow microspheres were prepared by ceramization of the polymer microspheres. Ceramic microspheres with diameters ranging from 1 to 1.5 mm and shell thicknesses from 15 to 30 μm were easily prepared by changing emulsion composition and curing conditions. Micrographs of SEM showed that the hollow microspheres had smooth surface and good sphericity. These boron carbide ceramic hollow microspheres are of significant importance for application in the field of neutron moderator in nuclear reactors, power generation in deep space flight, etc.
Authors: Liang Yan Chen, Chao Fang, Xi Qu Chen
Abstract: With ammonia and hydrazine hydrate as complexing agents, ZnSe has been deposited as the buffer-window layer of solar cells from chemical solution, in which the complexion played vital role in controlling the film growth. We calculated various complexion in chemical solution deposited ZnSe precursor with solubility theory. And the main complexion and their concentration with adding of complexing agents and pH value have been investigated. And we found that the main complexion are Zn (NH3)32+ and Zn (NH3)42+, the concentration of which varied with the adding of ammonia and pH value.
Authors: Yong Zhong Jin, Fa Ming Ye, Xian Guang Zeng, Rui Song Yang
Abstract: Cr3C2-WC-Ni nanocomposite powders with ~50-100 nm were synthesized from precursors by vacuum-aided carbothermal reduction at only 750 °C for 2 h. The phase composition and microstructure of the synthesized products were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The present study shows that Cr3C2-WC-Ni nanocomposite powders contain two kinds of solid-solution phases, namely Ni and (Cr, W)3C2 solid solution, respectively. WC and W2C phases do not appear inreaction products due to the dissolution of tungsten atoms into Ni and Cr3C2 unit cells. Especially, there is a change of the crystalline structure for (Cr, W)3C2 phase from 750 °C to 800 °C.
Authors: Sang Jin Lee, P.W. Shin, J.W. Kim, S.Y. Chun
Abstract: Pure and stable YAG (Y3Al5O12) powders were synthesized by a PVA (polyvinyl alcohol) polymer solution technique. PVA was used as an organic carrier for the precursor ceramic gel. The PVA affected crystallization behavior, powder morphology, specific surface area and crystalline size of the synthesized powders. The precursor gels were crystallized to YAG at relatively a low temperature of 900 °C. The synthesized powders, which have nano-sized primary particles, were soft and porous, and the porous powders were ground to sub-micron size by a simple ball milling process. The ball-milled powders were densified to 94% relative density at 1500 °C for 1h. In this study, the characteristics of the synthesized YAG powders were examined by using X-ray diffractometer, simultaneous differential scanning calorimetry and electrophoretic light scattering spectrophotometer. And the morphologies of the powders and the densified samples were observed by scanning electron microscopy.
Authors: Koichiro Inaba, Yujin Takemoto, Kouji Toyota, Kenichi Haga, Kouichi Tokudome, Masato Shinmiya, Naomi Kamiya, Minoru Oshima, Kenji Yoshino
Abstract: A novel precursor for ZnO film deposition with Zn-O structure was synthesized by the reaction of diethylzinc and water in some ether solvents. The novel precursor was characterized by 1H-NMR spectroscopy and differential scanning calorimetry (DSC). Nondoped and In-doped ZnO films on a glass substrate have been successfully grown by conventional spin coating using nondoped and In added novel precursor solution. The samples have an optical transmittance of more than 85%, and a smooth surface determined from optical transmittance and scanning electron microscopy, respectively. The sheet resistivity of In-doped ZnO films is lower than that of nondoped ZnO film.
Authors: S. Pomogailo, Gulzhian I. Dzhardimalieva, Anatolii D. Pomogailo
Authors: Roland Weiss
Abstract: Ceramic Matrix Composites (CMC) have a wide interest for high temperature applications. The materials can be modified by the selection of the matrix precursor as well as of the reinforcing materials. C/C-composites can be easily modified by post-treatments with silicon in order to acquire different tribological properties from good sliding behaviour up to braking systems only depending on the manufacturing technique of these materials. It will be demonstrated during the presentation that the manufacturing depends on one hand side on the material which has to be manufactured and on the other side on the structural component and the number of parts which are required. Furthermore, it will also be shown, that silicon treatments can be performed up to a full conversion of C/C materials creating a new family of monolithic ceramic materials. Within the presentation detailed information will be given on possible processing routes as well as the resulting physical and mechanical properties of the materials.
Authors: Yi Lung Cheng, Yi Shiung Lu, Tai Jung Chiu
Abstract: Two kinds of organosilicate precursors, trimethylsilane (3MS) and diethoxymethylsilane (DEMS), were used to produce low-k films by plasma-enhanced chemical vapor deposition (PECVD) in this work. The experimental results indicate that DEMS-based low-k films have superior electrical performance and better thermal stability as compared to 3MS-based low-k films. Therefore, DEMS-based films are the promising low-k materials which can be integrated in very large scale integration circuit as an inter-layer dielectric material.
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