Papers by Keyword: Reduction

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Authors: Chang Yi Kong, Yuuki Shiratori, Takeshi Sako, Futoshi Iwata
Abstract: A green method to synthesize the reduced graphene oxide using supercritical fluid has been developed, which is an environmentally friendly and efficient route. The reduced graphene oxide has been examined by X-ray diffraction, Raman spectroscopy. We have also studied the effects of reduction temperatures and supercritical fluids on the electrical properties of reduced graphene oxide. It was found that ethanol has higher reducing capability than CO2 at all temperatures (200 - 400 °C) examined in this study for graphene oxide reduction. As a result, reduced graphene oxide (6300 S/m) from supercritical ethanol treatment has 5 times as high conductivity as that from supercritical CO2 treatment at the reduction temperature of 400 °C. This green process is applicable for large scale production of reduced graphene oxides for various practical applications.
Authors: Yu Feng Wang, Chun Hua Han, Bao Liu, Dong Mei Zhao, Dong Yu Zhao, Li Guo Sun
Abstract: A mild and efficient approach for the reduction of graphene oxide by NaHTe is reported in this work. This reductant is of low toxicity and nonvolatile and it reduce GO to graphene at room temperature in 2h. X-ray diffraction results showed that NaHTe can reduce GO completely in shorter time, comparing with hydroxylamine. Furthermore, X-ray photoelectron spectroscopy also indicates the reduction of GO to grapheme.
Authors: C. Hérold, J.F. Marêché, A. Mabchour, G. Furdin
Authors: Kazuki Abe, Akira Izumi
Abstract: Cu has been used as interconnection and lead frame in ULSIs. However, the oxidation and contamination of Cu are not easily avoided. As a result, a thin layer of Cu2O, CuO and carbon contaminations are formed at the Cu surface and these resistances are increased. Therefore, Cu cleaning is necessary. There are some reports to remove Cu oxide layers. Chemical processes such as H2 and NH3 plasma reduction are being investigated [1-5]. These methods have the problem of the plasma damage. Lee et al. proposed Cu oxide reduction using vacuum annealing [6]. However, it seems not suitable for the ULSI process, because the heat-treatment of 400oC is necessary. Therefore, low temperature Cu cleaning without plasma assist is strongly desired. In our previous work, we proposed novel low temperature atomic hydrogen or NH3 decomposed species cleaning generated by heated catalyzer [7,8]. However, in the method it is used 100% hydrogen gas. From the view point of safety, hydrogen gas diluted below explosion limit is preferred to use. In this paper we proposed a novel Cu cleaning method by atomic hydrogen generated on a heated tungsten catalyzer using diluted hydrogen as a cleaning gas.
Authors: Zhao Han, Hong Min Zhu
Abstract: Nano-sized nickel powders were prepared through a wet chemical reduction, of NiCl2 by sodium in liquid ammonia at -45 °C, and a subsequent heat-treatment in vacuum at 300 °C. The prepared product was systematically characterized by X-ray diffraction (XRD), scan electron microscopy (SEM), transmission electron microscopy (TEM), and BET specific surface area measurement. The results show that the product was composed of nano-sized nickel particles, with average particle diameter of about 20 nm, and specific surface area of about 30 m2g-1. The possible formation mechanism of the nano-sized nickel powder was also discussed briefly.
Authors: Xin Ying Chen, Guan Yu Li
Abstract: This paper tries to find a more feasible method to achieve core and reduction. Against concepts "distinguishable relation of attribute set" and "distinguishable unit set of attribute set", it defines a concept "important index", and proposes an effective and quick approach for important index. After drawn out the involved theory and equivalent proposition, also presents algorithms for core and reduction upon the important index. The heuristic reduction algorithm adopts the bottom-up design, and gets reduction based on the heuristic information "important index of attribute set". The complexity of the algorithm in space is O(m), and the complexity in time is O(mn2). The theoretical analysis and results show that the ways proposed here simplify the relevant operations and are suitable to deal with the huge volume of data.
Authors: Xiao Ming Li, Shang Jie Wang, Jun Xue Zhao, Ya Ru Cui, Su Bo Hou
Abstract: Pickling sludge is the deposits that generated from the neutralization of pickling waste water with calcium hydroxide in stainless steel pickling process. The main composition of pickling sludge is CaF2, CaSO4, Me(OH)n (M:Fe,Cr,Ni). Solidification /stabilization method is believed to a most economical way to dispose these wastes at present. But the process caused serious compatibilization, it not only took up the scarce land resource, but also wasted nickel, chromium and other resources, in addition, the potential harm of Cr6+ to the environment still existed. A new thought to recycle the sludge was as following. After drying the sludge, it contained mainly calcium fluoride and metal oxides. The calcium fluoride could replace fluorspar, so the sludge could be used as a raw material for AOD process, where the metal oxides were reduced into the bulk of the metal. This would not only save fluorite, but also could reduce metal oxide of sludge. With more stringent environmental demands and increasingly output of the sludge, the most effective way to reduce the sludge from source is recycling the valuable elements from waste water directly. Solvent extraction combined with vacuum evaporation, spray evaporation and resin absorption coordination were all the effective methods. The resin adsorption process would be another promising method as ion exchange resin was continuously successfully developed. It had been found that treating the waste water with positive resin can remove the metal ions, but how to completely resolve the metal from the resin was still a problem.
Authors: Seung Yup Jeon, Eun Ju Chae, Won Ki Lee, Gun Dae Lee, Seong Soo Hong, Seog Young Yoon, Seong Soo Park
Abstract: Ni nanosheet has been prepared at various temperature and time with anion surfactant by chemical reduction of the nickel ion complexes formed from complexing reagent in a pressurized vessel. Sample was characterized by the means of an X-ray diffractomer (XRD), a field emission scanning electron microscopy (FESEM), an energy dispersive X-ray spectrometer (EDS), a selected-area electron diffraction (SAED) and a high sensitive magnetometer (HSM). The use of SDBS and sodium tartrate could be a key factor for the formation and growth of Ni nanosheet.
Authors: Hoo Soon Im, Jah Mahn Hur, Wan Jae Lee
Abstract: The dry-milling technique was used for mixing and crushing oxides and graphite powder to get homogeneous mixed powders. The weight ratio of ball-to-powder was 30:1 and argon gas was filled in jar. The carbon content was more 10~ 20wt% than the stoichiometric amount. The drymilling was carried for 20 hours. After milling, the mixed powders were reduced and carburized at 900~980°C for 3 hours flowing Ar gas in tube furnace. The dry-milled powders showed wide diffraction patterns of X-ray. The reactions of reduction and carburization were completed in 3 hours at 980°C. After the reactions, the mean size of WC particles was about 200 nm. The content of free carbon in WC/Co mixed powders decreased as the reaction temperature increased.
Authors: Marina L. Mozgaleva, Pavel A. Akimov
Abstract: This paper is devoted to verification of so-called wavelet-based discrete-continual finite element method (wDCFEM), proposed by authors, for three-dimensional problems of local structural analysis. Formulation of the problem for three-dimensional structure with constant physical and geometrical parameters along so-called its basic direction, solutions obtained by wDCFEM and discrete-continual finite element method (DCFEM) and their comparison are presented. It was confirmed that wDCFEM is rather effective in the most critical, vital, potentially dangerous areas of structure in terms of fracture (areas of the so-called edge effects), where some components of solution are rapidly changing functions and their rate of change in many cases can’t be adequately taken into account by the standard finite element method.
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