关键词： conductive particle   discharge energy  

摘要： A new method has been investigated to improve the surface integrity of electro-chemical discharge machining (ECDM) process by use of conductive particles in the electrolyte. In conventional ECDM processes the generation of fine sparks with uniform energy has been most desired technique to improve the machining efficiency and the surface quality. However, precise control of the spark generations in ECDM process has been a challenging problem. In electrical discharge machining (EDM) processes, which is thermal erosion machining process using spark energy similar to the ECDM, powder-mixed EDM (PM-EDM) fluids have been used to improve machining quality. Although the exact role of the conductive particles in the EDM process could not be clearly explained yet, it has been reported that the powder stabilizes discharge current as a result of discharge energy dispersion. Considering the similarity of the ECDM process compared to EDM where electrical sparks are utilized, powder-mixed electrolyte was introduced to create similar effects. In this paper fine graphite powder (which has good thermal and electrical conductivity) mixed with electrolyte has been applied to the ECDM process. Borosilicate glass, which is frequently used as a material for micro structures, was used as a workpiece. To investigate effectiveness of the proposed method experiments were conducted. The experiment results demonstrated that the breakdown voltage was reduced and the peak current during the process was decreased by ten percents. Discharging pattern was modified such that a single discharge pulse was branched into two or three. As a result, the surface quality was improved compared to that from the conventional process. Various experiment results of product quality with respect to powders volume ratio are also presented. (C) 2007 Elsevier B.V. All rights reserved.

关键词： kinetic parameter   electrochemical process   contact exchange dynamics   structural characteristic  

摘要： Effect of kinetic parameters of electrode processes on the growth dynamics and structural characteristics of the friable metal deposit, which forms via its contact deposition from an aqueous solution, is studied. A model concept is based on the electrochemical processes proceeding at the metal/solution interface. Dependences of the deposition dynamics and deposit characteristics on the exchange currents of depositing and dissolving metals and on the hydrogen exchange currents at the surfaces of both metals are studied.

关键词： disinfection   electrochemical process   hydrogen peroxide   mixed oxidants   (OH)-O-center dot   ozone  

摘要： The aim of this study was to investigate some aspects of the performance of electrochemical process as an alternative disinfection strategy, while minimising DBPs, for water purification. The study of electrochemical processes has shown free chlorine to be produced, but smaller amounts of stronger oxidants, such as ozone, hydrogen peroxide and OH radicals ((OH)-O-center dot), were also generated. The formation of mixed oxidants increased with increasing electric conductivity, but was limited at conductivities greater than 0.6 mS/cm. Using several microorganisms, such as E. coli and MS2 bacteriophage, inactivation kinetic studies were performed. With the exception of free chlorine, the role of mixed oxidants, especially OH radicals, was investigated for enhancement of the inactivation rate. Additionally, the formation and reduction of DBPs was studied by monitoring the concentration of haloacetic acids (HAAs) during the process.

关键词： lithium ion battery   silicon   anode   carbon   composite   nickel  

摘要： The Si-Ni composite and Si/Ni alloy composite were prepared by high-energy mechanical milling and arc-melting, respectively, in order to investigate the effects of these processes on the electrochemical performance. The microstructures of Si-Ni composite and Si/Ni alloy composite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The electrochemical properties have been investigated during 50 cycles for Si-Ni-C composite and Si/Ni alloy-C composite. As a result, both composites demonstrate a higher reversible capacity accompanied with a good cycling stability than the existing Si-C composite. Homogeneously dispersed Ni improved electric conductivity and induced fast charge transport significantly in Si-Ni-C composite whereas the secondary phases (NiSi and NiSi,) played a role of media to accommodate a large volume change of Si during cycling in Si/Ni alloy-C composite. Consequently, it was identified that electrochemical performances of electrode material are affected by structural factors caused by the different processes. (c) 2006 Elsevier B.V. All rights reserved.

关键词： C-60   onsite fluorescence   cyclic voltammetry   one-electron transfer   C-60(n-)   surface-enhanced Raman scattering (SERS)  

摘要： Three groups of strong fluorescence peaks Of C-60, centered at 440, 575 and 700 nm, are observed in the supersaturated C-60 Pyridine solution, and the onsite fluorescence spectra of this C-60-Pyridine system in the first and second electrochemistry reduction processes are obtained for the first time. The results indicate that the fluorescence peaks centered at 440 nm originate from C-60 molecules dissolved in supersaturated C-60-pyridine solution, while fluorescence bands centered at 575 and 700 nm are emitted from undissolved C-60- It is also proved that a strong charge transfer interaction, which is significant for the symmetry increase of C-60(n-), as well as the formation of a transmission channel of energy, occurs between C-60(n-) and pyridine, as is supported by surface-enhanced Raman scattering (SERS) spectra as well. (c) 2005 Elsevier B.V. All rights reserved.

关键词： electrochemical oxidation (ECO)   field emission   porous polysilicon   O-2 annealing  

摘要： The field emission characteristics of an oxidized porous polysilicon (OPPS) were investigated with Pt/Ti multilayer electrode using the electrochemical oxidation (ECO) process. A Pt/Ti multilayer electrode, using ECO, showed highly efficient and stable electron emission characteristics;moreover, it can be applied to large area of a glass substrate with a low temperature process. Electron emission characteristics were improved with O-2 annealing at 600 degrees C after the ECO process. It was found that forming a high quality oxide layer from the ECO-formed SiO2 was crucial in improving electron emission characteristics. The Pt/Ti OPPS field emitter, which was annealed at 600 degrees C for 5 h, showed an efficiency of 3.81% at V-ps = 14 V. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： tannic acid   bovine serum albumin   piezoelectric quartz crystal impedance   electrochemical impedance   electrochemical piezoelectric quartz crystal impedance system   FT-IR  

摘要： Combined measurements of piezoelectric quartz crystal impedance (PQCI) and electrochemical impedance (EI) were utilized in situ to monitor the adsorption of bovine serum albumin (BSA) onto the newly prepared Au colloid- modified electrode and study the binding process of tannic acid (TA) to BSA on the BSA- modified electrode surface. The time courses of the resonant frequency and the equivalent parameters of the sensor were simultaneously obtained during BSA adsorption and TA-BSA binding. Compared with the bare gold electrode, the Au colloid- modified gold electrode showed better biocompatibility, and the absorption capacity for BSA was increased by similar to 2.4 times. The observed frequency decrease was ascribed to the mass increase of the sensor surface resulting from the TA-BSA binding, which is believed to result mainly from the hydrogen bonding from FT-IR characterization. The maximal molar binding ratio of TA binding to immobilized BSA obtained from the frequency shift of the adsorbed BSA and TA was estimated to be 10.3:1. On the basis of the frequency decrease with time, the kinetics of the binding was quantitatively studied. By way of fitting the experimental data, the kinetics parameters, that is, binding and dissociation constant (k(1), k(-1)), and the binding equilibrium constant (k(a)) were determined, giving values of 9.51 x 10(4) M-1 s(-1), 3.15 s(-1), and 3.1 x 10(4) M-1, respectively.

关键词： 企业   企业管理   学习型组织   中铁电气化局   进程  

摘要： 职工素质的高低不仅与职工自身利益的实现有着密切的联系,更关系到经济社会的发展和企业的兴衰。组织和引导职工提高自身素质,实际上是对职工生存、竞争和发展能力的维护,是对职工根本利益的维护。因此,全面提高职工队伍的整体素质,推进职工队伍知识化进程,不仅是工会履行维护职能的重要内容和有效途

关键词： corrosion   paint coatings   scanning electrochemical microscopy   polyurethane   iron dissolution   oxygen reduction  

摘要： The scanning electrochemical microscope (SECM) is a non-optical scanning microscopic instrument capable of imaging highly localized electrical currents associated with charge transfer reactions occurring in the vicinity of the surface of coated metals. The SECM tip operates as working microelectrode in an electrochemical cell under potentiostatic control. Microelectrode current and position is recorded as the tip is scanned very near a coated sample at a constant Z height, and variations in the faradaical current measured at selected tip potential values can be related to changes in the local concentration of electroactive species involved in corrosion reactions occurring at the substrate. Carbon steel samples coated with polyurethane in which a holiday was produced prior to immersion in different aqueous electrolytes were investigated with this technique. The release of Fe(II) ionic species into the solution phase from local anodic sites, as well as the consumption of dissolved oxygen at the corresponding cathodic locations was successfully monitored. (c) 2005 Elsevier Ltd. All rights reserved.

关键词： electrochemistry   energy   membranes   system engineering   hydrogen production IS (S-I) process   thermal efficiency  

摘要： One of the key reactions for efficient hydrogen production using the water-splitting iodine-sulfur (IS or S-I) process is the Bunsen reaction (SO2 + I-2 + 2H(2)O = H2SO4 + 2HI). The Bunsen reaction was examined using an electrochemical cell with a cation exchange membrane as the separator. The optimal molalities of anolyte and catholyte were evaluated by total thermal efficiency using the heat/mass balance of the IS process. The I-2/HI ratio had little effect on the required total voltage;the I-2/HI ratio can be reduced to 0.5 without decreasing the total thermal efficiency. On the other hand, HI and H2SO4 molality greatly affected the total thermal efficiency. The total thermal efficiency increased with increasing HI molality up to 16.7 mol kg(-H2O)(-1) and the maximum thermal efficiency was found at 15.3 mol kg(-H2O)(-1) of H2SO4. Membrane resistances are very important parameters affecting the efficiency. The total thermal efficiency increased by 3.0% at a current density of the electrochemical cell of 10.0A dm(-2) by increasing the operating temperature from 313 to 363 K. (c) 2005 Elsevier Ltd. All rights reserved.