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Articles 2521 - 2550 of 3176

Full-Text Articles in Engineering Science and Materials

Study On The Preparetion And Electrochemical Beavior Of Nitrogen Doped Tetrahedral Amorphous Carbon Electrode, Ke Liu, Guang-Fu Wang, Zheng-Hao Wang Aug 2006

Study On The Preparetion And Electrochemical Beavior Of Nitrogen Doped Tetrahedral Amorphous Carbon Electrode, Ke Liu, Guang-Fu Wang, Zheng-Hao Wang

Journal of Electrochemistry

taC∶N films are a good materials for semiconductor electrodes.But further studies are hampered by the ohmic contact problem,which occurs between the silicon and the lead.By studying the influence of heat treatment on the film's property,it is believed that ohmic contact should be made on the silicon first,and then the film be deposited.A set of taC∶N electrodes with various nitrogen content have been prepared.CV study indicates that the cathodic limits move slowly to positive direction.while the anodic limits are unchanged with the increasing of nitrogen content.As a result,the electrochemical windows get narrow either.

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Electrochemical Behavior Of Electrolytic Manganese Dioxide In Mgso4 Solution, Dan-Mei Yu, Yu-Jun Si, Chang-Guo Chen, Yu-Ping Liu, Yan Liu Aug 2006

Electrochemical Behavior Of Electrolytic Manganese Dioxide In Mgso4 Solution, Dan-Mei Yu, Yu-Jun Si, Chang-Guo Chen, Yu-Ping Liu, Yan Liu

Journal of Electrochemistry

The rechargeability and crystal structure changing of electrolytic manganese dioxide(EMD) in MgSO4 electrolyte were investigated by cyclic voltammetry,galvanostatic charge/discharge and X-ray diffraction.The results have shown that the EMD has good rechargeability;after several initial cycles,the charge and discharge became stability;after discharge,the γ-MnO2 structure of EMD was changed,the production was reversible and could be recharged to γ-MnO2 structure again which ensured the rechargeability of EMD.

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The Property Study Of Libob-Pc/Dec Electrolyte, Ying-Kun Ning, Bi-Tao Yu, Fu-Shen Li, Wei-Hua Qiu Aug 2006

The Property Study Of Libob-Pc/Dec Electrolyte, Ying-Kun Ning, Bi-Tao Yu, Fu-Shen Li, Wei-Hua Qiu

Journal of Electrochemistry

The new electrolyte salt LiBOB for Li-ion battery was synthesized in laboratory,and series of electrolytes of LiBOB and PC/DEC was compounded.The conductivity of the electrolytes was compared by changing the temperature and concentration.The cycling performance of charging-discharging was also compared by the charging-discharging test,the results showed that the varying regularity of conductivities and cycling stability and capacity were not always identical,but there were a suitable electrolyte for Li/ARG cell.The A.C.impedance and CV were used to test the compatibility of the most suitable electrolyte and ARG anode.Conclusion can be drawn that the ARG anode can be protected very well by SEI …

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Electrodeposition Of Nano-Sb-Zn Alloy In Acetamide-Urea-Nabr-Kbr Melt, Peng Liu, Xin-Ai Guo, Ye-Xiang Tong, Qi-Qin Yang Aug 2006

Electrodeposition Of Nano-Sb-Zn Alloy In Acetamide-Urea-Nabr-Kbr Melt, Peng Liu, Xin-Ai Guo, Ye-Xiang Tong, Qi-Qin Yang

Journal of Electrochemistry

The electroreduction of Zn(II) and Sb(III) in acetamide-urea-NaBr-KBr(343 K) were studied by cyclic volatmmetry.The reduction of Zn(II) or Sb(III) to the metals is an irreversible process.The transfer coefficient of Zn(II)+2e→Zn and Sb(III) +3e→Sb were calculated to be 0.231 and 0.319,the diffusion coefficient of Zn(II) and Sb(III) in the melt were determined as 1.70*10-6 and 3.21*10-6 cm2· s-1 respectively.The Zn-Sb films with different Zn content from 29.67 at% to 97.34 at% were electrodeposited in acetamide-urea-NaBr-KBr melt at 343 K by controlling the deposition potential and the Zn(II)/Sb(III) molar ratio.The morphology of Zn-Sb film was observed by …

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Influence Of Crystallinity On The Kinetics Of Li Ion Insertation And Deinsertation In Spinel Limn2O4, Rong-Hua Zeng, Dong-Sheng Lv, Wei-Shan Li Aug 2006

Influence Of Crystallinity On The Kinetics Of Li Ion Insertation And Deinsertation In Spinel Limn2O4, Rong-Hua Zeng, Dong-Sheng Lv, Wei-Shan Li

Journal of Electrochemistry

Two spinel lithium manganese oxides of different crystallinity were prepared by sol-gel process and were studied by using inducfively coupled plasma,X-ray diffraction,scaning electron micrographs,constant charging and discharging,cyclic voltammetry and electrochemical impedance spectrometry,the results show that the sample treated under 700 ℃ has higher crystallinity than the sample treated under 500 ℃,however,the sample with lower crystallinity has higher discharge capacity and better cyclic performance that due to quicker charge exchange speed and quicker diffusion speed of Li-ion.

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Recycling Of The Spent Nickel-Cadmium Batteries Based On Bioleaching Process, Liang-Shu Xia, Shi-Fu Fu, Zhong-Qing Chen Aug 2006

Recycling Of The Spent Nickel-Cadmium Batteries Based On Bioleaching Process, Liang-Shu Xia, Shi-Fu Fu, Zhong-Qing Chen

Journal of Electrochemistry

Less than 1 percent of discarded dry batteries are recovered in china.it is necessary to find an economic,fast and environmentally friendly process to recycle spent dry batteries.Bioleaching is better one of the few technology applied for the recovery of the toxic metals from hazardous spent batteries.In this study,after the acidified sludge made by the inoculated and cultured indigenous sewage sludge was acted as leaching bacteria species,the influence of the different pH values,the different residence time of the sludge in bioreactor(RTB),the leaching time,whether or not adding Fe(iron powder) to the leaching liquid on the leaching rate of Ni,Cd was tested.The results …

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Wear Analysis Of Cu-Al Coating On Ti-6al-4v Under Fretting, Karl N. Murray Jun 2006

Wear Analysis Of Cu-Al Coating On Ti-6al-4v Under Fretting, Karl N. Murray

Theses and Dissertations

The effects of changes in the coefficient of friction (CoF) between the contacting surfaces on the fretting wear characteristics of Cu-Al coating on Ti-6Al-4V were investigated. This Cu-Al coating is part of a system that is applied to titanium turbine blades to reduce fretting at the interface. In the application, there is a solid lubricant that is added on top of the coating as an assembly aid and to help reduce the friction while the lubricant remains within the contact. Previous studies have researched the characteristics of the coating without the additional lubricant. In this study, liquid motor oil was …

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Effects Of Frequency And Environment On Fatigue Behavior Of An Oxide-Oxide Ceramic Matrix Composite At 1200°C, Griffin Hetrick Jun 2006

Effects Of Frequency And Environment On Fatigue Behavior Of An Oxide-Oxide Ceramic Matrix Composite At 1200°C, Griffin Hetrick

Theses and Dissertations

Advances in aeronautical engineering in the 21st century depend upon materials that can perform well in extreme environments such as high temperatures and oxidizing conditions. Nextel™720/Alumina (N720/A) is an oxide/oxide ceramic matrix composite with a porous alumina matrix that has been identified as a candidate material for such applications. This research investigated the effects of frequency on fatigue response of N720/A at 1200°C in both air and steam environment. Prior investigation of this material by Eber [8] in 2005 studied fatigue behavior at 1200°C in air and in steam environments at the frequency of 1.0 Hz. The current research focused …

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Effect Of Environment On Creep Behavior Of An Oxide/Oxide Cfcc With ±45° Fiber Orientation, Gregory T. Siegert Jun 2006

Effect Of Environment On Creep Behavior Of An Oxide/Oxide Cfcc With ±45° Fiber Orientation, Gregory T. Siegert

Theses and Dissertations

Aerospace applications require materials capable of maintaining superior mechanical properties while operating at high temperatures and oxidizing environments. Nextel™ 720/A (N720/A), an oxide/oxide ceramic matrix composite (CMC) with a porous alumina matrix was developed specifically to provide improved long-term properties and performance at 1200°C. This research evaluated the creep behavior of N720/A with a ±45° fiber orientation at 1200°C in: laboratory air, steam, and argon environments. Creep-rupture tests at the creep stress levels of: 45, 40, 35, and 15 MPa were conducted in each environment.
The ultimate tensile strength of N720/A with ±45° fiber orientation was 55 MPa, the elastic …

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Electrochemical Studies Of Iron-Doped Nickel Oxide Electrode For Oxygen Evolution Reaction, Jin-Zhao Huang, Zheng Xu, Hai-Ling Li, Guo-Hu Kang, Wen-Jing Wang May 2006

Electrochemical Studies Of Iron-Doped Nickel Oxide Electrode For Oxygen Evolution Reaction, Jin-Zhao Huang, Zheng Xu, Hai-Ling Li, Guo-Hu Kang, Wen-Jing Wang

Journal of Electrochemistry

In this paper,the iron-doped nickel oxide thin film as anode catalyst was prepared by RF reactivesputtering method.The oxygen evolution reaction(OER) on the iron-doped nickel oxide was investigated withcyclic voltammetry,liner sweep voltammetry,polarization curves and electrochemical impedance spectroscopy.Results showthat the iron acts as active site in the film which makes the overpotential lower,and changes therate-limiting from primary discharge of OH-ions to the recombination of oxygen atom.With the increasing of ox-ygen content in flu ratio during sputtering,the electrocatalytic activities of the film increase.Iron-doped nickeloxide thin film is promising material as OER electrocatalyst for hydrogen production than the nickel electrode.The oxygen overpotential on the …

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Electrochemical Behavior And Reduction Mechanism Of High Valence Silver Oxide Ag3O4 In Alkaline Solution, Yan Cheng, Ming Yu, Man-Ming Yan, Zhi-Yu Jiang May 2006

Electrochemical Behavior And Reduction Mechanism Of High Valence Silver Oxide Ag3O4 In Alkaline Solution, Yan Cheng, Ming Yu, Man-Ming Yan, Zhi-Yu Jiang

Journal of Electrochemistry

The electrochemical properties of high-valence silver oxide Ag3O4 in alkaline solution were investigated for the first time and the reduction mechanism of Ag3O4 was proposed. It can be recognized that Ag3O4 consists of Ag(Ⅲ) and Ag(Ⅱ)~(*). From the results of voltammetry and XRD experiments it was found that the reduction process of Ag3O4 was more complicated. It could be electrochemically reduced through the series reactions of Ag(Ⅲ) →Ag(Ⅱ) →Ag(Ⅰ) →Ag(O) at low discharge rate or Ag(Ⅲ) →Ag(Ⅰ) →Ag(O) at higher discharge rate.And the Ag(Ⅱ)~(*) could be reduced to …

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Synthesis Of Zinc Polyhedral Microspheres And Applications In Alkaline Zn-Mno2 Battery, Hua Ma, Chun-Sheng Li, Fang-Yi Cheng, Chun-Yuan Zhou, Feng Gao, Jun Chen May 2006

Synthesis Of Zinc Polyhedral Microspheres And Applications In Alkaline Zn-Mno2 Battery, Hua Ma, Chun-Sheng Li, Fang-Yi Cheng, Chun-Yuan Zhou, Feng Gao, Jun Chen

Journal of Electrochemistry

The zinc polyhedral microspheres were synthesized by evaporation of pure zinc powders via a vapor-transport process.The results characterized by XRD and SEM show that the as-synthesized zinc powders are polyhedral microspheres with the diameter of 2~3 μm.The electrochemical investigation showed that the capacity of the as-assembled AA-size primary alkaline Zn-MnO2 battery was increased to 3.14 Ah under the constant discharge current of 100 mA by using the as-deposited microspherical zinc powders as the anode active materials and γ-MnO2 nanowires as the cathode active materials,indicating their potential application in high-energy batteries.

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Electrodeposition Of Three-Dimensional Porous Copper Films Using Hydrogen Bubbles As Template, Ya-Feng Sun, Zhen-Jiang Niu, Shu-Qiong Cen, Ze-Lin Li May 2006

Electrodeposition Of Three-Dimensional Porous Copper Films Using Hydrogen Bubbles As Template, Ya-Feng Sun, Zhen-Jiang Niu, Shu-Qiong Cen, Ze-Lin Li

Journal of Electrochemistry

Using cathodic hydrogen bubbles as a template,the three-dimensional(3-D) porous copper films have been successfully electrodeposited from a bath of 0.2 mol·dm-3 CuSO4 and 1.5 mol·dm-3 H2SO4,effects of deposition parameters including temperature,current density and additives(Na2SO4,HCl and Polyethylene glycol(PEG)) on the morphologies of the deposits have been systematically studied.SEM results showed that both the pore size and thickness of the pore walls decreased with cooling the electrolyte temperature or adding(Na2SO4) or PEG into the bath when the other deposition parameters were fixed.With addition small amounts of HCl …

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Corrosion Behavior Of The Welding Seam Of The Q235 Steel Jointed By J420 Electrode In Ammonium Sulfite Solution, A-Li Lei, Qiao-Qin Guo, La-Jun Feng May 2006

Corrosion Behavior Of The Welding Seam Of The Q235 Steel Jointed By J420 Electrode In Ammonium Sulfite Solution, A-Li Lei, Qiao-Qin Guo, La-Jun Feng

Journal of Electrochemistry

The corrosion behavior of welding seam of the Q235 steel jointed by J420 electrode in ammonium sulfite solution was researched.The results of electrochemical method of welding seam and metallurgical structure analysis showed that the poor corrosion resisting property was determined by its structure after the Q235 steel was jointed by J420 electrode.The sulfite corrosion rate was accelerated by increasing the temperature and concentration of ammorium.

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Preparation Of Spherical Ni(Oh)2 Coated With Coooh And Its Fast Charge Performance, Min-Jie Yang, Jun-Min Nan, Jian-Jun Xue, Yan Cui, Ming Cui May 2006

Preparation Of Spherical Ni(Oh)2 Coated With Coooh And Its Fast Charge Performance, Min-Jie Yang, Jun-Min Nan, Jian-Jun Xue, Yan Cui, Ming Cui

Journal of Electrochemistry

Spherical Ni(OH)2 was coated with CoOOH through chemical precipitation and electrolytic oxidation.The influences of CoOOH coating on fast charge performance ofMH/Ni battery were studied by preparing high capacity and fast charge AA size MH/Ni batteries.The sample coated with CoOOH was characterized by Infrared spectrum(IR) and scanning electron microscopy(SEM).The results showed that the internal resistance decreased 3.4 mΩ,the charge plateau lower and the cell temperrature was below 55 ℃ at the end of charging process when the cathode active material used Ni(OH)2 coated with CoOOH as compared with that doped by CoO.In addition,an initial discharge efficiency of 90.6% and …

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Effect Of Preparation Conditions On Electroluminescence Of Porous Silicon, Ya-Jun Yang, Qing-Shan Li, Xian-Yun Liu, Ning Zhang, Bo Zhao, Xue-Gang Zheng, Ming-Ji Shi, Da Chen, Jing-Jing Wang May 2006

Effect Of Preparation Conditions On Electroluminescence Of Porous Silicon, Ya-Jun Yang, Qing-Shan Li, Xian-Yun Liu, Ning Zhang, Bo Zhao, Xue-Gang Zheng, Ming-Ji Shi, Da Chen, Jing-Jing Wang

Journal of Electrochemistry

Electrically induced visible light emitting porous silicon devices with the structure of ITO/PS/p-Si/Al were fabricated by evaporation-anodic oxidation method.The light emission last for a few hours under 7.5V forward bias conditions.It was shown that the electroluminescence(EL) peaks shifted to the blue with the increasing of current density,erosion time and solution concentration.In order to achieve samples with low driven voltage,long light emission time and high EL efficiency,porous silicon should be prepared under low current density and short erosion time.

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Electrochemical Impedance Spectrum Of Ferrocene At A Rotating Disk Glassy Carbon Electrode And Its Interaction With Dna, Can-Hui Chen, Hong Li, Jian-Zhang Zhou, Zhong-Hua Lin, Wei Zhu, Quan-Xin Zhang May 2006

Electrochemical Impedance Spectrum Of Ferrocene At A Rotating Disk Glassy Carbon Electrode And Its Interaction With Dna, Can-Hui Chen, Hong Li, Jian-Zhang Zhou, Zhong-Hua Lin, Wei Zhu, Quan-Xin Zhang

Journal of Electrochemistry

The electrochemical impedance spectrum(EIS) of ferrocene(Fc) at a rotating glassy carbon(GC) electrode and its interaction with calf thymus DNA in Tris-NaCl buffer solution(pH=7.2) have been investigated by using electrochemical techniques such as rotating disk electrode(RDE),EIS and its data fitting.A plateau of the limiting current for the voltammetric curve and two capacitance arches obtained at the rotating GC electrode are exhibited.The interaction of Fc with DNA is represented by the decrease of limiting diffusion current and the increase of electrochemical reaction resistances with the increase of DNA concentration,respectively.On the other hand,based on the theoretical analysis and data fitting of RDE and …

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Structure And Properties Of Electrodeposited Sn-Co Alloy Electrodes As Anode Material For Lithium-Ion Secondary Batteries, Hong-Hong Jiang, Ling Huang, Shun-Wei Zhou, Fu-Sheng Ke, Fang-Zu Yang, Xiao-Yong Fan, Shi-Gang Sun May 2006

Structure And Properties Of Electrodeposited Sn-Co Alloy Electrodes As Anode Material For Lithium-Ion Secondary Batteries, Hong-Hong Jiang, Ling Huang, Shun-Wei Zhou, Fu-Sheng Ke, Fang-Zu Yang, Xiao-Yong Fan, Shi-Gang Sun

Journal of Electrochemistry

The Sn-Co alloy deposits were prepared by electroplating.The structure and electrochemical performance of the electroplated Sn-Co alloys have been investigated in detail. Experimental results show that the porous Sn-Co alloy film exhibits hexagonal solid solution,with Sn as the solvent, Co as the solute. The texture of the Sn-Co alloy coating exhibits(110) preferred orientation. Electrochemical tests show that the porous Sn-Co alloy coating electrodes can deliver a discharge capacity of 643mAh/g in the first cycle. At the 20h cycle the charge was 461mAh/g. At initial charge curve the irreversible capacity is probably associated to a combination of processes, which may …

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High Density Lifepo4/C Synthesized By Controlled Crystallization And Microwave Carbon Thermal Reduction, Chang-Ping Tang, Jie-Rong Ying, Min Lei, Wei Li, Chang-Yin Jiang, Chun-Rong Wan May 2006

High Density Lifepo4/C Synthesized By Controlled Crystallization And Microwave Carbon Thermal Reduction, Chang-Ping Tang, Jie-Rong Ying, Min Lei, Wei Li, Chang-Yin Jiang, Chun-Rong Wan

Journal of Electrochemistry

The spherical FePO4·xH2O was prepared in the solution by controlled crystallization.The precursor FePO4 was obtained in high temperatureceramic approach,then the high density LiFePO4 /C was synthesized by microwave carbon thermal reduction.The structure and morphology of the materials were characterized by means of XRD and SEM techniques,and the electrochemical properties were studies by charge-discharge experiments.

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Effect Of Cracks On Corrosion Of Rebar In Concrete Studied By Wire Beam Electrode, Guo-Xi Li, Xian-Lu Hou, Ri-Long Zhu, Jin-Feng Hu, Yan-Na Du May 2006

Effect Of Cracks On Corrosion Of Rebar In Concrete Studied By Wire Beam Electrode, Guo-Xi Li, Xian-Lu Hou, Ri-Long Zhu, Jin-Feng Hu, Yan-Na Du

Journal of Electrochemistry

The effects of crack and ethanolamine on corrosion of rebar in concrete were studied by measuring the distribution of corrosion potential and polarization resistance of iron wires in 10% NaCl solution.The results showed that the diffusion of water,oxygen and chloric ion toward concrete was accelerated by the crack which intensified the nonuniform corrosion of iron wire with the regions near to crack as anode and the uncracked regions as cathode.Ethanolamine could diffuse into the body of concrete and absorb on the surface of iron wire,which reduced iron corrosion evidently and successfully inhibited the nonuniform corrosion caused by crack without changing …

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Tyrosinase Immobilizarion On Boron-Doped Diamond Electrodes And The Determination Of Phenolic Compounds, Yan-Li Zhou, Jin-Fang Zhi May 2006

Tyrosinase Immobilizarion On Boron-Doped Diamond Electrodes And The Determination Of Phenolic Compounds, Yan-Li Zhou, Jin-Fang Zhi

Journal of Electrochemistry

As-grown BDD surfaces were first functionalized by photochemically linking vinyl groups of allylamine,producing covalently linked amine-terminated active BDD surfaces.Then the tyrosinase was immobilized onto the BDD surface through peptide linking.Cyclic voltammograms of phenol,pcresol and hydroquinone were measured using the tyrosinase-modified BDD electrode and amperometric characteristics such as sensitivity,linear response range and stability were studied.

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Electrochemical Studies On Electrocatalytic Activity Of AuCore PtShell Nanoparticles To Methanol Oxidation, Fang Bao, Jian-Lin Yao, Ren-Ao Gu May 2006

Electrochemical Studies On Electrocatalytic Activity Of AuCore PtShell Nanoparticles To Methanol Oxidation, Fang Bao, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

AucorePtshell nanoparticles with different thicknesses were prepared by using chemical reduction method,and characterized by ultraviolet-visible spectroscopy(UV-Vis),transmission electron microscopy(TEM) and cyclic voltammetry(CV).The electrocatalytic activity of AucorePtshell nanoparticles with the mean diameter of 70~80 nm to methanol oxidation was investigated by cyclic voltammetry in the acid solution.The results revealed that the prepared core-shell nanoparticles were covered by Pt shell and exhibited the similar optical property and electrocatalytic activity with the normal Pt surface.Moreover,the electrocatalytic activity increased with the electrochemical sweep in the certain potential range.It might be contributed by the special loose structure of Pt shell …

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Electrochemical Preparation Of Gd-Ni Alloy Film In Acetamide-Urea-Nabr Melt, Bi-Qing Chen, Jian-Chao Wang, Chen-Yu Guo, Jin-Gui Wang, Qing Liu May 2006

Electrochemical Preparation Of Gd-Ni Alloy Film In Acetamide-Urea-Nabr Melt, Bi-Qing Chen, Jian-Chao Wang, Chen-Yu Guo, Jin-Gui Wang, Qing Liu

Journal of Electrochemistry

Cyclic voltammetry was used to study the electroreduction of Ni2+ to Ni on Pt and Cu electrode in acetamide-urea-NaBr melt at 353K.It is irreversible in one step.At Pt and Cu eletrode the diffusion coefficient and electron transfer coefficient of Ni2+ in 0.063mol/dm3) NiCl2-acetamide-urea-NaBr melt were determined.The transfer coefficient α=0.28 and diffusion coefficient D_(0)=4.63×10-5 cm2·s-1 of the Pt eletrode and transfer coefficient α=0.22 and diffusion coefficient D_(0)=6.05×10-7 cm2·s-1 of the Cu eletrode were measured.It was put emphasis on that Gd3+ is not reduced to Gd alone …

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Study On Composite Organic Inhibitor Of Zinc Electrode In Alkaline Solutions, Xue-Tao Bu, Guang-Chuan Liang, Cui Li May 2006

Study On Composite Organic Inhibitor Of Zinc Electrode In Alkaline Solutions, Xue-Tao Bu, Guang-Chuan Liang, Cui Li

Journal of Electrochemistry

The synergetic influence of sodium dodecyl benzene sulfonate(SDBS) with Tween-20(Tween) on zinc electrode was studied by polarization experiment,surface tension test,discharge test and SEM.It is found that the composite inhibitor ST has a much higher efficiency.The addition of Tween reduced the critical micell concentration of SDBS on zinc electrode remarkably and the distribution of adsorption became more homogeneous.ST inhibits corrosion of zinc electrode and improves discharge capacity of the whole battery.Through electrochemical morphological observation of anodic passivation behaviors of zinc electrode,the absorption of ST on electrode surface makes discharged production much smaller and keeps crude porous structure intact.Passivation of zinc electrode …

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Characterization Of Compressive Creep Behavior Of Oxide/Oxide Composite With Monazite Coating At Elevated Temperature, Patrick R. Jackson Mar 2006

Characterization Of Compressive Creep Behavior Of Oxide/Oxide Composite With Monazite Coating At Elevated Temperature, Patrick R. Jackson

Theses and Dissertations

The compressive creep behavior of a N610/monazite/alumina composite was investigated in this work. The composite consists of a porous alumina matrix reinforced with NextelTM610 fibers coated with monazite in a symmetric cross-ply (0°/90°/0°/90°)s orientation. Compressive stress-strain behavior was investigated as well. The addition of monazite coating resulted in ~ 35% loss in compressive strength at 900°C and in ~45% loss in compressive strength at 1100°C. Compressive creep behavior was examined at 900 and 1100°C for creep stresses ranging from 50 to 95 MPa. Primary and secondary creep regimes were observed at both temperatures. Minimum creep rate was reached in all …

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Validation Of A Scaled Plane Strain Hypervelocity Gouging Model, Ronald J. Pendleton Mar 2006

Validation Of A Scaled Plane Strain Hypervelocity Gouging Model, Ronald J. Pendleton

Theses and Dissertations

The phenomenon of high speed impact is of great interest to the Air Force of Scientific Research and the Air Force Research Laboratory's Holloman High Speed test track. Rocket sled tests at the facility frequently are limited to velocities lower than actually attainable due to damage to the rail in the form of gouges. Direct observation of the gouging phenomenon is not currently possible. This leaves computational modeling as the only means to study the phenomenon. A computer model has previously been used to model the development of gouging at the Holloman High Speed Test Track. However, this model has …

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Effect Of Hold Times On Fatigue Behavior Of Nextel 720™/Alumina Ceramic Matrix Composite At 1200°C In Air And In Steam Environment, John M. Mehrman Mar 2006

Effect Of Hold Times On Fatigue Behavior Of Nextel 720™/Alumina Ceramic Matrix Composite At 1200°C In Air And In Steam Environment, John M. Mehrman

Theses and Dissertations

The aerospace field requires structural materials that can maintain superior mechanical properties while subjected to high temperatures and oxidizing environments. This research investigated the effect of hold times at maximum load on fatigue performance of a Nextel 720/Alumina ceramic matrix composite at 1200 C, explored the influence of environment on material response to cyclic loading with hold times at maximum load, and assessed the effects of loading history on material behavior and environmental durability. The N720/A composite relies on an oxide/oxide composition for inherent oxidation resistance and a porous matrix with no interphase between the fiber and matrix for damage …

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Creep-Rupture And Fatigue Behaviors Of Notched Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature, Mark A. Sullivan Mar 2006

Creep-Rupture And Fatigue Behaviors Of Notched Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature, Mark A. Sullivan

Theses and Dissertations

Oxide/oxide composites are being considered for use in high temperature aerospace applications where their inherent resistance to oxidation provides for better long life properties at high temperature than most other ceramic matrix composites (CMCs). One promising oxide/oxide CMC is Nextel 720/A (N720/A) which uses an 8-harness satin weave (8HSW) of Nextel 720 fibers embedded in a porous alumina matrix. Possible aerospace applications for N720/A will likely require inserting holes into the material for mounting and cooling purposes. The notch characteristics must be understood to ensure designs using the material are sufficient for the desired application. This research effort examined the …

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Electroless Nickel Plating On Carbon Nanotube With Non-Palladium Activation Procedure, Guang-Hui Hu, Hui-Huang Wu, Fang-Zu Yang Feb 2006

Electroless Nickel Plating On Carbon Nanotube With Non-Palladium Activation Procedure, Guang-Hui Hu, Hui-Huang Wu, Fang-Zu Yang

Journal of Electrochemistry

A new procedure of surface activation without using palladium salt was proposed for electroless nickel plating on carbon nanotubes.In the procedure,carbon nanotubes were oxidized by nitric acid and then neutralized with NaOH to create carboxyl surface groups which were used to adsorb Ni2+ ions,thereafter the adsorbed Ni2+ ions were chemically reduced into Ni nano-particles as a catalytic center for electroless nickel deposition,all these were further confirmed by infrared absorption spectra and electron microscopic observations.The results indicate that the procedure is feasible to electroless nickel plating on carbon nanotubes.The different morphology of deposits obtained from electroless plating was also …

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Anodic Behaviors Of Pb-Ca-Sn-Re Alloy And Tradditional Pb-Ca-Sn Alloy In Sulfuric Acid Solutions, Dang-Guo Li, Gen-Shu Zhou, Liang Yao, Guan-Fa Lin, Mao-Sheng Zheng Feb 2006

Anodic Behaviors Of Pb-Ca-Sn-Re Alloy And Tradditional Pb-Ca-Sn Alloy In Sulfuric Acid Solutions, Dang-Guo Li, Gen-Shu Zhou, Liang Yao, Guan-Fa Lin, Mao-Sheng Zheng

Journal of Electrochemistry

The anodic behaviors of Pb-Ca-Sn-Re and Pb-Ca-Sn alloys were investigated at 1.28 V(vsHg/(H2SO4)) in 4.5 mol/L sulfuric acid solution by means of ac voltammetry,ac impedance and cyclic voltammetry.The results showed that the corrosion-resistance property of Pb-Ca-Sn-Re alloy is better than that of tradditional Pb-Ca-Sn alloy,the growth of Pb(Ⅱ) compounds was inhibited in the film of Pb-Ca-Sn-Re alloy,and the film impedance of Pb-Ca-Sn-Re alloy was decreased,indicating that the conductivity of the film was(increased),which is helpful to enhance the deep recycling property for lead acid battery.

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