Engineering Science and Materials Commons^™

Study On The Preparation, Properties And Applications Of The Polymer/Graphite Composite Electrode, Guohua Chen, Jinrui Xu

Journal of Electrochemistry

The graphite AS composite electrodes, which show high electric conductivity, high mechanical strength and operationl stability, were prepared by filling and extruding the AS copolymer with graphite powder. It exhibited a substantial hydrogen overvoltage and small residual current in different electrolytes, as compared with glassy carbon electrode. The electrode was applied to the determination of traces of Pb²⁺ in mineral water, Ag⁺ in waste water and In³⁺, Cu²⁺, Pb²⁺, Cd²⁺ in zinc ore, and showed high stability, reproducibility and selectivity. Owing to the existence of abundant polar functioal groups on the …

Surface Modification Of Molten Carbonate Fuel Cell Anode, Baizeng Fang, Xinyu Liu, Xindong Wang, Shuzhen Duan

Journal of Electrochemistry

In this study, the anode material of molten carbonate fuel cell was modified by the deposition of niobium on nickel surface. The results of polarization experiments reveal that the corrosion resistant properties as well as electrocatalytic activity have been improved greatly.

Study Of Electrodepositing Bright Tin Cobalt Zinc Alloy From Weak Acid Solution, Zhengzhong Zuo, Runxiang Hou, Shaochun Xia

Journal of Electrochemistry

A new process of electrodeposting bright Tin Cobalt Zinc alloy from weak acid solution is proposed in this paper. The solution compositions and operating conditions are Na₃C₆H₅O₇·2H₂O 100～150, Na₂EDTA·2H₂O 20～30, SnCl₂·2H₂O 15～20, CoSO₄·72H₂O 25～35, ZnCl₂ 15～20 g·L^-1; stabilizer WDZ-160～100, brightener WDZ-215～20 mL·L^-1; pH=4～6, D_K=0.5～5.0 A·dm^-2, T=5～35 ℃. A bright Sn-Co-Zn deposit having Co about 0.5～3.5% and Zn about 1～10% is produced. The effects of bath compositions on Co or …

Electroluminescence Of Photoelectrochemically Etched N+-Si, Guozheng Li, Chengqian Zhang, Xiumei Yang

Journal of Electrochemistry

Porous silicon with micrometer size pores, which is made on n⁺-Si by photoelectrochemically etched, has electroluminescent property. Each monochromic intensity and wavelength range of luminescent spectra depend on polarized potential. The intersity and the stability of cathodic electroluminescence is high than those of anodic one. Voltammetric behavior before quenching indicated that the electrochemical reactions of some surface species are involved in except the reduction of S₂O₈^2-, which leads to radiative recombination. The energy band diagram based on n⁺-Si(E_g=1.1 eV)/PS(E_g=1.8 eV) junction is proposed.

Effects Of Curvature On The Electrochemical Behaviors Of Tubular Electrode, Yirong Wu, Zhenghao Wang

Journal of Electrochemistry

The convective diffusion equation of tubular electrode was solved with the implicit finite difference numerical method. Comparing with the electrochemical behaviors of channel electrode, the behaviors of tubular electrode were analysised. The effects of curvature on the electrochemical behaviors of tubular electrode and the limit of applying Levich approximation to tubular electrode were discussed.

Mechanism And Texture Of Ni-Mo Alloy Electrodeposition, Ling Huang, Shukai Xu, Jaoning Tang, Fangzu Yang, Shaomin Zhou

Journal of Electrochemistry

Ni-Mo alloy deposits with (111) preferred orientation was obtained in a solution of 0.22 mol/L NiSO₄·6H₂O, 0.06 mol/L Na₂MoO₄·2H₂O and 0.3 mol/L Na₃C₆H₅O₇·2H₂O in temperature from 25℃ to 50℃, and current densities ranged from 10 mA·cm^-2 to 30 mA·cm^-2. The electrodeposition of Ni-Mo alloy was studied by cylic voltammetry and potential step experiment. It was shown that Ni-Mo alloy is formed by mechanism involving progressive nucleation followed by three dimensional growth of the metal centres. The complex …

Broadband Dynamic Modification Using Feedforward Control, Kendeas Antonis Karantonis

Mechanical & Aerospace Engineering Theses & Dissertations

The use of feedforward control for dynamic modification is relatively new to the area of structural vibration control. In this thesis the disturbance path dynamics of a flexible aluminum beam, pinned at both ends and under the influence of broadband excitation inputs, are modified through the use of feedforward control. The ideal algebraically determined feedforward control method for response cancellation is first presented. Theoretically, this compensator modifies the disturbance path dynamics to any desired behavior. This ideal algebraic approach can only be used for minimum phase systems. In non-minimum phase systems, right half s-plane plant zeros emerge as unstable poles …

Development Of Curved-Plate Elements For The Exact Buckling Analysis Of Composite Plate Assemblies Including Transverse-Shear Effects, David Michael Mcgowan

Mechanical & Aerospace Engineering Theses & Dissertations

The analytical formulation of curved-plate non-linear equilibrium equations including transverse-shear-deformation effects is presented. The formulation uses the principle of virtual work. A unified set of non-linear strains that contains terms from both physical and tensorial strain measures is used. Linearized, perturbed equilibrium equations (stability equations) that describe the response of the plate just after buckling occurs are then derived after the application of several simplifying assumptions. These equations are then modified to allow the reference surface of the plate to be located at a distance z_c, from the centroidal surface. The implementation of the new theory into the …

An Experimental Investigation Of Bolt Preload Relaxation In Pultruded Gfrp Composite Joints, Srinivas Ravi

Mechanical & Aerospace Engineering Theses & Dissertations

Mechanically fastened joints in pultruded composites are necessary for reasons of maintenance, repair, and assembly. Pultruded composites utilize polymers as matrices and therefore are susceptible to time-dependent effects. The positive effects of increasing the clamping force in bolted joints are well known. To maintain a safe operation of the assembly a minimum clamping force must be guaranteed. But since these materials show time-dependent effects, the bolt-preload relaxes over a period of time. The present study is aimed at investigating the bolt preload relaxation. In this study 1/2 in. thick pultruded sheets were first tested under compression in the thickness direction. …

Analysis And Testing Of Plates With Piezoelectric Sensors And Actuators, Jeffrey S. Bevan

Mechanical & Aerospace Engineering Theses & Dissertations

Piezoelectric material inherently possesses coupling between electrostatics and structural dynamics. Utilizing linear piezoelectric theory results in an intrinsically coupled pair of piezoelectric constitutive equations. One set describes the direct piezoelectric effect, where strains produce an electric field, and the other set describes the converse effect, where an applied electrical field produces strain. The purpose of this study is to compare the finite element analysis and experiments of a thin plate with bonded piezoelectric material.

Since an isotropic plate in combination with a thin piezoelectric layer constitutes a laminated composite, the classical laminate plate theory is used in the formulation to …

Electrochemical Studies Of Spinel Limn2O4 Rechargeable Lithium Battery, Li Feng, Yuqin Chang, Lie Wu, Hong Li, Yibin San, Tianhong Lu

Journal of Electrochemistry

The spinel Li intercalation compound LiMn₂O₄ was prepared and studied using ac impedance and cyclic voltammogram techniques. It was first discussed that the impedance behaviors of LiMn₂O₄ electrode varied as lithium ion was intercalated in or out the electrode with the help of fractal theory. The Li reversible behaviors in LiMn₂O₄ electrode were shown by the cyclic voltammogram results.

Studies On The Cathodic Current Efficiency In The Electrodeposition Ni-Psz Gradient Coating, Jun Li, Dianlong Wang, Li Chen, Xinguo Hu

Journal of Electrochemistry

The cathodic current efficiency and the electrochemical behavior in electrodeposition Ni-PSZ gradient coating were investigated by various electrochemical techniques and scanning electron microscope. The results showed that the Ni-PSZ composite coatings can accelerate evolution of hydrogen with the increase of PSZ content. The overpotential of nickel reduction will be increased and that of hydrogen reaction will be reduced in the presence of PSZ particles in electrolyte. The effect of PSZ particles on nickel electrodeposition was preferentially to catalyze the formation of H ads . These all contributed to the lower current efficiency.

Studies On An Iron Heteropolyacid Redox Flow Battery, Peiju Sun, Wansheng You, Zhorgyin Tan

Journal of Electrochemistry

This paper reports a new Fe-HP redox flow cell. The positive and negative electrodes active materials are phosphomolybdic acid and acidified ferrous sulphate solutions respectively. Two activated porous carbon felt electrodes where the electrochemical reactions take place, are separated by a selective cation exchange membrane. The both couples have a suitable electrochemical reversibility on carbon and graphite electrodes. The active materials of the cell have very high stability. Moreover the cell has no life cycle limiting.

Electrochemical Synthesis And Characterization Of Ba-Pb-O And Bi-Pb-O Oxides, Min Xie, Liangzhong Zhao, Cuiying Xu, Jinbiao Zhang

Journal of Electrochemistry

Pb-based oxides Ba-Pb-O and Bi-Pb-O were synthesized from aqueous solutions by using electrochemical method. The resulting Ba-Pb-O and Bi-Pb-O were characterized using XPS, EDX and XRD. The results show that perovskite BaPb_0.9O₃ can be electrodeposited on the anode only from strong alkaline solution. In acid aqueous solution, conducting BiPb₂O_z oxide is fromed on the anode. In these oxides the nominal valence of lead is +4.

Problems Of The Study Of Anodic Films On Pb In Sulfuric Acid Solution (Ⅲ), Houtian Liu, Qunzhou Wang, Weifang Zhou, Wenbin Cai

Journal of Electrochemistry

The interstitial liquid among the particles in anodic Pb(Ⅱ) films could be the major passage for ion transportation. This is discussed with the mechanism of the cathodic reduction of anodic PbSO₄ film and the effect of Sb on the growth of anodic Pb(Ⅱ) oxides film.

Electrochemical Behaviors Of Isoalloxazine Confined In Montomorillonite Olay Modified Electrode, Zhibin Wu, Yuan Lin, Daodao Zhang, Haoqin Wu

Journal of Electrochemistry

A cyclic voltametric investigation of stability and redox properties of isoalloxazne on cetytrimethyammonium bromide (CTAB) modified montomorillonite clay platinium electrode in aqueous solution has been performed. pH dependent film concentrations and apparent diffusion coefficents were measured. The mechanism of the charge transport process with in the clay film were discussed.

Study On Properties Of Magnesium Alloy Electrode With Anodized Film, Yi Chi, Ping Yang, Xiufeng Lin

Journal of Electrochemistry

The corrosion resistance of Mg alloy electrode with anodized film in atmosphere is bigger than that of the Mg alloy electrode with chromate film. The corrosion resisance and voltage delay of such electrode with anodized film in NaCl solution changed with anodizing comdition. The effects of composition, morphology and thickness of the anodized film on the peoperty of Mg alloy electrode are discussed.

Surface Modifications Of Carbon Materials Used As Anode Of Lithium Ion Battery Ⅱ. The Carbon Material With Core Shell Structure And Its Positive Effect On Cell Performance Of Graphite Anode, Shuhua Ma, Hanju Guo, Ji Li, Hongze Liang, Xiabin Jing, Fosong Wang

Journal of Electrochemistry

The carbon powders and film electrode with core shell structure were prepared by carbonization in gas state with using refined coal as shell material and Artificial Graphite and Mesocarbon Microbeads (2 800 ℃) graphite as core material. Galvanostatic charge/discharge measurement showed that both steady charge/discharge capacity and first charge/discharge efficiency were improved. Cyclic voltammetry indicated that the peak at about 0.7 V vs. Li⁺/Li characteristic of decomposition of electrolyte got weakened, and a more compact film was formed. X-ray diffraction measurement suggested the existence of amorphous carbon shell on the carbon powders and carbon film.

A Study On The Electrodeposition Of Palladium And It's Nucleation, Fangzu Yang, Shukai Xu, Shibing Yao, Bingyi Chen, Xueqing Zheng, Xiaohui Zhong, Shaomin Zhou

Journal of Electrochemistry

The electrodeposition and nucleation of palladium are studied in the system of potassium citrate and ammonium oxalate. The results show that, with the additives of XP-4 and XP-7 prepared in our laboratory, a full bright palladium electrodeposits will be obtained in the wide ranges of the cathode current densities 0.5～3.5 A/dm² and temperature 40～60 ℃; the qualities of the thick deposits will be effectively improved by means of pulse current plating. Cyclic voltammograms results show that the division of peaks between anodic and cathodic on the electrode process of palladium will be up to 1.05 V, which shows the …

Microporous Silicon Dioxide/Vycor Membranes For Gas Separation, Justin R. Barone

Theses

This study focused on producing membranes for molecular sieving of gases by reducing the pore size of an already existing membrane structure. To do this, SiO₂ was deposited inside the pores of a Vycor tube with initial pore diameter of 4 nm. The film deposition took place by a low pressure chemical vapor deposition (LPCVD) process where diethylsilane (DES) and nitrous oxide (N₂O) were used as precursor gases. A counterflow reactant geometry was used where the precursor gases were flowed on both sides of the porous membrane. This deposition geometry gave higher selectivities and better mechanical stability. …

Synthesis And Characterization Of Silicon Dioxide Thin Films By Low Pressure Chemical Vapor Deposition, Sutham Niyomwas

Theses

Ditertiarybutylsilane ( DTBS ) and oxygen have been used as precursors to produce silicon dioxide films by low pressure chemical vapor deposition. These films were synthesized in the temperature range of 600°C to 800°C at constant pressure, and at different gas flow composition. The films were found to be uniform with a composition that varied with deposition temperature and gas flow ratio. The growth rate was found to follow an Arrhenius behavior with an apparent activation energy of 2.62 kcal/mol. The growth rate was seen to increase with higher distance between wafers and to vary as a function of square …

Trifluoroiodomethane As An Environmentally Friendly Gas For Water Patterning By Plasma Etching Process, Krit Aryusook

Theses

Trifluoroiodomethane (CF₃I), a non-global warming gas, has been investigated with study as a substitute for typical CFC etchants, such as CF₄ and C₂F₆, used in wafer pattering technology. This investigation was carried out by exposing dielectric films of silicon oxide (SiO₂) and silicon nitride (Si₃N₄) in CF₃I and C₂F₆/O₂ (used as a reference) plasma environments. The etch rate of these films was ascertained as function of applied rf power, etchant gas flow rate, reaction chamber operating pressure, and O_{2 …}

An Investigation Of Mechanical Properties Of Composites Containing Recycled Rubber Particles, Ryan C. Archey

Masters Theses

In order to promote applications of recycled automobile tires, composite materials of recycled rubber tire particles with ethylene co-vinyl acetate (EVA), polybutadiene (PB), and Primacor were studied in the thesis. The composites were processed using a single screw extruder and a pelletizer. Compression molding was used to form specimens for hardness and impact tests. Mechanical properties of the composites were investigated in terms of tensile strength, percent elongation, Durometer hardness, and impact energy.

In this study, the content of recycled rubber was between 0 and 40 percent. Various matrices were processed using a combination of EVA, PB, or Primacor to …

Part Form Errors Predicted From Machine Tool Performance Measurements, R. G. Wilhelm, N. Srinivasan, F. Farabaugh, R. Hocken

Department of Mechanical and Materials Engineering: Faculty Publications

Machine tool performance testing, as defined by IS0 230 and ANSI B5.54 has been successfully used to maintain and improve the accuracy and repeatability of production-level machine tools. In this study, a controlled series of experiments have been used to test the efficacy of these performance tests in the prediction of part form errors. Results are shown for flatness, squareness, position, and profile tolerances. The experimental results suggest that standard machine tool performance tests can also be used to predict the “best-case” tolerances that can be achieved for particular part features.

Corrosion Inhibitor For Reinforcing Steel In Concrete, Hanan Abdel Aziz Elnouhy

Archived Theses and Dissertations

No abstract provided.

Progresses In The Studies On Electrochemical And Surface Properties Of Hydrogen Storage Alloy Materials, Yong Yang, Jum Li, Zugeng Lin

Journal of Electrochemistry

Recent progresses in the studies on electrochemical and surface properties of hydrogen storage alloy materials are reviewed. This paper includes three sections: 1) Thermodynamic and kinetic studies of metal hydride electrodes, 2) Effects of micro structure and alloy elements of the materials on the electrochemical properties of the electrodes and 3) Correlation between surface properties of the alloy materials and performance of the negative electrode in the nickel metal hydride batteries.

Studies Of Electrochemical Behaviors Of Cytochrome C On Pretreated Gold Electrode, Jin Luo, Lingling Wu, Shaohua Huang, Zhonghua Lin

Journal of Electrochemistry

The quasi reversible responses of both adsorbed and bulk cytochrome c at the pretreated gold electrode are observed. The adsorption behaviors and reaction kinetics have been studied using in situ FTIR spectroscopy, UV/Vis reflection spectroscopy, voltammetry, AC impedance and potential step methods. The results show that the cytochrome c can irreversibly adsorb on the gold surface in a complete monolayer and the adsorbed layer can mediate the redox reaction of the cytochrome c in the solution in the absence of promoter.

Surface Modifications Of Carbon Materials Used As Anode Of Lithium Ion Battery Ⅰ. Influences Of Oxidation And Reduction Pretreatment On Anode Performance, Shuhua Ma, Hanju Guo, Ji Li, Hongze Liang, Xiabin Jing, Fosong Wang

Journal of Electrochemistry

The influences of the trace oxygen containing functional groups on surface of carbon material on cell performance of carbon anode for lithium ion batteries were studied by means of the pretreament in various oxidant/reductant systems. The results showed that the rich oxygen containing functional groups impaired the cell performance of carbon material anode, and the reduction of these groups in quantity and oxidation degree can increase charge/discharge capacity and improve first charge/discharge efficiency. The reason was also discussed in the light of effects of surface organic groups on decomposition reactivity of electrolyte and formation process of surface passivating film.

The Current Distribution On The Anode Surface Of The Seale Oval Tubular Lead Acid Battery, Renao Gu, Jianlin Yao, Zhengfa Deng, Ru Sun, Liren Wu, Zhongsi Jiang, Wangen Miao

Journal of Electrochemistry

The current distribution on anode surface of sealed lead acid batter under different discharge current and degree was studied by chemical analytical method for the first time. We can conclude that the current distribution is not even. The current density on the edge of the electrode surface and the electrode terminal are bigger than other areas, that is, there are edge effect and terminal effect, and these effect are more obvious when the discharge current is 100 A and degree is 100%.

High Active Platinum Plated Titanium Electrode, Xiufeng Xiao, Zeshan Zhu, Yanzhen Chen, Wenyun Hu

Journal of Electrochemistry

To prepare the adherent and high active platinum plated titanium electrode, ultrasonic agitation technology and the best conditions of electrodeposition were adopted. Ultrasonic agitation technology can be improved the cohesion between coatings and substrate. The activity of electrode has related to the double layer capacity of electrode, which was due to the electrode rugosity.