Engineering Commons^™

Quantitative Evaluation Of Electrochemical Properties Of Mh Alloy By Powder Microelectrode, Ronghui Hu, Hanxi Yang, Jingcheng Liu, Shengxian Li, Chuanxin Cha

Journal of Electrochemistry

In this paper, a quantitative method by use of powder microelectrode combined with cyclic voltammetry and galvanostatic step is described for studying the electrochemical performance characteristic of hydrogen storage alloy(MH). Since the powder microelectrode uses only MH powder and has its depth and diameter of several tens of micrometer, the ohmic and concentration ploarization are greatly reduced and the influences of the technical factors in electrode preparation on the material performance are simply eliminated. Thus, with accurate determination of the load quantity of MH alloy in power microelectrode by absorption spectrometric technique, it is feasible to evaluate quickly and quantitatively …

The Preparation Of Heteropoly Compound Polypyrrole Film Modified Electrode And Its Electrochemical Properties, Weiqing Wang, Xiumei Zhang, Long Cheng, Baifeng Liu, Shaojun Dong

Journal of Electrochemistry

Electronically conducting polypyrrole doped with heteropolyanions K₁₀H₃[Nd(SiMo₇W₄)₂]·xH₂O(denoted as [Nd(SiMo₇W₄)₂]^13-) was synthesized by electrochemical polymerization. This modified electrode maintains the electrochemical and electrocatalytic properties of heteropolyanion, with having good stability and electrocatalytic activity on the reduction of nitric oxide in acidic aqueous solution.

Comparison Of The Charge/Discharge Charasteristics Between Ni-Cd And Ni-Mh Battery And Its Improvement Of Manufacture Technique, Yumimg Wang, Jinsheng Chen

Journal of Electrochemistry

Based on the difference of charge discharge charasteristies between Ni-Cd and Ni-MH battery, some appropriate manufacture technoque to improve the battery performances or to extend its service life are adopted.

Wear And Friction Behavior Of Metal Impregnated Microporous Carbon Composites, Gultekin Goller, D. P. Koty, Surendra N. Tewari, M. Singh, A. Tekin

Chemical & Biomedical Engineering Faculty Publications

Metal-matrix composites have been prepared by pressure-infiltration casting of copper-base alloy melts into microporous carbon preforms. The carbon preforms contained varying proportions of amorphous carbon and graphite. Load dependence of the wear and friction behavior of the composite pins has been examined under ambient conditions against cast-iron plates, using a pin-on-plate reciprocating wear tester. The wear resistance of the composite is significantly improved, as compared with the base alloy. Contrary to the normally expected behavior, the addition of graphite to the amorphous carbon does not reduce the friction coefficient, especially at high loads. The wear and friction behavior of the …

Permeability Of Microporous Carbon Preforms, S. K. Datta, N. Simhai, Surendra N. Tewari, Jorge E. Gatica, M. Singh

Chemical & Biomedical Engineering Faculty Publications

The permeability of microporous amorphous carbon preforms with varying pore size and pore distributions has been experimentally examined. The porous structures have been characterized by mercury porosimetry and by quantitative metallography of pressure-infiltration-cast metal matrix composites based on the carbon preforms. The permeability shows a linear correlation with the fraction porosity and the square of the pore diameter.

Optical Detection Properties Of Silicon-Germanium Quantum Well Structures, Michael R. Gregg

Theses and Dissertations

A study has been carried out on Si/SiGe multi quantum well structures to determine their applicability as normal incidence infrared detectors in the spectral range of 2-12 micrometers. The research effort was primarily experimental; however, extensive calculations were performed to initially explain the experimental data and then used to design subsequent structures. Multiple quantum well structures grown on both Si[001] and Si[110] substrates via molecular beam epitaxy were studied by photoluminescence, absorption, and photoresponse measurements over a wide parameter space. Variables included quantum well depth and width, well doping, number of wells and growth temperature. Well widths were varied from …

Monte Carlo Simulations Of Photoemission Characteristics From Gaas And Diamond, Abhishek Srivastava

Electrical & Computer Engineering Theses & Dissertations

Monte Carlo based numerical simulations were performed to study photoemission from GaAs and diamond. The central goal was to assess the potential for NEA photoemission from diamond, and to predict its characteristics. The GaAs material system was also included in the simulation study to provide: (i) calibration and validation of the numerical model developed by carefully matching the simulation results with available experimental data, and (ii) quantitative comparisons between the response characteristics of diamond and the better known GaAs system.

Predictions of the energy distribution, temporal response and angular distribution of emitted electrons were obtained. Effects of various parameters, such …

A Fluid Flow Analysis Of Aluminum 356.0 In The Vacuum Assisted Countergravity Method, John Launstein

Graduate Research Papers

The purpose of this study is to determine the fluid flow pattern obtained through the use of the countergravitaional process. The physical fluid flow model assists design engineers in their casting design of parts utilizing the LS-Vac technology thereby reducing tooling costs and time losses.

An Experimental Study Of An Advanced Polymeric Material For Use In Total Knee Replacements Including Gait Analysis Of Mobile Knee Bearings, Lisa Ann Scott

Mechanical & Aerospace Engineering Theses & Dissertations

The primary objectives of this research were to clinically examine the New Jersey Low Contact Stress (LCS)™ Rotating Platform and Meniscal knee bearing systems and to investigate the tribological properties of a new polymer for potential application in total joint replacement. Thus, clinical studies were performed on subjects having the LCSTM Rotating Platform knee bearing and subjects having the LCS™ meniscal knee bearing. The results indicated that there was a statistically significant difference in the braking force for both implant groups when compared to a control group. There was also a statistically significant difference noted for the LCS™ Rotating Platform …

An Esr Study Of Free Radicals In Electroreduction Process Of Allyl Alcohol, Jindong Zhang, Yafei Kuang, Shukun Huang, Naixian Xie, Fengzhen Wang, Dewen Chen

Journal of Electrochemistry

Electrochemical-ESR technique with spin trap phenyl-t-butyl nitrone(PBN)was used to study the intermediates of electroreduction of allyl alcohol at platinized platinum electrode in acidic alcohol-aqua solution. Hydrogen and allyl group and(or)propyl group radicals were identified by a hyperfine spectrum of the radical adducts, and that provided a direct evidence for the presence of these radicals in the electroreduction of allyl alcohol.

A Study On Solid Polymer Electrolyte Fuel Cell, Hongfeng Xu, Ming Han, Baolian Yi, Xinge Zhang, Shanhai Ge

Journal of Electrochemistry

Solid polymer electrolyte fuel cell (SPEFC) show promise of a high level of performance in the present fuel cell. In this paper, we report the method of SPEFC electrode preparation,and the effects of temperature, pressure and gas flow rate on the performance.

Improvement Of The Anti-Interference Characteristics Of God Electrode By Using The Powder Microelectrode Technique, Chen Jian, Chuansin Cha

Journal of Electrochemistry

The electrochemical behavior of ascorbic acid(AA), uric acid(UA), L-cystein(L-Cys) and acetaminophen (APAP), i.e. The main interference to the GOD electrode, were studied at the Pt,GC and powder microelectrode. Experimental results indicated that, due to the electrochemical activity of these interference, it is difficult to eliminate their interference effects by manipulation of electrode materials or working potential of the GOD electrode. However, it was found that the limiting curtents at the KB electrode are mainly controlled by mass transfer in liquid phase, so it is only related to the geometer size of the electrode, not its real surface area. Therefore, it …

The Effect Of Co On The Proton Diffusion Coefficient For The Ni(Oh)2 Electrodes, Xiaoyan Cao, Zuoxiang Zhou, Huatang Yuan, Yunshi Zhang

Journal of Electrochemistry

The diffusion coefficients of protons moving in the Ni(OH)₂ electrodes have being investigated by constant current, cyclic voltammetry and potential step technineques. The electrodes were prepared by cathodic deposition and their active material contained 0～53% cobalt. It was found that the diffusion coefficients are about 10^-9～10^-10 cm²/s during charging and about 10^-11 cm²/s during discharging. Moreover the value increases with the increacing content of Co in the electrodes. During the calculation, the relevant fomulars were modified especially the wrong fomular for constant current methode.

Electrochemical Study Of The Corrosion Behavior Of Coalesced Copper And Sw-206 Stainless Steel In The Acetic-Acid Solution, Rongzong Hu, Changjian Lin, Jianguang Tan, Zhanmei Sun, Xueqin Wu, Biao Wang

Journal of Electrochemistry

In order to provide a theoretic and experimental consideration for the material selection and anit-corrosion in the petrochemical industries the corrosion behavior of coalesced copper and sw-206 stainless steel in the acetic acid solution was studied by electrochemical impedance spectroscopy and polarization techniques. The effects of the temperature, acetic acid concentration and solubilized oxygen in the acetic acid solution on the corrosion process of this two metals were analyzed. It was found that these effects obviously accelerate corrosion process for the coalesced copper, but no apparent influnce for the sw-206 stainless steel.In the the acetic acid solution, containing water and …

A Study On Electrochemical Oxidation Of Reduced Nicotinamide Coenzyme Nadh In Organic Media, Fangzu Yang, Huihuang Wu, Shukai Xu, Shaomin Zhou

Journal of Electrochemistry

The behaviour of electrochemical oxidation of the reduced nicotinamide coenzyme NADH on glassy carbon was studied and some kinetic parameters were measured by means of voltammometry in the N-dimethylformamide (DMF) and 1,4-dioxane media respectively. The eletrochemical oxidation of NADH shows completely irriversable both in the two solvents,and the diagnostic experiments support that the process involves a fast chemical step.The oxidation rate and the diffusion coefficient of NADH in DMP are smaller than those in 1,4-dioxane, but the response current is more stable in DMF. The experimental results are discussed by solvent effects.

A Preliminary Study Of Electrochemically Amplified Measurement Of Gold Electrodeposition, Bingwei Mao, Caihui Shi, Xiaoqin Li, Lihua Xiong

Journal of Electrochemistry

Gold electrodeposition onto a glassy carbon microelectrode is studied using an electrochemical amplification method. Taking the advantage that the electrochemical reduction of K₂Cr₂O₇ has significantly higher reaction activity on gold electrode than carbon electrode, it is tentatively used to amplify the gold electrodeposition current. The results show that there is a marked increase in current of gold electrodeposition in presence of K₂Cr₂O₇ in comparison with that absent of K₂Cr₂O₇.The electrochemical amplification method can be applied to study the electrodeposition of very in intial stage …

Studies On The Charge And Discharge Reaction Of Li/Lini0.3Co0.7O2 Battery, Fupjng Zhang

Journal of Electrochemistry

The charge and discharge reaction of Li/LiNi_0.3Co_0.7O₂ battery have been studied by using CV,CT,XRD and GCP. It is shown that the discharge capacity of the cell reaches 120-140 mA·h·g^-1 in the 4.30-3.00 V in 1 mol/L LiClO₄/PC electrolyte system. The discharge mechanism involve a two-step Li⁺ intercalation reaction. The thermodynamic data such as ΔG,ΔS, ΔH, of the reaction are given. Furthermore, the changes of the D or σ_i of Li⁺ with its composition have been discussed.

Surface Raman Spectra Obtained From Various Electrodeposited Transidon Metals, Jingsong Gao, Bin Ren, Qunjian Huang, Zhongqun Tian

Journal of Electrochemistry

Good quality potential-dependent surface Raman spectra of pyridine were obtained for the first time from a series of transition metals, e. g., Fe, Co, Ni, Ru, Rh, Pd and Pt, which were electrodeposited on non-SERS-active substrates. The influences of the applied potential and the nature of metal on the adsorption behaviors were discussed briefly. This result illustrates that Raman spectroscopy is becoming a more general and powerful tool to study various electrochemical interfaces.

Electrodeposition Of Cu-Co Multilayer Thin Films, Jiangyun Xue, Jixun Wu, Dejun Yang

Journal of Electrochemistry

A method has been developed to produce Cu-Co Multilayer from a single electrolyte by electrodeposition. The effects of the concentration of copper ions, current density and the speed of rotation were investigated, and the Cu-Co electrodeposition films were analysed by TEM, AES and X-ray diffraction. The results indicated that the film was alternating pure copper and coppercobalt alloy layers. If the content of copper in cobalt layer is to be small, the concentration of its ions in solution must be small and the rotation speed must be low.

Study On The Ionic Conductivity Of Comb Polymer Electrolytes, Liming Ding

Journal of Electrochemistry

A comb polymer (CP350) with oligo-oxyethylene side chains was prepared from methyl vinyl ether/maleic anhydride copolymer.The ionic conductivity of CP350/LiAsF₆ and CP350/LiAsF₆ complexes was studied as a function of temperature and [Li]/[EO] ratios. A equivalent circuit was given to interpret complex impedance spectra. At 25 ℃, the ionic conductivity maxima of the two systems are 1.38×10^-4, 8.32×10^-5 S/cm respectively. The appearance of the conductivity maxima has been interpreted as being due to the effect of microviscosity on ion transport. lonic conduction displays non-Arrhenius behaviour. The temperature dependence of ionic conductivity was attributed mainly to the …

Electrochemical Studies On Chemical Polishing Of Copper, Keping Han, Jingli Fang

Journal of Electrochemistry

Changes in specular reflectivity,weight loss,surface topograph and potential with time and current-potential curves during chemical polishing were determined. The results showed that chemical polishing was composed of the etching, polishing and pitting stage. The passivating film theory also applied to the chemical polishing.

Study On The Growth Process Of Lead Dioxide On Lead-Antimony Electrodes By Impedance Tracing Method, Guolin Wei, Hongxin Yang, Jiarong Wang

Journal of Electrochemistry

The growth process of PbO₂ formed by the oxidation of PbSO₄ in the anodic film on lead-(1,3,5,7)wt% antimony electrodes was investigated with impedance tracing method of single frequency and the current-time transient method. The influence of antimony on this process was studied.The simulation curves obtained for capacity-time transients fit the experimental results very well. It has been shown that the mentioned growth process is a two-dimentional instantaneous nucleation and growth process. Antimony will inhibit the growth of PbO₂ nucleus but enhance its nucleation.

The Relationship Between Ionic Conductivity And The Structure Of The New Polymer Electrolytes, Hongze Liang, Yongxiang Song, Liming Ding, Yuchen Qi, Lixia Li, Xiabin Jing, Fusong Wang

Journal of Electrochemistry

Ionic conductivity of polymer-eutectic composed of lithium perchlorate and lithium nitrate has been studied. The effects of eutectic and polymers upon the conductivities have been discussed.The lonic conductivity depends on the eutectic properties as well as the treatment method of samples.

Recent Developments In Extrusion Freeform Fabrication (Eff) Utilizing Non-Aqueous Gel Casting Formulations, Greg Hilmas, John L. Lombardi, Robert A. Hoffman, Kevin Stuffle

Materials Science and Engineering Faculty Research & Creative Works

Extrusion Freeform Fabrication (EFF) was shown to be an extremely versatile method for fabricating Functionally Graded Materials (FGMs) The approach is inexpensive and potentially feasible for grading between any thermodynamically compatible ceramic-metal, ceramic-ceramic, or metal-metal material combination. Several material systems were investigated in this study including alumina-304 stainless steel, zirconia-304 stainless steel, alumina-Inconel 625, zirconiaInconel625, alumina-nickel aluminide, zirconia-nickel aluminide, titanium carbide-InconeI625, titanium diboride-nickel aluminide, and tungsten carbide-nickel aluminide. A controlled gradient was demonstrated between the end members for all of the above compositions. The FGMs were hot pressed to achieve near theoretical densities, providing flexural strengths as high as 1000 …

Theoretical And Empirical Investigation Into Polymer Blend Morphology In Fiber Spinning, Ajay D. Padsalgikar

All Dissertations

A promising way of developing new fiber forming materials is by utilization of polymer blends. The morphology of polymer blends has a significant effect on the properties of the resultant fiber. Morphological studies have shown that immiscible additives remain dispersed in the matrix as suspended droplets and that the droplets are elongated into fibrils under the action of shear or extensional forces during processing. The deformability of the dispersed phase is a controlling factor in deciding the resultant morphology and thereby the fiber properties. We report the results of a study of droplet deformation in uniaxial elongational flow under non …

38th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 38th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 21-26, 1996.

Incommensurate One-Dimensional Fluctuations In Yba2⁢Cu3⁢O6.93, Herbert A. Mook, Pengcheng Dai, Kamel Salama, Dominic Lee, Fatih Dogan, Gabriel Aeppli, Andrew T. Boothroyd, Mark E. Mostoller

Materials Science and Engineering Faculty Research & Creative Works

A novel neutron scattering technique has been utilized to discover one-dimensional fluctuations with a very sharply defined modulation period of 16.65⁢Å along the b⁡(a) direction in YBa₂⁢Cu_3⁢O_6.93. The fluctuations are found to be absent in the reduced oxygen compound YBa_2⁢Cu_3⁢O_6.15. The wave vector of the fluctuations is consistent with accepted values of 2⁢k_F for the Cu-O chains.

Low-Velocity Impact On Composite Sandwich Plates, Eric J. Herup

Theses and Dissertations

The objective of the research is to analytically model the response of composite sandwich plates to low velocity impact. A displacement based, plane stress, finite element code is modified for this purpose. Major new algorithms include 5th order Hermitian interpolation, three dimensional equilibrium integration for transverse stress calculations, sandwich core modeling as an elastic plastic foundation, loading by simulated contact with a spherical indentor, adaptive mesh, damage prediction, damage progression via stiffness reduction, and local-global analysis for displacement. An experimental effort is also included in which composite sandwich plates with graphite epoxy facesheets and Nomex honeycomb core are subjected to …

Incommensurate One-Dimensional Fluctuations In Yba2cu3o6.93, Herbert A. Mook, Pengcheng Dai, K. Salama, D. Lee, Fatih Dogan, G. Aeppli, A. T. Boothroyd, M. E. Mostoller

Materials Science and Engineering Faculty Research & Creative Works

A novel neutron scattering technique has been utilized to discover one-dimensional fluctuations with a very sharply defined modulation period of 16.65 Å along the ba direction in YBa₂Cu₃O_6.93. The fluctuations are found to be absent in the reduced oxygen compound YBa₂Cu₃O_6.15. The wave vector of the fluctuations is consistent with accepted values of 2kF for the Cu-O chains.

Elastic-Plastic Fracture Mechanics For Two-Dimensional Stable Crack Growth And Instability As Applied To Pvc Pipe Material, Ayman Aly Badawy

Archived Theses and Dissertations

No abstract provided.