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Materials Science and Engineering

1996

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Articles 1 - 30 of 95

Full-Text Articles in Engineering

Binary Ferrihydrite Catalysts, Gerald P. Huffman, Jianmin Zhao, Zhen Fang Dec 1996

Binary Ferrihydrite Catalysts, Gerald P. Huffman, Jianmin Zhao, Zhen Fang

Chemical and Materials Engineering Faculty Patents

A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The …


Elastic-Plastic Behavior And Limit Load Analysis Of Pipe Elbows Under In-Plane Bending And Internal Pressure, Mohab Ahmed Shalaby Dec 1996

Elastic-Plastic Behavior And Limit Load Analysis Of Pipe Elbows Under In-Plane Bending And Internal Pressure, Mohab Ahmed Shalaby

Archived Theses and Dissertations

No abstract provided.


Magnetic Dynamics In Underdoped Yba₂Cu₃O₇₋ₓ: Direct Observation Of A Superconducting Gap, Pengcheng Dai, Mohana Yethiraj, Herbert A. Mook, Terrence B. Lindemer, Fatih Dogan Dec 1996

Magnetic Dynamics In Underdoped Yba₂Cu₃O₇₋ₓ: Direct Observation Of A Superconducting Gap, Pengcheng Dai, Mohana Yethiraj, Herbert A. Mook, Terrence B. Lindemer, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Polarized and unpolarized triple-axis neutron measurements were performed on an underdoped crystal of YBa2Cu3O7-x (x = 0.4 ± 0.02, Tc = 62.7 K). Our results indicate, contrary to earlier evidence, that the spin excitations in the superconducting state are essentially the same as those in the fully doped material except that the unusual 41 meV resonance is observed at 34.8 meV. The normal state spin excitations are characterized by a weakly energy-dependent continuum whose temperature dependence shows the clear signature of a superconducting gap at Tc. The enhancement at the resonance is …


A Stochastic Model For Crystal-Amorphous Transition In Low Temperature Molecular Beam Epitaxial Si(111), R. Venkatasubramanian, Suresh Gorantla, S. Muthuvenkatraman, Donald L. Dorsey Dec 1996

A Stochastic Model For Crystal-Amorphous Transition In Low Temperature Molecular Beam Epitaxial Si(111), R. Venkatasubramanian, Suresh Gorantla, S. Muthuvenkatraman, Donald L. Dorsey

Electrical & Computer Engineering Faculty Research

Molecular beam epitaxial Si (111) grown below a certain temperature result in amorphous structure due to the limited surface mobility of atoms in finding correct epitaxial sites. In spite of many experimental and theoretical studies, the mechanism of crystal‐amorphous transition and its dynamics related to the growth conditions are not well understood. In this article, we present a theoretical model based on the formation of stacking fault like defects as a precursor to the amorphous transition of the layer. The model is simulated based on a stochastic model approach and the results are compared to that of experiments for temperatures …


Residual Strength And Fatigue Characterization Of Scs-6/Ti-6-4, Sang-Myung Lee Dec 1996

Residual Strength And Fatigue Characterization Of Scs-6/Ti-6-4, Sang-Myung Lee

Theses and Dissertations

Metal matrix composite have potential in a variety of aerospace applications, but they should be better understood before they can be employed. Despite the many studies that have contributed to characterizing the fatigue response of titanium alloy MMCs, few have researched the residual strength. The purpose of this study was to investigate the residual strength and the frequency effects on the residual strength of an unidirectional laminate of SCS-6/Ti-6-4, a titanium alloy matrix based composite under tension-tension, load-controlled conditions at elevated temperatures and different frequencies. Specimens were fatigued at frequencies of 1 and 0.01Hz, and at maximum stress of 900MPa …


Quantitative Evaluation Of Electrochemical Properties Of Mh Alloy By Powder Microelectrode, Ronghui Hu, Hanxi Yang, Jingcheng Liu, Shengxian Li, Chuanxin Cha Nov 1996

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 …


Comparison Of The Charge/Discharge Charasteristics Between Ni Cd And Ni Mh Battery And Its Improvement Of Manufacture Technique, Yumimg Wang Nov 1996

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

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


High Active Platinum Plated Titanium Electrode, Xiufeng Xiao, Zeshan Zhu Nov 1996

High Active Platinum Plated Titanium Electrode, Xiufeng Xiao, Zeshan Zhu

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.


Studies Of Electrochemical Behaviors Of Cytochrome C On Pretreated Gold Electrodereceived 16 May, 1996, Jin Luo, Lingling Wu, Shaohua Huang, Zhonghua Lin Nov 1996

Studies Of Electrochemical Behaviors Of Cytochrome C On Pretreated Gold Electrodereceived 16 May, 1996, 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.


Electrochemical Studies Of Cyanocobalamin On Silver Electrode, Zhai Jin, Yang Pin Nov 1996

Electrochemical Studies Of Cyanocobalamin On Silver Electrode, Zhai Jin, Yang Pin

Journal of Electrochemistry

The electrochemical characteristics of cyanocobalamin were separately studied on smooth and roughed silver electrode. It was found that the reduction of cyanocobalamin is two one electron steps on roughed silver but one two electron step on smooth electrode. The reason is due to the ability of absorption of the surface of electrode.


The Preparation Of Heteropoly Compound Polypyrrole Film Modified Electrode And Its Electrochemical Properties, Weiqing Wang, Xiumei Zhang, Long Cheng Nov 1996

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

Journal of Electrochemistry

Electronically conducting polypyrrole doped with heteropolyanions K 10 H 3[Nd(SiMo 7W 4) 2]·xH 2O(denoted as [Nd(SiMo 7W 4) 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.


Progresses In The Studies On Electrochemical And Surface Properties Of Hydrogen Storage Alloy Materials, Yong Yang, Jum Li, Zugeng Lin Nov 1996

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.


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 Nov 1996

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 Nov 1996

The Current Distribution On The Anode Surface Of The Seale Oval Tubular Lead Acid Battery, Renao Gu, Jianlin Yao, Zhengfa Deng, Ru Sun

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%.


Emisja Związków Siarki Z Procesu Wielkopiecowego, Marian Mazur, Marek Bogacki, Robert Oleniacz Nov 1996

Emisja Związków Siarki Z Procesu Wielkopiecowego, Marian Mazur, Marek Bogacki, Robert Oleniacz

Robert Oleniacz

The paper describes the problem of the presence of sulfur in the blast furnace process and identifies emission sources of sulfur compounds in this process. On the basis of the measurements and calculations, the types and quantities of these compounds emitted to the air were determined. It was found that pig iron smelting in a blast furnace causes emissions of COS, SO2 and H2S. These emissions occur by losses of blast furnace gas (COS and SO2), transport of blast furnace slag inside the furnace hall (SO2) and treatment of the slag by granulation (H2S). However, the most important are only …


Wpływ Komponentów Alkalicznych W Procesach Spiekania I Wielkopiecowym Na Technologię I Emisję Zanieczyszczeń, Marian Mazur, Ryszard Benesch, Andrzej Łędzki, Robert Oleniacz Nov 1996

Wpływ Komponentów Alkalicznych W Procesach Spiekania I Wielkopiecowym Na Technologię I Emisję Zanieczyszczeń, Marian Mazur, Ryszard Benesch, Andrzej Łędzki, Robert Oleniacz

Robert Oleniacz

The paper presents the impact of alkali metals on sintering and blast furnace processes and air pollutant emissions including particulate matter. On the basis of the balance calculations, it was found that the main source of alkali (Na2O and K2O) in the sintering process is a raw mixture unweathered. The calculations showed that the level of dust emissions from the sinter strand to a large extent depends on: the total alkali content in a mixture of sinter, ash content in coke breeze, K2O concentration in coke ash and alkalinity of the produced sinter. Alkali metals are introduced into the blast …


Wear And Friction Behavior Of Metal Impregnated Microporous Carbon Composites, Gultekin Goller, D. P. Koty, Surendra N. Tewari, M. Singh, A. Tekin Nov 1996

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 Nov 1996

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 Oct 1996

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 …


Improvement Of The Anti-Interference Characteristics Of God Electrode By Using The Powder Microelectrode Technique, Chen Jian, Chuansin Cha Aug 1996

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 electrede 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 rcal surface area. Therefore,it is possible to enhance significantly the signal/noise ratio of the GOD electrode by …


Electrodeposition Of Cu-Co Multilayer Thin Films, Jiangyun Xue, Jixun Wu, Dejun Yang Aug 1996

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 electredeposition. 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.


A Study On Electrochemical Oxidation Of Reduced Nicotinamide Coenzyme Nadh In Organic Media, Fangzu Yang, Wuhuihuang Wuhuihuang, Xushukai Xushukai, Zhoushsomin Zhoushsomin Aug 1996

A Study On Electrochemical Oxidation Of Reduced Nicotinamide Coenzyme Nadh In Organic Media, Fangzu Yang, Wuhuihuang Wuhuihuang, Xushukai Xushukai, Zhoushsomin Zhoushsomin

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 N ADH 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.


Studies On The Charge And Discharge Reaction Of Li/Lini_(0.3)Co_(0.7)O_2 Battery, Fupjng Zhang Aug 1996

Studies On The Charge And Discharge Reaction Of Li/Lini_(0.3)Co_(0.7)O_2 Battery, Fupjng Zhang

Journal of Electrochemistry

The charge and discharge reaction of Li/LiNi0.3Co0.7O2 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 △G,△S,△H,of the reaction are given. Furthermore,the changes of the Dor σi of Li+ with its composition have been discussed.


Study On The Growth Process Of Lead Dioxide On Lead-Antimony Electrodes By Impedance Tracing Method, Guolin Wei, Hongxin Yang, Jiarong Wang Aug 1996

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.


Surface Raman Spectra Obtained From Various Electrodeposited Transidon Metals, Jingsong Gao, Bin Ren, Qunjian Huang, Zhongqun Tian Aug 1996

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.


Study On The Ionic Conductivity Of Comb Polymer Electrolytes, Liming Ding Aug 1996

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/LiPF6 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 temperature dependence of charge carrier hopping,ion pairing and micro Brown motion of side chains.The larger …


An Esr Study Of Free Radicals In Electroreduction Process Of Allyl Alcohol, Jindong Zhang, Yafei Kuang, Shukun Huang, Naixian Xie Aug 1996

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

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.


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 Aug 1996

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

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 oxygen were beneficial …


A Study On Solid Polymer Electrolyte Fuel Cell, Hongfeng Xu, Ming Han, Baolian Yi, Xinge Zhang, Shanhai Ge Aug 1996

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.


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 Aug 1996

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.