Engineering Commons^™

Electrooxidation Of Benzene To Benzoquinone In A Packed Bed Reactor, Xin-Sheng Zhang, Ping Ding, Ying-Chun Dai, Wei-Kang Yuan

Journal of Electrochemistry

A packed electrode reactor was used to oxidize to benzoquinone. Anode bed of the reactor has a size of 10～30 mm×450 mm×50 mm(thickness×length×width),and was packed porous lead alloy. A dispersion of benzene in 1 mol/L aqueous sulfuric acid was passed through the reactor. Current efficiency for benzoquinone generation is 62.9% at optimal operating condition: velocity of electrolyte flow, 0.19 ms ^-1 ;current, 10 A; thickness of anode bed, 10 mm, and percentage of benzene, 24%.

Study Of Proton Exchange Membrane Fuel Cells(Pemfc), Shan-Hai Ge, Bao-Lian Yi, Hong-Fen Xu, Ming Han, Zhi-Gang Shao

Journal of Electrochemistry

The electrode kinetic parameters for proton exchange membrane fuel cells(PEMFC) were investigated by measuring the relations of cell potential and current density. An experimental stack of PEMFC which can be operated at E cell =0.7V, I =0.55A/cm² steadily is presented, and the effects of electrode structure and operation conditions such as temperature, pressure, humidification, flow rate on the performance of PEMFC are discussed.

Defects And Site Occupancies In Nb-Cr-Ti C15 Laves Phase Alloys, P. G. Kotula, C. B. Carter, Katherine C. Chen, Dan J. Thoma, F. Chu, T. E. Mitchell

Materials Engineering

No abstract provided.

40th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 40th 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 25 - August 1, 1998.

The Solution Of Hypersingular Integral Equations With Applications In Acoustics And Fracture Mechanics, Richard S. St. John

Mathematics & Statistics Theses & Dissertations

The numerical solution of two classes of hypersingular integral equations is addressed. Both classes are integral equations of the first kind, and are hypersingular due to a kernel containing a Hadamard singularity. The convergence of a Galerkin method and a collocation method is discussed and computationally efficient algorithms are developed for each class of hypersingular integral equation.

Interest in these classes of hypersingular integral equations is due to their occurrence in many physical applications. In particular, investigations into the scattering of acoustic waves by moving objects and the study of dynamic Griffith crack problems has necessitated a computationally efficient technique …

Promoting Excellence In Education With An Outstanding Student Instructor Award Program, Jennifer Kadlowec, Justin Shriver, Trevor S. Harding, Charles Choi

Materials Engineering

The ASEE Student Chapter at the University of Michigan in conjunction with the College of Engineering has developed and organized an annual Outstanding Student Instructor Award in recognition of excellence in engineering education. The award not only acknowledges the outstanding contributions of the individuals selected for the award, but also coincides with the ASEE’s goals of promoting excellence in engineering education and attracting new members. The paper outlines the planning procedures developed since the inception of the award in 1994 and provides suggestions and insights for other ASEE Student Chapters to create and organize such an award.

Mixed Electron Emission From Doped Pb(Zr,Ti)O₃ Ceramics: Microstructural Aspects, Weiming Zhang, Wayne Huebner

Materials Science and Engineering Faculty Research & Creative Works

A mixed type electron emission, i.e., simultaneous ferroelectric and plasma emission, was observed with a negative driving pulse applied to doped Pb(Zr,Ti)O₃ ceramics in the absence of any external potential on the electron collector. During these emission studies, significant microstructural changes on the emission surface were observed, and corresponded to the different emission modes. Erosion craters at the edge of the electrode and small particles near these craters reflected the formation of a dense plasma there. Comparatively, cavities, i.e., grain pullouts, accumulated on the bare ferroelectric surface, the frequency of which depended upon its distance from the grid. This …

Effect Of Temperature And Strain Rate On The Mechanical Behavior Of Al/Sic Particulates Metal Matrix Composites, Mohamed Mahmoud Zaki Emara

Archived Theses and Dissertations

No abstract provided.

An Expert System Approach For Process Planning Of Rotational Components, Sherif Salah Raslan

Archived Theses and Dissertations

No abstract provided.

Mixed Electron Emission From Lead Zirconate-Titanate Ceramics, Weiming Zhang, Wayne Huebner, Stephen E. Sampayan, Mike L. Krogh

Materials Science and Engineering Faculty Research & Creative Works

Simultaneous ferroelectric and plasma emission from Pb(Zr,Ti)O₃ was observed with only a negative driving pulse applied to the sample, and without an extraction potential on the electron collector. Plasma emission was a strong, inconsistent, and self-destructive process. In addition, a positive ion current was detected. Comparatively, ferroelectric emission was a relatively stable self-emission process, exhibiting no apparent delay time, and no positive ion current. The relationship between the switching and emission current of ferroelectric samples measured simultaneously cannot only be used to determine the existence of ferroelectric emission, but can also give direction to choosing suitable ferroelectric materials for …

Plasma Enhanced Chemical Vapor Deposition Of Diamondlike Carbon Films Using Acetylene, Sriram Vishwanathan

Theses

This study is focussed on the synthesis and characterization of diamondlike carbon (DLQ films deposited on silicon wafers and glass by plasma enhanced chemical vapor deposition (PECVD), using acetylene (C₂H₄) as a precursor. The process parameters, such as temperature, pressure, power and reactant gas flow rate have been systematically varied and their effects on the film growth rate and properties were investigated. The optimized deposition condition appeared to be at 150°C, 200mTorr, 200 Watts and flow rate = 25 sccm. For these conditions, the films were hard and found to have good adhesion to the substrate, …

In-Situ Raman Spectroscopic Study Of The Oxidation And Reduction Of Ag Electrode In Na2So4, Yan-Xia Chen, Kai-Qi Huang, Zhong-Qun Tian

Journal of Electrochemistry

In-situ Raman spectroscopy combined with cyclic voltammogram measurements was used to investigate formation of oxygen species at Ag electrode surfaces during the oxidation and reduction process in 0.1 mol/L Na₂SO₄ solution. The time dependent Raman spectra show that at potentials positive of 0.2 V, adsorption of oxygen atom occurs, while at the potentials positive of 0.4 V, some oxygen atoms migrate into subsurface of the Ag electrode and the other form strongly bound oxygen on the surface through chemical bond. At the same potentials, part of the silver atoms are oxidized and form Ag₂SO_{4 …}

An Investigation On Galvanic Corrosion Behavior Of Co-Cr-Mo Alloy And Ti-6al-4v Alloy, Zhi-Jun Bai, Yin-Shun Wu, Tian-Cheng Zhang

Journal of Electrochemistry

The combination of Co-Cr-Mo alloy and Ti-6Al-4V alloy is widely used as total hip prostheses. The objective of this work is to quantify the possibility of the acceleration of corrosion due to the galvanic effect. Electrochemical tests based on mixed potential and protection potential theories were used to study the galvanic corrosion behavior of coupling these alloys. The results indicated that the galvanic potential between two alloys always was in the passive potential zone of the isolated alloy respectively, and that the galvanic current of the couple is same as the corrosion current of isolated alloy under passive state. The …

Investigation Of Pb/Pb2+ And Polypyrrole Electrodes By Use Of Ac Electrochemical-Thermal Method, Ji-Hua Zhuang, Jie Zhang, Liang-Jun Dong, Hong Xie, Zhi-Yu Jiang

Journal of Electrochemistry

The values of entropy change for Br^-/Br₂ and Pb/Pb²⁺ electrode reactions were measured by use of the ac electrochemical-thermal method. The influence of alkaline pretreatment on the electrochemical behavior for a polypyrrole electrode was also investigated by this method. It was found that after alkaline pretreatment the eletrochemical activity of polypyrrole electrode was decreased obviously, but it kept partly electrochemical-thermal characteristic as same as that before pretreatment.

Studies On Impedance Of Acid-Copper Electroplating System, Wen Deng, Zhao Liu, Xiang-Min Lin, He-Tong Guo

Journal of Electrochemistry

The impedance characteristics of elementary solution (0.3 mol/L CuSO₄+1.94 mol/L H₂SO₄) and that with the addition of 60 mg/L Cl^-, 300 mg/L OP-21, 30 mg/L PEG, 10 mg/L 2thiazolinyldithiopropane sulfate (self-synthesized additive) are investigated and interpreted in terms of equivalent circuit. The results indicated: (1) Cl^- ion can increase cathodic polarization. (2) A twostep reaction mechanism corresponds to Cu^₂₊ reduction, that is: Cu^₂₊→Cu⁺, Cu⁺→Cu(adsorption)→Cu(lattice), Cu^₂₊ react in different forms of complex ion in sulfuric acidcupric sulfate solution with or without Cl^- ion. …

Electrochemical Preparation Of Rare Earth Functional Materials And Application Of Rare Earth To Electrochemistry, Qi-Qin Yang, Tong-Xiang Ye

Journal of Electrochemistry

The new progress and related mechanism of the electrochemical preparation of rare earth materials (magnets, magnetooptic materials, battery materials, luminescent devices, semiconductors, superconductors) and the application of rare earth to the electrochemical areas (e.g. electroplating, corrosion, electrosynthses) have introduced.

A Novel Pt(Ir) Plated Stainless Steel Electrode, Jing-Ying Shi, Xiu-Feng Xiao, Ze-Shan Zhu, Xi Zheng, Yan-Zhen Chen, Wen-Yun Hu

Journal of Electrochemistry

A novel Pt(Ir) plated stainless steel electrode have been developed, to be applied underpotential deposition and anchor effect. The electrode is provided with the excellent electrochemical characteristic, lt is possible to use the matter as micro-sensor.

Studies On The Transport Properties Of Zn2+ In The Zn/V2O5 Secondary Battery With Aqueous Medium, Jia-Hong Zhou, Kuan-Hong Xue, Gu-Ping Pan

Journal of Electrochemistry

The transport properties and the reaction mechanism of Zn²⁺ in the cathode material of Zn/V₂O₅ secondary battery with aqueous medium were studied by use of intermittent titration experiments and X-Ray diffraction analysis. The relations of some kinetic parameters to the discharge depth were discussed. The results of the experiments show that the cathodic discharge reaction is an intercalation process.

Electrode Process Of Lithium Ions On Aluminum Electrode In Molten Licl-Kcl, Shu-Zhen Duan, Cong-Sheng Guan, Qing-Rong Shi, Xin-Dong Wang

Journal of Electrochemistry

The Deposition mechanism of Lithium on aluminium electrode was studied by using linear sweep voltammetry and potential step method. The formation of α-solid solution was controlled by the diffusion of lithium within the aluminium substance. The formation of β-LiAl alloy was limited by the rate of forming the alloy at the legining, and by diffiusion of lithium through the β- LiAl alloy layer was limited by the rate of forming the alloy at the begining, and by the diffusion of lithium through the β-LiAl alloy later. Neucleation polarization for the formation of β-LiAl alloy was observed. This polarization is an …

Molecular Inclusion Of Cyclodextrin Polymer And Its Application To Enzyme Electrodes, Hui-Huang Wu, Bao-Zhang Wu

Journal of Electrochemistry

The inclusion complexation of α-cyclodextin prepolymer host with benzoquinone guest was studied by voltametry. The spectroscopic measurements show that the polycondensation of CD with glutaric dialdehyde forms the polymer (PCD) with pending carbonyl, the latter brings about covalent immobilisation of glucose oxidase (GOD) to polymer chains. Owing to the inclusion complexation of CD, the benzoquinone(BQ) as mediator of GOD can be collected in the enzyme-containing PCD membrane, resulting in high concentration of BQ in the membrane while decreasing its amount in solution. TTF was tested to prepare the immobilised enzyme together with mediator in PCD. The enzyme loading in PCD …

Application Of Electrochemical Process To Recycling Waste Water From Flotation Of Phosphate Ores, Shi-Xin Yu, Wen Sun

Journal of Electrochemistry

The waste water from flotation of phosphate ores can be used to recycling by electrochemical process. The suitable factors of electrochemical process is made by measuring ζ potential and transmittance of the waste water in modified way.

Studies Of Surface Alloy As High Efficient Electrocatalyst For Glyoxylic Acid Synthesis, Sheng-Pei Chen, Sheng-Qing Xia, Shi-Gang Sun

Journal of Electrochemistry

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Influences Of Ptfe On Electrochemical Properties Of Foam-Type Ni(Oh)2 Electrodes, Zhen Zhou, Jie Yan, Xian-You Wang, Jin Lin, Hua-Tang Yuan, De-Ying Song, Yun-Shi Zhang

Journal of Electrochemistry

Research work was performed for the influences of PTFE on the electrochemical properties of foam-type Ni(OH)₂ electrodes by constant current discharge. CV and EIS method. Experimental results exhibit that the existence of PTFE would decrease the reversibility of electrode reaction and increase the reaction resistance of the electrode; thus lower the discharge potential and capacity, so PTFE should be added as little as possible during the preparation of paste-type electrodes.

Study Of The Mechanisms Of The Electrochemical Reactions Of The Soluble Polyimides, Ying Zhu, Wei Xing, Hui Zhao, Gui-Zheng Shi, Yue-Sheng Li, Meng-Xian Ding, Hui Yang, Tian-Hong Lu

Journal of Electrochemistry

For the first time, the electrochemical behaviors of the three soluble polyimides were studied in the organic and aqueous solutions. It was found that the electrochemical behaviors of PI in the organic solutions are significantly different from that in the aqueous solution. Using the IR spectroscopy and semi-empirical molecular orbital calculation and combining the results of the electrochemical measurements, the mechanisms of the electrochemical reactions of polyimides were demonstrated.

Study On The Substitution Of Chromium Alloy Electroplating From Trivalent Plating Bath For The Hard Chromium Plating, Hui-Dong Li, Min Li, Hui-Qi Li

Journal of Electrochemistry

Recently, a vast amount of exploring experiments have been made to solve many deadly defect of existing trivalent chromium plating processes and promote to finally substitute the trivalent chromium for the hexvalent chromium plating. Technical scheme which we substitute the amorphous chromium alloy deposition for the pure chromium is determined step by step and process of amorphous Cr-Fe-C alloy plating from trivalent chromium plating bath has been developped successfully. The deposition maintains standard of traditional hexvalent chromium deposition in properties of wear-resistance and corrosive wear resistance. Moreover, it completely eliminates serious enviromental pollution and has certain advantages of technological property …

Influence Of Buffers On The Blectrodeposition Of Nickel From A Watts Bath, Can-Zh Gao, Yu-Li Lu, Ru-Tao Liu, Fang Chen, Shu-Ben Li

Journal of Electrochemistry

The electrochemical reactions occurring during the deposition of nickel from Watts bath have been examined using the voltammetric technique. The important reactions taking place at the anode and cathode have been identified. The influence of buffers HAc, H₃BO₃ and NH₄Cl on the rate of nickel deposition was marked in the lower concentration (0.01-0.05 mol/L) of buffers. The reason why buffers make the rate of nickel deposition increase were discussed.

Iron Phosphate Compositions For Containment Of Hazardous Metal Waste, D. E. Day

Materials Science and Engineering Faculty Research & Creative Works

An improved iron phosphate waste form for the vitrification, containment and long-term disposition of hazardous metal waste such as radioactive nuclear waste is provided. The waste form comprises a rigid iron phosphate matrix resulting from the cooling of a melt formed by heating a batch mixture comprising the metal waste and a matrix-forming component. The waste form comprises from about 30 to about 70 weight percent P205 and from about 25 to about 50 weight percent iron oxide and has metals present in the metal waste chemically dissolved therein. The concentration of iron oxide in the waste form along with …

The Effects Of Beryllium Additions On The Oxidation Of Nickel Aluminide And Titanium Aluminide Based Intermetallics, R. H. Hanrahan Jr., Katherine C. Chen, M. P. Brady

Materials Engineering

The effects of Be additions on the oxidation behavior of β-NiAl in moist air at 1000°C and borderline alumina-forming y (TiAI) + Laves Ti-Al-Cr based alloys at 800°C and 1000°C in dry and moist air were investigated. The addition of Be to β-NiAl suppressed the formation of transient alumina, and resulted in the formation of a protective BeAl₂O₄ spinel phase. In dry air, the addition of Be to the Ti-AI-Cr alloys also resulted in the formation of a protective BeAl₂O₄ spinel phase. In moist air, only Ti-AlCr- Be alloys with a high Cr content …

Strength Degradation Of Sapphire Fibers During Pressure Casting Of A Sapphire-Reinforced Ni-Base Superalloy, R. Asthana, Surendra N. Tewari, S. L. Draper

Chemical & Biomedical Engineering Faculty Publications

Transient-liquid-phase (TLP) bonding was used to fabricate a Haynes 230 Ni-base superalloy/sapphire fiber composite for high-temperature applications. Boron was used as a melting-point depressant for the Ni, to aid superalloy infiltration of the fibers. Preliminary study of the composite indicated an incomplete TLP bonding cycle. Therefore, microstructural and microchemical analyses were carried out to determine the TLP bonding mechanism. It was found that the TLP process did not occur under local thermodynamic equilibrium conditions at the solid/liquid interfaces, contrary to the primary assumption of conventional models, so a modified model for TLP bonding is proposed. The main differences between the …

Characteristics And Performance Of R413a As An Alternative Refrigerant To R12, Waleed Mahmoud El-Nahas

Archived Theses and Dissertations

No abstract provided.