Materials Science and Engineering Commons^™

Ion Assisted Magnetron Sputtering Of Tantalum Thin Film Deposition And Characterization, Hua Ren

Dissertations

The purpose of this research was to investigate the effects of ion bombardment on the crystallographic phases of tantalum films during their deposition by magnetron sputtering process, and to gain understanding of the mechanism of the ion-solid interactions during the thin film growth. Tantalum (Ta) exists in two distinct crystallographic phases: a stable α-phase with a body centered cubic (bcc) lattice structure and a metastable β-phase with a tetragonal lattice structure. The tough and ductile α-phase Ta is desired in most industrial applications, such as diffusion barrier layers in integrated circuits, metallic corrosion protective layers, and in biomedical devices. The …

Oxygen Enrichment Effect Of Mno2-Pt/C Compound Catalyst To The Cathode Of Pemfc, Hong-Feng Xu, Mao-Feng Zhang, Quan-Quan Gan, Cai-Sheng Huang

Journal of Electrochemistry

TO study of the oxygen storage material of air cathode is crucial for increasing performance of proton exchange membrane fuel cell.Using the MnO₂ as oxygen storage materials,a MnO₂-Pt/C catalysts were prepared and is used to replace the conventional Pt/C in air cathode.The electrochemical performance of air cathode composed of MnO₂ supported on Pt/C and the properties of fuel cell composed of MnO₂-Pt/C were investigated by using the CV,galvanostatic dischange method and TEM.

Growth Mechanism And Morphology Of Electrodeposited Micro-Nanocrystalline Iron, Qiao-Xin Zhang, Jia-Ming Zhang, Li-Ning Yang

Journal of Electrochemistry

Effects of current density,reaction temperature,electrolyte concentration and surfactant on the electrochemical deposition of micro-nanocrystalline iron were studied.Morphologies and structures of the samples were characterized by SEM and XRD,the results showed that the electrodeposits is slice α-Fe under little current and the density,lower temperature and higher concentration,and the dentritic α-Fe is under opposite conditions,but the influence from surfactant is unconsicously.Moreover,the growth mechanism of the electrodeposits was also analysed here.

Studies On Catalytic Mechanism Of Li/Socl2 Batteries By Metal Phthalocyanine Complexes, Zhan-Wei Xu, Qing-Jin Sun, Bi-Yun Su, Tu-Lin Che, Yan-Hong Song, Yao-Min Li, Jian-She Zhao

Journal of Electrochemistry

Effects of metal phthalocyanine comlexes MPc(M= Mn(Ⅱ),Fe(Ⅱ),Co(Ⅱ),Ni(Ⅱ),Cu(Ⅱ)) as electrochemical catalysts on the performance of Li/SOCl₂ batteries have been examined at constant resistance.And the reasons of MPc affecting the discharged voltage and discharged time of Li/SOCl₂ batteries were also brought forward.A few new viewpoints on the catalytic mechanism of the reduction of thionyl chloride by phthalocyanine complexes were proposed.

Electro-Chemical Oxidation Kinetics Of The V(Iv) In The Sulfuric Acid Solution, Yong-Lian Qiao, Qian Xu, Jie Zhang, Yu-Chun Zhai

Journal of Electrochemistry

The electro-chemical oxidation kinetics for V(IV) in the sulfuric acid solution were investigated by cyclic voltammetry and steady state polarization curves at a graphite,platinum or conducting polymer electrode.Some kinetics parameters for the electrochemical reaction of V(IV) were calculated according to the Tafel curves.The results showed that the exchange current density and reversibility of V(V)/V(IV) redox reaction at the graphite electrode is largest among the three electrodes.There is the broadest extent of water stability and large oxidgen evolution potential when the conducting polymer was used as a working electrode in the solution of VOSO₄(0.5 mol/L) and H₂SO …

Electro-Generated Mno2 In Supersonic Wave Bath And Its Application In Preparation Of Glyceraldehyde, Yan-Hong Cai, Li-Qun Chen, Ri-Yao Chen, Xi Zheng, Xiao Chen, Zhen Chen

Journal of Electrochemistry

Glyceraldehyde is prepared by using MnO₂/ Mn²⁺as the media in a cationic membrane electrolytic cell.Under ultrasonic high-frequency oscillation,the electro-generated nanometer MnO₂ dispersed in the solution with several tens nm till several micron.Then the MnO₂ is used for selective oxidation of glycerine to glyceraldehydes.The catalyzing selectivity of MnO₂/ Mn²⁺is high and the current efficiency may account to 97.4 %.

Electrocatalytic Separation For Dopamine And Ascorbic Acid Using Poly-Evans Blue Modified Glassy Carbon Electrode And Simultaneous Determination, Li-Qing Lin, Xin-Hua Lin, Hong Yao, Jing-Hua Chen, Guang-Wen Li

Journal of Electrochemistry

Voltammetric behavior of the Dopamine(DA) and ascorbic acid(AA) at Poly-Evans Blue modified electrode were studied and a novel method for determination of the content of DA and AA is established.In pH 4.5 phosphate buffer solution,the modified electrode shows enhanced sensitivity and excellent electrochemical discrimination to DA and AA.The relationship between oxidation peak current and the concentration of DA or AA is linear in the range of 1.0 10^-6 ～3.0×10^-5mol/L and 5.0×10^-6~1.05×10^-4 mol/L,the detection limit has been estimated as 2.5(10^-7 mol/L and 3.0 ×10^-7 mol/ L,respectively.The oxidable potential difference of DA and AA …

Prerapation And Supercapacitor Property Of Al Doped Co3O4, Xin Ge, Ye Chen, Chun-Xia Zhang, Chang Shu

Journal of Electrochemistry

With KOH as precipitator to prepare Aluminum doped Co₃O₄,X-ray diffraction indicated that the doping Al did not change the crystal structure of Co₃O₄.Electrochemical properties of the sample were tested by cyclic voltammetry and constant-current charge/discharge.The results showed that the chemical doping improved the specific capacitance.When the mol ratio of Co(Ⅱ) with Al(Ⅲ)was 1∶0.05,the specific capacitance was up to 518.07 F/g within 0～400 mV potenitial at current density 5 mA/cm².

Preparation Of Manganese/Chromium Hexacyanoferrate Modified Glassy Carbon Electrode And Its Electrochemical Behavior, Sheng-Tao Zhang, Xiao-Yan Han, Ming-Yue Xue

Journal of Electrochemistry

A film of poly(manganese/chromium hexacyanoferrate)(MnCrHCF)is formed on the glassy carbon electrode(GCE) by Cyclic Voltammetry scanning,and its electrochemical behavior was studied.Factors affecting the electro-deposition of the film such as pH values and sustaining electrolytes,were discussed.And mechanism of the reaction was investigated.

Influence Of Chromium On The Semi-Conductive Property Of Passive Film Formed On Carbon Steel In Bicarbonate/Carbonate Buffer Solution, Jin-Bo Li, Jie-Wu Zhu, Mao-Sheng Zheng

Journal of Electrochemistry

The influence of chromium on the semi-conductive property of the passive film formed at carbon steel in bicarbonate/carbonate buffer solution,is investigated by using electrochemical impedance spectroscopy(EIS).The results showed that the passive film fomed at carbon steel appeared an n-type semi-conductive property,but if the passive film formed at carbon steel with 3% chromium content exhibited an a-p semi-conductive charatcer.The slopes of Mott-Schottky plot of two passive films increased with rising the formation potential,it indicating the defect density of the film decreasing,but for the passive film formed at carbon steel with chromium additive,its donor density was lower about one order of magnitude …

Fabrication And Charaterization Of Nitrogen-Doped Tio2 Nanotube Array And Its Visible Light Activity, Hui-Fang Zhuang, Yue-Kun Lai, Jing Li, Lan Sun, Chang-Jian Lin

Journal of Electrochemistry

Nitrogen-doped TiO₂ nanotube array was fabricated by an electrochemical anodic oxidation followed a wet process.XPS result indicates that the nitrogen atoms were doped into lattice of TiO₂ nanotubes.The UV-Vis spectra show that the photoabsorption of N-doped TiO₂ nanotube array film is enhanced in the visible light region.Compared with the TiO₂ nanotube array film,the N-doped TiO₂ nanotubes exhibite a higher photocatalytic activity which is evaluated by the decomposition rate of methyl orange using the tungsten-halogen lamp as light source.

Preparation, Structure, And Cv Study Of The Supported Ptruir/Tic Electrocatalysts For Oxygen Electrodes, Sheng Sui, Li-Rong Ma

Journal of Electrochemistry

The PtRuIr/TiC electrocatalysts were prepared by method of reduction and deposition on TiC powders as supports together with ultrasonic wave dispersion.The sampls were characterized by BET surface area,scanning electron microscope,X-ray diffraction,and cyclic voltammetry techniques.The active components of Pt,Ru,and Ir particles(2.6%Pt,1.3%Ru,16%Ir,and 80%TiC,by mass) were mainly dispersed on the outer surface of the TiC supports,which structures were in favor of fine variable crystallites.It was found that the electrochemical performance of the PtRuIr/TiC electrodes was about three times as that of the unsupported electrocatalysts with the same active compositions for oxygen evolution reaction.After 120 times of CV cycles,there was almost no PtRuIr/TiC dissolving …

Electrocatalytic Oxidation Of Methanol At The Nano Ni-B Amorphous Alloy Powdermicroelectrode, Yi-Xiong Zheng, Shi-Bing Yao, Shao-Min Zhou

Journal of Electrochemistry

Electrocatalytic oxidation of methanol at the nano Ni-B amorphous alloy powder-microelectrode in alkaline media was studied by using cyclic voltammetry.Compared to the highly preferred orientation(220) nickel electrode,The onset potential of methanol electrooxidation at the nano Ni-B microelectrode is negatively shifted about 0.04V,and the current density is increased approximately by 2 orders of magnitude.Thus,the nano Ni-B microelectrode has very strong electrocatalytic activity for the oxidation of methanol.The kinetic parameters were determined with the steady polarization curves.The results show that the rate constants for both the oxidation of Ni(Ⅱ) to Ni(Ⅲ) and the reduction of Ni(Ⅲ) to Ni(Ⅱ) at the nano Ni-B …

The Syntheses And Electrochemical Performance Of Nano-Mno2 For Supercapacitor, Jun Ma, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

Nano-manganese dioxide were prepared by two different methods which are low temperature solid reaction and chemical deposition.The products were characterized by XRD,SEM,BET and constant current charge-discharge tests.The result shows that there is a close relationship between specific capacitance and BET surface areas.Meanwhile the specific capacitance was impacted little by the structure of the nano-manganese dioxides.However,the product performance of high rates,was influenced by structure,the higher rate can be obtained with the more perfect crystal structure.

Transportation Fuel Research And Development: Statistically Validated Codes And Standards, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

The recent establishment of the National University Transportation Center at MST under the "Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users," expands the research and education activities to include alternative transportation fuels and other issues that are at the forefront of society and the national agenda. UMR in partnership with MTI will establish a rural hydrogen transportation test bed for developing, demonstrating, evaluating, and promoting hydrogen-based technologies in a real-world environment. The State of Missouri is ideally suited to develop and demonstrate the proper operation of hydrogen highways in a rural setting, which represents over 25 percent …

Morphology Of The Pb-Sn Alloy Thin-Layer Electrodeposition, Yan-Jun Du, Zhi-Gang Yin, Tong-Chi Xia

Journal of Electrochemistry

The morphology of Pb-Sn alloy thin-layer electrodeposition was studied.Experimental results showed that the morphology of deposit could vary as the concentration of Pb²⁺, Sn²⁺ two kind metallic ion to be changed.The patterns of product appeared the dendritic, ramification, dense branch, fractal, and homogeneous structure and their morphological evolution was caused by the change in anisotropy of crystal growth and different stage of electrodeposits.

Effect Of Tension On Corrosion Behavior Of Galvanized Steel Wire For Cable-Stayed Bridge, Xue-Ming Li, Jie-Min Zhou, Qiang Liu, Ling-Feng Kong, Jian-Ting Zhou

Journal of Electrochemistry

Corrosion of steel wire in cables is a major cause of cable-stayed bridge deterioration. The corrosion behavior of galvanized steel wire at different tension is investigated by polarization voltammetry method and neutral salt spray test in 5% NaCl solution. The physical and chemical properties of corrosion products are characterized by XRD and TG-DTA.The result shows that the corrosion current or corrosion rate of galvanized steel wire is larger with increasing the tension, the white rust of galvanized steel wires at different tension appears within one cycle, the red rust appears after 16 cycles at 15~22kN tension, and 23 cycles at …

Preface, Judy Schneider, Rajiv S. Mishra, Thomas R. Bieler, Yuntian T. Zhu, Khaled B. Morsi, Viola L. Acoff, Eric M. Taleff, Ruslan Valiev

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Laser-Assisted Synthesis And Optical Properties Of Bismuth Nanorods, Jason Reppert

All Theses

Bismuth in the bulk form is a semimetal with a rhombohedral structure. It has a small band overlap between the conduction and valence bands and a highly anisotropic electron effective-mass tensor. Thermoelectric materials, in which one of the three dimensions is in the nanometer regime, exhibit unique quantum confinement properties and have generated much interest in recent years. Theoretical investigations have suggested that nanowires with diameters <10 nm will possess a figure-of-merit ZT>2. Prior to this research, it has been shown by the Dresselhaus group at MIT that Bi nanowires with small enough diameters (~50 nm), prepared via the template-method, undergo a transition from a semimetal …

Modeling And Simulation Of A Laser Deposition Process, Frank W. Liou, Zhiqiang Fan, Heng Pan, Kevin P. Slattery, Mary Kinsella, Joseph William Newkirk, Hsin-Nan Chou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A laser deposition process involves the supply of metallic powders into a laser-heated spot where the powder is melted and forms a melt puddle which quickly solidifies into a bead. In order to design an effective system, the laser beam, the powder beam, and their interactions need to be fully understood. In this paper, the laser-material interaction within the melt pool is reported using a multi-scale model: A macroscopic model to model mass, heat, and momentum transfer. Experiments were also conducted to validate the simulation model.

Experimental Investigation Of Effect Of Environment Temperature On Freeze-Form Extrusion Fabrication, Xiyue Zhao, Michael S. Mason, Tieshu Huang, Ming-Chuan Leu, Robert G. Landers, Greg Hilmas, Samuel J. Easley, Michael W. Hayes

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Freeze-form Extrusion Fabrication (FEF) is an additive manufacturing technique that extrudes ceramic loaded aqueous pastes layer by layer below the paste freezing temperature for component fabrication. A computer controlled 3-D gantry system has been developed for the FEF process. The system includes a temperature control subsystem that allows for fabrication of components below the paste freezing temperature. The low temperature environment allows for larger component fabrication. Comparisons in terms of layer thickness, self-sustaining ability, and system response were performed between 0⁰C and -20⁰C for alumina sample fabrications. The minimum deposition angles without use of support material have been determined for …

Aqueous-Based Extrusion Fabrication Of Ceramics On Demand, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas, Michael W. Hayes

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes ceramic slurries of high solids loading layer by layer for part fabrication. The material reservoir in a previously developed system has been modified to allow for starting and stopping of extrusion process on demand. Design pros and cons are examined and a comparison between two material reservoir designs is made. Tests were conducted to determine the optimal deposition parameters for starting and stopping of the extrudate on demand. The collected test data is used to create a process model that describes the relationship between ram velocity and material extrusion rate. …

Numerical Simulation Of The Evolution Of Solidification Microstructure In Laser Deposition, Zhiqiang Fan, Todd E. Sparks, Frank W. Liou, Anand Jambunathan, Yaxin Bao, Jianzhong Ruan, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A predictive model is developed to simulate the evolution of the solidification microstructure during the laser deposition process. The microstructure model is coupled with a comprehensive macroscopic thermodynamic model. This model simulates dendritic grain structures and morphological evolution in solidification. Based on the cellular automata approach, this microstructure model takes into account the heterogeneous nucleation both within the melt pool and at the substrate/melt interface, the growth kinetics, and preferential growth directions of dendrites. Both diffusion and convection effects are included. This model enables prediction and visualization of grain structures during and after the deposition process. This model is applied …

Effects Of Surface-Deposited Nanocrystalline Chromite Thin Films On The Performance Of A Ferritic Interconnect Alloy, I. Belogolovsky, X. D. Zhou, H. Kurokawa, P. Y. Hou, S. Visco, H. U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

LaCrO₃ -Based nanocrystalline thin films, substituted with Sr and Zn and coated onto a Fe-26 atom % Cr Ebrite alloy were evaluated at 750-900°C as potential enhancers of oxide properties in ferritic alloy interconnects of a solid oxide fuel cell. It was found that at 750°C the coatings provided (i) lower oxidation rates, (ii) increased electrical conductivity, (iii) protection during 24 h cycling and at least 2375 h of isothermal oxidation, and (iv) a fine-grained and uniform oxide microstructure. Although after oxidation at 850°C the grains grew substantially and the scale seemed to be overgrowing the film, conductivity and …

Quantum Ballistics, Andrei Sokolov

Materials Research Science and Engineering Center: Faculty Publications

For the last 40 years, computer-chip manufacturers have been constantly improving the performance of their products by shrinking the size of transistors—the building blocks of processors and memory chips. Having gone from dimensions of a few microns in the early 1970s to 45 nm in Intel’s latest prototypes, the number of transistors that can be etched on a given area of silicon has been doubling every 18 months. This exponential trend, which is known as Moore’s law, has been the driving force behind the relentless miniaturization of microelectronic devices. However, we are now approaching the physical limits of existing technology. …

Interlaminar Fracture Of Unidirectional Reinforced Composites With Toughnened Resin Systems, Aaron Slager

Material Science and Engineering Theses - Archive

Several undisclosed fiberglass and carbon fiber laminates with toughened resin systems were tested and examined. Experiments were conducted to determine Modes I and II interlaminar fracture toughness for each of the nine laminates with varying types of processing forms such as roving, tape, and slit tape of glass and carbon fibers. Fractography was then used to correlate the fracture toughness results with the unique characteristics and failure mechanisms. Overall, fiberglass laminates had larger interlaminar fracture toughness for both Modes I and II over the carbon laminates. This was also confirmed by the significant amount of the fractured surface area and …

Dna Based Thin Film As Hole Transport Layer In Bulk Heterojunction Polymer Solar Cells, Vidyalakshmi Kolachure

Material Science and Engineering Theses - Archive

In the field of organic solar cell, the conjugated polymer-fullerene bulk heterojunction concept is one of the ongoing research interests. In this work, the use of de-oxyribose nucleic acid/ hexadecyl trimethyl ammonium chloride (DNA/CTMA) thin films as hole transport layer in poly(3-hexylthiophene)-methanofullerene (P3HT-PCBM) bulk heterojunction polymer solar cell is demonstrated. P3HT-PCBM bulk heterojunction polymer solar cell was fabricated with a DNA complex layer replacing commonly used PEDOT-PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS). While PEDOT-PSS, as a hole transport and electron blocking layer, often improves the solar cell performance by improving fill factor, it requires careful engineering of spin-coating for the aqueous solution of …

Impact Of A Microwave Curing Process On Tensile Strength Of Selected Carbon Fiber Composites, Brian B. Balzer

All-Inclusive List of Electronic Theses and Dissertations

The traditional process for curing carbon fiber (CF) composites has been the autoclave system. A review of recent research indicates curing CF composites in a microwave oven has the potential for reducing processing time. The problem statement of the experimental study was that the impact of a microwave curing process on tensile strength of selected CF composite specimens was unknown. The research study describes the statistical procedure and analysis of data to answer the specific question for the experimental trials: What is the effect on the tensile strength of cured CF composite samples due to the relationship of the autoclave …

Determination Of Three-Dimensional Grain Boundary Connectivity From Two-Dimensional Microstructures, Megan Frary

Materials Science and Engineering Faculty Publications and Presentations

The connectivity of so-called "special" and "general" grain boundaries at a quadruple node is known to be nonrandom as a result of crystallographic constraints. Although a quadruple node is a three-dimensional feature, there exist two-dimensional features which are topologically identical. Therefore, the distribution of these two-dimensional features may be used to determine the three-dimensional connectivity. Computer simulations of a three-dimensional microstructure which is virtually serial sectioned are used to validate the proposed approach.

High Temperature Heat Exchanger Project: Quarterly Progress Report April 1, 2007 Through June 30, 2007, Anthony Hechanova

Publications (NSTD)

• Ceramatec Sulfuric Acid Decomposer. Modeling with different reacting flow channel configurations (ribbed-surface channels, hexagonal channels, and diamond-shaped channels) was performed. The probability of failure for the one channel geometry with different reacting flow channel configurations was calculated to be zero in the three principal directions for all of the cases.

• Bayonet Heat Exchanger. The Matlab code for calculating the probability of failure using a two-dimensional axisymmetric model of the bayonet decomposer was developed. The probability of failure was calculated for the inner and outer SiC walls, and the intermediate quartz wall of the decomposer and found to be …