Materials Science and Engineering Commons^™

Studies On Sulfate Reducing Bacteria Influenced Corrosion Of 90/10 Cu/Ni Alloy, Guang-Zhou Liu, Jian-Hua Qian, Yan Ma, Jian-Hua Wu

Journal of Electrochemistry

Electrochemical techniques such as measurements of corrosion potential,the polarization resistance, and potentiodynamic scanning technique were used to investigate the electrochemical behavior of 90/10 Cu/Ni alloy in Postgate C medium containing sulfate reducing bacteria(SRB). The results showed that the corrosion potential of the alloy changed from -0.20 to -0.75 V(SCE) when bacteria inocula was added, and the polarization resistance R_p decreased obviously, which corresponds to an increased corrosion rate. The shape ofthe anodic polarization curves was drastically changed in the presence of SRB, and an active-passive transition was observed. Electron probe microanalyzer was used to investigate the morphology and chemical …

Effect Of Cl- On The Transition Current Density Of Zn During The Electrodeposition Of Zn-Ni Alloys, Ren-He Yin, Zheng-Hua Fang, Wei-Min Cao

Journal of Electrochemistry

There exists a transition current density of Zn when the normal co-deposition of Zn-Ni alloys at chloride baths turns to anomalous type. The value increases with Cl^- concentration, but is independent of pH, this is because the existence of Cl^- decreases the evolution overpotential of Ni metal and has a catalytic effect on it.

An Investigation On Sr-Doped Spinel Phase-LisrXMn2-XO4, Hui Zhan, Yun-Hong Zhou

Journal of Electrochemistry

Sr-doped spinel phase-LiSr_xMn_2-xO₄ was successfully prepared by solid-state method. Structural and electrochemical characterizations were carried out. Although Sr²⁺ has a large ion radius-1.12 , the spinel structure can be well maintained for LiSr_xMn_2-xO₄ sample as far as the x value doesn't surpass 0.05. Electrochemical study presents supporting evidence that doping the stoichiometric LiSr_xMn_2-xO₄ phase with Sr is an effective way to improve the cycleability of LiSr_xMn_2-xO₄ spinel material. A remarkable enhancement of the cycleability with retention of the initial …

Polishing Rate And Dependent Factors Of Copper In Nh3 ·H2O Aqueous Solution Containing K3Fe(Cn)6 During Cmp, Han-Wei He, Yue-Hua Hu, Ke-Long Huang

Journal of Electrochemistry

Dependence of polishing rates of copper on concentrations of NH₃·H₂O, passivator K₃[Fe(CN)₆], γ-Al₂O₃ abrasives and polishing pressures, polishing rotative rates were studied. Dependent mechanisms were explained. It was shown a linear relation between polishing and polishing pressures and rotative rates within some range, non-linear relation between polishing and various reagent concentrations. Preston coefficient was varied. CMP recipe of the best polishing rate was gained: 4%K₃Fe(CN)₆+1%NH₃·H₂O+25%γ-Al₂O₃, K_p=0.02383. Technics conditions were 300 rpm and 80 kpa. The …

Electrosynthesis Of Glyoxylic Acid In A Cooled Cathode Reactor, Jin-Hong Fan, Jun Li, Xue-Yun Chen, Wei Li, Hao-Qi Gao

Journal of Electrochemistry

Glyoxylic acid was produced by electroreduction of oxalic acid in a well designed cooled cathode reactor. The cathodic and anodic electrolytes were super-saturated oxalic acid and hydrochloric acid aqueous solutions separated by a super-acid ion-exchange membrane. The current efficiency and time-space yield of glyoxylic acid were studied under different temperatures of cathode and electrolyte, current densities, materials of cathode. With the cooled cathode reactor, the energy consumption was reduced and higher oxalic acid concentration was available in solution, so that current efficiency was improved. The results indicated that the average time-space yield of glyoxylic acid was about 0.032 kg·dm^{-3 …}

Electrocatalytic Oxidation Of Formaldehyde On The Proline Film Modified Electrode, Yu-Rong Ma, Qiu-Xia Yang, Guo-Bao Li, Zheng-Kai Xi, Xue-Lin Wang

Journal of Electrochemistry

The proline film modified electrode and its electrochemical behavior was studied by cyclic voltammetry and spectroelectrochemistry. After incorporation of Ni(Ⅱ), the cyclic voltammograms of the proline Ni(Ⅱ) film electrode exhibited a typical redox peak, which appeared at potential of 0.52 V anodic and 0.44 V cathodic in NaOH. The formal potentials E' were linearly dependent on the pH, and the peak currents ip were linearly dependent on the square root of the scan rates, thus charge transfer in the film was controlled by diffusion. The diffusion coefficient is figured out to be 2×10^_-10 cm²·s^-1. The …

Preparation,Structure And Properties Of Electrochromic Rhodium Oxide Films, Hai-Hong Wang, Tao Wang, Man-Ming Yan, Zhi-Yu Jiang

Journal of Electrochemistry

Electrochromic rhodium oxide films were prepared on ITO substrate by sol-gel method. The films exhibited reversible two-color (bright yellow at reduction and dark green at oxidation) electrochromic behavior in alkaline solution with good cycle stability. In-situ XRD, TGA-DTA, IR, XPS methods were used for studying the structure and chemical process of the films. The diffusion coefficient during the electrochromic process was measured by electrochemical impedance spectra method. It was found that the rhodium oxide films may be suitable for the use in electrochromic devices.

Self-Assembled Monolayer Of Schiff Bases On Au Electrode, Ke-Qiang Ding, Qing-Fei Wang, Zhen-Bin Jia, Na Tian, Ning Wang, Ru-Ting Tong, Xin-Kui Wang, Hui-Bo Shao

Journal of Electrochemistry

Schiff bases tailored with -SH group, was self-assembled on Au substrate for the first time. The packing degree of this monolayer was described with SEM technique. Spontaneously, the self-assembled monolayer (SAM) was briefly characterized with CV and EIS methods. Though Comparing with the SAM of alkanethiol, the membrane we fabricated was relatively loose, our work is the first step to study Schiff bases by means of self-assembled monolayer.

Development Of A Mechanistic Understanding Of High-Temperature Deformation Of Alloy Ep-823 For Transmutation Applications, Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The purpose of this project is to evaluate the elevated temperature tensile properties of Alloy EP-823, a leading target material for accelerator-driven waste transmutation applications. This alloy has been proven to be an excellent structural material to contain the lead-bismuth-eutectic (LBE) nuclear coolant needed for fast spectrum operations. However, very little data exist in the open literature on the tensile properties of this alloy. The selection of Alloy EP-823 as the test material in the proposed task is based on the recommendation of our collaborator at the Los Alamos National Laboratory (LANL). The test material will be thermally treated prior …

Magnetic And Mössbauer Studies On Oxygen Deficient Perovskite, La₀.₆Sr₀.₄Feo3-Δ, Jinbo Yang, William B. Yelon, William Joseph James, X.-D. Zhou, Yixiang Xie, Harlan U. Anderson, Zili Chu

Physics Faculty Research & Creative Works

Samples of La_0.6Sr_0.4Fe_3-δ with varying oxygen vacancy contents were prepared by heating them in different gas flows. Magnetization measurement showed that samples with low oxygen vacancies have a magnetic ordering temperature in the range of 300-325 K while those with 9%-12% oxygen vacancies have a magnetic ordering temperature of 800 K and higher. Mössbauer spectra at 300 K exhibit paramagnetic or weak magnetic characteristics for the N₂, O₂, and air-quenched samples, whereas an average hyperfine field of 52 T is found for the CO/CO₂ reduced samples. The heat treatment in …

Humidity And Temperature Boundaries For Biofilm Formation In Yucca Mountain, Terry Ann Else, Penny S. Amy, James Jay, Amy J. Smiecinski

Publications (YM)

To determine the long-term success of the recommended Yucca Mountain high-level nuclear waste repository, studies of bacterial colonization and biofilm development are needed. Bacteria involved in microbially-influenced corrosion and degradation are known to form biofilms with the potential to impact the integrity of repository packaging and structural materials. Temperature and humidity are environmental factors that can greatly affect biofilm formation. Therefore, it is necessary to determine the temperature and humidity conditions that affect biofilm formation. Microcosms, which simulated the repository environment of Yucca Mountain, were placed at temperatures ranging from 30° C to 70° C and in relative humidities ranging …

Design And Analysis Of A Process For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Yitung Chen, Darrell Pepper, Randy Clarksean

Fuels Campaign (TRP)

UNLV has developed and will continue to develop process models for the analysis of melt casting processes. This work will continue to be performed under the guidance of Argonne National Laboratory (ANL) engineers to ensure that their knowledge and experience benefits the project. The research to be conducted during the second year will center on performing detailed analyses on a conceptual design of an inductively heated skull-crucible casting furnace. Processing conditions will be analyzed, basic models utilized, and detailed heat and mass transfer models will be developed to analyze the most promising processes. The goal of this second year is …

Use Of Positron Annihilation Spectroscopy For Stress-Strain Measurements, Ajit K. Roy

Transmutation Sciences Materials (TRP)

The purpose of this collaborative research project involving the University of Nevada, Las Vegas (UNLV) and Idaho State University (ISU) is to evaluate the feasibility of determining residual stresses of welded (after pre-straining) engineering materials using a new nondestructive technique based on positron annihilation spectroscopy. The proposed technique is to use γ-rays 2 from a small MeV electron Linac to generate positrons inside the sample via pair production. This method can be used for materials characterization and investigation of defects in thick samples that could not be accomplished by conventional positron techniques or other nondestructive methods. The data generated will …

Improvements In Wavelength Modulation Spectroscopy Using Ratios Of Higher Harmonics, James Michael Barrington

Electrical & Computer Engineering Theses & Dissertations

Experiments in Wavelength Modulation Spectroscopy have been conducted at Old Dominion University since 1996. The method provides a highly sensitive, nonintrusive method of probing gases. Research has concentrated on effectively modeling the higher harmonic shapes that are measured experimentally. Accurately modeling these signals will result in the ability to reliably extract the information contained in transition line shapes.

In order to accurately depict the signals, the theory must be thoroughly understood. This thesis develops the theory of Wavelength Modulation Spectroscopy from two aspects: a direct Fourier series expansion of a time varying intensity profile and through communication theory. In addition, …

Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials: Aaa Task-4 Quarterly (December 1, 2001 – February 28, 2002) Report, Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The primary objective of this task is to evaluate the effect of hydrogen on environment-assisted cracking of candidate materials for applications in spallation-neutron-target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The materials selected for evaluation and characterization are martensitic stainless steels including HT- 9, EP 823 and 422. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of these alloys will be evaluated in environments of interest using tensile specimens under constant load and slow-strain-rate (SSR) conditions. The extent and morphology of cracking of these alloys will further be evaluated …

Development Of A Mechanistic Understanding Of High-Temperature Deformation Of Alloy Ep-823: Aaa Task-10 Quarterly (12/1, 2001 –02/28, 2002) Report, Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The objective of this task is to evaluate the elevated temperature tensile properties of Alloy EP-823, a leading target material for accelerator-driven waste transmutation applications. The test material will be thermally treated prior to evaluation of its tensile properties at temperatures relevant to the transmutation applications. The deformation characteristics of tensile specimens, upon completion of testing, will be evaluated by surface analytical techniques including scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The overall results are expected to provide a mechanistic understanding of high-temperature deformation behavior of Alloy EP-823 as a function of heat treatment.

Highlights of Accomplishment

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Third Quarter Report, Covering January Through March 2002, John Farley

Transmutation Sciences Materials (TRP)

Progress from June 2001-November 2001 was presented at the winter meeting of the American Nuclear Society in Reno (November 12-15, 2001), and incorporated into a refereed conference proceeding. A copy of the refereed conference proceeding has been provided to Tony Hechanova. In brief, the paper described the new program to examine the corrosive effects of lead-bismuth eutectic (LBE) on steels. We employed various types of surface studies (Scanning Electron Microscope [SEM], and X-ray Photoelectron Spectrometry [XPS]) to examine steel samples that had been exposed to LBE for various lengths of time at various temperatures. The goal is to understand the …

Smart Structures For Control Of Optical Surfaces, D. Michael Sobers Jr.

Theses and Dissertations

The development of lightweight, large-aperture optics is of vital importance to the Department of Defense and the US Air Force for advancing remote sensing applications and improving current capabilities. Synthetic polymer optics offer weight and flexibility advantages over current generation glass mirrors, but require active control to maintain tight surface figure tolerances. This research explores the feasibility of using imbedded piezoelectric materials to control optical surfaces. Membrane-based and stiff piezo-controlled mirrors were constructed to develop and validate control techniques. Test results verified that surface control on the order of tens of wavelengths is possible using these systems.

Effect Of The Brightener On The Behavior Of The Silver Electrodeposition, Jin Hu, Hui-Min Wu, Xiang-Ming Feng, Wei-Dong Li, Zheng-Zhong Zuo, Yun-Hong Zhou

Journal of Electrochemistry

The effect of the brightener on the behavior of the silver electrodeposition in cyanide solution was studied by potentiostatically step and rotating dise electrode (RDE) as well as X-ray diffraction (XRD) and scanning electron microscope (SEM). It was found that the silver electrodeposition was not changed by the addition of the brightener to the fundarmental solution. But it apparently increased the solution's micro-leveling effection and remarkably improved the coating's surface lightness. The coating's orientation isn't changed by the addition of the brightener in the light of the XRD result. The effectivness of the brightener was also discussed by the half-wideth …

Study On The Orthogonal Test Of Al-Substituted α-Ni(Oh)2 Prepared By Complexation-Precipitation Method, Hui Chen, Jian-Ming Wang, Tao Pan, Hui-Ming Xiao, Jian-Qing Zhang

Journal of Electrochemistry

Al-substituted α-Ni(OH)₂ was prepared by a complexation-precipitation method and characterized by XRD.The electrochemical performance was tested by the charge-discharge method. The experimental results of orthogonal test showed that the effect order of some key preparative conditions on the electrochemical performance of Al-substituted α-Ni(OH)₂ was the concentration of aqueous ammonia, the content of aluminum and pH value.The optimum prepareative conditions for obtaining the sample with maximum specific discharge capacity (304 mAh·g^-1) were 0.5 mol·L^-1 aqueous ammonia, 15 mol% Al content and pH 11.0.

Uncertainty In Determination Of Hydrogen Diffusion Coefficient In Metal Hydride Electrode Based On The Transition Region Of Diffusion-Controlled Impedance, Xian-Xia Yuan, Nai-Xin Xu

Journal of Electrochemistry

Hydrogen diffusion coefficient in MlNi_3.75Co_0.65 Mn_0.4Al_0.2 metal hydride electrode has been determined with transition region of diffusion-controlled impedance. Multiple solutions were obtained at each data point because of the periodic characteristic of some functions used in the calculation, and the maximum difference between the solutions reached several orders of magnitude. On the other hand, the solutions varied for different data points in the transition region of diffusion-controlled impedance of the same experimental plot. It could be concluded that this method is not so well defined and some modification is required.

The Determination Of The Best Modified Way And Microscopical Analysis For Enzyme/Immunoelectrodes, Sa-Ying Dong, Hong-Ren Wang, Yu-Zhu Gao, Guang-Zhang Chen, Ming-Xiang Lv, Bo-Yi Tian

Journal of Electrochemistry

In this paper, the electrochemical response characteristics of enzyme and immuno electrodes were studied by cyclic voltammetry under different conditions. Our goals were to determine the best modified way of bioelectrode, which was the base of biosensor's application. 30U GOD and 0.8 mg/mL SEC1 antibody were suitable to bioelectrode preparation and detection. The microscopical analysis was finished with scan microscopy.

Preliminary Study On Direct Ethanol Fuel Cell, Shu-Qin Song, Li-Kang Chen, Jian-Guo Liu, Zhao-Bin Wei, Qin Xin

Journal of Electrochemistry

The performance of a direct ethanol fuel cell based on Nafion115 was reported.PtRu/C and Pt/C were used as ethanol anode and oxygen cathode catalysts in a single cell of size 9 cm² .The effects of temperature, oxygen pressure, the flow rate of ethanol, and oxygen, and ethanol concentration were tentatively studied. The experimental results showed that the cell open circuit voltage 0.608 V, the cell voltage 0.329 V at 50 mA/cm², and the peak power density 19.25 mW/cm² were reached under the conditions of T_cell =85 ℃, P_O2 =0.5 MPa, C_ethanol =1.0 mol/L …

Photocurrent Enhancement By Ticl4 Post-Treatment For Tio2 Nanoporous Film Electrode, Yan-Jie Ren, Li Zhang, Sheng-Min Cai

Journal of Electrochemistry

Enhanced photocurrent in dye-sensitized photoelectrochemical cell was obtained by post-treating the TiO₂ nanoporous film electrode with TiCl₄. By investigating the effect of the post-treatment on surface area, pore size distribution, laser pulse induced current transient of the film electrode, photocurrent increase by the post-treatment was assigned to the improved electron percolation resulting from broadening of interparticle neck.

An Investigation Of Inhibition Mechanism Of Cerium For Aluminum Alloy 2024-T3, Min-Hua Shao, Yan Fu, Rong-Gang Hu, Chang-Jian Lin

Journal of Electrochemistry

Cerium compounds are promising inhibitors for aluminum alloy. However, the inhibition mechanism is not very clear. Scanning microreference electrode (SMRE) technique was used to probe the potential imaging of Al 2024 T3 in NaCl and CeCl₃ solution. The results of SMRE showed that in NaCl solution a severe localized corrosion occurred on the surface of Al 2024 specimen at once and maintained for a long time. The corrosion activity of Al alloy in CeCl₃ decreased with immersion time and disappeared finally. Additionally, the competition of inhibition and aggression between Ce³⁺ and Cl^- on Al alloy was …

Electrosynthesis Of Glyoxylic Acid In A Packed Bed Reactor, Jin-Hong Fan, Jun Li, Yu-Zhong Su, Hao-Qi Gao

Journal of Electrochemistry

Glyoxylic acid was produced by electroreduction of oxalic acid in a packed bed reator. The cathodic and anodic electrolytes were super-saturated oxalic and hydrochloric acid aqueous solutions separated by a super-acid ion-exchange membrane. The current efficiency and yield of glyoxylic acid were studied under different structured packed bed reactors and different electrode materials, temperatures and current densities. The results indicated that the current efficiency of synthsis of glyoxylic acid was over 66.2% and the concentration of glyoxylic acid could reach 2.02% after 45min electrolysis with cathode of lead particles and anode of graphite board under conditions of temperature 32 ℃, …

Determination Of Copper In The Waste Water Of Plating By Chronocoulometry For Flowing Solution, Xin-Hua Lin, Wei Chen

Journal of Electrochemistry

The chronocoulometry for flowing solution was devoloped and applied to the detemination of copper(Ⅱ) in the waste water of plating. The linear range of copper(Ⅱ) was 2～16mg/L, and the relative standard deviation was less than 0.1% (n =8). The recovery was 98%～103% for copper(Ⅱ) in the waste water.Chronocoulometry for flowing solution overcomed noise disturbance resulting from capacity current and variety of property of electrode surface. This method was sensitive,accurate and well reproducible.

Photoelectrochemistry Of La3+ Doped Semiconductor Porous Films Sensitized By Ru(Bpy)2(Ncs)2 Dye, Li Zhang, Yan-Jie Ren, Sheng-Min Cai

Journal of Electrochemistry

The La³⁺-doped TiO₂ nanoparticles were prepared with hydrothermal method.The photoelectrochemical properties of La³⁺-doped TiO₂ nanoporous-film electrode sensitized by Ru(bpy)₂(NCS)₂ were studied. The conversion efficiency of light to electricity and the energy conversion efficiencies were ineased with the depth of La³⁺-doped TiO₂ nanoporous-film electrode.

Varying Current Electro-Synthesis Of Glyoxalic Acid In Pairs In The Fixed-Bed Electrolytic Cell, Yin-Sheng Chen, Xin-Sheng Zhang, Ying-Chun Dai, Wei-Kang Yuan

Journal of Electrochemistry

As for the process of the electro oxidation of glyoxal to glyoxalic acid, the electrolytic result of either fixed bed electrolytic cell or varying current electrolysis was better than that of either flat plate electrolytic cell or constant current electrolysis. The average current density of varying current electro synthesis of glyoxalic acid in pairs was 1535 A/m² and the current efficiency were 85.3% and 86.7% and the selectivity were 93.9% and 94.0% for the anodic oxidation and cathodal reduction respectively. The initial composition of anodic electrolyte was 7% glyoxal and 8% hydrochloric acid (W/W) and the cathodal electrolyte consisted …

Electrochemical Synthesis And Characterization Of The Nickel Electropolyurushiol Coordination Polymer, Feng Gao, Guo-Cai Shen, Jie-Yuan Tang, Wen-Gong Zhang

Journal of Electrochemistry

The nickel electropolyurushiol coordination polymer (EPU Ni²⁺) was obtained by the reaction between nickel chloride isopropyl alcohol solution with electropolyurushiol (EPU). The electrochemical polymerization of urushiol and the preparation of nickel electropolyurushiol coordination polymer were investigated. The coordination polymer was characterized by XPS, FT-IR, DMTA and AES methods, and its composition and structure were determined.The content of Ni²⁺ reached up to 7.5%. It was shown that there was certain coordination between Ni²⁺ and electropolyurushiol in the coordination polymer, thus cross-inks were formed. Therefore the glass transition temperature of the coordination polymer increased and heat resistance was …