Engineering Commons^™

Raman Scattering And Lattice Defects In Nanocrystalline Ceo2 Thin Films, Igor Kosacki, Toshio Suzuki, Harlan U. Anderson, Philippe Colomban

Materials Science and Engineering Faculty Research & Creative Works

The results of Raman scattering studies of nanocrystalline CeO₂ thin films are presented. The spectra have been described using the spatial correlation model from which the correlation length has been determined as a function of grain size. A direct comparison between the concentration of defects related to correlation length and CeO₂ non-stoichiometry has been achieved. The relationship between the lattice disorder and the form of the Raman spectra in nanocrystalline CeO₂ is discussed. © 2002 Elsevier Science B.V. All rights reserved.

Study Of Non-Equilibrium Electron Dynamics In Metals, Wael Mohamed Gomaa Ibrahim

Electrical & Computer Engineering Theses & Dissertations

Thermal phenomena, such as heat propagation, lattice melting, and ablation, are the result of energy deposition in metals. A fundamental understanding of the electron dynamics leading to these thermal phenomena would benefit many laser applications, such as laser deposition of thin films and laser processing.

In this work, thin metal films were prepared using the resistive heating evaporation technique. High dynamic range autocorrelators were constructed to characterize the different laser systems used in this study. The nonequilibrium electron dynamics in single layer gold films, multi-layer gold-vanadium, and gold-titanium films were studied. The time evolution of the electron temperature was monitored …

Evaluation Of Corrosion Inhibitor On Pre-Corroded Carbon Steel In Co2 Medium By Impedance Spectroscopy, Joseph Buchweishaija

Tanzania Journal of Engineering and Technology (TJET)

The effect of pre-corrosion of carbon steel on the performance of a commercial amine based fatty acid corrosion inhibitor, KI384, was investigated in formation water solutions saturated with CO₂ using electrochemical impedance spectroscopy (EIS) measurements. The investigation was performed at constant partial pressure of CO₂ using an autoclave system with Rotating Cylinder Electrodes (RCE). Carbon steel was pre-corroded for periods up to 7 days at 35 and 80 °C in the test solution prior to inhibitor injection. The results showed that when KI384 was applied on non-corroded carbon steel specimen, high inhibitor performance (99.8 %) was achieved independent of temperature. …

Investigation Of Forces Acting On Plain Discs, S. M. Mpanduji

Tanzania Journal of Engineering and Technology (TJET)

An investigation was carried out to study the mutually perpendicular forces generated by rotating and non-rotating plain discs similar to those used in disc ploughs. Experiments were conducted in a soil bin containing sand loam soil (Ryton sand) where forces were measured while changing disc rake and sweep angles. The results showed that draught forces were higher for non-rotating discs, while vertical and lateral forces were lower compared to rotating discs. Rotating discs were found to be suitable for counteracting high side forces because of less draught and higher lateral forces. The recommended optimum angles are between 8°–12° for disc …

Requirements Of A Sustainable Pavement Management System For Tanzania, N. K.M. Mushule

Tanzania Journal of Engineering and Technology (TJET)

Since the introduction of pavement management concepts in mid-1960s, more than three decades ago, a considerable number of Pavement Management Systems (PMS) have been developed and implemented widely in many parts of the world. These systems differ in scope and sophistication. However, in some cases, pavement management systems have fallen into marginal use, if not into complete disuse, because of a number of reasons. One of the major reasons leading to the marginalisation or abandonment of pavement management systems, is the failure of system developers to recognise specific and unique needs of the agency or authority responsible for road management. …

Hydrogen-Induced Embrittlement Of Candidate Target Materials For Applications In Spallation-Neutron-Target Systems: Annual Progress Report (May 2001 – May 2002), 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 target 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 Alloy HT-9, Alloy EP 823 and Type 422 stainless steel. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of these materials are being evaluated in environments of interest using tensile specimens under constant load and slow-strain-rate (SSR) conditions. Further, the localized corrosion behavior of these alloys …

Development Of A Mechanistic Understanding Of High-Temperature Deformation Of Alloy Ep-823: Aaa Task-10 Quarterly (03/01, 2002 –05/31, 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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Suggestions For Establishing Centers For Engineering Education, Trevor S. Harding, Cynthia J. Finelli

Materials Engineering

No abstract provided.

P.A.C.E.S. - A Study On Academic Integrity Among Engineering Undergraduates (Preliminary Conclusions), Donald D. Carpenter, Trevor S. Harding, Susan M. Montgomery, Nicholas H. Steneck

Materials Engineering

Student academic dishonesty, commonly referred to as cheating, has become a serious problem at institutions of higher education. This is particularly true of engineering students who, according to previous research, are among the most likely to cheat in college. To investigate this concern, the authors have undertaken a research project on the Perceptions and Attitudes toward Cheating among Engineering Students (P.A.C.E.S.). The premise of this research is that a combination of pressures, rather than malicious motivations, account for most student cheating. The P.A.C.E.S study consists of a seven page, self-reported survey that investigates: (1) student definitions of academic dishonesty; (2) …

Integrating Manufacturing, Design And Teamwork Into A Materials And Process Selection Course, Trevor S. Harding, G. Y. Lai, B. L. Tuttle, C. V. White

Materials Engineering

No abstract provided.

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics: Quarterly Progress Report 03/16/02- 06/15/02, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the AAA proposed application. Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with very limited density. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high oxygen concentration, …

Remote Magneto-Elastic Analyte, Viscosity And Temperature Sensing Apparatus And Associated Methods Of Sensing, Craig A. Grimes, Plamen G. Stoyanov

Chemical and Materials Engineering Faculty Patents

An analyte, viscosity, or temperature sensing apparatus for operative arrangement within a time-varying magnetic field, including a sensor with an outer surface that is chemically, frictionally, or thermally responsive and adhered to a base magnetostrictive element, and a receiver to measure a first and second value for magneto-elastic emission intensity of the sensor taken at, respectively, a first and second interrogation frequency. A change in mass or a change in material stiffness of the sensor due to the responsiveness, the viscosity and mass density of a fluid therearound, or the temperature, can be identified. The receiver, alternatively, measures a plurality …

The Effect Of Alloying On The Properties Of (Nb, Ti)Cr2 C15 Laves Phases, Dan J. Thoma, K. A. Nibur, Katherine C. Chen, J. C. Cooley, L. B. Dauelsberg, W. L. Hults, Paul G. Kotula

Materials Engineering

The effect of composition on the ternary (NbCr₂–TiCr₂) C15 phase properties has been investigated, focusing upon the defect structure, elastic properties, and mechanical behavior. The C15 phase field is continuous between NbCr₂–TiCr₂, with a maximum phase field width of at least 7 at.% solubility. The defect mechanism is governed by anti-site constitutional defects for all alloys. Mechanically, the alloys display a maximum in hardness in the center of the ternary phase field (and a minimum of toughness). The ternary phase field has features that are characteristic of solid-solution strengthening mechanisms. …

Crystallization Kinetics, Structural Parameters And Optical Properties Of Some Semiconducting Oxide Glasses Doped With Rare Earth And Transition Metal Ions, Khawlah Mohammad Ahmad Al-Yahyaei

Theses

No abstract provided.

Synthesis, Characterization And Applications Of Some Conducting Polymers, Fatma Yousif Mohamed Balhey

Theses

Conducting polymers emerged as a new class of materials by the end of the sixties. Since then many efforts have been made to put these materials to

industrial use. Among the achievements are their applications in the semiconductor industry, medical field, chemical and biological sensors, etc. A

different track that alleviated the prospects of the application of conducting

polymers is the modification of the polymer film, namely through the inclusion of metallic moieties for specific target usage. In this thesis the candidate aimed

to synthesis well established and extensively studied class of electrically conductive polymer, 3-methylthiophene. The polymer was then …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Phase Two, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The proposed work will combine chemical kinetics and hydrodynamics in target and test-loop lead-bismuth eutectic (LBE) systems to model system corrosion effects. This approach will result in a predicative tool that can be validated with corrosion test data, used to systematically design tests and interpret the results, and provide guidance for optimization in LBE system designs. The task includes two subtasks. The first subtask is to try to develop the necessary predictive tools to be able to predict the levels of oxygen and corrosion products close to the boundary layer through the use of Computational Fluid Dynamics (CFD) modeling. The …

Magnetoelastic Sensing Apparatus And Method For Remote Pressure Query Of An Environment, Craig A. Grimes, Plamen G. Stoyanov, Dimitris Kouzoudis

Chemical and Materials Engineering Faculty Patents

A pressure sensing apparatus for operative arrangement within an environment, having: a sensor comprising a hermetically-sealed receptacle, at least one side of which has an flexible membrane to which a magnetically hard element is attached. Enclosed within the receptacle is a magnetostrictive element that vibrates in response to a time-varying magnetic field. Also included is a receiver to measure a plurality of successive values for magneto-elastic emission intensity of the sensor taken over an operating range of successive interrogation frequencies to identify a resonant frequency value for the sensor. Additional features include: (a) the magnetically hard element may be adhered …

Syntheses And Photoluminescence Of Zinc Oxide Polyaniline Coaxial Nanowires And Their Array, Zhi-Xin Zheng, Yan-Yan Xi, Ping Dong, Huai-Guo Huang, Jian-Zhang Zhou, Lin-Lin Wu, Zhong-Hua Lin

Journal of Electrochemistry

A novel nanomaterial, zinc oxide (ZnO) and polyaniline (PANI) coaxial nanowires and their array in the template, was synthesized using anodic aluminum oxide (AAO) membrane as template. The morphology of these coaxial nanowires was observed with transmission electron microscope (TEM). The experiments on photoluminescence (PL) of coaxial nanowires and their array in AAO membrane show that the visible emission band of ZnO shifts from 530 nm to 400 nm and the luminescence is enhanced for the coaxial nanowires array in AAO membrane,and the visible emission band shifts to a lower wavelergth (385 nm) for coatial nanowires in NaOH solution. Possible …

Electrochemical Properties Of Mixed Metal Oxide Coated Titanium Anodes In Seawater, Ting-Yong Wang, Li-Kun Xu, Guang-Zhang Chen

Journal of Electrochemistry

Mixed metal oxide coated titanium anodes prepared by thermal decomposition were characterized by scanning electron microscopy and electrochemical measurement, while the consumption rate of an anode was also measured in seawater. In order to examine the practical performances of mixed metal oxide-coated anodes, a simulating test on floating dock in seawater has also been carried out. The SEM results indicate that oxide layers exhibited a cracked-mud morphology which endows the anode with good electrocatalytic activity. The electrochemical measurements showed that mixed metal oxide-coated anodes exhibit excellent electrochemical activity and electrochemical stability in seawater. Owing to good corrosion resistance and low …

Corrosive Electrochemical Behavior Of Carbon Steel In Microbiological Medium, Jing Liu, Hong-Bo Fan, Hai-Ping Xu, Jia-Shen Zheng, Li-Ming Xu, Zong-Qiang Mao

Journal of Electrochemistry

Sulfate-reducing bacteria (SRB)grows and propagates, PH of the solution is dropped from 7.5 to 5.8, and forms the biofilms on carbon steel in culture medium. The micro-environment on the surface of carbon steel is changed under the biofilms, the factors accelerate the formation of the pitting corrosion. When the biofilm on carbon steel is cleaned out, the surface of carbon steel have the non-uniform pitting corrosion. The activity of SRB and the porous structure of biofilms induced the initiation and development of the pitting corrosion of carbon steel. The process of microbiologically induced corrosion (MIC) involves the development of SRB …

Recent Developments In The Electrolyte For Lic6/Electrolyte/Cathode Battery, Cui-Ying Wang, Sheng-Liang Zhao, Guang-Ming Zhu, Jin-Kua You, Zu-Geng Lin

Journal of Electrochemistry

We present a reviewed the development and status of electrolyte for LiC 6/electrolyte/cathode battery. The effect of the salt, solvent, additive and impurity on the conductivity of the electrolyte, formation of the solid-electrolyte-interphase (SEI) and cycle life of the battery were described.

A Blend Conducting Membranes For Direct Methanol Fuel Cells, Lei Li, Jun Zhang, Hong Wu, Yu-Xin Wang

Journal of Electrochemistry

An attempt was made to modify membranes for direct methanol fuel cells by blending Nafion or polystyrene sulfonic acid (PSSA) with polyvinylidene fluoride (PVDF) from their solutions. The proton conductivity and methanol barrier property as a function of the membrane compositions are discussed. Compared with the Nafion 117 membrane, the PVDF-Nafion blend membranes with 25 wt% of Nafion showed a decrease in the conductivity by about 2 orders of magnitude, and the methanol barrier properties increased about 3 orders of magnitude. If the ratio (σ/P) is adopted to characterize the performance of the membrane, the PVDF-PSSA and PVDF-Nafiion blend membranes …

Development Of 200～500 W Portable Proton Exchange Membrane Fuel Cell Power System, Li-Qing Hu, Li-Rong Zhou, Zheng Li, Jian-Wei Xia, Ming-Zhu Fu, Xin Wu, Yun Zhu

Journal of Electrochemistry

The Properties of the Portable PEM Fuel Cell Power Source are very unique compared with the common primary or rechargeable electro-chemical battery. This paper describes the In this work, of the 200～500 W portable PEM fuel cell power system, was developed. The system mainly composed of four subsystem: 1)Fuel cell stack; 2)Air delivery; 3)Hydrogen source; 4)Heat dissipation and system control.

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 …

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.

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 …