Materials Science and Engineering Commons^™

Evaluation Of A Threshold-Based Model Of The Elevated-Temperature Fatique Of Impact-Damaged Γ-Tial, Trevor S. Harding, J. Wayne Jones

Materials Engineering

Step-loading fatigue tests have been conducted on two γ-TiAl alloys with differing microstructures following quasi-static indentations intended to simulate assembly-related impact damage to low-pressure turbine blades. Fatigue tests were conducted at 600 °C using computer-controlled servohydraulic loading at a frequency of 20 Hz. Reasonably good agreement was achieved between the fatigue data and calculated fatigue strength based on the fatigue threshold and measured impact severity. In certain cases, the fatigue threshold model fails to completely describe the data. These discrepancies may be related to residual stresses, variations in crack-shape morphology, and small-crack effects. Residual stresses could not be directly measured, …

Lateral Migration Of A Solid Particle In Shear Flow, Wutthapong Jiraporncharoen

Masters Theses

Lateral migration of solid particles in shear flow is observed in various industrial applications. Suspensions in a blade coater, a device used to apply coating pigment to a base paper to improve paper properties, is an example. Particle hydrodynamics will affect the quality of coated paper and runnability of the coater especially when the speed of the coating machine is very high or the pigment concentration is increased.

Many factors will affect the particle migration. The wall repulsion or lubrication effect forces the particle away from a wall to the channel center. The inertial effects are increased by increasing the …

Corrosion Of Steel In Sea-Bottom Mud Of Nothern China Sea Area, Gong-Yu Guo, Jing-Lei Zhang, Bao-Rong Hou, Fang-Ying Yang

Journal of Electrochemistry

Corrosion experiments of A₃, 16Mn, 20^# as well as ZCE36-225 steel were carriedout in southern Bohai sea and Qingdao sea areas. The sea-bottom mud in southern Bohai sea areais the sandy mud and that in Qingdao sea area is pure beach sand. In this experiment, the compareing test of two modes with electric connected and non-electric connected modes was carriedout. The experiment results showed that: 1) The corrosion rate of steel in sea-bottom mud has astrong relation with mud types. The corrosion rates of steels in pure beach sand are much higherthan those in sandy mud. 2) …

Electrosynthesis Of A New Electroactive Poly(2,2'-Diaminophenyloxydisulfide), Yu-Zhi Su, Yan-Wen Rao, Ye Yang, Mei-Bing Chen, Yin-Ling Qiu, Yong-Hua Zhang, Ke-Cheng Gong

Journal of Electrochemistry

A new electroactive poly (2,2' diaminophenyloxydisulfide) (PDAPD) was successfully synthesized from acetonitrile(AN)/tetrahydrofuran (THF) solutions containing the supporting electrolyte (LiClO₄) and the various kinds of acids (HCl, CF₃COOH, CCl₃COOH) on Pt electrode by consecutive cyclic voltammiry. The effects of the concentrations of supporting electrolyte (LiClO₄) and acid (HCl, CF₃COOH, CCl₃COOH) on electrodepositon of PDAPD film were investigated. The best experimental conditions for electrosynthesis of a highly electroactive conducting polymer film are that the concentrations are 0.1 mol/L and between 0.05 mol/L～0.5 mol/L,respectively for LiClO₄ and HCl.

Studies On The Anti-Corrosion Behavior Of Corrosion Inhibitor To The Ship Building Steel In Moist Air, Yong-Tao Zhao, Jian-Hua Wu, Jia Wang

Journal of Electrochemistry

The anti corrosion behavior of 907A steel, which were covered with thin inibitor layers in moist air, were simulated, The electrochemical measurements, including EIS method and the coulostatic method, were used to atmospheric corrosion monitor (ACM) under thin inhibitor layers to study the mechanism of rust preventiion. the results shown that the mechanism of inhibiting corrosion was different from the steel immersed in inhibitor solutin, the anodic reaction process under thin inhibitor layers had the advantage over that of cathodic for blocking the speed of corrosion. At the later stage of soaking, the blend feature due to the electrochemical process …

The Investigation Of Prepare Condition For Micropores Membranes From Poly(Vinylidene Fluoride), Xu-Mei Ren, Feng Wu, Ying Bai, Hang-Jun Li, Xue-Jie Huang

Journal of Electrochemistry

The micropores membranes from Poly (vinylidene fluoride) were prepared by the phase inversion process. The effects of the casting solution composition, exposure time prior to coagulation and temperature of the coagulation bath on properties of prepared membranes were investigated. For all prepared membranes an asymmetric structure, sometimes without a dense skin layer, was observed.

An Investigation Of Structural Properties Of Li-Al-Mixed Doped Spinels Materials Li 1+XAlYMn Z-YO4, Zi-Shan Zheng, Zi-Long Tang, Zhong-Tai Zhang, Wan-Ci Sheng

Journal of Electrochemistry

Al and Li elements were co-doped into host spinel lithium manganese oxide by a simple and economical preparation technology. There was an investigation of the influence of doped Al contents on the initial capacity and cycling performance of the materials. The investigation of the XRD patterns, the analysis of the SEM micrographs and the determination of IR spectroscopy showed that the particles of dopant materials are fine, narrowly distributed and well crystallized, and the bonds Mn-O are stronger than these of undoped materials. The resulted materials have a high initial capacity of 119 mAh/g and good cycling characterization. The capacity …

Studies On The Properties Of The Anodic Films Formed On Lead- Lanthanum And Lead-Samarium Alloys In Sulfuric Acid Solution, Hou-Tian Liu, Chun-Xuao Yang, Hai-Heng Liang, Jiong Yang, Wei-Fang Zhou

Journal of Electrochemistry

AC voltammetry, linear sweep voltammetry, and cyclic voltammetry were applied to study the anodic corrosion of Pb, Pb-1.0 at% La and Pb-1.0 at% Sm electrodes in 4.5 mol·dm^-3 H₂SO₄ solution (25 ℃). The experiment results show that samarium can inhibit the anodic corrosion of lead and decrease the impedance of anodic Pb(Ⅱ) film. Lanthanum can also decrease the impedance of the anodic Pb(Ⅱ)film, but the effect is smaller.

The Research Of Organic Electrolyte Solutions For Li-Ion Batteries, Quang-Chao Zhuang, Shan Wu, Wen-Yuan Liu, Zhao-Da Lu

Journal of Electrochemistry

The characteristics of organic electrolyte solutions and its influences on the ion conductivity are summarized. The chemistry and electrochemistry of organic electrolyte solutions and characteristics of ordinary organic solvents are introduced. Progresses in studies of organic electrolyte solutions such as electrolyte salts, organic solvents, additives in recent years are reviewed, current situation of the studies of organic electrolyte solutions were also discussed.

New Progress Of Intrinsic Conducting Polymers' Application, Wan Chen, Cheng-Hao Liang, Yang Xie

Journal of Electrochemistry

As a kind of functional polymer, the intrinsic conducting polymer has the special chemical, electrochemical and optical properties. So it has wide application such as batteries, electromagnetic wave shielding, electroluminescent etc. Recent development and the problems of the intrinsic conducting polymers' application were briefly reviewed in this paper.

Thermal Effects On The Measurement Of Photocurrent At Anodic Films On Silver Electrode, Yuan Gu, Zhi-Yu Jiang

Journal of Electrochemistry

The influence of heat on the photocurrent of Ag electrde in alkaline solution was investigated by measuring photocurrent, photothermal signal and thermal current under the irraiation of laser beams with the wavelengths of 488 nm and 532 nm. It was found the photocurrent atthe Ag₂O film was influenced by the temperature change at the electrode surface under the irradiation of light. During the electrochemical transfer between Ag, Ag₂O and AgO in the anodic filmthe surface temperature changed obviously due to the different absprptance of the surface subrstances.It was suggested by comparing the voltammograms, photocurrent curves and …

Study Of Hydrogen Diffusion Behavior In Hydrogen Storage Alloy Mlni3.75Co0.65Mn0.4Al0.2 With Potential Step Method, Xian-Xia Yuan, Nai-Xin Xu

Journal of Electrochemistry

Potential step method was employed to study the hydrogen diffusion behavior in hydrogen storage alloy MlNi_3.75 Co_0.65Mn_0.4Al_0.2 with various depth of discharge (DOD) at ambient temperature and with 50% DOD at various temperatures. It was found that hydrogen diffusion cofficient in the hydrogen storage alloy increaes with the increase in DOD at ambient temperature. and for the alloy with 50% DOD, the hydrogen diffusion coefficient increases with the increase in temperature and the activation energy for hydrogen diffusion in the alloy is 19.87 kJ/mol.

Research Progress On Proton Exchange Membranes Of Fuel Cells, Jing-Rong Yu, Dan-Min Xing, Fu-Qiang Liu, Jian-Guo Liu, Bao-Lian Yi

Journal of Electrochemistry

The proton exchange membrane fuel cells (PEMFC) use proton exchange membranes(PEM) as their electrolytes. The performance of the PEMFC is strongly dependent on the characteristics of the PEM. In this paper, the requirements of the PEM utilized in the PEMFC were analyzed. The per-fluorinated, partially fluorinated and non-fluorinated PEM were introduced respectively. The structures, preparation, properties of the various types of PEM and their applications in the PEMFC were also discussed in detail.

The Influence Of Synthesis Conditions On The Electrochemical Properties Of Spinel Limn2O4, Jun-Feng Xu, Zhi-Yu Jiang

Journal of Electrochemistry

The electrochemical properties of spine LiMn₂O₄ synthesized via a solid state reaction were investigated. Electrolysis MnO₂(EMD), Li₂CO₃ ,LiOH and LiNO₃ were used as the initial materials. It was found that the electrochemical properties of LiMn₂O₄ were strongly influenced by the synthesis conditions. The LiMn₂O₄ sample sprepared via the reactionof EMD and LiNO₃ showed the best properties for a lithiumion intercalation reaction. The procedure includes two steps:pretreatment at 280 ℃ for 6 hours to initiate the permeation of melting LiNO₃ into the microporesof EMD …

Adsorption And Oxidation Of Methanol On Pt And Sb, S Modified Pt Electrodes Using Cyclic Voltammetry And Eqcm, Guo-Liang Chen, Sheng-Pei Chen, Heng Lin, Xing-Hong Zheng, Shi-Gang Sun

Journal of Electrochemistry

The processes of adsorption and oxidation of methanol on Pt, Pt/Sb ad and Pt/S ad electrodes were studied by using cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). The results demonstrated that the oxidation of methanol depends strongly on oxidation states of electrode surface. Sb adatoms on Pt surface can adsorb oxygen at relatively low potentials, and exhibit catalytic effects for methanol oxidation. In contrast to Pt electrodes, the oxidation peak potential of methanol in this case negatively shifted to about 130 mV. In a contrary, the oxidation of S_ad atoms consumes oxygen species of Pt electrode surface. As …

Study On Electrochemical Behavior Of Copper In Nh3 ·H2O Solution Medium Including K3[Fe(Cn)6] During Cmp, Yue-Hua Hu, Han-Wei He, Ke-Long Huang

Journal of Electrochemistry

Influence of medium pH value and passivator concentrations on the copper passivation and CMP process were studied by electrochemical measurement technologies, relations of the film thickness and tightness with polishing process and polishing rates were investigated. Electrochemical variables influencing polishing process and rates were found out. Electochemical mechanism of polishing processes were explained by corrosion potential and corrosion current density. A recipe of K₃[Fe(CN)₆] as passivator and nano sized γ-Al₂O₃ as abrasives in medium of NH₃·H₂O solution was confirmed reasonable. It is shown that the conditions of polishing process …

Study On The Anticorrosion Of Ld-2 Compound Inhibitor On Reinforcing Steel In Seawater, Rong-Gui Du, Zhou-Cheng Wang, Ruo-Shuang Huang, Rong-Gang Hu, Bing Zhao, Jian-Guang Tan, Chang-Jian Lin

Journal of Electrochemistry

The effect of LD-2 compound inhibitor developed in our laboratory on its anticorrosion action on the reinforcing steel in concrete immersed in seawater was shown in this paper. The corrosion behavior of the reinforcing steel in seawater was studied using electrochemical techniquesand immersion tests. The polarization curve of the reinforcing steel immersed in seawater showedthe free corrosion potential of the steel increased by 0. 220 V (vs. SCE), and the corrosion current decreased by two orders of magnitude by adding 25 g⋅L^-1 compound inhibitor to the seawater. The potentiodynamic anodic polarization curve of reinforcing steel in the seawater with …

Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials: Aaa Task-4 Quarterly (September 1 – November 30, 2001) 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: Task 10, First Quarter 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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Modeling, Fabrication, And Optimization Of Niobium Cavities – Phase I: Quarterly Progress Report August 20, 2001 - November 20, 2001, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Multipacting is one of the major loss mechanisms in rf superconductivity cavities for accelerators. This loss mechanism limits the maximum amount of energy/power supported by the cavities. Optimal designs have been identified in others’ studies. In practice, these designs are not easily manufactured. Chemical etching processes used to polish the cavity walls result in a nonuniform surface etch. A nonuniform surface etch will leave some unclean areas with contaminants and micron size particles. These significantly affect mutipacting. Further, a nonuniform etch will leave areas with damaged grain structure, which is not good for superconducting properties. Typically, the depth of chemical …

Electrical Activation Studies Of Ion Implanted Gallium Nitride, James A. Fellows

Theses and Dissertations

A comprehensive and systematic electrical activation study of Si-implanted GaN was performed as a function of ion implantation dose, anneal temperature, and implantation temperature. Additionally, Mg-implanted GaN was also investigated. Temperature-dependent Hall effect measurements and photoluminescence (PL) spectra were used to characterize the samples. GaN wafers capped with AlN were implanted with Si ions at doses ranging from 1x10¹³ to 5x10¹⁵ cm^-2 and annealed from 1050 to 1350 °C. The optimum anneal temperature for samples implanted with the higher Si doses is around 1350 °C, exhibiting nearly 100% electrical activation efficiency. Exceptional mobilities and carrier concentrations were …

Analysis Of Corrosion Of Steel By Lead Bismuth Eutectic, John Farley, Dale L. Perry

Transmutation Sciences Materials (TRP)

We examined stainless samples that were exposed to LBE in experiments conducted by the Russians, under contract to Los Alamos. We examined both corroded and uncorroded samples using the Scanning Electron Microscope (SEM), the Energy Dispersive X-Ray (EDAX) Spectroscopy, and the X-ray Photoelectron Spectrometer (XPS). We found that the surface of the corroded sample is covered by oxygen-containing compounds, presumably mostly iron oxide. In samples exposed for shorter times or lower temperatures, we found that some areas were covered by an oxide layer, and some areas was uncovered. We found that the level of Cr in the uncovered area is …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics: Quarterly Progress Report August 16,2001- November 15, 2001, 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. The transport of oxygen and corrosion products, their interaction and variation of corrosion/precipitation along the flow are not well understood.

The first subtask of this project involves using a …

Charge Fluctuations In Yba2cu3o6+X Superconductors, Herbert A. Mook, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Striped phases in which spin and charge separate into different regions in the material have been proposed to account for the unusual properties of the high-T_c cuprate superconductors. The driving force for a striped phase is the charge distribution, which self-organizes itself into linear regions. In the highest Tc materials such regions are not static but fluctuate in time. Neutrons, having no charge, cannot directly observe these fluctuations but they can be observed indirectly by their effect on the phonons. Neutron scattering measurements have been made using a specialized technique to study the phonon line shapes in four crystals …

A New Crystalline Phase (Na2o · 8teo2) In The Na2o-Teo2 System, Dongmei Zhu, Wancheng Zhou, C. S. Ray

Materials Science and Engineering Faculty Research & Creative Works

The formation and decomposition of NT8 crystal phase was investigated using differential scanning calorimetry (DSC) and x-ray diffraction analysis (XRD). DSC measurements indicated that all the glasses used in the investigation crystallized at about 330±5 °C. Results suggested that the NT₈ phase, which was very stable at 330 °C was not stable at or above 340 °C and readily decomposed to NT₄ and TeO₂.

Size-Induced Lattice Relaxation In Ceo₂ Nanoparticles, X.-D. Zhou, Wayne Huebner

Materials Science and Engineering Faculty Research & Creative Works

Size-induced lattice relaxation was observed for nanoscale CeO₂ single crystals with an average size from 4 to 60 nm. Results showed the finest crystallites exhibited no strain-induced line broadening, while high temperature annealing resulted in larger grain sizes and significant strains. The observed shift in the x-ray diffraction lattice parameters was assumed to be due to the formation of defects on the lattice, specifically oxygen vacancies. Modeling revealed that the oxygen vacancy concentration ([V^••_O]) was found to be ≈4 x 10²⁰/cm³ for the 4 nm crystallites, and decreased two orders of magnitude for …

Capillary Flow In Interior Corners: The Infinite Column, Mark M. Weislogel

Mechanical and Materials Engineering Faculty Publications and Presentations

Capillary flow of a sinusoidally perturbed liquid column in an interior corner of infinite extent is solved using lubrication theory. Due primarily to the length scales selected to nondimensionalize the momentum equation, an analytic time scale governing the settling of the perturbation is determined. The time scale, which is shown to be independent of a steady base state flow, proves useful in rapidly predicting transients for surface settling in certain liquid-bearing tanks of spacecraft employing interior corners for fluids management purposes. The asymptotic analysis is extended to address flows along interior corners whose faces are slightly nonplanar. The generalized formulation …

Silica-Based Membrane Sorbent For Heavy Metal Sequestration, Dibakar Bhattacharyya, Stephen M. Ritchie, Leonidas G. Bachas, Jamie A. Hestekin, Subhas K. Sikdar

Chemical and Materials Engineering Faculty Patents

An apparatus providing for metal ion/nitrate entrapment comprises a chemically activated, microfiltration, composite polymer and silica-based membrane including a polyamino acid attached thereto through reaction of a terminal amine group of the polyamino acid with the membrane. A method for preparing such a chemically activated or polyamino acid functionalized membrane includes the steps of permeating the silica-based membrane with a solution of silane and a solvent so as to react methoxy groups of the silane with silanol groups of the membrane to incorporate epoxide groups and attaching a polyamino acid to the membrane by reacting a terminal amine group of …

Ultrasonic Characterization Of Poling In Lead Zirconate Titanate Ceramics, James R. Friend, Eric Jamieson, Marvin Pennell, Wayne Huebner

Materials Science and Engineering Faculty Research & Creative Works

A method for measuring the spatial variation of the macroscopic poling state of a piezoelectric material using an ultrasonic transducer is described. The relatively simple method clearly indicates the distribution of poling within the material, demonstrated by the testing of a collection of partially poled lead zirconate titanate samples.

Highly Plasma Etch-Resistant Photoresist Composition Containing A Photosensitive Polymeric Titania Precursor, Tony D. Flaim, Douglas J. Guerrero, Michelle R. Fowler, William Joseph James, Vladimir Petrovsky, Harlan U. Anderson

Chemistry Faculty Research & Creative Works

A composition is derived from an addition polymerizable organotitanium polymer which upon exposure to an oxygen plasma or baking in air, is converted to titanium dioxide (titania) or is converted to a mixed, titanium-containing metal oxide. The metal oxide formed in situ imparts etch- resistant action to a patterned photoresist layer. The composition may also be directly deposited and patterned into permanent metal oxide device features by a photolithographic process.