Materials Science and Engineering Commons^™

Virtual Blasting System For Removal Of Coating And/Or Rust From A Virtual Surface, Michael Bolick, Chris Lampe, Jason Ebensberger, Jeremiah Treloar, Rick Klein, Eric Conrad Peterson, Chad Jason Zalkin

Patents (University of Northern Iowa)

A computer simulation and virtual reality system simulates the use of a blasting nozzle to remove one or more coatings and/or rust from a virtual surface. The user operates an electronic controller in the form of a blasting nozzle that outputs a signal indicating whether the blasting nozzle controller is in an "on" position or in an "off" position. The system also has a motion tracking system that tracks the position and orientation of the blasting nozzle controller with respect to the virtual surface defined on the display screen. Simulation software in a computer generates virtual blast pattern data, and …

Nanoindentation Of Annealed And As-Sputtered Thin Films Of Nickel Titanium Shape Memory Alloys, Matthew Tyson Lewis

Master's Theses

The bottom-up processing techniques used for making Microelectromechanical systems (MEMS) devices can produce material properties different from bulk processing. The material properties must be evaluated with the process parameters used and for changes in the process parameters. The mechanical properties are needed to design MEMS devices. A material of interest for MEMS devices is nickel titanium (NiTi) shape memory alloy (SMA) because of the high work output (~107 J/m3). This thesis will focus on the fabrication of thin film NiTi by DC magnetron sputtering deposition and testing mechanical properties of the fabricated films by nanoindentation. Thin film NiTi SMA was …

Effect Of Friction Stir Processing On Microstructure And Tensile Properties Of An Investment Cast Al-7si-0.6mg Alloy, Saumyadeep Jana, Rajiv S. Mishra, John A. Baumann, Glenn J. Grant

Materials Science and Engineering Faculty Research & Creative Works

Friction stir processing (FSP) is emerging as a promising tool for microstructural modification. the current study assesses the effects of FSP on the microstructure and mechanical properties of an investment cast Al-7Si-Mg alloy. FSP eliminates porosity and significantly refines eutectic Si particles. the extent of particle refinement varied with changes in processing conditions. a high tool rotation rate and a low-to-intermediate tool traverse speed generated a higher volume fraction of finer particles. Tensile ductility changed significantly as a result of FSP, whereas ultimate tensile strength improved only marginally. Yield strength was similar in both cast and FSP samples under various …

Thermodynamics Of Strained Vanadium Dioxide Single Crystals, Yijia Gu, Jinbo Cao, Junqiao Wu, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

Vanadium dioxide undergoes a metal-insulator transition, in which the strain condition plays an important role. To investigate the strain contribution, a phenomenological thermodynamic potential for the vanadium dioxide single crystal was constructed. The transformations under the uniaxial stress, wire, and thin film boundary conditions were analyzed, and the corresponding phase diagrams were constructed. The calculated phase diagrams agree well with existing experimental data, and show that the transformation temperature (and Curie temperature) strongly depends on the strain condition.

Complex Impedance Study Of Fine And Coarse Grain Tio2 Ceramics, Sheng Chao, Vladimir Petrovsky, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Titanium dioxide (TiO₂) ceramics with various grain sizes were investigated by impedance spectroscopy techniques. Dielectric loss peak identified in coarse grain TiO₂ was attributed to space charge polarization occurring at the grain boundaries. Electric modulus representation of the impedance data showed two types of relaxation processes in coarse grain TiO₂, whereas only one type was observed in fine grain TiO₂. Long-range migration of oxygen vacancies was found to be the dominant conduction mechanism for fine grain TiO₂, while electron hopping between localized states was attributed to dielectric relaxation in coarse grain …

Analysis Of Microstructural Evolution During Friction Stir Welding Of Ultrahigh-Strength Steel, M. Ghosh, K. Kumar, R. S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

Friction stirs lap-welded advanced high-strength M190 steel exhibited formation of lath martensite at weld nuggets, a ferrite layer at faying surfaces and a ferrite-pearlite microstructure at the bottom of the stir zone. the phase transformation was governed by severe plastic deformation in the austenitic region followed by cooling. the strain rate and peak temperature played key roles in controlling the prior-austenitic grain size and were correlated to the Zener-Hollomon parameter. an empirical relationship has been obtained for dynamically recrystallized austenite grains. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Plain And Steel-Reinforced Concrete Shear Walls With And Without Cfrp Retrofitting, Ali Mohammed Salih Al Aloosi

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the outcome- of a study of the behavior and strength of plain and steel-reinforced concrete shear walls with and without a window opening and Carbon Fiber-Reinforced Polymer (CFRP) retrofitting. A total of seven tests were conducted using six different shear walls. Each wall was subjected to a gradually increasing static load at one of it's top corners until the maximum load was reached. The load-deflection relations and the walls' failure patterns were observed and recorded. It was found that the window opening in the plain concrete wall reduced the wall load capacity by 18 percent. For the …

Measurement And Modeling Of Infrared Nonlinear Absorption Coefficients And Laser-Induced Damage Thresholds In Ge And Gasb, Torrey J. Wagner, Matthew J. Bohn, Ronald A. Coutu Jr., L. P. Gonzales, J. M. Murray, K. L. Schepler, S. Guha

Faculty Publications

Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, we measure two-photon and free-carrier absorption coefficients for Ge and GaSb at 2.05 and 2.5 µm for the first time, to our knowledge. Results agreed well with published theory. Single-shot damage thresholds were also measured at 2.5 µm and agreed well with modeled thresholds using experimentally determined parameters including nonlinear absorption coefficients and temperature dependent linear absorption. The damage threshold for a single-layer Al₂O₃ anti-reflective coating on Ge was 55% or 35% lower than the uncoated threshold for picosecond or nanosecond …

Programmable Periodicity Of Quantum Dot Arrays With Dna Origami Nanotubes, Hieu Bui, Craig Onodera, Carson Kidwell, Yerpeng Tan, Elton Graugnard, Wan Kuang, Jeunghoon Lee, William B. Knowlton, Bernard Yurke, William L. Hughes

Materials Science and Engineering Faculty Publications and Presentations

To fabricate quantum dot arrays with programmable periodicity, functionalized DNA origami nanotubes were developed. Selected DNA staple strands were biotin-labeled to form periodic binding sites for streptavidin-conjugated quantum dots. Successful formation of arrays with periods of 43 and 71 nm demonstrates precise, programmable, large-scale nanoparticle patterning; however, limitations in array periodicity were also observed. Statistical analysis of AFM images revealed evidence for steric hindrance or site bridging that limited the minimum array periodicity.

Po2 Dependant Resistance Switch Effect In Highly Epitaxial (Laba)Co2o5+[Delta] Thin Films, Jian Liu, Gregory Collins, Ming Liu, C L. Chen, Jiechao Jiang, Efsftathios Meletis, Qingyu Zhang, Chuang Dong

Material Science and Engineering Faculty Publications - Archive

Giant resistance switching behavior in mixed conductive LaBaCo2O5+ epitaxial thin film were discovered in high temperature and reducing environments during the reduction and reoxidation process. A reproducible resistance response of over 99% was achieved in the films during a change of 4% H2 /96% N2 to oxygen at temperature range of 400– 780 °C. The results indicate that at, low oxygen partial pressure, the extension of oxygen deficiency is an essential factor to the high temperature physical properties of LaBaCo2O5+ and demonstrates its potential application as a chemical sensor device for reducing environments at high temperature. © 2010 American Institute …

All Solid-State Mid-Ir Laser Development, Nonlinear Absorption Investigation And Laser-Induced Damage Study, Torrey J. Wagner

Theses and Dissertations

In this research, nonlinear optical absorption coefficients and laser-induced damage thresholds are measured in Ge and GaSb, which are materials that are used in IR detectors. Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, two-photon and free-carrier absorption coefficients are measured in Ge and GaSb at 2.05 and 2.5 μm for the first time. At these wavelengths, nonlinear absorption is the primary damage mechanism, and damage thresholds at picosecond and nanosecond pulse widths were measured and agreed well with modeled thresholds using experimentally measured parameters. The damage threshold for a single-layer Al …

Kinetics Of Dna And Rna Hybridization In Serum And Serum-Sds, Elton Graugnard, Amber Cox, Jeunghoon Lee, Cheryl Jorcyk, Bernard Yurke, William L. Hughes

Materials Science and Engineering Faculty Publications and Presentations

Cancer is recognized as a serious health challenge both in the United States and throughout the world. While early detection and diagnosis of cancer leads to decreased mortality rates, current screening methods require significant time and costly equipment. Recently, increased levels of certain micro-ribonucleic acids (miRNAs) in the blood have been linked to the presence of cancer. While blood-based biomarkers have been used for years in cancer detection, studies analyzing trace amounts of miRNAs in blood and serum samples are just the beginning. Recent developments in deoxyribonucleic acid (DNA) nanotechnology and DNA computing have shown that it is possible to …

Coated Steel Rebar For Enhanced Concrete-Steel Bond Strength And Corrosion Resistance, Genda Chen, Jeffery S. Volz, Richard K. Brow, Dongming Yan, Signo Tadeu Dos Reis, Chenglin Wu, Fujian Tang, Charles R. Werner, Xing Tao

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This report summarizes the findings and recommendations on the use of enamel coating in reinforced concrete structures both for bond strength and corrosion resistance of steel rebar. Extensive laboratory tests were conducted to characterize the properties of one- and two-layer enamel coatings. Pseudostatic tests were performed with pullout, beam and column specimens to characterize mechanical properties and develop design equations for the development length of steel rebar in lap splice and anchorage areas. The splice length equation was validated with the testing of large-scale columns under cyclic loading. For corrosion properties, ponding, salt spray, accelerated corrosion, potentiodynamic and electrochemical impedance …

Manipulation Of Suspended Single Cells By Microfluidics And Optical Tweezers, Nathalie Neve De Mevergnies, Sean S. Kohles, Shelley R. Winn, Derek C. Tretheway

Mechanical and Materials Engineering Faculty Publications and Presentations

Chondrocytes and osteoblasts experience multiple stresses in vivo. The optimum mechanical conditions for cell health are not fully understood. This paper describes the optical and microfluidic mechanical manipulation of single suspended cells enabled by the μPIVOT, an integrated micron resolution particle image velocimeter (μPIV) and dual optical tweezers instrument (OT). In this study, we examine the viability and trap stiffness of cartilage cells, identify the maximum fluid-induced stresses possible in uniform and extensional flows, and compare the deformation characteristics of bone and muscle cells. These results indicate cell photodamage of chondrocytes is negligible for at least 20 min for laser …

The Electronic Structure And Secondary Pyroelectric Properties Of Lithium Tetraborate, Volodymyr T. Adamiv, Yaroslav V. Burak, David J. Wooten, John W. Mcclory, James C. Petrosky, Ihor Ketsman, Ya B. Losovyj, Peter A. Dowben, Jie Xiao

Faculty Publications

We review the pyroelectric properties and electronic structure of Li₂B₄O₇(110) and Li₂B₄O₇(100) surfaces. There is evidence for a pyroelectric current along the [110] direction of stoichiometric Li₂B₄O₇ so that the pyroelectric coefficient is nonzero but roughly 10³ smaller than along the [001] direction of spontaneous polarization. Abrupt decreases in the pyroelectric coefficient along the [110] direction can be correlated with anomalies in the elastic stiffness contributing to the concept that the pyroelectric coefficient is not simply a vector but has qualities of …

Atomic And Electronic Structure Studies Of Nano-Structured Systems : Carbon And Related Materials, Sumit Saxena

Dissertations

Modeling in the framework of density functional theory has been conducted on carbon nanotubes and graphene nano-structures. The results have been extended to non-carbon systems such as boron nanostructures. Computational studies are complemented by experimental methods to refine the structural models and obtain a better understanding of the electronic structure.

It is observed that the zigzag edged bilayered graphene nanoribbons are highly unstable as compared to their armchair counterparts. A novel approach has been proposed for the patterning of chirality/diameter controlled single walled carbon nanotubes. Nanotube formation is found to be assisted by edge ripples along with the intrinsic edge …

The Mechanism Of 13CoAd/12Co Isotope Exchange At Pt Electrode,A Combined Study By Electrochemical In-Situ Infrared Spectroscopy And Dipole-Dipole Coupling Analysis, Sang-Zi Liang, Shao-Xiong Liu, Ling-Wen Liao, Qian Tao, Jing Kang, Yan-Xia Chen

Journal of Electrochemistry

In this contribution,we have analyzed the IR spectra of saturated CO adlayer at rough Pt film electrode as a function of fractional surface coverage of ¹³CO_ad /¹²CO recorded during ¹³CO_ad /¹²CO isotope exchange process according to dipole-dipole coupling theory and coherent potential approximation. By properly choosing the parameters of adlayer structure and dipole-dipole coupling interaction under coherent potential approximation, we demonstrated that we can successfully simulate the IR spectra as a function of the surface coverage of CO adlayer at rough Pt film electrodes by assuming that CO_ad molecules with low …

An In Situ Fourier Transform Infrared Spectroelectrochemical Study On Alcohols Electrocatalytic Oxidation At Pd Electrode In Acidic Solution, Hai-Ping Huang, Lian-Qin Wang, Pei-Kang Shen

Journal of Electrochemistry

The methanol and ethylene glycol electrooxidation on palladium electrode in acidic solution has been investigated by cyclic voltammetry and in situ Fourier transform infrared spectroelectrochemistry. It shows that the oxidation of methanol and ethylene glycol at Pd electrode cannot proceed until over 1.5 V in acidic and neutral media. The overpotential decreases and the peak current density increases with the reduction in pH values. The formation of the oxygen-containing species significantly affects the alcohol oxidation on Pd electrode. The in situ FTIR spectroscopic measurements show that the oxidation products of ethylene glycol on Pd electrode are CO₂ and oxalic …

In-Situ Surface Enhanced Raman Scattering Electrochemical Investigation Of 4-Aminoantipyrine On Silver Electrode, Li-Jun Zhang, Wei Song, Ling Chen, Zong-Rang Zhang, Hai-Feng Yang

Journal of Electrochemistry

In this paper, 4-AAP was self-assembled on silver surface to form monolayers. Surface-enhanced Raman Spectroscopy (SERS) was used to in-situ investigate the adsorption mechanism of the 4-aminoantipyrine(4-AAP) on silver surface dependent on shifting potentials and the effect of solution pH. Based on density functional theory(DFT) calculation of vibration modes,approximate assignment of 4-AAP SERS spectrum was conducted. In situ SERS spectral electrochemical experiments indicated that the 4-AAP monolayers experience a dynamic adsorption process from a tilted fashion to a more vertical mode for benzene ring and more parallel for pyrine ring with the potential applied toward more negative voltages. The complete …

Electrooxidation Of Carbon Monoxide On Pd Thin Film-Coated Au Electrodes: Film Thickness Dependence, Yuqing Yang, Shouzhong Zou

Journal of Electrochemistry

The adsorption and electrooxidation of CO on Pd-coated Au electrodes were studied by cyclic voltammetry and surface-enhanced Raman spectroscopy (SERS) . It is found that CO oxidation activity is film thickness dependent. Cyclic voltammograms (CVs) showed that CO oxidation peak potential shifted positively with the increase of the Pd thickness. SERS showed a redshift of the C—O stretching frequency with increasing Pd film thickness. These observations were explained by the dband theory. The strain effect strengthens CO adsorption and stabilizes adsorbed CO,while the ligand effect weakens CO adsorption and eases its oxidation. The ligand effect overpowers the strain effect.