Materials Science and Engineering Commons^™

Effect Of Chloride Ions On The Corrosion Behavior Of Reinforcing Steel In Simulated Concrete Pore Solutions, Yu Liu, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

The potentiodynamic anodic polarization was used to study the corrosion behavior of the reinforcing steel in simulated concrete pore solutions with different pH and chloride ion concentrations. The effect of chloride ions on passivity breakdown of the steel was examined by measuring the breaking potentials of reinforcing steel, and the critical chloride concentrations for depassivation were found in simulated concrete pore solutions at pH 12.50 and pH 12.00.

Effect Of Sintering Temperatures On Synthesis Of Mgco0.4Mn1.6O4 Positive Materials In Magnesium Ion Battery, Xiu-Ling Gao, Li-Fang Jiao, Hua-Tang Yuan, Jian-Sheng Cao, Ming Zhao, Hai-Xia Li, Yong-Mei Wang

Journal of Electrochemistry

The cathode material MgCo_0.4Mn_1.6O₄ for magnesium ion battery was synthesized by sol-gel method. The TG-DTA and XRD analyses showed that the prepared samples has simple spinel structure. Effect of annealing temperature on electrochemical properties was researched. The result shows that the sample sintered at 700℃ has the best electrochemical properties.

Electrochemical Reduction Characteristics Of Nitrobenzene At The Copper Electrode, Jin-Hong Fan, Wen-Ying Xu, Ting-Yao Gao

Journal of Electrochemistry

The electrochemical reduction characteristics and transition steps of nitrobenzene aqueous solution at the copper electrode, as well as its reduction mechanism were extensively investigatedby using the techniques such as cyclic voltammetry (CV) and linear scan voltammetry (LSV). The results showed that the reduction peaks of nitrobenzene at the copper electrode were located at 0.58 V and 1.32 V or so (vs. SCE), both acidity and alkalinesolutionsfavoredthe reduction of nitrobenzene. The adsorption of compounds followed by the reduction process, which is controlled by the mass transfer step at higher nitrobenzene concentration. In addition, the higher anaerobic degree led to faster reduction …

Modular Communication System, Stephen O. Bozzone, Bonnie Bachman, Ryan Nilsen

Economics Faculty Research & Creative Works

A modular communication system (10) can include an adaptable communication module (12) having a transceiver (13) coupled to a processor (14) and memory (20), and a first interface block (24) coupled to the processor, and a host device (30) having a power source (36), a user interface (34), and a second interface block (46). The host device can be among a plurality of host devices having different user interfaces and the processor is adaptable to control the different user interfaces when the first interface block recognizes the second interface block. The module can further include a DSP (16) and a …

Freeze-Form Extrusion Fabrication Of Ceramics, Tieshu Huang, Michael S. Mason, Greg Hilmas, Ming-Chuan Leu

Materials Science and Engineering Faculty Research & Creative Works

A novel, environmentally friendly solid freeform fabrication method called Freeze-form Extrusion Fabrication (FEF) has been developed for the fabrication of ceramic-based components. The method is based on deposition of ceramic pastes using water as the media. The ceramic solids loading can be 50 vol. % or higher and initial studies have focused on the use of aluminum oxide (Al₂O₃). The FEF system components and their interaction are examined, and the main process parameters affecting part geometry defined. 3-D shaped components have been fabricated by extrusion deposition of the ceramic paste in a layer-by-layer fashion. The feasibility …

Integral Channels In Metal Components And Fabrication Thereof, Rajiv S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

An internal channel in a metal body for use in applications where internal fluid flow within a metal body is desired, as in a heat exchanger. The internal channel is formed in the metal body by frictionally stirring with a pin plunged into the metal body, and traversing the metal body with the pin.

Piezoelectric Micropump For Drug Delivery Application, Miteshkumar Sureshchandra Joshi

Material Science and Engineering Theses - Archive

Bending type actuators providing high displacement (~1mm) with low blocking force (~0.5N) and the stack actuators providing low displacement (~1m) with high blocking force (~1kN) represent the extreme ends of the current piezoelectric actuation technology. In the intermediate range there is deficiency of the actuator designs that provide high displacement with high blocking force in low frequency range of ~2 kHz. This thesis addresses this issue and describes a metal-ceramic actuator design that exhibits high displacement with high blocking force. The structure consist of a piezoelectric bar poled along the length and metal caps were attached to the two opposite …

Piezoelectric Analysis For Hetrogeneous Medium, Solmaz Torabi

Material Science and Engineering Theses - Archive

In the recent years, several types of piezocomposites have been fabricated since they have provided material properties superior to conventional piezoelectric materials. In order to design these composites, it is essential to find the elastic and electric fields for their different parts, as well as the effective properties of the composite. In the present study, the analytical approach based on the extension of Eshelby's theory in piezoelectricity and the numerical approach based on FEM modeling and ANSYS software have been used to find these elastic and electric fields inside the piezoceramic inhomogeneity for two different piezocomposite according to their connectivity, …

Journal Of Materials Engineering And Performance: Editorial, C. Suryanarayana, Leon L. Shaw, Rajiv S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Domain-Wall Magnetoresistance Of Co Nanowires, Renat F. Sabiryanov, Ashok K. Solanki, John D. Burton, Sitaram Jaswal, Evgeny Y. Tsymbal

Materials Research Science and Engineering Center: Faculty Publications

Using density functional theory implemented within a tight-binding linear muffin-tin orbital method we perform calculations of electronic, magnetic, and transport properties of ferromagnetic free-standing fcc Co wires with diameters up to 1.5 nm. We show that finite-size effects play an important role in these nanowires resulting in oscillatory behavior of electronic charge and the magnetization as a function of the wire thickness, and a nonmonotonic behavior of spin-dependent quantized conductance. We calculate the magnetoresistance (MR) of a domain wall (DW) modeled by a spin-spiral region of finite width sandwiched between two semi-infinite Co wire leads. We find that the DW …

Cathodic Electrodeposition Of Cadmium Oxide, Zinc Oxide And Mixed Cadmium Oxide-Zinc Oxide Thin Films, Ashwin Seshadri

Material Science and Engineering Theses - Archive

Cadmium oxide (CdO) and (CdO)x(ZnO)1-x mixed semiconductor films were cathodically electrodeposited for the first time on F-doped SnO2 substrates. The CdO thin films were deposited from an aqueous 0.1 M KCl medium containing dissolved Cd2+ species and O2. The (CdO)x(ZnO)1-x mixed oxide films were deposited from a bath which contained Zn2+ in addition to the CdO bath constituents. Films were potentiostatically deposited at 80 0C followed by a post-deposition thermal anneal at 450 0C. The mechanism of the electrodeposition was explored using cyclic voltammetry. These samples were then analyzed by X-ray diffraction, scanning electron microscopy, and UV-visible reflectance spectrophotometry. The …

Modeling, Fabrication, And Optimization Of Niobium Cavities Final Phase: Final Report, Robert A. Schill Jr., Mohamed Trabia, William Culbreth

Transmutation Sciences Materials (TRP)

This final report provides the activities and accomplishments of Modeling, Fabrication, and Optimization of Niobium Cavities – Final Phase. The fluid flow experiments for the etching of the superconducting cavity walls and baffle designs of phase II of the three phases has been completed leading to a MS thesis in December of 2003. Designing the experimental setup of secondary electron emission was well underway in early summer of 2003 when funding was made available for this portion of the study. By March 2004, many of the components of the experimental study reached UNLV with some assembly accomplished. The first secondary …

47th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 47th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-endorsed by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 31 - August 4, 2005.

High Temperature Heat Exchanger Project: Quarterly Progress Report April 1, 2005 Through June 30, 2005, Anthony Hechanova

Publications (NSTD)

Quarterly Collaboration Meeting. General Atomics hosted a UNLVRF HTHX Project quarterly meeting on June 5 in San Diego, California. The purpose of the meeting was to promote collaboration and communication among the UNLV Research Foundation partners. Collaborators had the opportunity to discuss their research program plan and update their progress. The next meeting will be in September in Berkeley hosted by UC Berkeley.

HTHX Computational Design (UNLV). Work on optimizing the ceramic offset strip in compact HTHX design through parametric studies was performed and completed. A simple single channel model was used to perform parametric studies on dimensions and flow …

Use Of Positron Annihilation Spectroscopy For Stress-Strain Measurements: Quarterly Progress Report (March – May 2005), Ajit K. Roy

Transmutation Sciences Materials (TRP)

Accomplishments:

● Analyses of defects (dislocations) in martensitic Alloy EP-823, cold-reduced to different levels, have been performed by using transmission electron microscopy. The dislocation density has been related to the degree of cold-reduction and residual stress in terms of a line-shape parameter determined by the positron annihilation spectroscopy (PAS).

● Additional PAS measurements are ongoing on tensile, welded and cold-worked specimens of Alloys EP-823 and HT-9 at the Idaho Accelerator Center of ISU. Both Subhra and Silpa are involved in these measurements.

● Silpa is performing neutron diffraction (ND) measurements at the Atomic Energy of Canada Limited (AECL), Chalk River …

Sub-Surface Corrosion Research On Rock Bolt System, Perforated Ss Sheets And Steel Sets For The Yucca Mountain Repository — Quarterly Technical Report No. 4, Dhanesh Chandra, Jaak J.K. Daemen

Publications (YM)

This report encompasses the work done for this third quarter, 2005, in accordance to cooperative agreement of University of Nevada system for the Task 019 “Subsurface Corrosion Research on Rock Bolt System, Perforated SS Sheets and Steel Sets for the Yucca Mountain Repository”, the overall objective of which is to conduct corrosion research and predict the durability of rock-bolts and other underground metallic roof supports. We have started oxidation tests using Thermogravimetric Analyzer (TGA), and Potentiodynamic tests to determine the corrosion rates of rock bolts, other support materials including bench mark materials. In this quarter, we have also performed hydrogen …

Effect Of Silicon Content On The Corrosion Resistance And Radiation-Induced Embrittlement Of Materials For Advanced Heavy Liquid Metal Nuclear Systems: Quarterly Progress Report (February – April 2005), Ajit K. Roy

Transmutation Sciences Materials (TRP)

This proposal is intended to study the effect of Si content not only on the corrosion resistance but also on the radiation-induced embrittlement of martensitic stainless steels. The susceptibility of these alloys with different Si content to stress corrosion cracking, general corrosion and localized corrosion will be evaluated in the molten LBE and aqueous environments of different pH values using state-of-the-art testing techniques. Testing in the aqueous media is intended to develop baseline data for comparison purpose. Radiation-induced embrittlement of these alloys will initially be studied by irradiating the test specimens with bremmstrahlung gamma radiation from 20-40 MeV electron beams …

Giant Electroresistance In Ferroelectric Tunnel Junctions, Mikhail Ye Zhuravlev, Renat F. Sabirianov, Sitaram Jaswal, Evgeny Y. Tsymbal

Materials Research Science and Engineering Center: Faculty Publications

The interplay between the electron transport in metal-ferroelectric-metal junctions with ultrathin ferroelectric barriers and the polarization state of a barrier is investigated. Using a model which takes into account screening of polarization charges in metallic electrodes and direct quantum tunneling across a ferroelectric barrier, we calculate the change in the tunneling conductance associated with the polarization switching. We find the conductance change of a few orders of magnitude for metallic electrodes with significantly different screening lengths. This giant electroresistance effect is the consequence of a different potential profile seen by transport electrons for the two opposite polarization orientations.

Strain Induced Half-Metal To Semiconductor Transition In Gdn, Chun-Gang Duan, Renat F. Sabirianov, Jianjun Liu, Wai-Ning Mei, Peter A. Dowben, J. R. Hardy

Materials Research Science and Engineering Center: Faculty Publications

We investigate the electronic structure and magnetic properties of GdN as a function of unit cell volume. Based on the first-principles calculations of GdN, we observe that there is a transformation in the conduction properties associated with the volume increase: first from half-metallic to semimetallic, then ultimately to semiconducting. We show that applying stress can alter the carrier concentration as well as mobility of the holes and electrons in the majority spin channel. In addition, we found that the exchange parameters depend strongly on lattice constant, thus the Curie temperature of this system can be enhanced by applying stress or …

Passport To The Materials World: Materials Engineering Outreach Activities, Katherine C. Chen, Lisa Christensen, Amanda Runciman

Materials Engineering

No abstract provided.

Method And Sealant For Weld Joints, David C. Van Aken, John A. Baumann, Richard J. Lederich, Rajesh Talwar

Materials Science and Engineering Faculty Research & Creative Works

A sealant for a weld joint and an associated weld joint and method are provided. The sealant includes aluminum and germanium and is characterized by a melting temperature that is lower than the melting temperature of the structural member that is joined. The sealant, which is disposed between faying surfaces of the structural members, can fill the spaces between the structural members to prevent the entry of chemicals, moisture, debris, and other substances, thereby reducing the likelihood of corrosion of the joint or structural members at the interface. Further, the sealant can be diffusion bonded to the faying surfaces, for …

Development Of Project-Based Introductory To Materials Engineering Modules, Stacy Gleixner, Elliot Douglas, Olivia Graeve, Hilary Lackritz, Laura Demsetz, Amy Moll

Faculty Publications

This paper will discuss the progress of curriculum development under an NSF, CCLI-EMD sponsored work, “Development of Project-Based Introductory to Materials Engineering Modules” (DUE # #0341633). A multi-university team of faculty are developing six lecture and three laboratory modules for use in Introductory to Materials courses. This course is required by most engineering programs in the U.S., with an annual enrollment of 50,000 students. This freshman/ sophomore class is an ideal place to excite students about their engineering majors and expose them to engineering design experiences. PRIME Modules, Project Based Resources for Introduction to Materials Engineering, are being developed that …

Design, Fabrication, And Characterization Of An Electrostatically Actuated Microfluidic Valve, Ryan Dale Rivers

Master's Theses

Microfluidic device construction uses certain critical structures throughout many different applications. The valve structure remains one of the primary structures that present a barrier to miniaturization and portability. The extensive support devices required to power common microfluidic valves remove a significant amount of freedom from microfluidic device design. Moving to electrostatic methods of actuation could reduce the overall footprint of the microfluidic valve. This thesis covers three concept prototypes. Concept I presents an attempt at inlaying gold electrodes into polydimethylsiloxane substrates. Concept II attempts to use liquid silver injected into channels as electrode materials. Concept III uses aluminum sputtering to …

Positive Spin Polarization In Co/Alo3 /Co Tunnel Junctions Driven By Oxygen Adsorption, Kirill D. Belashchenko, Evgeny Y. Tsymbal, Ivan I. Oleynik, Mark Van Schilfgaarde

Materials Research Science and Engineering Center: Faculty Publications

Using a first-principles Green's function technique, we study spin-dependent tunneling in two model realizations of (111) fcc Co/Al3/Co tunnel junctions assuming O-terminated crystalline epitaxy in the corundum structure. For the first model, which includes 3 O atoms at the interface, the tunneling current is polarized negatively, just as for the clean Co surface. The second model contains additional oxygen atoms inside large pores at each interface. Located at the three-fold hollow adsorption sites, these O atoms bind very strongly to Co. This bonding creates an interface band in the majority-spin channel which strongly enhances the tunneling current in this channel. …

Dynamic Matrix Composition In Engineered Cartilage With Stochastic Supplementation Of Growth Factors, Asit K. Saha, J. (Jagannath) Mazumdar, Sean S. Kohles

Mechanical and Materials Engineering Faculty Publications and Presentations

Dynamic extracellular matrix (ECM) synthesis is explored in a hypothesized engineered cartilage construct. Growth (α) and decay (β) rate parameters are developed from a previous engineered cartilage model. The presented mathematical model was constructed from the parameterized experimental data using a deterministic and stochastic examination of ECM synthesis based on a negative feedback control mechanism. A growth factor supplementation is incorporated in a probabilistic mathematical approach. The growth factor component modified an initial deterministic model through a Gaussian white noise fluctuation. As the primary constituents of ECM, the mathematical tool is intended to characterize the probable steady state distribution of …

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix: Quarterly Report, April 2005 To June 2005, Earl Wolfram, Thomas Hartmann, Kenneth Czerwinski

Fuels Campaign (TRP)

This project will examine inert matrix fuels containing ZrO₂ and MgO as the inert matrix, with the relative amount of MgO varied from 30% to 70% in ZrO₂. Reactor physics calculations will be used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf with reactor grade Pu providing the fissile component, with up to 10 % of ²³⁹Pu. Ceramics will be synthesized and characterized based on the reactor physics results. The solubility the fuel ceramics, in reactor conditions, reprocessing conditions, and repository conditions, will be investigated in a manner to …

Determination Of The Constitutive Equations For 1080 Steel And Vascomax 300, Zachary A. Kennan

Theses and Dissertations

The objective of this research is to establish a better representation of the components utilized in a gouging event being considered in research leading to a better understanding of the Holloman High Speed Test Track. Gouging occurs when two metals are traveling at a slight incline to each other at velocities nearing 1.5 kilometers per second, and results in a structural failure of both the metals. The gouging process occurs at very high strain rates, which results in non-linear stress-strain relations. The coefficients that lead to the Johnson-Cook equations have been determined by the Split Hopkinson Bar test for 1080 …

High Temperature Chemical Degradation Of Pmr-15 Polymer Resins, Grant W. Robinson

Theses and Dissertations

PMR-15 is a polymer resin for glass and carbon reinforced composites used for high temperature, civilian and military aerospace applications. The harsh environments of PMR-15 applications lead to long term structural degradation and, in turn, impact the readiness capabilities of the system. This study investigated the thermal and oxidative degradation of PMR-15 neat resin powder through the use of thermal gravimetric analysis (TGA) in oxygen, argon and air at isothermal hold temperatures of 260, 288, 316, and 343 °C for 250 hours. The TGA measured the degradation by recording the change in neat resin powder mass versus time. The qualitative …

Nanostructured Composite Materials Based On Carbon Nanotubes And 3-D Photonic Crystals, Jing Chen

Dissertations

Carbon nanotubes (CNT) and in particular, single-wall carbon nanotubes (SWCNT) have been extensively studied, in large part, due to their unique one-dimensional crystalline structures and related electronic and optical properties. Various polymeric composite materials, which were based on carbon nanotubes, have been also developed in an attempt to combine the properties of polymer and CNT in a single film. Such composites were mainly formed by mixing carbon nanotubes within the polymer without special emphasis on the structure and thereby, the nanoscopic properties of the resultant material.

Photonic crystals belong to a class of man-made structures aimed at manipulating the propagation …

Study On Synthesis Of M-Phenoxy Benzoic Acid By Electrolysis Oxidation Method, Wei Xu, Chong-Tao Zhao

Journal of Electrochemistry

The m-phenoxy benzoic acid was synthesized by oxidation m-phenoxy toluene using Cr(Ⅵ)as oxidation media, which was prepared by electrolysis oxidation of Cr(Ⅲ)in the electrochemical bath using Nafion 417 as a diaphragm, Pb-PbO₂ as an anode and Pb as cathode. The effect factors on the electrochemical oxidation of Cr(Ⅲ)to Cr(Ⅵ)in this electrolysis were studied. Furthermore, the optimal conditions for electronic synthesis of m-phenoxy benzoic acid were also discussed.