Materials Science and Engineering Commons^™

Preparation And Electrochemical Performance Of Hollow Carbon Spheres/Sulfur Composite, Jun Zang, Hang Qian, Er-Man Zeng, Juan-Ni Fu, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

Hollow carbon spheres were prepared by the PMMA template. Hollow carbon spheres/sulfur composite was made from sulfur and hollow carbon spheres as a conducting framework. The results of SEM and TEM showed that sulfur was uniformly filled in both of the shell and hollow core of hollow carbon spheres. The electrochemical performance of hollow carbon spheres/sulfur composite was characterized by the charge/discharge method. The results showed the excellent rate and cycle performance of hollow carbon spheres/sulfur composite. The reversible capacities of hollow carbon spheres/sulfur composite are 1145 mAh·g^-1, 824 mAh·g^-1, 702 mAh·g^-1, 586 mAh·g …

Fabrication And Performance Of Lani0.6Fe0.4O3-δCathode Modified By Coating With Gd0.2Ce0.8O2 For Intermediate Temperature Solid Oxide Fuel Cell, Rui-Xuan Ren, Bo Huang, Xin-Jian Zhu, Yi-Xing Hu, Xiao-Yi Ding, Zong-Yao Liu, Ye-Bin Liu

Journal of Electrochemistry

The symmetric cell of LaNi_0.6Fe_0.4O_3-δ/Sc_0.1Zr_0.9O_1.95/LaNi_0.6Fe_0.4O _3-δ was fabricated with screen printing method. A LaNi_0.6Fe_0.4O_3-δ (LNF) cathode was modified by coating with nano-sized gadolinium-doped ceria (GDC, Gd_0.2Ce_0.8O₂) prepared using a simple combustion process within the pores of the cathode. According to the electrochemical impedance spectra (EIS), the polarization resistance of the pure LNF was 0.70 W·cm² at 750 ºC, while 0.13 W·cm² for the 21.3% GDC (by mass)-coated LNF cathode at the …

Polypyrrole-Transition Metal-Oxygen Coordination Complexes As High Performance Lithium Storage Material, Ya Mao, Qingyu Kong, Bingkun Guo, Zhaoxiang Wang, Liquan Chen

Journal of Electrochemistry

No abstract provided.

Influence Of Electrode Hydrophobicity On Performance Of Alkaline Polymer Electrolyte Fuel Cells, Li-Sheng Tan, Jing Pan, Yao Li, Lin Zhuang, Jun-Tao Lu

Journal of Electrochemistry

In the present work, we study the influence of the electrode hydrophobicity on the performance of alkaline polymer electrolyte fuel cells (APEFCs). QAPS or xQAPS is employed as the membrane and the ionomer, while PTFE is used as a hydrophobic additive in order to adjust the electrode hydrophobicity. We find that enhancing the hydrophobicity of anode can promote the performance of APEFCs, while a moderate hydrophobicity of cathode is required to achieve optimal performance. By using xQAPS as the electrolyte and adding some PTFE in the anode, a peak power density of 132 mW·cm^-2 can be obtained at a …

Progress Of Lithium Rich Cathode Materials For Li-Ion Batteries, Jie Zhang, Jiu-Lin Wang, Jun Yang

Journal of Electrochemistry

Lithium rich materials xLi₂MnO₃·(1-x)LiMO₂ (0-1 and low cost. However, the large irreversible capacity during the first cycle, low rate capability and structure collapse during cycling remain impediments in developing these cathodes for applications. The structure analyses and charge/discharge mechanisms for lithium rich materials are currently main research contents. Although whether the lithium rich materials are solid solutions or composite is still controversial, oxygen release mechanism on the first charge 4.5 V plateau of lithium rich materials has come to consistency. Several modifications, such as bulk doping, surface coating and microstructure control, demonstrate promising strategies to …

Electrochemical Performance Of Al-Doped Spinel Limn2O4 Cathode Material For Li-Ion Batteries, Yong-Long Wang, Wen-Ge Wang, Qian Zhang, Xin Wang, Jian-Sheng Cao, Shi-Hai Ye

Journal of Electrochemistry

Spinel LiMn₂O₄, a cathode material for Li-ion batteries, is featured as good high-rate performance, low cost and environmental friendly. The pristine and Al-doped LiMn₂O₄ samples were prepared by sol-gel method. The structure and micromorphology of the as-prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results demonstrated that the as-prepared LiMn₂O₄ samples had a typical cubic spinel structure and were composed of sphere-like particles with a diameter range of 300 ~ 500 nm. Galvanostatic charge-discharge tests showed that the LiMn₂O₄ samples doped …

Effect Of Ethyl Propionate On Low-Temperature Performance Of Lifepo4-Based Li-Ion Battery, Xiao-Ping Li, Lian-Sheng Hao, Wei-Shan Li, Meng-Qing Xu, Li-Dan Xing

Journal of Electrochemistry

A linear carboxylic, ester ethyl propionate (EP), was used as the co-solvent of carbonates, ethylene carbonate (EC), ethyl-methyl carbonate (EMC) and dimethyl carbonate (DMC), and its effect on low-temperature performance of LiFePO₄-based Li-ion battery was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge test. The application of EP enhances the ionic conductivity of the electrolyte, improves the compatibility of the electrolyte with both LiFePO₄ and graphite materials, and thus improves the low-temperature performance of LiFePO₄-based Li-ion battery. The Li-ion battery using the optimized electrolyte of 1 mol·L^-1 LiPF₆/EC:EMC:DMC:EP …

Electrocatalytic Mechanism And Porous Electrode Mass Transfer Process In Membrane Electrode Assembly For Direct Methanol Fuel Cells, Xin-Dong Wang, Yi-Tuo Wang, Gui-Cheng Liu, Meng Wang, Zhe Tian

Journal of Electrochemistry

Direct methanol fuel cell (DMFC) is considered to be a promising commercial energy conversion device for portable electronics due to its many advantages. In order to improve the performance of DMFC, many companies and research institutes have been launching the deep research and obtaining a lot of conspicuous achievements. In this paper, the electrocatalytic mechanism and porous electrode mass transfer process in membrane electrode assembly (MEA) are analyzed. In addition, combined with the preparation process of MEA, multilayer ordered structures and internal transfer process of the cell, recent progresses of MEA in DMFC are discussed.

Multifunctional Corrosion Inhibition Behavior Of Zn-Al Calcined Layered Double Hydroxides For Steel Rebar In Nacl Solution, Xiao-Juan Zhang, Jing-Jing Wang, Shi-Gang Dong, Chang-Jian Lin

Journal of Electrochemistry

The Zn-Al layered double hydroxides (Zn-Al LDHs) and calcined products (Zn-Al CLDHs) were synthesized successfully under a routine air atmosphere. The results showed that both Zn-Al LDHs and Zn-Al CLDHs had obvious flake structures. The corrosion inhibition of Zn-Al CLDHs for steel rebar in NaCl solution was studied by electrochemical techniques. It was found that the corrosion rate of steel rebar decreased significantly after the steel rebar was treated by Zn-Al CLDHs in NaCl solution for 3 h. It was indicated that Zn-Al CLDHs could absorb Cl^- and release OH^- during their reconstruction process, which provided dual protection …

Influences Of The Cinnamic Acid On Zinc Electrodeposition At Glassy-Carbon Electrode, Kai Li, Shen Chen, Shen-Na Liu, Bi-Sang Chen, Heng Lin, Guo-Liang Chen, Qing-Xiang Wang

Journal of Electrochemistry

The influences of cinnamic acid (CIN) on the mechanism of Zn deposition and nucleation kinetics onto glassy-carbon electrode were studied by cyclic voltammetry (CV) and chronoamperometry (CA). The results revealed that the zinc reduction took place via Zn²⁺ + 2e → Zn in the presence of CIN, but the kinetics of zinc deposition was changed and the formation rate of zinc nuclei was accelerated. In the absence of CIN, the mechanism of zinc nucleation followed the 3D-instantaneous diffusion-controlled nucleation, while the 3D-progressive diffusion-controlled nucleation in the presence of CIN. The addition of CIN reduced the nucleation rate, but increased …

Engineering Performance Of A New Siloxane-Based Corrosion Inhibitor, Niall Holmes, R. O'Brien, P. A. M. Basheer

Articles

This paper presents an evaluation of a new non-toxic corrosion inhibitor on selected engineering properties of concrete mixes with different cementitious materials following a corrosion and durability study on concrete samples. Corrosion inhibitors consist of powders or solutions which are added to concrete when mixed to prevent or delay corrosion of steel by their reaction with ferrous ions to form a stable and passive ferric oxide film on the steel surface. The new inhibitor functions slightly differently and its corrosion inhibition effect is due to the formation of a siloxane coating on the steel surface. Therefore, the performance of the …

The Equi-Biaxial Fatigue Characteristics Of Epdm Under True (Cauchy) Stress Control Conditions, Mark Johnson

Conference Papers

Strain amplitude control is most often employed when carrying out fatigue testing of rubber components. Often the design engineer requires fatigue test data that is based on load amplitude control. This is analogous to engineering or nominal stress amplitude control. This usually makes it easy to maintain the load within the specified test limits during extended testing. Values of true stress and strain can be obtained from this approach, but the magnitudes of the maximum true stresses in these tests increase with accumulated cycles, whereas the equivalent maximum engineering stress values remain constant. This is easily demonstrated in the uniaxial …

The Equi-Biaxial Fatigue Characteristics Of Epdm Under True (Cauchy) Stress Control Conditions, Mark Johnson, Ray Ekins, Niall Murphy, Stephen Jerrams, John Hanley

Conference Papers

ABSTRACT: Strain amplitude control is most often employed when carrying out fatigue testing of rubber components. Often the design engineer requires fatigue test data that is based on load amplitude control. This is analogous to engineering or nominal stress amplitude control. This usually makes it easy to maintain the load within the specified test limits during extended testing. Values of true stress and strain can be obtained from this approach, but the magnitudes of the maximum true stresses in these tests increase with accumulated cycles, whereas the equivalent maximum engineering stress values remain constant. This is easily demonstrated in the …

High-Speed Imaging Of A Bulk Metallic Glass During Uniaxial Compression, Wendelin Wright, Rachel R. Byer, Xiaojun Gu

Faculty Journal Articles

High-speed imaging directly correlates the propagation of a particular shear band with mechanical measurements during uniaxial compression of a bulk metallic glass. Imaging shows shear occurs simultaneously over the entire shear plane, and load data, synced and time-stamped to the same clock as the camera, reveal that shear sliding is coincident with the load drop of each serration. Digital image correlation agrees with these results. These data demonstrate that shear band sliding occurs with velocities on the order of millimeters per second. Fracture occurs much more rapidly than the shear banding events, thereby readily leading to melting on fracture surfaces.

Microstructure And Mechanical Properties Of A Friction Stir Processed Ti-6al-4v Alloy, Jianqing Su, Jiye Wang, Rajiv S. Mishra, Ray Xu, John A. Baumann

Materials Science and Engineering Faculty Research & Creative Works

Friction stir processing (FSP) trials were performed on 2mm-thick Ti-6Al-4V sheets using various processing parameters including tool rotational speed (800-1000RPM) and tool traverse speed (1-4IPM). A processing window was established with the W-1% La₂O₃ tool to produce defect-free friction stir processed (FSP'd) materials. The stir zone (SZ) material of the FSP'd samples showed a fully Β transformed microstructure characterized by typical basket-weave lamellar α/Β structure. The prior Β grains in the SZs contained multiple α variants, and the average sizes ranged from 12μm to 38μm influenced by the processing parameters. Based on metallurgical evaluation, the microstructural evolution …

On Electric Conduction Of Amorphous Silicon Carbonitride Derived From A Polymeric Precursor, Yaohan Chen, Fuqian Yang, Linan An

Chemical and Materials Engineering Faculty Publications

A long-existing problem that the conductivity of amorphous silicon carbonitrides derived from polymeric precursor increases significantly with pyrolysis temperature is investigated. We show that the conductivity exhibited an Arrhenius dependence on pyrolysis temperature, with the activation energy of ∼3.41 eV. Structural analysis using Raman spectroscopy reveals that the free carbon within the material undergoes a sp³-to-sp² transition as pyrolysis temperature increases, with the activation energy of ∼3.6 eV. We conclude that the pyrolysis-temperature induced increase in the conductivity is mainly due to the increase in the conductivity of the free carbon. A simple model is proposed to …

Glass-Ceremics For The Innovative Secondary Batteries, Tsuyoshi Honma

Functional Glasses: Properties And Applications for Energy and Information

No abstract provided.

Materials Education And Research In Art And Design: A New Role For Libraries (Survey Stats), Mark Pompelia

Materials Education and Research in Art and Design: A New Role for Libraries

No abstract provided.

Materials Education And Research In Art And Design: A New Role For Libraries (Program Sheet), Mark Pompelia

Materials Education and Research in Art and Design: A New Role for Libraries

No abstract provided.

Materials Education And Research In Art And Design: A New Role For Libraries (Program Booklet), Mark Pompelia

Materials Education and Research in Art and Design: A New Role for Libraries

No abstract provided.

Materials Education And Research In Art And Design: A New Role For Libraries (Website), Mark Pompelia

Materials Education and Research in Art and Design: A New Role for Libraries

No abstract provided.

Materials Collection Creation And Administration: A New Role For Libraries (White Paper), Mark Pompelia

Materials Education and Research in Art and Design: A New Role for Libraries

The Problem/Opportunity: To define, identify, and guide design-based materials collections in academic settings and foster community among those with existing collections and/or those considering creating and supporting one.

Contents and topics:

1. What is a materials collection?
2. Why have a materials collection?
3. Acquisition strategies
4. Organizational approaches
5. Programming possibilities
6. Symposium summary
7. Resources

Mechanical Properties And Microstructures Of Incoloy 909 Rolled Rings Subjected To A Modified Forging Cycle, Colin Lee Elliott Glaves

Materials Engineering

The microstructure of rolled rings of Incoloy 909 nickel-iron-cobalt superalloy subjected to a standard customer solution and aging treatment exhibited unacceptably large grains. Samples cut from a failed ring were mounted and polished for analysis. The samples were etched with a modified Kalling’s waterless reagent and metallographic analysis was done to identify characteristic large grain structures distributed among the desired smaller grain structures. The large grains were identified and noted for comparison to later samples. Two test rings were forged out of Incoloy 909 using revised forging procedures involving reduced soak temperatures before each forging step. Metallographic samples were cut …

Lunalight - Bringing Light To The Expanding World, Gabriela M. Igel, Daniel J. Patrick, Kimberley M. Smith

Materials Engineering

The LunaLight, a solar rechargeable light and cell phone charger, addresses the lack of access to electricity faced by 1.4 billion of the world’s population (International Finance Corporation). The LunaTech team has developed a product that is bright, simple, compact, versatile and competitive with existing products. Through a partnership with the non-profit organization One Million Lights, LunaTech has improved a previous team’s design to address user feedback, concerns of durability, and manufacturability.

The LunaLight design includes a 5 component plastic housing held together by 4 screws, a surface mounted PCB, a lithium-ion (Li-Ion) battery, one high-brightness LED, a solar panel, …

The Fabrication & Characterization Of An Electrokinetic Microfluidic Pump From Su-8, A Negative Epoxy-Based Photoresist, Nash Anderson

Master's Theses

Microfluidics refers to manipulation, precise control, and behavior of fluids at the micro and nanoliter scales. It has entered the realm of science as a way to precisely measure or mix small amounts of fluid to perform highly controlled reactions. Glass and polydimethylsiloxane (PDMS) are common materials used to create microfluidic devices; however, glass is difficult to process and PDMS is relatively hydrophobic. In this study, SU-8, an epoxy based (negative) photoresist was used to create various electrokinetic microfluidic chips. SU-8 is commonly used in microelectromechanical design. Spin coating of various SU-8 formulations allows for 1 μm to 100 μm …

The Relationship Of Barcol Hardness And Interlaminar Shear Strength In Glass Reinforced Polyester Composite Laminates, Ann E. Livingston-Peters

Materials Engineering

Chopped strand mat E-glass layers were impregnated with isophthalic marine laminating resin by hand lay-up techniques. Once the primary laminate reached the desired Barcol hardness value, the secondary laminate was applied and allowed to cure. These samples were bonded together at hardness values of 10, 30, 50, 70, and 90 Barcol. Lamination was conducted at 70°F with 35% glass fibers and 65% polyester resin catalyzed with 1.5% methyl ethyl ketone peroxide. The target thickness of each laminate was 6mm for short-beam shear testing requiring eight layers of glass and resin. Using the procedures outlined in ASTM D-2344, each sample set …

Evaluation Of Corrosion Properties Of Proprietary Metal Alloy Stents For In-Vivo Use, Michael David Bremner

Materials Engineering

To assess corrosion rates of metal alloy bio-absorbable stents an experimental set-up was designed to mimic the coronary artery environment. The artery was modeled using 4mm diameter Tecoflex tubing and the metal alloy stents were inserted into the tubing using a catheter. As is the case in cardiac surgery, the catheter with the stent and a microballoon were maneuvered to the desired position. The microballoon was then slowly inflated to expand the stent and compress it against the tubing walls. The catheter and microballoon were then withdrawn. A circulating pump system was set up to cycle fetal bovine serum (FBS) …

Fluorescence Characterization Of Quantum Dots For Use As Biomarkers, Logan M. Grimes

Materials Engineering

Fluorescence profiles of quantum dots (QDs) were characterized to select the ideal QDs for encapsulation in phospholipids for use as biomarkers to selectively adhere to cancer cells. QDs were synthesized and extracted 0, 30, 60, and 90 seconds after precursor compounds were mixed. These extractions were isolated by extraction time. Portions from each vial were coated in a zinc sulfide shelling procedure, leaving at least half of the QD solution unshelled. These samples were characterized over four days to monitor fluctuations in fluorescence. This was done utilizing an Ocean Optics spectrometer in conjunction with Spectra Suite software. The central wavelength, …

Scanning Tunneling Spectroscopy Under Atmospheric Conditions To Characterize A Tungsten Tip Stm System For Use With Hydrogen Desorption, Ross Gregoriev

Materials Engineering

The electrical surface structure of (111) n-type silicon was investigated through the use of scanning tunneling spectroscopy (STS) to develop a model to determine oxide presence on a passivated silicon surface. I-V curves were obtained with a scanning tunneling microscope (STM) using a tungsten tip on various locations of passivated silicon while the passivation layer desorbed from the surface under standard atmospheric conditions. The derivative (dI/dV) of these curves then revealed the electronic structure of the surface of the sample. Through these scans, it was determined the system was operating in the same mode as a Shockley diode. The separation …

Preparation Of A Polylactic Acid With Hydroxyapatite Reinforcement Composite, Odessa N. Quezon

Materials Engineering

Biodegradable polymers are a prime material choice for temporary biomedical devices due to its ability to degrade into non-toxic products for their use in vivo. However, polylactic acid (PLA) by itself lacks the sufficient strength and stiffness to permit their use as its properties begin to decrease as the polymer degrades. To improve the polymer’s mechanical properties, hydroxyapatite (HA) will be added to the PLA solution to act as reinforcement. The chemical property, glass transition temperature of a polymer, also plays a key role in the mechanical properties of the polymer. PLA’s glass temperature is 130⁰F. A polymer that …