Materials Science and Engineering Commons^™

Memristive Responses Of Jammed Granular Copper Array Sensors To Mechanical Stress, Gary A. Willey

Theses and Dissertations

A granular memristive device with the end goal of creating a novel system protection device is introduced in a 1-Dimension array. The electromechanical network will lay the groundwork for future 2-Dimensional and 3-Dimensional devices for simultaneous protection from intrusion. Off the shelf copper spheres with diameter of 710 ± 11microns were found through nano-indentation measurements to have elastic modulus of 106GPa, and compressive yield strength of 729MPa, these spheres were prepared for test in a 1-Dimensional array device. The arrays response to mechanical perturbations modeled by Hertz contact mechanics can be monitored by simultaneous electrical measurements across the multiple metal-insulator-metal …

Ceramic Matrix Characterization Under A Gas Turbine Combustion And Loading Environment, Dustin J. Bertrand

Theses and Dissertations

The fatigue behavior of Hyper-Therm High Temperature Composites (HTC) Sylramic-iBN/BN/CVI SiC material was investigated while being subjected to a unique high temperature environment. The specimens used in this research were subjected to a high temperature combustion environment intended to simulate the conditions this material would see in turbine engine applications. Results show that the effects of the combustion environment on the materials fatigue behavior are significant with increasing temperature.

Experimental Investigation Of Mechanical Behavior Of An Oxide/Oxide Ceramic Composite In Interlaminar Shear And Under Combined Tension-Torsion Loading, Skyler R. Hilburn

Theses and Dissertations

Creep behavior in interlaminar shear of an oxide-oxide ceramic composite, Nextel 720™/aluminosilicate (N720/AS), was investigated at 1100°C in laboratory air and in steam. The interlaminar shear strength (ILSS) was determined as 7.65 MPa. The creep behavior was examined for interlaminar shear stresses in the 2-6 MPa range. Primary and secondary creep regimes were observed in all tests conducted in air and in steam. Tertiary creep was noted in the tests performed at 6 MPa. Larger creep strains and higher creep strain rates were produced in steam. Surprisingly, the presence of steam had a beneficial effect on creep lifetimes. It appears …

Post-Fracture Capacity Of Railroad Flat Car Bridges, Teresa L. Washeleski

Purdue Road School

Railroad flatcars (RRFCs) are a convenient option to replace existing deteriorating bridge structures on low-volume roads. They are typically used as the bridge superstructure by placing two or more flatcars side-by-side to achieve the desired bridge width. Utilizing RRFCs as a bridge allows for rapid construction and greater cost savings compared to traditional practices. These benefits make them an attractive solution for rural communities in Indiana, as well as other states.

Uncertainty remains about the response under higher loads than could be easily achieved in the field and the level of redundancy of railroad flatcar bridges. Using RRFCs as bridges …

Post-Failure Capacity Of Built-Up Steel Members, Matthew H. Hebdon

Purdue Road School

Mechanically fastened built-up steel members have long been known to possess internal member redundancy and, as a result, multiple load paths which can be exploited to increase their functional life. Internal redundancy provides the ability to resist total member failure in the event of a fracture of an individual component. However, there is little experimental data in the literature regarding post-fracture capacity in terms of strength and subsequent fatigue life. The experimental study currently underway will provide needed information on parameters that affect the ability of built- up members to arrest a fracture as well as the available remaining fatigue …

Zno Nanosheet Arrays Constructed On Weaved Titanium Wire For Cds-Sensitized Solar Cells, Cuncun Wu, Lin Wei, Yitan Li, Chang Liu, Jun Jiao, Yanxue Chen, Liangmo Mei

Mechanical and Materials Engineering Faculty Publications and Presentations

Ordered ZnO nanosheet arrays were grown on weaved titanium wires by a low-temperature hydrothermal method. CdS nanoparticles were deposited onto the ZnO nanosheet arrays using the successive ionic layer adsorption and reaction method to make a photoanode. Nanoparticle-sensitized solar cells were assembled using these CdS/ZnO nanostructured photoanodes, and their photovoltaic performance was studied systematically. The best light-to-electricity conversion efficiency was obtained to be 2.17% under 100 mW/cm/cm² illumination, and a remarkable shortcircuit photocurrent density of approximately 20.1 mA/cm² was recorded, which could attribute to the relatively direct pathways for transportation of electrons provided by ZnO nanosheet arrays as …

[M3(Μ3-O)(O2cr)6] And Related Trigonal Prisms: Versatile Molecular Building Blocks For 2-Step Crystal Engineering Of Functional Metal-Organic Materials, Alexander Schoedel

USF Tampa Graduate Theses and Dissertations

Metal-organic materials (MOMs) assembled from metal-based building blocks and organic linkers have attracted much interest due to their large pore dimensions and their enormous structural diversity. In comparison to their inorganic counterparts (zeolites), these crystalline materials can be easily modified to tailor pore dimensions and functionality for specifically targeted properties.

The work presented herein encompasses the development of a synthetic 2-step process for the construction of novel families of MOMs or 'platforms' and allow us exquisite design and control over the resulting network topologies. Examples of cationic mesoporous structures were initially exploited, containing carboxylate based centers connected by metal-pyridine bonds. …

Cds Quantum Dot-Sensitized Solar Cells Based On Nano-Branched Tio2 Arrays, Chang Liu, Yitan Li, Lin Wei, Cuncun Wu, Yanxue Chen, Liangmo Mei, Jun Jiao

Mechanical and Materials Engineering Faculty Publications and Presentations

Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on …

Identification Of Silver And Palladium In Irradiated Triso Coated Particles Of The Agr-1 Experiment, I. J. Van Rooyen, T. M. Lillo, Y. Q. Wu

Materials Science and Engineering Faculty Publications and Presentations

Evidence of the release of certain metallic fission products through intact tristructural isotropic (TRISO) particles has been seen for decades around the world, as well as in the recent AGR-1 experiment at the Idaho National Laboratory (INL). However, understanding the basic mechanism of transport is still lacking. This understanding is important because the TRISO coating is part of the high temperature gas-cooled reactor functional containment and critical for the safety strategy for licensing purposes.

Our approach to identify fission products in irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), Electron Energy-Loss Spectroscopy (EELS) and Energy Filtered TEM (EFTEM), …

Triplet Ground State Of The Neutral Oxygen-Vacancy Donor In Rutile Tio2, A. T. Brant, Eric M. Golden, Nancy C. Giles, Shan Yang, M. A. R. Sarker, S. Watauchi, M. Nagao, I. Tanaka, D. A. Tryk, A. Manivannan, Larry E. Halliburton

Faculty Publications

Electron paramagnetic resonance (EPR) is used to investigate the triplet (S = 1) ground state of the neutral oxygen vacancy in bulk rutile TiO₂ crystals. This shallow donor consists of an oxygen vacancy with two nearest-neighbor, exchange-coupled ³⁺ ions located along the [001] direction and equidistant from the vacancy. The spins of the two trapped electrons, one at each ³⁺ ion, align parallel to give the S = 1 state. These neutral oxygen vacancies are formed near 25 K in as-grown oxidized TiO₂ crystals by illuminating with sub-band-gap 442 nm laser light. The angular dependence of the EPR …

Investigation Of Degradation Effects Due To Gate Stress In Gan-On-Si High Electron Mobility Transistors Through Analysis Of Low Frequency Noise, Michael Curtis Meyer Masuda

Master's Theses

Gallium Nitride (GaN) high electron mobility transistors (HEMT) have superior performance characteristics compared to Silicon (Si) and Gallium Arsenide (GaAs) based transistors. GaN is a wide bandgap semiconductor which allows it to operate at higher breakdown voltages and power. Unlike traditional semiconductor devices, the GaN HEMT channel region is undoped and relies on the piezoelectric effect created at the GaN and Aluminum Gallium Nitride (AlGaN) heterojunction to create a conduction channel in the form of a quantum well known as the two dimensional electron gas (2DEG). Because the GaN HEMTs are undoped, these devices have higher electron mobility crucial for …

Corrosion-Resistant Glasses For Steel Enamels, Richard K. Brow, Signo Tadeu Dos Reis, Michael L. Koenigstein, Genda Chen

Materials Science and Engineering Faculty Research & Creative Works

A cementitious composite material wherein glass-coated steel rods are positioned in a cementitious matrix. The glass composition for coating the steel reinforcing rods includes between about 33-45 weight percent SiO₂, 13.5-19.5 weight percent B₂O₃, 3.5-4.6 weight percent Al₂O₃, 4.0-13.5 weight percent K₂O, 5.5-15.5 weight percent ZrO₂, 8.6-15.9 weight percent Na₂O, 4.6-5.1 weight percent CaO, 0.6-0.7 weight percent MnO₂, 1.0-1.0 weight percent NiO, and 1.0-1.1 weight percent CoO. The glass composition is typically in compression on the rods at ambient temperatures, has a …

Structural Study Of Na2o-Feo-Fe2o3-P 2o5 Glasses By High-Pressure Liquid Chromatography, Lina Ma, Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

Three series of Na₂O-FeO-Fe₂O₃-P₂O₅ glasses with compositional ranges of 3.25 < O/P < 3.5 and 0 < Fe/P < 0.67 were prepared. Glass structure was studied using high-pressure liquid chromatography (HPLC). The average chain-length of phosphate anions decreases with increasing O/P ratios and glasses with similar O/P ratios and greater Fe/P ratios have wider distributions of phosphate anion lengths due to disproportionation reactions in the glass melts. © 2013 Elsevier B.V.

Preparation Of High Performance Porous Silicon Powders By Etching Al-Si Alloy In Acid Solution For Lithium Ion Battery, Shi-Ji Hao, Chun-Li Li, Kai Zhu, Ping Zhang, Zhi-Yu Jiang

Journal of Electrochemistry

Porous silicon powders prepared by etching Al-Si alloy using an acid solution was reported in the first time. The morphology and structure of as-obtained material were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) method. It was found that the spongy porous silicon powders presented well crystalline structure and consisted of nano-Si particles. The particle size of porous Si powders was about 20 μm, and the specific surface area was 102.7 m²·g^-1. The electrochemical properties of porous silicon powders were evaluated as an anode material for lithium ion batteries. The material proportion in the …

Preliminary Study On Morphology Controllability Of Electrochemically Prepared Polyaniline By Using Aniline Aimer, Yang Zuo, Kang Shi

Journal of Electrochemistry

Employing of aniline dimer (N-phenyl-p-phenylenediamine, NPD) as the starting monomer, polyaniline was electrochemically synthesized on the surface of glassy carbon electrode in acetonitrile-aqueous mixing solutions（20% by volume）containing 1 mol·L^-1 HClO₄. Experimental results demonstrated that the polymerization of NPD occurs at the potentials about 0.2 V lower than those of aniline monomer. Furthermore, the resulting polyaniline has higher morphology controllability than those synthesized by using aniline as the stating monomer. The uniform polyaniline nanoparticles (30 nm in diameter), ultralong nanowires (length > 5 μm, 50 nm in diameter) or large area nanosheets (4 μm in length, 2 μm in …

Electrochemical Oxidation Of Ammonium Nitrite In Absorption Solution Of Flue Gas, Yong-Hong Lu, Xiao-Bo Dong, Li-Sha Wang, Yan Liu, Chen-Jian Zhu, Hai-Bo Xu

Journal of Electrochemistry

In order to make full uses of ammonium nitrite in absorption solution from flue gas simultaneous desulfurization, denitrification and demercurization processes, here the electrochemical oxidation method was used to transform ammonium nitrite into ammonium nitrate. By using polarization curve, cyclic voltammogram and galvanostatic methods, suitable electrode materials were evaluated and chosen. The influence of electrolyte composition was discussed and the appropriate process parameters were obtained. Finally, the effect of electrochemical oxidation was confirmed by chemical analysis method. In 0.05 mol·L^-1 NaNO₂ + 0.05 mol·L^-1 (NH₄)₂SO₄ simulated absorption solution (5 L, pH = …

Study On Carbon Supported Pd Catalysts Modified By Phosphomolybdic Acid For H2O2 Electrocatalytic Reduction, Li-Mei Sun, Cheng Zhang, Ying-Rong Bao, Hong-Xia Li

Journal of Electrochemistry

The Pd/C catalyst was prepared with the chemical reduction method, and phosphomolybdic acid (PMA) was modified on the Pd/C catalyst using the dipping method. The compositions and structures of the Pd/C and Pd/C modified by phosphomolybdic acid (PMA-Pd/C) catalysts were characterized with X-ray diffraction and Fourier Transform infrared spectroscopy analyses. The electrocatalytic activity and stability of the catalysts for the reduction of hydrogen peroxide (H₂O₂) were studied using cyclic voltammetry and chronoamperometry. The results showed that the phosphomolybdic acid was tightly fixed on the surface of Pd/C catalyst through the chemical interaction. The eletrocatalytic activity of …

Preparation Of Pd/Tio2/C Catalyst And Its Electrocatalytic Performance In Basic Solution For Ethanol Oxidation, Qiao-Xia Li, Yi-Chao Yang, Ming-Shuang Liu, Hong-Min Mao, Qun-Jie Xu

Journal of Electrochemistry

Nanoparticles TiO₂ were prepared by hydrothermal method using precursor tetrabutyl titanate. The Pd/TiO₂/C catalyst was synthesized by liquid phase reducing method supported on nano TiO₂ and Vulcan carbon XC-72. The Pd/TiO₂/C catalyst was characterized by XRD, TEM, cyclic voltammetry, and chronopotentiometry. XRD confirmed the face-centered cubic structure of Pd particles, and TEM indicated that Pd particles (size 3 ~ 4 nm) dispersed uniformly on TiO₂ and carbon XC-72. The results from cyclic voltammogram and chronopotentiogram showed the higher ethanol oxidation activity and stability of Pd/TiO₂/C catalyst (20% Pd) as compared with …

Pulse Electrodeposition Of Pd-Ni Alloy Nanoparticles For Electrocatalytic Oxidation Of Formic Acid, Fang-Zu Yang, Jun-Pei Yue, Zhong-Qun Tian, Shao-Min Zhou

Journal of Electrochemistry

The Pd-Ni alloy nanoparticles with nickel atomic contents of 12.0%, 16.4% and 22.6% were successfully electrodeposited from a Pd-Ni alloy electrolyte by square wave pulse plating. The alloy nanoparticles were in the spherical shape with a diameter of 50 ~ 80 nm. As the growth potential of the alloy was negatively shifted, the nickel content of the alloy was increased, and the size of the nanoparticles was almost the same, whereas the number, the degree of crosslinking and the real active area of the nanoparticles were increased. As the nickel content of the alloy nanoparticles increased, the peak current for …

Synthesis And Electrochemical Properties Of Lico1-XMgXMno4 And Lico1-XAlXMno4 (X= 0, 0.02, 0.05, 0.1) As Positive Materials For Lithium-Ion Batteries, Mei-Ling You, Qing-Song Tong, Xiu-Hua Li, Min Lin, Xing-Kang Huang, Yong Yang

Journal of Electrochemistry

The Al-doped and Mg-doped LiCoMnO₄ materials were synthesized through solid-state reaction. The effects of doping amounts of Mg and Al on the initial capacities, discharge plateaus, and cycle performances were investigated. The morphologies and structures of the as-prepared materials were studied by scanning electron microscopy and powder X-ray diffraction. The results indicate that the as-prepared samples were composed of uniform, well-crystallized particles. The pristine LiCoMnO₄ possessed an initial capacity of 87.0 mAh·g^-1, while LiCo_0.98Mg_0.02MnO₄ and LiCo_0.98Al_0.02MnO₄ delivered 91.3 and 93.6 mAh·g^-1, respectively. The proper …