Materials Science and Engineering Commons^™

Smart Structures For Control Of Optical Surfaces, D. Michael Sobers Jr.

Theses and Dissertations

The development of lightweight, large-aperture optics is of vital importance to the Department of Defense and the US Air Force for advancing remote sensing applications and improving current capabilities. Synthetic polymer optics offer weight and flexibility advantages over current generation glass mirrors, but require active control to maintain tight surface figure tolerances. This research explores the feasibility of using imbedded piezoelectric materials to control optical surfaces. Membrane-based and stiff piezo-controlled mirrors were constructed to develop and validate control techniques. Test results verified that surface control on the order of tens of wavelengths is possible using these systems.

Measurements Of Neutron Induced Surface And Bulk Defects In 4h Silicon Carbide, Kent T. Jones

Theses and Dissertations

Epitaxial n-type 4H-silicon carbide (SiC) is irradiated with 2 MeV protons to evaluate the dislocation damage effects on the optical and electrical characteristics of the material. The optical properties of the material are investigated using temperature-dependant photoluminescence (PL) and the effects of proton irradiation on the electrical properties are evaluated using current-voltage measurements and constant-voltage deep level transient spectroscopy (CV-DLTS). Subsequent high-temperature thermal annealing and recovery of the irradiated material is investigated over the temperature range of 900-1500°C. Proton-induced irradiation damage is apparent in the 4H-SiC material, affecting both the optical and electrical characteristics of the devices. The radiative behavior …

The Determination Of The Best Modified Way And Microscopical Analysis For Enzyme/Immunoelectrodes, Sa-Ying Dong, Hong-Ren Wang, Yu-Zhu Gao, Guang-Zhang Chen, Ming-Xiang Lv, Bo-Yi Tian

Journal of Electrochemistry

In this paper, the electrochemical response characteristics of enzyme and immuno electrodes were studied by cyclic voltammetry under different conditions. Our goals were to determine the best modified way of bioelectrode, which was the base of biosensor's application. 30U GOD and 0.8 mg/mL SEC1 antibody were suitable to bioelectrode preparation and detection. The microscopical analysis was finished with scan microscopy.

Study On The Orthogonal Test Of Al-Substituted α-Ni(Oh)2 Prepared By Complexation-Precipitation Method, Hui Chen, Jian-Ming Wang, Tao Pan, Hui-Ming Xiao, Jian-Qing Zhang

Journal of Electrochemistry

Al-substituted α-Ni(OH)₂ was prepared by a complexation-precipitation method and characterized by XRD.The electrochemical performance was tested by the charge-discharge method. The experimental results of orthogonal test showed that the effect order of some key preparative conditions on the electrochemical performance of Al-substituted α-Ni(OH)₂ was the concentration of aqueous ammonia, the content of aluminum and pH value.The optimum prepareative conditions for obtaining the sample with maximum specific discharge capacity (304 mAh·g^-1) were 0.5 mol·L^-1 aqueous ammonia, 15 mol% Al content and pH 11.0.

Preliminary Study On Direct Ethanol Fuel Cell, Shu-Qin Song, Li-Kang Chen, Jian-Guo Liu, Zhao-Bin Wei, Qin Xin

Journal of Electrochemistry

The performance of a direct ethanol fuel cell based on Nafion115 was reported.PtRu/C and Pt/C were used as ethanol anode and oxygen cathode catalysts in a single cell of size 9 cm² .The effects of temperature, oxygen pressure, the flow rate of ethanol, and oxygen, and ethanol concentration were tentatively studied. The experimental results showed that the cell open circuit voltage 0.608 V, the cell voltage 0.329 V at 50 mA/cm², and the peak power density 19.25 mW/cm² were reached under the conditions of T_cell =85 ℃, P_O2 =0.5 MPa, C_ethanol =1.0 mol/L …

Photocurrent Enhancement By Ticl4 Post-Treatment For Tio2 Nanoporous Film Electrode, Yan-Jie Ren, Li Zhang, Sheng-Min Cai

Journal of Electrochemistry

Enhanced photocurrent in dye-sensitized photoelectrochemical cell was obtained by post-treating the TiO₂ nanoporous film electrode with TiCl₄. By investigating the effect of the post-treatment on surface area, pore size distribution, laser pulse induced current transient of the film electrode, photocurrent increase by the post-treatment was assigned to the improved electron percolation resulting from broadening of interparticle neck.

An Investigation Of Inhibition Mechanism Of Cerium For Aluminum Alloy 2024-T3, Min-Hua Shao, Yan Fu, Rong-Gang Hu, Chang-Jian Lin

Journal of Electrochemistry

Cerium compounds are promising inhibitors for aluminum alloy. However, the inhibition mechanism is not very clear. Scanning microreference electrode (SMRE) technique was used to probe the potential imaging of Al 2024 T3 in NaCl and CeCl₃ solution. The results of SMRE showed that in NaCl solution a severe localized corrosion occurred on the surface of Al 2024 specimen at once and maintained for a long time. The corrosion activity of Al alloy in CeCl₃ decreased with immersion time and disappeared finally. Additionally, the competition of inhibition and aggression between Ce³⁺ and Cl^- on Al alloy was …

Electrosynthesis Of Glyoxylic Acid In A Packed Bed Reactor, Jin-Hong Fan, Jun Li, Yu-Zhong Su, Hao-Qi Gao

Journal of Electrochemistry

Glyoxylic acid was produced by electroreduction of oxalic acid in a packed bed reator. The cathodic and anodic electrolytes were super-saturated oxalic and hydrochloric acid aqueous solutions separated by a super-acid ion-exchange membrane. The current efficiency and yield of glyoxylic acid were studied under different structured packed bed reactors and different electrode materials, temperatures and current densities. The results indicated that the current efficiency of synthsis of glyoxylic acid was over 66.2% and the concentration of glyoxylic acid could reach 2.02% after 45min electrolysis with cathode of lead particles and anode of graphite board under conditions of temperature 32 ℃, …

Effect Of The Brightener On The Behavior Of The Silver Electrodeposition, Jin Hu, Hui-Min Wu, Xiang-Ming Feng, Wei-Dong Li, Zheng-Zhong Zuo, Yun-Hong Zhou

Journal of Electrochemistry

The effect of the brightener on the behavior of the silver electrodeposition in cyanide solution was studied by potentiostatically step and rotating dise electrode (RDE) as well as X-ray diffraction (XRD) and scanning electron microscope (SEM). It was found that the silver electrodeposition was not changed by the addition of the brightener to the fundarmental solution. But it apparently increased the solution's micro-leveling effection and remarkably improved the coating's surface lightness. The coating's orientation isn't changed by the addition of the brightener in the light of the XRD result. The effectivness of the brightener was also discussed by the half-wideth …

Determination Of Copper In The Waste Water Of Plating By Chronocoulometry For Flowing Solution, Xin-Hua Lin, Wei Chen

Journal of Electrochemistry

The chronocoulometry for flowing solution was devoloped and applied to the detemination of copper(Ⅱ) in the waste water of plating. The linear range of copper(Ⅱ) was 2～16mg/L, and the relative standard deviation was less than 0.1% (n =8). The recovery was 98%～103% for copper(Ⅱ) in the waste water.Chronocoulometry for flowing solution overcomed noise disturbance resulting from capacity current and variety of property of electrode surface. This method was sensitive,accurate and well reproducible.

Photoelectrochemistry Of La3+ Doped Semiconductor Porous Films Sensitized By Ru(Bpy)2(Ncs)2 Dye, Li Zhang, Yan-Jie Ren, Sheng-Min Cai

Journal of Electrochemistry

The La³⁺-doped TiO₂ nanoparticles were prepared with hydrothermal method.The photoelectrochemical properties of La³⁺-doped TiO₂ nanoporous-film electrode sensitized by Ru(bpy)₂(NCS)₂ were studied. The conversion efficiency of light to electricity and the energy conversion efficiencies were ineased with the depth of La³⁺-doped TiO₂ nanoporous-film electrode.

Uncertainty In Determination Of Hydrogen Diffusion Coefficient In Metal Hydride Electrode Based On The Transition Region Of Diffusion-Controlled Impedance, Xian-Xia Yuan, Nai-Xin Xu

Journal of Electrochemistry

Hydrogen diffusion coefficient in MlNi_3.75Co_0.65 Mn_0.4Al_0.2 metal hydride electrode has been determined with transition region of diffusion-controlled impedance. Multiple solutions were obtained at each data point because of the periodic characteristic of some functions used in the calculation, and the maximum difference between the solutions reached several orders of magnitude. On the other hand, the solutions varied for different data points in the transition region of diffusion-controlled impedance of the same experimental plot. It could be concluded that this method is not so well defined and some modification is required.

Varying Current Electro-Synthesis Of Glyoxalic Acid In Pairs In The Fixed-Bed Electrolytic Cell, Yin-Sheng Chen, Xin-Sheng Zhang, Ying-Chun Dai, Wei-Kang Yuan

Journal of Electrochemistry

As for the process of the electro oxidation of glyoxal to glyoxalic acid, the electrolytic result of either fixed bed electrolytic cell or varying current electrolysis was better than that of either flat plate electrolytic cell or constant current electrolysis. The average current density of varying current electro synthesis of glyoxalic acid in pairs was 1535 A/m² and the current efficiency were 85.3% and 86.7% and the selectivity were 93.9% and 94.0% for the anodic oxidation and cathodal reduction respectively. The initial composition of anodic electrolyte was 7% glyoxal and 8% hydrochloric acid (W/W) and the cathodal electrolyte consisted …

Electrochemical Synthesis And Characterization Of The Nickel Electropolyurushiol Coordination Polymer, Feng Gao, Guo-Cai Shen, Jie-Yuan Tang, Wen-Gong Zhang

Journal of Electrochemistry

The nickel electropolyurushiol coordination polymer (EPU Ni²⁺) was obtained by the reaction between nickel chloride isopropyl alcohol solution with electropolyurushiol (EPU). The electrochemical polymerization of urushiol and the preparation of nickel electropolyurushiol coordination polymer were investigated. The coordination polymer was characterized by XPS, FT-IR, DMTA and AES methods, and its composition and structure were determined.The content of Ni²⁺ reached up to 7.5%. It was shown that there was certain coordination between Ni²⁺ and electropolyurushiol in the coordination polymer, thus cross-inks were formed. Therefore the glass transition temperature of the coordination polymer increased and heat resistance was …

Modeling, Fabrication, And Optimization Of Niobium Cavities – Phase I: Quarterly Progress Report November 20, 2001 - February 20, 2002, 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 multipacting. Further, a nonuniform etch will leave areas with damaged grain structure, which is not good for superconducting properties. Typically, the depth of chemical …

Charge And Spin Structure In Yba2⁢Cu3⁢O6.35, Herbert A. Mook, Pengcheng Dai, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Neutron scattering has been used to measure the charge and spin structure in the highly underdoped superconductor YBa_2⁢Cu_3⁢O_6.35. Incommensurate static charge ordering is found that remains at high temperatures. The magnetic pattern is complex with a resonance and incommensurate structure observed at low temperatures. The results clarify the role of striped phases in YBa₂⁢Cu_3⁢O_6+x superconductors.

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics: Quarterly Progress Report 11/16/01- 2/15/02, 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 …

Design And Analysis For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides: Quarterly Progress Report 11/16/01- 2/15/02, Yitung Chen, Randy Clarksean, Darrell Pepper

Fuels Campaign (TRP)

An important aspect of the Advanced Accelerator Applications (AAA) program is the development of a casting process by which volatile actinide element (i.e., americium) can be incorporated into metallic alloy fuel pins. The traditional metal fuel casting process uses an inductively heated crucible.

This process works well for the fabrication of metal fuel pins traditionally composed of alloys of uranium and plutonium, but does not work well when highly volatile actinides are included in the melt. The problem occurs both during the extended time period required to superheat the alloy melt as well as when the chamber must be evacuated. …

Hydrogen-Induced Embrittlement Of Candidate Target Materials For Applications In Spallation-Neutron-Target Systems, Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The purpose of this project is to evaluate the effect of hydrogen on cracking of candidate target materials for applications in spallation-neutron-target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The test materials will undergo appropriate thermal treatments prior to being hydrogen-charged by potentiostatic cathodic polarization technique in a simulated aqueous environment at different temperatures of interest. The specimens, upon completion of testing, will be metallographically examined. Further, the scanning electron microscopy (SEM) will be used to determine the extent and nature of cracking in the specimens tested. The thrust of the proposed …

Apparatus And Method For Determining The Dynamic Indentation Hardness Of Materials, Ghatu Subhash, Abhijit Chandra, Brian J. Koeppel

Michigan Tech Patents

An apparatus and method for determining dynamic indentation hardness values of a material using a propagating stress wave to make an indentation in the material. The invention provides such values without any prior knowledge of the material properties and enables the dynamic indentation hardness values to be directly compared to static indentation hardness values for the material.

Optical Properties Of Undoped And Gd-Doped Ceo2 Nanocrystalline Thin Films, Toshio Suzuki, Igor Kosacki, Vladimir Petrovsky, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The results of studies of the preparation, structure, and optical properties of undoped and Gd-doped CeO₂ thin films are presented. Dense films with 4-150 nm grain size have been obtained on monocrystalline sapphire substrates using a polymeric precursor spin coating method. The results of the optical measurements are presented and correlated with the microstructure of the films. The transmission spectra have been used to determine the energy dependence of the refractive index, n and the extinction coefficient, k. Both n and k of the thin films decreased as grain size decreased and these results showed that this change could …

Corrosion Resistant Nickel-Based Alloy, Joseph William Newkirk, Sanhong Zhang

Materials Science and Engineering Faculty Research & Creative Works

A nickel based, high silicon alloy exhibits very high corrosion resistance in high temperature sulfuric acid environments. The alloy may be cast and is sufficiently ductile to be fabricated and machined. The alloy is ductile and has sufficient resistance to mechanical and thermal shock to be reliable in service when used as rotating parts.

Efficacy Of Interactive Internet-Based Education In Structural Timber Design, Aaron B. Henson, Kenneth J. Fridley, David Pollock, C Jayne Brahler

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

While traditional teaching methods (e.g., real-time, synchronous lectures) have proven effective for training future engineers, the Internet provides an avenue to reinforce the material and augment student learning, comprehension, and retention of material. This paper presents the integration and assessment of a library of interactive instructional modules specifically for a senior-level undergraduate elective course in civil engineering. An ongoing, comprehensive assessment process was implemented in the fall 1999 semester. The results of this quantitative assessment indicate that the use of well designed and pedagogically sound Internet-based supplemental modules provide students with a better understanding of course material. However, when Internet-based …

Effect Of Ga Content On Defect States In Cuin1-XGaXSe2 Photovoltaic Devices, Jennifer T. Heath, J. David Cohen, William N. Shafarman, Dongxiang Liao, Angus Rockett

Faculty Publications

Defects in the band gap of CuIn_1-xGa_xSe₂ have been characterized using transient photocapacitance spectroscopy. The measured spectra clearly show response from a band of defects centered around 0.8 eV from the valence band edge as well as an exponential distribution of band tail states. Despite Ga contents ranging from Ga/(In+Ga)=0.0 to 0.8, the defect bandwidth and its position relative to the valence band remain constant. This defect band may act as an important recombination center, contributing to the decrease in device efficiency with increasing Ga content.

Strongly Screened Vortex Lattice Model With Disorder, C. Giardina', Nikolai V. Priezjev, J. M. Kosterlitz

Mechanical and Materials Engineering Faculty Publications

The three dimensional XY model with quenched random disorder and finite screening is studied. We argue that the system scales to model with λ≃0≃T and the resulting effective model is studied numerically by defect energy scaling. In zero external field we find that there exists a true superconducting phase with a stiffness exponent θ≃+1.0 for weak disorder. For low magnetic field and weak disorder, there is also a superconducting phase with θ≃+1.0 which we conjecture is a Bragg glass. For larger disorder or applied field, there is a non superconducting phase with θ≃−1.0. We estimate the critical external field whose …

Stability And Optimization Of Photoconductivity In Thermally Vacuum Evaporated Indium (Iii) Sulfide Thin Films, Gustavo Rehder, Robert Engelken, Randy Stidham, Richard Tanner, Lee Ketchum, Anil Baral

Journal of the Arkansas Academy of Science

Long term stability of photosensitivity versus time in indium (III) sulfide thin films thermally vacuum evaporated onto photocell-patterned printed circuit boards varies sensitively with several factors including contact metal type, contact metal diffusion and electromigration into the semiconductor, doping, and encapsulation method. Because of the significant photoconductivity and relative low toxicity and environmental impact of this compound semiconductor, it is important to better characterize these dependences toward commercial applications. We will report on measurements of photoconductivity vs. time as functions of such factors and evolving methods to stabilize this photoconductivity.

Reactive Hot Pressing Of Alumina-Molybdenum Disilicide Composites, William Fahrenholtz, Ronald E. Loehman, Kevin G. Ewsuk

Materials Science and Engineering Faculty Research & Creative Works

Al₂O₃-MoSi₂ Composites Were Prepared by Reactive Hot Pressing using Molybdenum, Aluminum, and Mullite Powders as Precursors. the Gibbs Free Energy Was Highly Negative for the Composite-Forming Reaction, Which Indicated that the Products Were Stable Relative to the Reactants. after the Reaction, the Composites Had High Relative Density, ∼96%. based on the Composite-Forming Reaction, the Composites Should Have Contained 18 Vol% MoSi₂ in an Al₂O₃ Matrix. Scanning Electron Microscopy Revealed that the MoSi2 Inclusions Were Elongated, with an Average Thickness of ∼5 Μm and Inclusion Lengths that Ranged from 5 to 50 …

Raman Spectroscopy Of Nanocrystalline Ceria And Zirconia Thin Films, Igor Kosacki, Vladimir Petrovsky, Harlan U. Anderson, Philippe Colomban

Materials Science and Engineering Faculty Research & Creative Works

The results of Raman-scattering studies of nanocrystalline CeO₂ and ZrO₂:16% Y (YSZ) thin films are presented. The relationship between the lattice disorder and the form of the Raman spectra is discussed and correlated with the microstructure. It is shown that the Raman line shape results from phonon confinement and spatial correlation effects and yields information about the material nonstoichiometric level.

Misinformation [1], Hollis P. Leighly

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Defect And Mixed Conductivity In Nanocrystalline Doped Cerium Oxide, Toshio Suzuki, Igor Kosacki, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The results obtained from a study on the microstructure and the electrical properties of Gd-doped CeO₂ thin films were reported. Dense, nanocrystalline films on sapphire substrates are prepared using a polymeric precursor spin coating technique. The electrical conductivity was studied as a function of temperature and oxygen activity and correlated with the grain size. For nanocrystalline Gd-doped CeO₂ thin films, the ionic conductivity increased with decreasing activation energy as the grain size decreased. A conductivity model was developed to analyze PO₂ behavior of the electrical conductivity. Using the conductivity model, the hopping energy of electron conduction and …