Engineering Commons^™

Galvanic Corrosion Of Tin-W Electro-Couple During Tungsten Chemical Mechanical Polishing, Xuan Cheng, Chang-Jian Lin

Journal of Electrochemistry

Chemical mechanical polishing (CMP) is a process whereby mechanicaland chemical forces are combined to remove material from a wafer and polish it to a flatsurface. Tungsten CMP is an important prcess to gain the global planarity of siliconwafers with tungsten (W) plugs. Tungsten is actually deposited on a thin adhesive layerof titanium nitride (TiN) on silicon. When close to the final stage of polishing, TiN and W will be simultaneously exposed to the polishing chemistry, forming a galvaniccouple. The corrsion of TiN and W couple will result in different polish rate.

Electrochemical Behavior Of Tinicu Shape Memry Alloy In Simulated Body Fluid, Cheng-Hao Liang, Hong-Yan Sui

Journal of Electrochemistry

The study of TiNiCu shape memory alloys (SMA) in Hank's simulated body fluidwas carried out. The results showed that narrow passive range was found in acid environment andactive anodic dissolution was discovered at 100~150 mV vs SCE on anodic polarization cure ofTiNiCu SMA. Temperature had little effect on anodic polarization. With the decrease of pH andthe increase of Cl^- concentration ,pitting corrosion potential (E_b) shifted negatively. The electrochemical capability of TiNiCu SMA was inferior to that of TiNi SMA. Observations by means ofXRD and SEM indicate that TiNiCu SMA is not in single crystal structure, which caused …

Study Of The Oxidation Dynamics Of Tizro2 Metal-Ceramics, Wen-Chao Li, Li-Dong Teng

Journal of Electrochemistry

The oxidation dynamics of hot-pressed Ti-ZrO₂ metal-ceramics with the compositionof 50 vol.% Ti and 50 vol.% ZrO₂ has been studied.Thermodynamic analysis shows that Ticould react with O₂ but not with N₂ in the oxidizing process of TiZrO₂ composites at 0.1 MPa air. The oxidation dynamic behavior of Ti-ZrO₂ composites is analogous to that of pure Ti. Theactivation energy for the oxygen diffusion in Ti-ZrO₂ composites is higher than that in Ti solutions, for the presence of ZrO₂ restrains the oxygen diffusion in Ti-ZrO₂ composites. At early stagethe oxidation of Ti-ZrO_{2 …}

Preparation And Properties Of Separator For Lithium-Ion Battery, Xu-Mei Ren, Feng Wu, Chuan Wu, Han-Jun Li, Xue-Jie Huang

Journal of Electrochemistry

Lithium-ion batteries are well adapted to the new multimedia applications. PP/PE based microporous film is commonly used as separator in commercial lithium ion batteries. Herewe report a microporous film which is superior to the commercial available separator. The microporous PVDF polymer separators were prepared by the phase inversion process. The pore size of the separator is Φ 7 μm , and it's porosity is 75 %. The membrane in LiPF₆-EC/DEC showedhigh ionic conductivity (above 10^-3 S/cm at room temperature), and good mechanical properties(10³ kg/cm²). The half-cells consisted of Li/PVDF separator/MCMB showed excellent cyclingcharacteristics and …

The Effect Of Calcium On The Properties Of Molybdenum Nitride Electrode, Yun-Gui Zhu, Xue-Liang Li, Dao-Rong Lu, Jian-Bo He, Ji-Huai Xia

Journal of Electrochemistry

The effect of calcium on the properties of molybdenum nitride film electrode wasstudied by using XRD, SEM and cyclic voltammetry. The results show that the specific electriccapacity and the voltage operating range of electrode vary with the concentration of additive in thedipping solution. At the optimum concentration of additive in the dipping solution, the specificelectric capacity of the electrode is 2.1 times as large as that of the electrode prepared in the dipping solution without additive, and the voltage operating range of electrode is increased by 0.11 V. The active mechanism of calcium on the properties of film electrode suggested …

Corrosion Behavior Of Titanium In Fgd System, J-C Lin, T-L Chang, C-T Dung, S-L Lee, S-D Chyou, S-D Guo

Journal of Electrochemistry

In-situ corrosion test of titanium in flue gas desulfurization(FGD) system has been studied. Specimens of commercial Ti alloy have been put in four different locations (i. e , cooler, pre-scruber, absorber and heater) of the FGD system for 271 days. The corrosion rate is very low (i.e.<1 mpy) in all locations. Almost no corrosion can be found in the prescruber(0 mpy), but a sensible corrosion rate is estimated in the heater (0.58 mpy). Examination through SEM, all the specimens are subject to pitting corrosion except those in the prescruber. ESCA analysis indicates that the surface film for the specimen in prescruber is calcium carbonate, but titanium nitrate for the specimen in heater. Cyclic anodic potentiodynamic polarization (CAPP) of titanium in aerated and deaerated green solution provides an interpretation on the corrosion behavior of the titanium in the FGD system.

Comparison In Surface Enhanced Raman Scattering On Salicylideneamine Between Silver And Gold Colloid And Silver Mirror Substrate, Bing Zhao, Yukihiro Ozaki

Journal of Electrochemistry

This work studied the potential difference and galvanic currents on particulate contamination of the abrasive on the patterned surface and on corrosion behaviors of TiN and W. The polarization curves of TiN and W were, respectively, obtained in 0.01mol/L KNO₃ solutions in the absence and presence of three typical oxidants (H₂O_2, KIO₃, Fe(NO₃)₃) by DC polarization technique. The corrsion potentials and galvaniccurrents were measured when TiN and W were placed in a specially designed electr-chemical cell to form electro-couple. The preliminary results revealed that the corrosionrate of TiN-W electro-couple significantly …

Performance Of A Direct Methanol Fuel Cell, Zhao-Bin Wei, Jian-Guo Liu, Ya-Guang Jiao, Wei-Jiang Zhou, Wen-Zhen Li, Li-Kang Chen, Qin Xin, Bao-Lian Yi

Journal of Electrochemistry

A direct methanol fuel cell with 9cm² active area consists of Pt-Ru/C anode ,Pt/Ccathode and Nafion 115 membrane. The effect of operating conditions: methanol solution concentration, oxygen pressure and cell temperature on the cell performances was investigated. The results show that performance of single cell was enhanced by increasing oxygen pressure and celltemperature ,and a maximum power density 75 mW/cm² was obtained in the range of 250-300mA/cm² current density, 0.2 MPa oxygen pressure, 1.0 mol/L methanol concentration and 75 ℃ cell temperature. When cell operating at room temperature, a relatively low, but a stable performance of cell …

The Effect Of Preparation Condition On The Photoelectrochemical Performance Of Both The Pani Film And Tio2-Pani Composite Film On Au, Huai-Guo Huang, Hong-Ping Zhang, Zhi-Xin Zheng, Yan-Yan Xi, Ling-Ling Wu, Zhong-Hua Lin

Journal of Electrochemistry

Both the PANI (polyaniline) film and TiO₂-PANI composite film on the PATP(paminothiophenol)/Au substrate were obtained under different preparation condition by electrochemical methods, and their photoelectrochemical performances were alo studied. The resultsshowed that the photoelectrochemical performances of the films depend deeply on the comditionsof preparation. The self-assembling of PATP favors the adhesion of PANl. The partially-oxidizedPANI has a greater photoelectrochemical response than that of the reduced PANI and oxidized PANl. There is an optimum of film thickness for the photoelectrochemical performance of PANI film. Heat treating is in favor of the photoelectrochemical performance of TiO₂, but decreases …

The Dependence Of Relative Enhancement Of Sers Bands On Temperature, Ling Huang, Jian Shen, Tsing Yu, Qing-Jin Meng

Journal of Electrochemistry

The adsorption and binding behavior of 2,5-dimercapto-1,3,4-thiadizole(DMTD) on silver surface was studied by near-infrared Fourier Transfer surface enhanced Raman scattering(NIR FT-SERS) technique. It was found that the relative intensities of the SERS bands change regularly with the increasing of temperature, which suggests the transformation of the tautomers or the re-orientation of DMTD molecules in the surface layer.

Study On Corrosion Resistance Of Electroless Nickel Composite Coatings, Tsong-Jen Yang, Meng-Feng Jou

Journal of Electrochemistry

The eletroless nickel composite coating was prepared by uniform dispersion of diamond (or PTFE) particles throughout electroless nickel deposition. Corrosion resistance of composite coating in 3.5% NaCl aqueous solution was investigated by electrochemical analysis, dipping test and salt spray test. The results showed that the corrosion resistance of composite coating was inferior to that of electroless nickel coating if small amount of particles was added to the composite coating. Microsturctural analysis by SEM, AES, XRD, and EPMA indicated that the distribution of phosphorus is not homogeneous in the composite coating. The phosphorus_rich region acts as microcathode, however, the phosphorus-lean region …

Preparation Of Ti-Based Nanocrystalline Tio2 Film Electrode With High Activity, Dao-Bao Chu, Guang-Xia Shen, Xing-Fu Zhou, Chang-Jian Lin, Hua-Shui Lin

Journal of Electrochemistry

The potentiostatic electrosynthesis of Ti(EtO)₄ was studied by anodic dissolution of metal titanium(TA1) in solution of 0.005 mol·L^-1 (EtO)₄NBr in the ethanol (AR) in the presence negligible CH₃COCH₂COCH₃. The Ti-based nanocrystalline TiO₂ Film electrode (Ti/nano-TiO₂) was prepared by sol-gel method. By TEM, SEM and XRD, it has been shown that the anatase particle of TiO₂ was 10～35 nm in diameter and the film was 0.5 μm in thickness. The nanocrystalline film was composed of a three-diminsional network of interconnected particles. Reodx behavior and electrocatalytic activities of …

New Progress In Studies Of Lithium Nickel Oxide As Positive Electrode Materials Of Lithium Ion Batteris, Han-San Liu, Yong Yang, Zhong-Ru Zhang, Zu-Geng Lin

Journal of Electrochemistry

Lithium nickel oxide as the positive electrode of lithium ion batteries has aroused more and more interests.This paper reviews the recent reserches on synthesis and element-substitution of LiNiO₂ cathode material,and summarizes the intrinsical relationship between properties and sturcture of the material.The developments of new synthesis methods and mutilsubstitution of the material are expecting to be studied in the future research.

Electrochemistry Characteristic Of Carbon Steel Under Biofilm And Sulfide Film, Ze-Hua Dong, Xing-Peng Guo, Jia-Shen Zheng, Li-Ming Xu

Journal of Electrochemistry

Wire Beam Electrode (WBE) made of Q235 carbon steel was applied to study theheterogeneous corrosion beneath biofilm formed by Sulfate Reducing Bacteria (SRB) in cultureand sulfide film in solution with 1% NaCl and 300 mg/L⋅S^2-. The potential, galvanic density mapping, as well as polarization curve and Electrochemical Impedance Spectrum (EIS) were measured to predict the localized corrosion under biofilm and sulfide film. As a result, the mappingshowed the potential fluctuation on the WBE suface decreased over time due to the conductivityof the biofilm and sulfide film. Therefore, the potential mapping could not be a criterion of localized corrosion …

A Lagrangian Description Of Flows In Stirred Tanks Via Computer-Automated Radioactive Particle Tracking (Carpt), A. R. Rammohan, A. Kemoun, M. (Muthanna) H. Al-Dahhan, M. P. Dudukovic

Chemical and Biochemical Engineering Faculty Research & Creative Works

In This Study, Computer-Automated Radioactive Particle Tracking (CARPT) is Implemented for the First Time in the Characterization of Flows in Stirred Tanks. Both the Experimental Set-Up Are Discussed. the CARPT Technique is Seen to Capture Qualitatively Most of the Important Flow Phenomena Observed in Stirred Tank Flows, Like the Two Recirculating Loops above and Below the Impeller and the Dead Zones at the Bottom of the Tank. the CARPT Data is Also Used to Extract ''Sojourn'' Time Distributions in Different Zones of the Reactor. These Distributions Are Used to Partially Quantify the Observed Dead and Active Zones in the Tank. …

Improved Direct Displacement-Based Design Procedure For Performance-Based Seismic Design Of Structures, Rakesh K. Goel, Anil K. Chopra

Civil and Environmental Engineering

Direct displacement-based design requires a simplified procedure to estimate the seismic deformation of an inelastic SDF system, representing the first (elastic) mode of vibration of the structure. This step is usually accomplished by analysis of an “equivalent” linear system using elastic design spectra. In this paper, an equally simple procedure is developed that is based on the well-known concepts of inelastic design spectra. This procedure provides: (1) accurate values of displacement and ductility demands, and (2) a structural design that satisfies the design criteria for allowable plastic rotation. In contrast, the existing procedure using elastic design spectra for equivalent linear …

Waveguide Delivery Of X Rays For Minimally Invasive Tumor Therapy, Ronald W. Waynant, Ilko K. Ilev, Kunal Mitra

Biomedical Engineering and Sciences Faculty Publications

We are studying the potential use of x-rays, which are collected by non-imaging optics and delivered through stereotactically guided needles by hollow waveguides, for irradiation of tumors. X-rays have greater transparency in tissue than most longer optical wavelengths and may provide a more uniform dose to a tumor without harming normal tissue. Dosimetry is the key to minimal damage. We are investigating the use of fiber optics, tipped with calibrated scintillators and strategically located near the tumor, to measure the delivered dose. We are testing this procedure by using a 3 ns, variable accelerator voltage Fexitron 706 to produce approximately …

Fsec Procedure For Testing Stand-Alone Photovoltaic Systems, Florida Solar Energy Center

FSEC Energy Research Center®

This procedure is based on IEEE P1526/D1, Draft Recommended Practice for Testing the Performance of Stand-Alone Photovoltaic Systems. The system performance is based upon how well it can charge the battery. The usable battery capacity is measured by charging and discharging the battery three separate times. The tests are designed to test the overall system performance in the span of about one month.

Using Genetic Algorithms And Swat To Minimize Sediment Yield From An Agriculturally Dominated Watershed, Misgana K. Muleta, John W. Nicklow

Civil and Environmental Engineering

Non-point source pollution is well recognized as one of the most critical environmental hazards of modern times. In Illinois, non-point source pollution is the major cause of water quality problems, and soil erosion from agricultural lands is the major source of such pollution. Accelerated by anthropogenic activities, soil erosion reduces crop productivity and leads to subsequent problems from deposition on farmlands and in water bodies. Watershed management, however, promotes protection and restoration of these natural resources while allowing for sustainable economic growth and development. In this study a discrete time optimal control methodology and computational model are developed for determining …

Cluster Monte Carlo Simulations Of The Nematic--Isotropic Transition, Nikolai V. Priezjev, Robert A. Pelcovits

Mechanical and Materials Engineering Faculty Publications

We report the results of simulations of the three-dimensional Lebwohl-Lasher model of the nematic-isotropic transition using a single cluster Monte Carlo algorithm. The algorithm, first introduced by Kunz and Zumbach to study two-dimensional nematics, is a modification of the Wolff algorithm for spin systems, and greatly reduces critical slowing down. We calculate the free energy in the neighborhood of the transition for systems up to linear size 70. We find a double well structure with a barrier that grows with increasing system size. We thus obtain an upper estimate of the value of the transition temperature in the thermodynamic limit.

Studies On The Formation Of Dna-Cationic Lipid Composite Films And Dna Hybridization In The Composites, Murali Sastry, Vidya Ramakrishnan, Mrunalini Pattarkine, Krishna N. Ganesh

Faculty Works

The formation of composite films of double-stranded DNA and cationic lipid molecules (octadecylamine, ODA) and the hybridization of complementary single-stranded DNA molecules in such composite films are demonstrated. The immobilization of DNA is accomplished by simple immersion of a thermally evaporated ODA film in the DNA solution at close to physiological pH. The entrapment of the DNA molecules in the cationic lipid film is dominated by attractive electrostatic interaction between the negatively charged phosphate backbone of the DNA molecules and the protonated amine molecules in the thermally evaporated film and has been quantified using quartz crystal microgravimetry (QCM). Fluorescence studies …

Heat Treatment Of Gamma Titanium Aluminide Alloys, Thomas J. Kelly, Michael J. Weimer, Curtiss M. Austin, Blair London, Donald E. Larson Jr., Dean A. Wheeler

Materials Engineering

A gamma titanium aluminide alloy article, is prepared using a piece of a gamma titanium aluminide alloy having a composition capable of forming alpha, alpha-2, and gamma phases. The alpha transus temperature of the gamma titanium aluminide alloy piece is determined. The gamma titanium aluminide alloy piece is consolidated by hot isostatic pressing at a temperature of from about 50 F. to about 250 F. below the alpha transus temperature and at a pressure of from about 10,000 to about 30,000 pounds per square inch, for a duration of from about 1 to about 20 hours. The piece is heat …

Membrane Electrostatic Precipitator, Hajrudin Pasic, M. Khairul Alam, David J. Bayless

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A membrane is used as a collection substrate in an electrostatic precipitator (ESP). Possible material choices include fibers in the form of woven mats, screens made from stainless steel wires or fiber reinforced polymer composite membranes. The membranes have a tensile bias applied during operation, and have impulse tensile force applied during a dust removal step. By combining a dry ESP membrane field with wet-film cleaning field, it may be possible to improve collection efficiencies both by reducing turbulence and eliminating re-entrainment losses due to rapping. Through implementation of new materials that resist hostile ESP environments, the invention enhances the …

Emerging And Advanced Technologies: Small Satellites, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Emerging and Advanced Technologies: Small Satellites" presented at the Aerospace Industries Association Space Council on May 15, 2001.

Stanford Space Systems Program, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Stanford Space Systems Program" from May 15, 2001.

Difi: Digital And Fiber, Wendy Angel

SWITCH

This article discusses the similarities between the histories of digital technologies and textiles. The author describes the ways that digital and fiber technologies are affected by the growing arts and cultures. The author provides details of how digital and fiber technologies are both used as signal-transmitting information media. The article describes the importance of both digital and fiber in societal standing, the power and status it generates, and how they separates the wealthy and the working class. The article closes with an interpretative analysis of the interwoven properties between industry, information, technology, and art.

Sri: Stanford Space Systems Program, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "SRI: Stanford Space Systems Program" from May 14, 2001.

Superconductivity Of Metallic Boron In Mgb2, J. Kortus, I.I. Mazin, Kirill D. Belashchenko, Vladimir P. Antropov, L.L. Boyer

Nebraska Center for Materials and Nanoscience: Faculty Publications

Boron in MgB₂ forms stacks of honeycomb layers with magnesium as a space filler. Band structure calculations indicate that Mg is substantially ionized, and the bands at the Fermi level derive mainly from B orbitals. Strong bonding with an ionic component and considerable metallic density of states yield a sizable electron-phonon coupling. Together with high phonon frequencies, which we estimate via zone-center frozen phonon calculations to be between 300 and 700 cm^-1, this produces a high critical temperature, consistent with recent experiments. Thus MgB₂ can be viewed as an analog of the long sought, but still …

Emerald Nanosatellite: Structures & Mechanisms, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Emerald Nanosatellite: Structures & Mechanisms" from May 10, 2001.

Dynamic Characterization Of Aluminum Softball Bats, Danny V. Lee

Dissertations and Theses

On January 1, 2000, the Amateur Softball Association of America (ASA) imposed maximum bat performance limitations on commercial softball bats. The ASA adopted a testing standard defined by the American Society of Testing and Materials (ASTM) to determine the bat performance factor (BPF), a normalized coefficient of restitution that must be less than 1.2 for the bat to be eligible for ASA sanctioned events.

The ASTM standard requires that the softball strike the bat, which is free to rotate in the horizontal plane, at 26.8 mfs ± 0.3 mfs (88 ftfs ± 1 ftfs) with little or no spin. The …