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Articles 25681 - 25710 of 27338

Full-Text Articles in Engineering

Pitting Corrosion Of Ni-Based Alloy In Thiosulfate-Ion Containing Chloride Solutions, Yung-Fa Lee, Ting-Yu Wang, Wen-Ta Tsai Feb 1999

Pitting Corrosion Of Ni-Based Alloy In Thiosulfate-Ion Containing Chloride Solutions, Yung-Fa Lee, Ting-Yu Wang, Wen-Ta Tsai

Journal of Electrochemistry

The effect of thiosulfate ion on the pitting corrosion behavior of Ni-Based Alloy 690 in chloride solution was investigated. In plain sodium thiosulfate solution, Alloy 690 was immune to pitting corrosion. However, the addition of low concentration of sodium thiosulfate can enhance the initiation of pitting corrosion of Alloy 690. Nevertheless, inhibition of pitting corrosion was observed at high concentration of addition.

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Oxidation Mechanism Of Hypophosphite, Dong-Bai Sun, Ying Jin, Hong-Ying Yu, De-Jun Yang Feb 1999

Oxidation Mechanism Of Hypophosphite, Dong-Bai Sun, Ying Jin, Hong-Ying Yu, De-Jun Yang

Journal of Electrochemistry

There exist two oxidation current peaks on the anodic polarization curve between -0.7 V and 0 V (SCE) in Na-hypophosphite solution. Peak Ⅰ (-0.55 V, SCE) , which represents the oxidation process from H2PO2- to H2PO3-, has been studied previously. Peak Ⅱ, which is located at the potential about -0.4 V (SCE), is investigated emphatically in this paper. The results show that, peak Ⅰ and Ⅱ are corresponding to two successive steps in oxidation process of H2PO2-, i.e. peak Ⅱ corresponds to the oxidation process of …

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Synthesis And Application Of Polymeric Corrosion Inhibitor For Reinforced Concrete, Wei-Wei Lin, Sheng-Xian Wang, Jian-Qing Zhang, Jun Yuan, Zhen-Guo Ji Feb 1999

Synthesis And Application Of Polymeric Corrosion Inhibitor For Reinforced Concrete, Wei-Wei Lin, Sheng-Xian Wang, Jian-Qing Zhang, Jun Yuan, Zhen-Guo Ji

Journal of Electrochemistry

A new polymer E-T was synthesized and used as a corrosion inhibitor for reinforced concrete. The inhibitive behavior and mechanism were studied with linear polarization, Tafel polarization, EIS and XPS method in simulated pore solution system with concrete samples. The result showed that the polymer was a mixing type inhibitor. A 1% dosage was sufficient to imhibit the corrosion of steel in simulated pore solution system. The salt endurance was enhanced from 0.02 mol/L to 0.10 mol/L. The result also showed the good synergetic effect of NaNO2, especially in low NaNO2 concentration. The EIS showed that E-T …

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Structural And Electrochemical Studies On Todorokite/Vernadite As Cathodes For Rechargeable Lithium Ion Batteries, Wei Chu, De-Yao Liu, Jin-Kua You, Yong Yang, Zu-Geng Lin Feb 1999

Structural And Electrochemical Studies On Todorokite/Vernadite As Cathodes For Rechargeable Lithium Ion Batteries, Wei Chu, De-Yao Liu, Jin-Kua You, Yong Yang, Zu-Geng Lin

Journal of Electrochemistry

XRD, TEM, ICP, low scan-rate CV and charge/discharge tests were carried out for the studies on the structural and electrochemical behavior of a prepared 3 V manganese oxide cathode for rechargeable lithium ion batteries.XRD analysis revealed that the cathode sample is mainly composed of tunneled Todorokite and layered Vernadite. TEM investigation confirmed that the morphology of the sample is a laminated construction with approximate 10nm layer space. The reversibility of Li+ removal/intercalation and structural stability of this sample framework to lithium insertion are good in CV and charge/discharge tests. The discharge capacities were found to be about 129mAh/g obtained …

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A New Cell Structure For Proton Exchange Membrane Fuel Cell, Ming Han, Hong-Feng Xu, Bao-Lian Yi Feb 1999

A New Cell Structure For Proton Exchange Membrane Fuel Cell, Ming Han, Hong-Feng Xu, Bao-Lian Yi

Journal of Electrochemistry

Separating the functions of current collection and gas flow distribution and then to design two separate elements to achieve the desired performance characteristics, a nonconventional cell structure for proton exchange membrane fuel cells bave been developed. The current collector is achieved using a thin stain steel sheet, the gas flow distribution is achieved using a carbon paper that has the desired chemical durabiliy when in contact with the proton exchange membrane. Combining these two separate elements into a single divice yields a bifunctional device that performs as a bipolar separator plate. The advantages of this alternative appproach to making biplar …

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Study Of Localized Corrosion Of Metals By Using The Electrochemical Techniques With Spatial Resolution, Chang-Jian Lin, Xiang-Dong Zhuo, Zu-De Feng, Rong-Gui Du, Zhao-Wu Tian Feb 1999

Study Of Localized Corrosion Of Metals By Using The Electrochemical Techniques With Spatial Resolution, Chang-Jian Lin, Xiang-Dong Zhuo, Zu-De Feng, Rong-Gui Du, Zhao-Wu Tian

Journal of Electrochemistry

The electrochemical inhomogeneities at interface of metal/solution play an important and often controlling role in localized corrosion of metals. The traditional electrochemical techniques involving potential, current density or ac impedance measurements over bulk specimens can only provide average and general information of the interface. Thus, the development of in situ imaging techniques is essential for further characterizing electrochemical inhomogeneities at the metal/solution interface of localized corrosion system. The electrochemical techniques with spatial resolution,including scanning single micro electrode, scanning double micro electrodse and scanning micro chemical probes are reviewed. The effects of electrochemical inhomogeneities on the corrosion behavior, and the mechanism …

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Effect Of Stress On Electrochemical Behaviour Of Various Thermal History Zones And Different Phase Structures On The Weldment For Low Alloy Steel, Yin-Shun Wu, De-Yu Liu, Bei Cao, Feng-Li Wang, Zhi Fang, Lin Zhang, Zheng-Rong Zhang, Hai Yang Feb 1999

Effect Of Stress On Electrochemical Behaviour Of Various Thermal History Zones And Different Phase Structures On The Weldment For Low Alloy Steel, Yin-Shun Wu, De-Yu Liu, Bei Cao, Feng-Li Wang, Zhi Fang, Lin Zhang, Zheng-Rong Zhang, Hai Yang

Journal of Electrochemistry

The electrochemical behaviour of various thermal history zones on the weldment for steel 16Mn and also of the ferrite, pearlite in various zones was measured by use of a self-developed measuring technique for investigating the electrochemicl behaviour of single and mixed phase structures in metal materials. Especially the effect of stress on this electrochemical behaviour was investigated. The results showed that by comparison with non-stress condition, the free corrosion potential of the various thermal history zones and of the ferrite, pearlite under stress condition was shifted in negative direction, correspondingly their free corrosion current density was increased, the free corrosion …

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Study On Steel Corrosion In Simulated Biofilm Environment In Seawater, Qing-Fei Wang, Jing Sui, Run-Xi Su, De-Ying Kong, Shi-Zhe Song Feb 1999

Study On Steel Corrosion In Simulated Biofilm Environment In Seawater, Qing-Fei Wang, Jing Sui, Run-Xi Su, De-Ying Kong, Shi-Zhe Song

Journal of Electrochemistry

Biofilm is one of the main factors that influence metal corrosion in seawater environment. According to the structure and property of biofilm, a natural biopolymeric gel, calcium alginate(an extracellular biopolymer containing carboxylate functional groups) can deposite on metal surfaces to form films. Corrosion behavior of alloyed steel E2, 10CrMoAl and 18-8 stainless steel were studied in simulated biofilm environment by various electrochemical methods ,including measurements of the corrosion potential, polarization curves,galvanic current and electrochemical impedance. The results show that such an approach is informative to reveal “how” and “to what extent” biofilm can influence the metal corrosion process.

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Studies Of Electrochemical Characteristics Of Pasted Nickel Hydroxide Electrode With Surface Deposited Cobalt, Xian-You Wang, Yun-Shi Zhang, Jie Yan, Zheng Zhu, Hua-Tang Yuan, De-Ying Song Feb 1999

Studies Of Electrochemical Characteristics Of Pasted Nickel Hydroxide Electrode With Surface Deposited Cobalt, Xian-You Wang, Yun-Shi Zhang, Jie Yan, Zheng Zhu, Hua-Tang Yuan, De-Ying Song

Journal of Electrochemistry

The surface of the spherical nickel hydroxide particles used as an active material in pasted nickel electrodes is surface-deposited with cobalt. This paper investigated the effects of the amount of cobalt deposit on the characteristics of nickel hydroxide electrode. The performances of the electrode, such as discharge capacity, utilization of active material and reversibility of Ni(OH)2/NiOOH redox reaction, were studied by comparing the charging/discharging curves and cyclic voltammograms. The mechanism of action of cobalt deposits has been described in terms of the electrochemical impedance spectroscopy of nickel hydroxide electrode.

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Electrohydrodimerization Of Fumarodinitrile On Liquid Gallium Electrode, He Wei, Huang Ying, Sheng-Tao Zhang Feb 1999

Electrohydrodimerization Of Fumarodinitrile On Liquid Gallium Electrode, He Wei, Huang Ying, Sheng-Tao Zhang

Journal of Electrochemistry

Electrohydrodimerization (EHD) of fumarodinitrile on liquid gallium electrode can take place not only in hydrotropic solution of tetraethylammonium p-toluenesulphonate (TEA-PTS), but also in aqueous solution containing low concentration of strong surfactants, such as TritonX-100. In solution without organic surfactant, FDN yields a single two-electron reduction wave corresponding to the formation of a saturated monomer called as butanedinitrile. If some TEA-PTS or TritonX-100 is added into the solution, the original two-electron wave is splitted into two continuous single-electron reduction wave and corresponding EHD of fumarodinitrile is obtained.

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The Nuclear Policy Of India And Pakistan: Implications For Deterrence, Ibpp Editor Feb 1999

The Nuclear Policy Of India And Pakistan: Implications For Deterrence, Ibpp Editor

International Bulletin of Political Psychology

This article analyzes the implications of India's and Pakistan's decisions to "go nuclear" in 1998.

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Bs News Feb 1999

Bs News

Building Services Engineering

No abstract provided.

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Aviation Security: The Human Element In Human Factors, Ibpp Editor Jan 1999

Aviation Security: The Human Element In Human Factors, Ibpp Editor

International Bulletin of Political Psychology

This article describes aspects of social and political human functioning that are germane to security violations discovered by representatives of the Federal Aviation Agency (FAA) in tests at various United States (U.S.) airports. FAA reports on the violations were obtained by The New York Times through the U.S. Freedom of Information Act and discussed in the Times' January 11th Issue.

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I-Line Exposure Capability For 6 Inch Wafers, Jerome Wandell Jan 1999

I-Line Exposure Capability For 6 Inch Wafers, Jerome Wandell

Journal of the Microelectronic Engineering Conference

The HIT Factory is currently in the development phase for a 6 inch sub-micron CMOS process. The addition of the Canon FPA-2000i1 stepper completes the necessary equipment required to perform a 6 inch photo process at HiT. The major focus of this project is to further the 6 inch photo process development, specifically to setup the exposure process for the first two levels (p-well and active) of the HIT test chip. TV pre-align mark number 2 and auto-align mark 20P-4F were added to all eleven levels of the HIT test chip layout around the originally designed pattern~ area. The revised …

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Critical Dimension Analysis On The Rit Canon I-Line Stepper, Justin Novak Jan 1999

Critical Dimension Analysis On The Rit Canon I-Line Stepper, Justin Novak

Journal of the Microelectronic Engineering Conference

This project involved the simulation and analysis of critical dimensions (CD) using the RIT Canon 2000i1 i-line stepper. This was accomplished by optimizing the stepper parameters for specific resist feature widths. There are many tools and methods that lithography engineers have at their disposal for use in optimizing current and future lithography processes. The focus-exposure (1?~E) matrix and resulting plot are integral parts of standard IC processing~ It is one of the most important plots used in lithography since it demonstrates how exposure and focus work together to affect critical dimension, sidewall angle, and resist thickness loss data. This data …

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Amorphous Silicon For 157nm Lithography, Carlos Fonseca Jan 1999

Amorphous Silicon For 157nm Lithography, Carlos Fonseca

Journal of the Microelectronic Engineering Conference

Amorphous silicon (a-Si) was investigated as a potential masking material at 157nm wavelength. Characterization of a-Si included film deposition on CaF2 (calcium fluoride) substrates through reactive sputtering, spectroscopic ellipsometry in the UV range, reflection and transmission at 157nm wavelength, and extraction of optical constants (n&k) with a commercial software package. Experimental results suggest that a-Si films deposited at RIT have similar optical constants as published values in the UV range. Simulation work suggests that a 50A silicon nitride film can be used as an anti-reflective layer to minimize reflections at the a-Si I air boundary. Consequently, silicon nitride films were …

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Resist Characterization For 157nm Lithography, Christopher Bolton Jan 1999

Resist Characterization For 157nm Lithography, Christopher Bolton

Journal of the Microelectronic Engineering Conference

A resist characterization experiment was performed utilizing 157nm Vacuum Ultra-violet (VUV) Lithography. A number of older technology resists such as MXP8, APEX-E, and UVIII were placed in the beam path of a Lumonics Series 700 fluorine excimer laser and subjected to timed exposures on the tool. The features were then developed in a low normality CD26 developer and characterization curves for each of the resists were plotted. Through the experimentation it was found that each of the three resists investigated was able to clearly demonstrate imaging qualities at 157nm. The contrast curves of the MXP8 and APEX-E resist indicate that …

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Oxidation Kinetics Of Nitrogen Implanted Silicon, Nathaniel E. Wescott Jan 1999

Oxidation Kinetics Of Nitrogen Implanted Silicon, Nathaniel E. Wescott

Journal of the Microelectronic Engineering Conference

Incorporation of nitrogen into the silicon lattice has been shown to severely retard the oxidation rate. The objective of this experiment was to determine a) whether it was a damage related issue and b) the kinetics. Equal doses of silicon were implanted along with the diatomic nitrogen (AMU 28) to determine whether it was a damage related issue. The added silicon did not hinder or benefit oxide growth. From this experiment, the oxidation rate of nitrogen implanted silicon can be best fit by the use of a linear model. Surface charge analysis indicated that flatband charge, interface trap density, and …

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Plasma Induced Damage To Thin Gate Oxides, Dustin L. Winters Jan 1999

Plasma Induced Damage To Thin Gate Oxides, Dustin L. Winters

Journal of the Microelectronic Engineering Conference

Two mechanisms of plasma processing damage to thin gate oxide structures were studied. Thin 17.5 mu oxide on Si substrate structures were studied after direct exposure to a oxygen plasma environment with surface charge analysis and breakdown voltage measurements. A second antenna structure was used to study the charging effects of an oxygen plasma on 17.5 nm gate oxides through breakdown voltage measurements. A correlation was found between duration of plasma exposure and the extent of damage in terms of decreased dielectric strength and changes in oxide charge levels for both experiments.

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Oxide Passivated Nanocrystalline Silicon Trap-Controlled Memory Devices, Burcay Gurcan Jan 1999

Oxide Passivated Nanocrystalline Silicon Trap-Controlled Memory Devices, Burcay Gurcan

Journal of the Microelectronic Engineering Conference

An alternative to the single floating gate on a standard EEPROM device could be a continuous semi insulating layer in which the distribution of charge can be controlled. By partial oxidation of porous silicon, a new material named Oxide Passivated Nanocrystalline Silicon (OPNSi) is formed, which has embedded Si nanocrystals in a porous glass structure. With oxide barriers between silicon nanocrystals, carriers can be confined to the silicon crystallites or trapped at interface states on the surface of these nanocrystals. With the assistance of an electric field, carriers can undergo direct tunneling through the very thin barriers and alter the …

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Integration Of Sige Resonant Interband Tunneling Diodes With Rit Cmos, Petya Vachranukunkiet Jan 1999

Integration Of Sige Resonant Interband Tunneling Diodes With Rit Cmos, Petya Vachranukunkiet

Journal of the Microelectronic Engineering Conference

This study investigates the integration of SiGe resonant interband tunneling diodes (RTD) with a standard silicon p-well CMOS process. It is feasible to build the RTD devices on the MOS source/drain regions if the RTD process did not degrade MOS devices. Besides, some etch selectivity issues need to be addressed. MOS transistors were subjected to the thermal cycling of the molecular beam epitaxial growth process and the rapid thermal anneal used in the fabrication of RTDs prior to contact formation. No destructive effects on the operation of NMOS and PMOS devices were observed. NMOS devices exhibited a positive shift of …

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Development Of An Anisotropic, Highly Selective Tungsten Silicide Dry Etch Process, Thomas Schulte Jan 1999

Development Of An Anisotropic, Highly Selective Tungsten Silicide Dry Etch Process, Thomas Schulte

Journal of the Microelectronic Engineering Conference

The development of an anisotopic Tungsten Suicide etch that will provide good selectivity to photoresist as well as an underlying oxide has been studied. It has been found that by reducing the amount of fluorine (SF6) in the system and increasing the chlorine concentration, slightly tapered sidewalls can be achieved without the use of a polymer forming gas. An optimum process was developed on an Applied Materials P-5000 MxP system. A condition of 10 sccm SF6, 40 sccm Cl2, 20 sccm 11e02 at 30 mTorr, and 400W presents slightly tapered sidewalls with within wafer uniformity of 4.85%. The selectivity of …

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Electrolytic Plating Of Copper For Advanced Interconnects, Michael T. Myszka Jan 1999

Electrolytic Plating Of Copper For Advanced Interconnects, Michael T. Myszka

Journal of the Microelectronic Engineering Conference

There is great interest in the semiconductor industry to move to copper for advanced interconnect processing. The purpose of this study was to develop an electroplating process so further studies in copper processing can be undertaken at R.LT. Electroplating was performed using the facilities available at the University of Rochester. This system utilizes a copper sulfate based electrolyte and an 8” wafer holder. In order to use the electroplating tool for four-inch wafers, a fixture was designed. Plating was performed on Si wafers coated with adhesion and seed layer of copper at varying current densities. Plated films were characterized for …

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Pattern Density Effects On The Chemical Mechanical Planarization Of An Interlevel Polymer Dielectric, Teresa M. Evans Jan 1999

Pattern Density Effects On The Chemical Mechanical Planarization Of An Interlevel Polymer Dielectric, Teresa M. Evans

Journal of the Microelectronic Engineering Conference

Chemical Mechanical Planarization is quickly becoming a standard in microelectronical processing. CMP can decrease the depth of focus constraints in photolithography, resolve topography issues for multilevel interconnects, improve metal step coverage, and be used as an alternative etch process. The recent break-through in the copper damascene process has invoked a large number of studies focused on the planarization of oxides and metals. The research has proven beneficial for other applications where oxides are used as an interlevel dielectric material It has also shown the need for further studies in the polishing of other dielectric materials. The purpose of this experiment …

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8 Bit Analog-To-Digital Converter Design And Simulation, Alberto J. Reyes Jan 1999

8 Bit Analog-To-Digital Converter Design And Simulation, Alberto J. Reyes

Journal of the Microelectronic Engineering Conference

The purpose of this study is to present and characterize an 8 bit AD converter implemented with flash architecture. Flash architecture provides with one of the fastest and easiest ways to convert analog input signals to digital outputs. Analog-to-digital conversion is the process in which a continuously varying analog signal is transformed into a multilevel digital signal. Analogue electrical waveforms are applied to the converter and are sampled at a fixed rate. Sample values are then expressed as a binary number consisting of 0’s and l’s. The resulting digital code can be used to encode digital audio, applications in video …

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Fabrication And Development Of A Charge Injection Device Imager, Ivan Puchades Jan 1999

Fabrication And Development Of A Charge Injection Device Imager, Ivan Puchades

Journal of the Microelectronic Engineering Conference

As Rochester Institute of Technology (RH) brings into production i-line capabilities with a new Canon stepper, resolution beyond 2μm will be possible. The present project prepares one of RIT’s most novel and successful processes for this transition. The process for a Charge Injection Device Imager (CD)) has been entirely developed at RIT through the work and collaboration between the Imaging Science and Microelectronic Engineering Departments. After the initial success in the design and fabrication of 8X8 and 32X32 imager, a more challenging 54X40 process was developed employing 6-micron PMOS technology. The goal of this project is the successful …

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Oxide Passivated Nanocrystalline Silicon Led Optimization, Tina M. Wheaton Jan 1999

Oxide Passivated Nanocrystalline Silicon Led Optimization, Tina M. Wheaton

Journal of the Microelectronic Engineering Conference

The objective of this project was to create an optimized, repeatable process for integrated PSI (Porous Silicon) LEDs. Porous Silicon is a lightemitting version of silicon, formed by electrochemical etching in an HF-containing solution. This material becomes stable once passivated with oxygen at high temperatures (900°C) and maintains its light-emitting properties. This study systematicaUy investigated the process effects on electroluminescence (EL) and electrical transport characteristics. The relationship between fabrication conditions and the structural and electronic properties of porous silicon have been subsequently examined. It was discovered that pre anodization substrate preparation had a dominant influence on the device characteristics. Analysis …

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Investigation Of A Silicon Bulk Etched Incandescent Light Source, Keith A. Roehner Jan 1999

Investigation Of A Silicon Bulk Etched Incandescent Light Source, Keith A. Roehner

Journal of the Microelectronic Engineering Conference

An attempt of fabricating an incandescent light source was made at Rochester Institute of Technology. Filament length, width, material and shape as well as encapsulation method were under investigation in the experiment. Due to a design flaw, the devices could not be tested for functionality. This has since been fixed and another attempt will be made to fabricate the devices.

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Silicon Based Light Emission By Avalanche Breakdown Of Shallow P+/N+ Junctions, Peter I. Ritchie Jan 1999

Silicon Based Light Emission By Avalanche Breakdown Of Shallow P+/N+ Junctions, Peter I. Ritchie

Journal of the Microelectronic Engineering Conference

The objective of this study was to develop and demonstrate a technology for producing optical signals on a VLSI chip using only standard silicon processing techniques. The design of the process requires shallow p+/n+ junctions to minimize the high absorption inherent in silicon for λ< 8SOnm and to obtain low reversed biased voltages for avalanche break down of the p+/n+junction due to impact-ionization. The effects of doping and device geometry on the visible luminescence of reverse biased Si p+In+ junction diodes has been investigated. Each diode designed has a unique design incorporating sharp edges that promote high fields that aid the onset of break down. The p+ doping was varied while other processing parameters were held constant. All vertical junction diodes had excellent diode characteristics but no light emission was observed. Lateral junction diodes had typical reverse breakdown voltages of between 6 and 7 volts while certain devices of set geometry broke down rather sharply at 4 volts with light emission. Intensity and breakdown characteristics seemed to correlate with magnitude of p+ dose and device geometry.

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Looking Back: Synthetic Turf And Football Injuries, Allan Mazur, Jennifer Bretsch Jan 1999

Looking Back: Synthetic Turf And Football Injuries, Allan Mazur, Jennifer Bretsch

RISK: Health, Safety & Environment (1990-2002)

From the Astrodome to Astro-Turf, the authors revisit the issue of sports injuries and synthetic surfaces. The first in a series of comments exploring historic risk topics.

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