Other Chemical Engineering Commons^™

Etching With Electron Beam Generated Plasmas, D. Leonhardt, Scott G. Walton, Christopher Muratore, Richard F. Fernsler, R. A. Meger

Chemical and Materials Engineering Faculty Publications

A modulated electron beam generated plasma has been used to dry etch standard photoresist materials and silicon. Oxygen–argon mixtures were used to etch organic resist material and sulfur hexafluoride mixed with argon or oxygen was used for the silicon etching. Etch rates and anisotropy were determined with respect to gas compositions, incident ion energy (from an applied rf bias) and plasma duty factor. For 1818 negative resist and i-line resists the removal rate increased nearly linearly with ion energy (up to 220 nm/min at 100 eV), with reasonable anisotropic pattern transfer above 50 eV. Little change in etch rate was …

Effect Of Plasma Flux Composition On The Nitriding Rate Of Stainless Steel, Christopher Muratore, Scott G. Walton, D. Leonhardt, Richard F. Fernsler, David D. Blackwell, R. A. Meger

Chemical and Materials Engineering Faculty Publications

The total ion flux and nitriding rate for stainless steel specimens exposed to a modulated electron beam generated argon-nitrogen plasma were measured as a function of distance from the electron beam axis. The total ion flux decreased linearly with distance, but the nitriding rate increased under certain conditions, contrary to other ion flux/nitriding rate comparisons published in the literature. Variation in ion flux composition with distance was explored with a mass spectrometer and energy analyzer as a possible explanation for the anomalous nitriding rate response to ion flux magnitude. A transition in ion flux composition from mostly N2 1 to …

Localized Charge Transfer In Csau·Nh3:  1h And 133cs Nuclear Magnetic Resonance, Steffen Kramer, Michael Mehring, Anja V. Mudring, Martin Jansen

Anja V. Mudring

We report results from 1H and 133Cs nuclear magnetic resonance (NMR) studies on CsAu·NH3. This compound has recently been synthesized and belongs to the family of ammoniates. The intense blue color of the material, which is not observed in the parent compounds, suggests that a charge-transfer electronic state is formed. The 1H NMR line shape and relaxation rates are found to be very similar to the corresponding properties in pure ammonia. However, the 133Cs-NMR properties of CsAu·NH3 strongly deviate from the corresponding ones in CsAu, and we show that the former can be interpreted consistently within a localized charge distribution …

Multimode Quantitative Scanning Microwave Microscopy Of In Situ Grown Epitaxial Ba1-XSrXTio3 Composition Spreads, K. S. Chang, M. Aronova, O. Famodu, I. Takeuchi, S. E. Lofland, Jason R. Hattrick-Simpers, H. Chang

Faculty Publications

We have performed variable-temperature multimode quantitative microwavemicroscopy of in situepitaxial Ba_1−xSr_xTiO₃ thin-film composition spreads fabricated on (100) LaA₁O₃ substrates. Dielectric properties were mapped as a function of continuously varying composition from BaTiO₃ to SrTiO₃. We have demonstrated nondestructive temperature-dependent dielectric characterization of local thin-film regions. Measurements are simultaneously taken at multiple resonant frequencies of the microscope cavity. The multimode measurements allow frequency dispersion studies. We observe strong composition-dependent dielectric relaxation in Ba_1−xSr_xTiO₃ at microwave frequencies.

Imaging The Reactivity Of Electro-Oxidation Catalysts With The Scanning Electrochemical Microscope, Biren C. Shah, Andrew C. Hillier

Andrew C. Hillier

We describe an application of the scanning electrochemical microscope that utilizes tip-sample feedback to characterize the reactivity of electro-oxidation catalysts. The kinetics of hydrogen oxidation are probed at a platinum electrode as a function of applied potential in aqueous sulfuric acid solution. Tip-sample feedback generates a tip response that reflects the rate of hydrogen oxidation at the substrate. The ability to directly measure the rate constant for hydrogen oxidation is, subsequently, used to perform reactivity mapping of heterogeneous electrodes consisting of catalytic and noncatalytic domains. Differences in reaction kinetics clearly distinguish surface composition variations based upon their reactivity toward hydrogen …

Development Of A Curved Layer Lom Process For Monolithic Ceramics And Ceramic Matrix Composites, Donald A. Klosterman, Richard P. Chartoff, Nora R. Osborne, George A. Graves, Allan Lightman, Gyoowan Han, Akos Bezewredi, Stan Rodrigues, Sung Pak, Gary Kalmanovich, Leon Dodin, Song Tu

Chemical and Materials Engineering Faculty Publications

A novel rapid prototyping technology incorporating a curved layer building style was developed. The new process, based on Laminated Object Manufacturing (LOM), was designed for efficient fabrication of curved layer structures made from ceramics and fiber reinforced composites. A new LOM machine was created, referred to as Curved Layer LOM. This new machine uses ceramic tapes and fiber prepregs as feedstocks and fabricates curved structures on a curved-layer by curved-layer basis. The output of the process is a three dimensional "green" ceramic that is capable of being processed to a seamless, fully dense ceramic using traditional techniques. A detailed description …

Derivation Of An Analytical Model To Calculate Junction Depth In Hgcdte Photodiodes, Stacy H. Gleixner, H. G. Robinson, C. R. Helms

Faculty Publications

Presents an enhanced analytical model to calculate junction depth and Hg interstitial profile during n-on-p junction formation in HgCdTe photodiodes. Detailed information on the enhanced model; Function of the model; Information on HgCdTe; Detailed information on how the model was obtained.

Derivation Of An Analytical Model To Calculate Junction Depth In Hgcdte Photodiodes, Stacy H. Gleixner, H. G. Robinson, C. R. Helms

Stacy H. Gleixner

Presents an enhanced analytical model to calculate junction depth and Hg interstitial profile during n-on-p junction formation in HgCdTe photodiodes. Detailed information on the enhanced model; Function of the model; Information on HgCdTe; Detailed information on how the model was obtained.

Mass Transfer With Chemical Reaction In The Process Of Ammonia Desorption From Aqueous Solutions Containing Carbon Dioxide, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.

Fuel Cells, Frederick J. Munster Jr.

Maine Collection

Fuel Cells

by Frederick J. Munster Jr.

Edited by: Mr. Christopher Carroll

Maine Department of Economic Development, Augusta, Maine, 1998.

Contents: Hydrogen / Hydrogen Safety / Electrolysis / Electrolyzers / History of Fuel Cells / How Fuel Cells Operate / Fuel Cell Types / Fuel Cell Electrochemistry / Power Systems / Fuel Cells in Transportation / Hydrogen Powered Internal Combustion Engines / Home, Garden, Education and Industry / For More Information / Glossary / References

Mathematical Modeling Of Proton‐Exchange‐Membrane Fuel‐Cell Stacks, Dhanwa Thirumalai, Ralph E. White

Faculty Publications

No abstract provided.

Galvanostatic Pulse And Pulse Reverse Plating Of Zinc–Nickel Alloys From Sulfate Electrolytes On A Rotating Disc Electrode, Branko Popov, M. Ramasubramanian, S. N. Popova, Ralph E. White, Ken-Ming Yin

Faculty Publications

Galvanostatic pulse and pulse reverse techniques have been used to study the plating of zinc–nickel alloys in the presence of nonyl phenyl polyethylene oxide. The effects of average current density, rotation speed of disc electrode and the presence of nonyl phenyl polyethylene oxide in the electrolyte on deposition of zinc–nickel alloys were evaluated. Zinc–nickel plating bath solution chemistry was studied by determining the equilibrium concentrations at various pH levels. It was found that the alloy composition was determined by solution equilibria, mass transfer of the electroactive species within the diffusion layer and by the surface coverage of nonyl phenyl polyethylene …

Galvanostatic Pulse And Pulse Reverse Plating Of Zinc-Nickel Alloys From Sulfate Electrolytes On A Rotating Disc Electrode, Branko N Popov, M. Ramasubramanian, S. N. Popova, Ralph E. White, K-M. Yin

Faculty Publications

Galvanostatic pulse and pulse reverse techniques have been used to study the plating of zinc–nickel alloys in the presence of nonyl phenyl polyethylene oxide. The effects of average current density, rotation speed of disc electrode and the presence of nonyl phenyl polyethylene oxide in the electrolyte on deposition of zinc–nickel alloys were evaluated. Zinc–nickel plating bath solution chemistry was studied by determining the equilibrium concentrations at various pH levels. It was found that the alloy composition was determined by solution equilibria, mass transfer of the electroactive species within the diffusion layer and by the surface coverage of nonyl phenyl polyethylene …

Low Cost Schottky Barrier Solar Cells Fabricated On Cdse And Sb2S3 Films Chemically Deposited With Silicotungstic Acid, O. Savadogo, K. C. Mandal

Faculty Publications

No abstract provided.

An Analysis Of A Back Fed Porous Electorde For The Br2/Br- Redox Reaction, John W. Van Zee, Ralph E. White

Faculty Publications

No abstract provided.

Parallel Plate Electrochemical Reactor Model, Ralph E. White, Mike Bain, Mike Raible

Faculty Publications

No abstract provided.

Scattering Of Argon And Neon From W(112), Ralph E. White, Jean Jacques Ehrhardt, Robert P. Merrill

Faculty Publications

No abstract provided.

The Fluid Motion Due To A Rotating Disk, Ralph E. White, Charles M. Mohr Jr, John Newman

Faculty Publications

No abstract provided.

A Study Of The Flow Characteristics In The Core Region Of The Sandia Engineering Reactor, James A. Moeller

Chemical and Biological Engineering ETDs

The core region of a nuclear rector is an extremely compact area with a capability of providing a very high heat output. Regardless of the type of coolant used, the heat transfer characteristics of this region must be adequately designed to prevent any undesirable "hot-spots" from developing. The Sandia Engineering Reactor has one of the most compact cores of any in currently operating nuclear reactors. For this reason it is necessary to investigate fully the heat transfer characteristics of the core. The rate of heat transfer from the fuel elements to the coolant is directly dependent upon the temperature difference …