Adaptive Impedance Analysis of Grooved Surface using the Finite Element Method (open access)

Adaptive Impedance Analysis of Grooved Surface using the Finite Element Method

Grooved surface is proposed to reduce the secondary emission yield in a dipole and wiggler magnet of International Linear Collider. An analysis of the impedance of the grooved surface based on adaptive finite element is presented in this paper. The performance of the adaptive algorithms, based on an element-element h refinement technique, is assessed. The features of the refinement indicators, adaptation criteria and error estimation parameters are discussed.
Date: July 6, 2007
Creator: Wang, L.
Object Type: Article
System: The UNT Digital Library
AIR PATHWAY DOSE MODELING FOR THE F-AREA TANK FARM (open access)

AIR PATHWAY DOSE MODELING FOR THE F-AREA TANK FARM

Dose-release factors (DRFs) were calculated for potential atmospheric releases of C-14, Cl-36, H-3, I-129, Sb-125, Se-79, Sn-126, and Te-99 from the F-Area Tank Farm (FTF). DRFs represent the dose to the receptor exposed to 1 Ci of the specified radionuclide being released to the atmosphere. Receptors at the SRS boundary, 100, 400, 800, 1200 and 1600 meters from the source were evaluated assuming a point or area source where appropriate. These DRFs can be used to estimate flux rates for this facility to estimate the potential dose to an individual.
Date: August 6, 2007
Creator: Farfan, Eduardo B.
Object Type: Report
System: The UNT Digital Library
Ammonia at Blodgett Forest, Sierra Nevada, USA (open access)

Ammonia at Blodgett Forest, Sierra Nevada, USA

Ammonia is a reactive trace gas that is emitted in large quantities by animal agriculture and other sources in California, which subsequently forms aerosol particulate matter, potentially affecting visibility, climate, and human health. We performed initial measurements of NH{sub 3} at the Blodgett Forest Research Station (BFRS) during a two week study in June, 2006. The site is used for ongoing air quality research and is a relatively low-background site in the foothills of the Sierra Nevada. Measured NH{sub 3} mixing ratios were quite low (< 1 to {approx} 2 ppb), contrasting with typical conditions in many parts of the Central Valley. Eddy covariance measurements showed NH{sub 3} fluxes that scaled with measured NH{sub 3} mixing ratio and calculated aerodynamic deposition velocity, suggesting dry deposition is a significant loss mechanism for atmospheric NH{sub 3} at BFRS. A simple model of NH{sub 3} transport to the site supports the hypothesis that NH{sub 3} is transported from the Valley to BFRS, but deposits on vegetation during the summer. Further work is necessary to determine whether the results obtained in this study can be generalized to other seasons.
Date: November 6, 2007
Creator: Fischer, Marc L. & Littlejohn, David
Object Type: Article
System: The UNT Digital Library
Application of exterior complex scaling to positron-hydrogencollisions including rearrangement (open access)

Application of exterior complex scaling to positron-hydrogencollisions including rearrangement

The first application of an exterior complex scaling method to an atomic scattering problem with distinct rearrangement channels is reported. Calculations are performed for positron-hydrogen collisions in an s-wave model employing an electron-positron potential of V{sub 12} = -(8+(r{sub 1}-r{sub 2}){sup 2}){sup 1/2}, using the time-independent propagating exterior complex scaling (PECS) method. This potential has the correct long-range Coulomb tail of the full problem and the results demonstrate that ECS-based methods can accurately calculate scattering, ionization and positronium formation cross sections in this three-body rearrangement collision.
Date: December 6, 2007
Creator: Bartlett, Philip L.; Stelbovics, Andris T.; Rescigno, Thomas N. & McCurdy, C. William
Object Type: Article
System: The UNT Digital Library
Assessment of Barotrauma Resulting from Rapid Decompression of Depth Acclimated Juvenile Chinook Salmon Bearing Radio Telemetry Transmitters (open access)

Assessment of Barotrauma Resulting from Rapid Decompression of Depth Acclimated Juvenile Chinook Salmon Bearing Radio Telemetry Transmitters

A multifactor study was conducted by Battelle for the US Army Corps of Engineers to assess the significance of the presence of a radio telemetry transmitter on the effects of rapid decompression from simulated hydro turbine passage on depth acclimated juvenile run-of-the-river Chinook salmon. Study factors were: (1) juvenile chinook salmon age;, subyearling or yearling, (2) radio transmitter present or absent, (3) three transmitter implantation factors: gastric, surgical, and no transmitter, and (4) four acclimation depth factors: 1, 10, 20, and 40 foot submergence equivalent absolute pressure, for a total of 48 unique treatments. Exposed fish were examined for changes in behavior, presence or absence of barotrauma injuries, and immediate or delayed mortality. Logistic models were used to test hypotheses that addressed study objectives. The presence of a radio transmitter was found to significantly increase the risk of barotrauma injury and mortality at exposure to rapid decompression. Gastric implantation was found to present a higher risk than surgical implantation. Fish were exposed within 48 hours of transmitter implantation so surgical incisions were not completely healed. The difference in results obtained for gastric and surgical implantation methods may be the result of study design and the results may have been different …
Date: September 6, 2007
Creator: Brown, Richard S.; Carlson, Thomas J.; Welch, Abigail E.; Stephenson, John R.; Abernethy, Cary S.; McKinstry, Craig A. et al.
Object Type: Report
System: The UNT Digital Library
Asymptotic Behavior of the Electron Cloud Instability (open access)

Asymptotic Behavior of the Electron Cloud Instability

The fast beam-ion instability and the single bunch electron-cloud instability are substantially nonlinear phenomena and can be analyzed in a similar way. The initial exponential growth of the amplitudes known for both instabilities takes place only in the linear approximation. Later, in the nonlinear regime, amplitudes grow according to a power law or even decrease. We analyze the nonlinear regime describing the growth of amplitudes in time and along the train of bunches. Analytic analysis is compared with simulations.
Date: June 6, 2007
Creator: Heifets, Samuel
Object Type: Article
System: The UNT Digital Library
An atomic force microcopy study of the mechanical and electricalproperties of monolayer films of molecules with aromatic end groups (open access)

An atomic force microcopy study of the mechanical and electricalproperties of monolayer films of molecules with aromatic end groups

The effect of intermolecular {pi}-{pi} stacking on the electrical and mechanical properties of monolayer films molecules containing aromatic groups was studied using atomic force microscopy. Two types of aromatic molecules, (4-mercaptophenyl) anthrylacetylene (MPAA) and (4-mercaptophenyl)-phenylacetylene (MPPA) were used as model systems with different {pi}-{pi} stacking strength. Monolayer films of these molecules on Au(111) surfaces exhibited conductivities differing by more than one order of magnitude, MPAA being the most conductive and MPPA the least conductive. The response to compressive loads by the AFM tip was also found to be very different for both molecules. In MPAA films distinct molecular conductivity changes are observed upon mechanical perturbation. This effect however was not observed on the MPPA film, where intermolecular {pi}-{pi} interactions are likely weaker.
Date: September 6, 2007
Creator: Fang, Liang; Park, J.Y.; Ma, H.; Jen, A.K.-Y. & Salmeron, M.
Object Type: Article
System: The UNT Digital Library
B^0 to \pi^+ \pi^- \pi^0Time Dependent Dalitz Analysis at BaBar (open access)

B^0 to \pi^+ \pi^- \pi^0Time Dependent Dalitz Analysis at BaBar

The author presents here results of a time-dependent analysis of the Dalitz structure of neutral B meson decays to {pi}{sup +}{pi}{sup -}{pi}{sup 0} from a dataset of 346 million B{bar B} pairs collected at the {Upsilon}(4S) center of mass energy by the BaBar detector at the SLAC PEP-II e{sup +}e{sup -} accelerator. No significant CP violation effects are observed and 68% confidence interval is derived on the weak angle {alpha} to be [75,152].
Date: April 6, 2007
Creator: Cavoto, Gianluca
Object Type: Article
System: The UNT Digital Library
B(E1) Strengths from Coulomb excitation of 11Be (open access)

B(E1) Strengths from Coulomb excitation of 11Be

The B(E1;1/2{sup +}{yields} 1/2{sup -}) strength for {sup 11}Be has been extracted from intermediate energy Coulomb excitation measurements, over a range of beam energies using a new reaction model, the extended continuum discretized coupled channels (XCDCC) method. In addition, a measurement of the excitation cross section for {sup 11}Be+{sup 208}Pb at 38.6 MeV/nucleon is reported. The B(E1) strength of 0.105(12) e{sup 2}fm{sup 2} derived from this measurement is consistent with those made previously at 60 and 64 MeV/nucleon, in contrast to an anomalously low result obtained at 43 MeV/nucleon. By coupling a multi-configuration description of the projectile structure with realistic reaction theory, the XCDCC model provides for the first time a fully quantum mechanical description of Coulomb excitation. The XCDCC calculations reveal that the excitation process involves significant contributions from nuclear, continuum, and higher-order effects. An analysis of the present and two earlier intermediate energy measurements yields a combined B(E1) strength of 0.105(7) e{sup 2}fm{sup 2}. This value is in good agreement with the value deduced independently from the lifetime of the 1/2{sup -} state in {sup 11}Be, and has a comparable precision.
Date: March 6, 2007
Creator: Summers, N. C.; Pain, S. D.; Orr, N. A.; Catford, W. N.; Angelique, J. C.; Ashwood, N I et al.
Object Type: Article
System: The UNT Digital Library
BaBar Status and Prospects for CP Asymmetry Measurements: Sin(2beta + gamma) (open access)

BaBar Status and Prospects for CP Asymmetry Measurements: Sin(2beta + gamma)

The recent experimental results on CP violation related to the angles of the Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle 2{beta} + {gamma} are summarized in these proceedings. These results are obtained with approximately 232 million {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II asymmetric-energy B-factory at SLAC. Using the measurements on time-dependent CP asymmetries in B{sup 0} {yields} D{sup (*){-+}} {pi}{sup {-+}} and B{sup 0} {yields} D{sup {-+}}{rho}{sup {+-}} decays and theoretical assumptions, one finds | sin(2{beta} + {gamma}) | > 0.64 (0.40) at 68% (90%) confidence level. The perspectives of sin(2{beta} + {gamma}) measurement with {bar B}{sup 0} {yields} D{sup (*)0} {bar K}{sup (*)0} and B{sup 0} {yields} D{sup (*){-+}}{alpha}{sub 0(2)}{sup {+-}} decay channels are also discussed.
Date: April 6, 2007
Creator: Ganzhur, Sergey
Object Type: Article
System: The UNT Digital Library
Biomass-Derived Hydrogen from a Thermally Ballasted Gasifier (open access)

Biomass-Derived Hydrogen from a Thermally Ballasted Gasifier

The goal of this project is to develop an indirectly heated gasification system that converts switchgrass into hydrogen-rich gas suitable for powering fuel cells. The project includes investigations of the indirectly-heated gasifier, development of particulate removal equipment, evaluation of catalytic methods for upgrading producer gas, development of contaminant measurement and control techniques, modeling of the thermal performance of the ballasted gasifier, and estimation of the cost of hydrogen from the proposed gasification system. Specific technologies investigated include a thermally ballasted gasifier, a moving bed granular filter, and catalytic reactors for steam reforming and water-gas shift reaction. The approach to this project was to employ a pilot-scale (5 ton per day) gasifier to evaluate the thermally ballasted gasifier as a means for producing hydrogen from switchgrass. A slipstream from the gasifier was used to evaluate gas cleaning and upgrading options. Other tests were conducted with laboratory-scale equipment using simulated producer gas. The ballasted gasifier operated in conjunction with a steam reformer and two-stage water-gas shift reactor produced gas streams containing 54.5 vol-% H2. If purge gas to the feeder system could be substantially eliminated, hydrogen concentration would reach 61 vol-%, which closely approaches the theoretical maximum of 66 vol-%. Tests with …
Date: April 6, 2007
Creator: Brown, Robert C.
Object Type: Report
System: The UNT Digital Library
BOA, Beam Optics Analyzer A Particle-In-Cell Code (open access)

BOA, Beam Optics Analyzer A Particle-In-Cell Code

The program was tasked with implementing time dependent analysis of charges particles into an existing finite element code with adaptive meshing, called Beam Optics Analyzer (BOA). BOA was initially funded by a DOE Phase II program to use the finite element method with adaptive meshing to track particles in unstructured meshes. It uses modern programming techniques, state-of-the-art data structures, so that new methods, features and capabilities are easily added and maintained. This Phase II program was funded to implement plasma simulations in BOA and extend its capabilities to model thermal electrons, secondary emissions, self magnetic field and implement a more comprehensive post-processing and feature-rich GUI. The program was successful in implementing thermal electrons, secondary emissions, and self magnetic field calculations. The BOA GUI was also upgraded significantly, and CCR is receiving interest from the microwave tube and semiconductor equipment industry for the code. Implementation of PIC analysis was partially successful. Computational resource requirements for modeling more than 2000 particles begin to exceed the capability of most readily available computers. Modern plasma analysis typically requires modeling of approximately 2 million particles or more. The problem is that tracking many particles in an unstructured mesh that is adapting becomes inefficient. In particular …
Date: December 6, 2007
Creator: Bui, Thuc
Object Type: Report
System: The UNT Digital Library
Bobbin-Tool Friction-Stir Welding of Thick-Walled Aluminum Alloy Pressure Vessels (open access)

Bobbin-Tool Friction-Stir Welding of Thick-Walled Aluminum Alloy Pressure Vessels

It was desired to assemble thick-walled Al alloy 2219 pressure vessels by bobbin-tool friction-stir welding. To develop the welding-process, mechanical-property, and fitness-for-service information to support this effort, extensive friction-stir welding-parameter studies were conducted on 2.5 cm. and 3.8 cm. thick 2219 Al alloy plate. Starting conditions of the plate were the fully-heat-treated (-T62) and in the annealed (-O) conditions. The former condition was chosen with the intent of using the welds in either the 'as welded' condition or after a simple low-temperature aging treatment. Since preliminary stress-analyses showed that stresses in and near the welds would probably exceed the yield-strength of both 'as welded' and welded and aged weld-joints, a post-weld solution-treatment, quenching, and aging treatment was also examined. Once a suitable set of welding and post-weld heat-treatment parameters was established, the project divided into two parts. The first part concentrated on developing the necessary process information to be able to make defect-free friction-stir welds in 3.8 cm. thick Al alloy 2219 in the form of circumferential welds that would join two hemispherical forgings with a 102 cm. inside diameter. This necessitated going to a bobbin-tool welding-technique to simplify the tooling needed to react the large forces generated in friction-stir …
Date: June 6, 2007
Creator: Dalder, E C; Pastrnak, J W; Engel, J; Forrest, R S; Kokko, E; Ternan, K M et al.
Object Type: Article
System: The UNT Digital Library
Borehole Gravity Meter Surveys at the Waste Treatment Plant, Hanford, Washington. (open access)

Borehole Gravity Meter Surveys at the Waste Treatment Plant, Hanford, Washington.

Microg-LaCoste (MGL) was contracted by Pacfic Northwest National Laboratories (PNNL) to record borehole gravity density data in 3 wells at the HanfordWaste Treatment Plant (WTP) site. The survey was designed to provide highly accurate density information for use in seismic modeling. The borehole gravity meter (BHGM) tool has a very large depth of investigation (hundreds of feet) compared to other density tools so it is not influenced by casing or near welbore effects, such as washouts.
Date: April 6, 2007
Creator: MacQueen, Jeffrey D. & Mann, Ethan
Object Type: Report
System: The UNT Digital Library
A brief survey on climate change effects on the Indian Monsoon (open access)

A brief survey on climate change effects on the Indian Monsoon

Each year, Indian summer monsoon season begins in June and ends in September. Surface winds blow from the southwest during this season. The Indian summer monsoon typically covers large areas of India with western and central India receiving more than 90% of their total annual precipitation during this period, and southern and northwestern India receiving 50%-75% of their total annual rainfall. Overall, monthly totals average 200-300 mm over the country as a whole, with the largest values observed during the heart of the monsoon season in July and August. In all total, India receives about 870 mm of rainfall in a normal summer monsoon season. This summary discusses the effects of climate change on the frequency, mean rainfall, duration and the variability of the Indian Monsoon. East Asian Monsoon in the southeastern part of Asia is not discussed in this summary. Changes in monsoon characteristics are mainly inferred from climate model simulations submitted to the Intergovernmental Panel on Climate Change (IPCC)'s Fourth Assessment Report (AR4). It should be cautioned that there is a large range in the results from these models. For instance, the range of mean monsoon precipitation as simulated by the AR4 models over India is from 500 …
Date: February 6, 2007
Creator: Bala, G.
Object Type: Report
System: The UNT Digital Library
Bulk Vitrification Performance Enhancement: Refractory Lining Protection Against Molten Salt Penetration (open access)

Bulk Vitrification Performance Enhancement: Refractory Lining Protection Against Molten Salt Penetration

Bulk vitrification (BV) is a process that heats a feed material that consists of glass-forming solids and dried low-activity waste (LAW) in a disposable refractory-lined metal box using electrical power supplied through carbon electrodes. The feed is heated to the point that the LAW decomposes and combines with the solids to generate a vitreous waste form. This study supports the BV design and operations by exploring various methods aimed at reducing the quantities of soluble Tc in the castable refractory block portion of the refractory lining, which limits the effectiveness of the final waste form.
Date: August 6, 2007
Creator: Hrma, Pavel R.; Bagaasen, Larry M.; Schweiger, Michael J.; Evans, Michael B.; Smith, Benjamin T.; Arrigoni, Benjamin M. et al.
Object Type: Report
System: The UNT Digital Library
Butt Joint Tool Commissioning (open access)

Butt Joint Tool Commissioning

ITER Central Solenoid uses butt joints for connecting the pancakes in the CS module. The principles of the butt joining of the CICC were developed by the JAPT during CSMC project. The difference between the CSMC butt joint and the CS butt joint is that the CS butt joint is an in-line joint, while the CSMC is a double joint through a hairpin jumper. The CS butt joint has to carry the hoop load. The straight length of the joint is only 320 mm, and the vacuum chamber around the joint has to have a split in the clamp shell. These requirements are challenging. Fig.1 presents a CSMC joint, and Fig.2 shows a CS butt joint. The butt joint procedure was verified and demonstrated. The tool is capable of achieving all specified parameters. The vacuum in the end was a little higher than the target, which is not critical and readily correctable. We consider, tentatively that the procedure is established. Unexpectedly, we discover significant temperature nonuniformity in the joint cross section, which is not formally a violation of the specs, but is a point of concern. All testing parameters are recorded for QA purposes. We plan to modify the butt …
Date: December 6, 2007
Creator: Martovetsky, N. N.
Object Type: Report
System: The UNT Digital Library
Carpet As An Alternative Fuel in Cement Kilns (open access)

Carpet As An Alternative Fuel in Cement Kilns

Approximately 5 billion lbs of carpet will be removed from buildings in the US each year for the foreseeable future. This carpet is potentially a valuable resource because it contains plastic in the face of the carpet that can be re-used. However, there are many different types of carpet, and at least four major different plastics used to make the face. The face is woven through a backing fabric and held in place by a “glue” that is in most cases a latex cross-linked polymer which is heavily loaded with chalk (calcium carbonate). This backing has almost no value as a recycled material. In addition, carpet is a bulky material that is difficult to handle and ship and must be kept dry. It would be of significant benefit to the public if this stream of material could be kept out of landfills and some of its potential value unlocked by having high volume alternatives for recycled carpet use. The research question that this project investigated was whether carpet could be used as a fuel in a cement kiln. If this could be done successfully, there is significant capacity in the US cement industry to absorb carpet and use it as …
Date: February 6, 2007
Creator: Realff, Matthew J
Object Type: Report
System: The UNT Digital Library
Cfetool: A General Purpose Tool for Anomaly Detection in Periodic Data (open access)

Cfetool: A General Purpose Tool for Anomaly Detection in Periodic Data

Cfengine's environment daemon ''cfenv'' has a limited and fixed set of metrics it measures on a computer. The data is assumed to be periodic in nature and cfenvd reports any data points that fall too far out of the pattern it has learned from past measurements. This is used to detect ''anomalies'' on computers. We introduce a new standalone tool, ''cfetool'', that allows arbitrary periodic data to be stored and evaluated. The user interface is modeled after rrdtool, another widely used tool to store measured data. Because a standalone tool can be used not only for computer related data, we have extended the built-in mathematics to apply to yearly data as well.
Date: March 6, 2007
Creator: Wachsmann, Alf & Cassell, Elizabeth
Object Type: Report
System: The UNT Digital Library
CHALLENGES WITH RETRIEVING TRANSURANIC WASTE FROM THE HANFORD BURIAL GROUNDS (open access)

CHALLENGES WITH RETRIEVING TRANSURANIC WASTE FROM THE HANFORD BURIAL GROUNDS

The U.S. DOE's Hanford Reservation produced plutonium and other nuclear materials for the nation's defense starting in World War II. The defense mission generated wastes that were either retrievably stored (i.e. retrievably stored waste) and/or disposed of in burial grounds. Challenges have emerged from retrieving suspect TRU waste including adequacy of records, radiological concerns, container integrity, industrial hygiene and safety issues, the lack of processing/treatment facilities, and the integration of regulatory requirements. All retrievably stored waste is managed as mixed waste and assumed to be TRU waste, unless documented otherwise. Mixed waste is defined as radioactive waste that contains hazardous constituents. The Atomic Energy Act governs waste with radionuclides, and the Resource Conservation and Recovery Act (RCRA) governs waste with hazardous constituents. Waste may also be governed by the Toxic Substances Control Act (TSCA), and a portion may be managed under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). In 1970, TRU waste was required to be placed in 20-year retrievable storage and segregated from other Waste. Prior to that date, segregation did not occur. Because of the changing definition of TRU over the years, and the limitations of early assay equipment, all retrievably stored waste in the burial …
Date: August 6, 2007
Creator: SWAN, R.J. & LAKES, M.E.
Object Type: Article
System: The UNT Digital Library
CHARACTERIZATION OF DWPF MELTER OFF-GAS QUENCHER AND STEAM ATOMIZED SCRUBBER DEPOSIT SAMPLES (open access)

CHARACTERIZATION OF DWPF MELTER OFF-GAS QUENCHER AND STEAM ATOMIZED SCRUBBER DEPOSIT SAMPLES

This report summarizes the results from the characterization of deposits from the inlets of the primary off-gas Quencher and Steam Atomized Scrubber (SAS) in the Defense Waste Processing Facility (DWPF), as requested by a technical assistance request. DWPF requested elemental analysis and compound identification to help determine the potential causes for the substance formation. This information will be fed into Savannah River National Laboratory modeling programs to determine if there is a way to decrease the formation of the deposits. The general approach to the characterization of these samples included x-ray diffraction (XRD), scanning electron microscopy (SEM), and chemical analysis. The following conclusions are drawn from the analytical results found in this report: (1) The deposits are not high level waste glass from the DWPF melt pool based on comparison of the compositions of deposits to the composition of a sample of glass taken from the pour stream of the melter during processing of Sludge Batch 3. (2) Chemical composition results suggest that the deposits are probably a combination of sludge and frit particles entrained in the off-gas. (3) Gamma emitters, such as Co-60, Cs-137, Eu-154, Am-241, and Am-243 were detected in both the Quencher and SAS samples with Cs-137 …
Date: June 6, 2007
Creator: Zeigler, K & Ned Bibler, N
Object Type: Report
System: The UNT Digital Library
Charmless B Decays (open access)

Charmless B Decays

Rare charmless hadronic B decays are a good testing ground for the standard model. The dominant amplitudes contributing to this class of B decays are CKM suppressed tree diagrams and b {yields} s or b {yields} d loop diagrams (''penguins''). These decays can be used to study interfering standard model (SM) amplitudes and CP violation. They are sensitive to the presence of new particles in the loops, and they provide valuable information to constrain theoretical models of B decays. The B factories BABAR at SLAC and Belle at KEK produce B mesons in the reaction e{sup +}e{sup -} {yields} {Upsilon}(4S) {yields} B{bar B}. So far they have collected integrated luminosities of about 406 fb{sup -1} and 600 fb{sup -1}, respectively. The results presented here are based on subsets of about 200-500 fb{sup -1} and are preliminary unless a journal reference is given.
Date: March 6, 2007
Creator: Gradl, Wolfgang & U., /Edinburgh
Object Type: Article
System: The UNT Digital Library
Comment on "Paleoclassical Transport in Low-Collisionality Toroidal Plasmas" [Phys. Plasmas 12, 092512 (2005)] (open access)

Comment on "Paleoclassical Transport in Low-Collisionality Toroidal Plasmas" [Phys. Plasmas 12, 092512 (2005)]

None
Date: August 6, 2007
Creator: LoDestro, L.
Object Type: Article
System: The UNT Digital Library
Comparative Dissolution Modes of Iron-Based Amorphous Alloys and Other Corrosion Resistant Polycrystalline Materials (open access)

Comparative Dissolution Modes of Iron-Based Amorphous Alloys and Other Corrosion Resistant Polycrystalline Materials

Metallic amorphous alloys or metallic glasses have been studied extensively for the last three decades due to their unique characteristics, including superior mechanical properties and corrosion resistance. Iron-based amorphous alloys have in general better corrosion resistance than their polycrystalline cousins such as the austenitic 18-8 stainless steel series (e.g. 316L SS). Fe-based amorphous alloys have even higher localized corrosion resistance than the nickel-based Alloy 22 under many laboratory tested conditions. Electrochemical laboratory tests have shown that when polycrystalline alloys such as Alloy 22 are anodically polarized in hot concentrated chloride brines, they dissolve unevenly following patterns associated with their crystalline character. However, amorphous alloys, when polarized to even higher potentials than the polycrystalline alloys, they dissolve in a desirable uniform manner. This is because the amorphous Fe-based alloys do not offer defects in the metal that can be preferentially attacked. Comparative studies will also be presented on the dissolution modes of Ni-gadolinium and borated stainless steels.
Date: March 6, 2007
Creator: Rebak, R B; Hailey, P D; Day, S D & Farmer, J C
Object Type: Article
System: The UNT Digital Library