Cancellation of the Chromatic Effects with proper Field Profile (open access)

Cancellation of the Chromatic Effects with proper Field Profile

N/A
Date: April 1, 2004
Creator: A., Ruggiero
Object Type: Report
System: The UNT Digital Library
Large batch dimensional metrology demonstrated in the example of a LIGA fabricated spring. (open access)

Large batch dimensional metrology demonstrated in the example of a LIGA fabricated spring.

Deep x-ray lithography in combination with electroforming is capable of producing high precision metal parts in small lot series. This study deals with a high aspect ratio structure with overall dimensions on the order of 10 mm x 7 mm x 1.5 mm, with the smallest line width being 150 {micro}m. The lateral deviation from the design is to be kept to a minimum, preferably below 5 {micro}m. To ensure adequate quality control, a semi-automated metrology technique has been established to measure all parts. While the paper will give a brief overview of all involved techniques, it focuses on the method to measure the top and bottom of the parts and the top of geometries following the process. The instrument used is a View Engineering Voyager V6x12 microscope, which is fully programmable. The microscope allows direct measurement of geometries but also is capable of saving all captured data as point clouds. These point clouds play a central role when evaluating part geometry. After measuring the part, the point cloud is compared to the computer aided design (CAD) contour of the part, using a commercially available software package. The challenge of proper edge lighting on a nickel alloy part is evaluated …
Date: April 1, 2004
Creator: Aigeldinger, Georg; Skala, Dawn M. & Ceremuga, Joseph T.
Object Type: Report
System: The UNT Digital Library
SMART SCREENING SYSTEM (S3) IN TACONITE PROCESSING (open access)

SMART SCREENING SYSTEM (S3) IN TACONITE PROCESSING

The conventional vibrating machines used in processing plants have had undesirable high noise and vibration levels. They also have had unsatisfactorily low screening efficiency, high energy consumption, high maintenance cost, low productivity, and poor worker safety. These conventional vibrating machines have been used in most every processing plant. Most of the current material separation technology uses heavy and inefficient electric motors with an unbalance rotating mass to generate the shaking. In addition to being excessively noisy, inefficient, high-maintenance, these vibrating machines are often the bottleneck in the entire process. Furthermore, these motors along with the vibrating machines and supporting structure shake other machines and structure in the vicinity. The latter increases maintenance costs while reducing worker health and safety. The conventional vibrating fine screens at taconite processing plants have had the same problems as those listed above. This has resulted in lower screening efficiency, higher energy and maintenance cost, and lower productivity and workers safety concerns. The focus of this work is on the design of a high performance screening machine suitable for taconite processing plants. SmartScreens{trademark} technology uses miniaturized motors, based on smart materials, to generate the shaking. The underlying technologies are Energy Flow Control{trademark} and Vibration Control by …
Date: April 1, 2004
Creator: Allaei, Daryoush & Mohammed, Asim Syed
Object Type: Report
System: The UNT Digital Library
Precipitation-Front Modeling: Issues Relating to Nucleation and Metastable Precipitation in the Planned Nuclear Waste Repository at Yucca Mountain, Nevada (open access)

Precipitation-Front Modeling: Issues Relating to Nucleation and Metastable Precipitation in the Planned Nuclear Waste Repository at Yucca Mountain, Nevada

The focus of the presentation is on certain aspects concerning the kinetics of heterogeneous reactions involving the dissolution and precipitation of unstable and metastable phases under conditions departing from thermodynamic equilibrium. These aspects are particularly relevant to transient thermal-hydrological-chemical (THC) processes that will occur as a result of the emplacement of radioactive waste within the Yucca Mountain Repository. Most important of these is a phenomenon commonly observed in altering soils, sediments and rocks, where less stable minerals precipitate in preference to those that are more stable, referred to as the Ostwald Rule of Stages, or the Ostwald Step Rule. W. Ostwald (1897) described the phenomenon characterizing his rule (as cited in Schmeltzer et al., 1998), thus: ''...in the course of transformation of an unstable (or metastable) state into a stable one the system does not go directly to the most stable conformation (corresponding to the modification with the lowest free energy) but prefers to reach intermediate stages (corresponding to other metastable modifications) having the closest free energy to the initial state''. This phenomenon is so widespread in natural geochemical systems, particularly under hydrothermal or low temperature conditions, that few geochemical parageneses involving the subcritical aqueous phase can be described without …
Date: April 1, 2004
Creator: Apps, J. A. & Sonnenthal, E. L.
Object Type: Article
System: The UNT Digital Library
Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report (open access)

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. The luminescence of Mo{sub 6}Cl{sub 12} immobilized in a sol-gel matrix was measured as a function of heater temperature up to 200 C, in an inert environment. While the luminescence decreased with temperature, the integrated intensity at 200 C should be sufficient to enable detection of the luminescence in a fiber geometry. Previously we found that aging Mo{sub 6}Cl{sub 12} at temperatures above 250 C converts the canary yellow Mo{sub 6}Cl{sub 12} to a non-luminescent gray solid. Optical and thermal aging experiments show that the alkali metal salts of Mo{sub 6}Cl{sub 12} have higher thermal stabilities and remain luminescent after aging at 280 C.
Date: April 1, 2004
Creator: Baker, Gregory L.; Ghosh, Ruby N. & III, D.J. Osborn
Object Type: Report
System: The UNT Digital Library
Cellulose and the Control of Growth Anisotropy (open access)

Cellulose and the Control of Growth Anisotropy

The authors research aims to understand morphogenesis, focusing on growth anisotropy, a process that is crucial to make organs with specific and heritable shapes. For the award, the specific aims were to test hypotheses concerning how growth anisotropy is controlled by cell wall structure, particularly by the synthesis and alignment of cellulose microfibrils, the predominant mechanical element in the cell wall. This research has involved characterizing the basic physiology of anisotropic expansion, including measuring it at high resolution; and second, characterizing the relationship between growth anisotropy, and cellulose microfibrils. Important in this relationship and also to the control of anisotropic expansion are structures just inside the plasma membrane called cortical microtubules, and the research has also investigated their contribution to controlling anisotropy and microfibril alignment. In addition to primary experimental papers, I have also developed improved methods relating to these objectives as well as written relevant reviews. Major accomplishments in each area will now be described.
Date: April 1, 2004
Creator: Baskin, Tobias I.
Object Type: Report
System: The UNT Digital Library
Secondary Emission Enhanced Photoinjector (open access)

Secondary Emission Enhanced Photoinjector

N/A
Date: April 1, 2004
Creator: Ben-Zvi, Ilan; Chang, X.; Johnson, P.D.; Kewisch, J. & Rao, T.S.
Object Type: Report
System: The UNT Digital Library
Review of Current FFAG Lattice Studies in North America (open access)

Review of Current FFAG Lattice Studies in North America

There has been a revival of interest in the use of fixed field alternating gradient accelerators (FFAGs) for many applications, including muon accelerators, high-intensity proton sources, and medical applications. The original FFAGs, and those recently built in Japan, have been based on a so-called scaling FFAG design, for which tunes are constant and the behavior in phase space is independent of energy with the exception of a scaling factor. Activity in the US and Canada has instead mostly focused on nonscaling designs, which, while having the large energy acceptance that characterizes an FFAG, do not obey the scaling relations of the scaling FFAG. Most of these designs have been based on magnets with a linear midplane field profile. A great deal of analysis, both theoretically and numerically, has occurred on these designs, and they are very well understood at this point. Some more recent work has occurred on designs with a nonlinear field profile. Since no non-scaling FFAG has ever been built, there is interest in building a small model which would accelerate electrons and demonstrate our understanding of non-scaling FFAG design.
Date: April 1, 2004
Creator: Berg, J. Scott; Plamer, Robert; Ruggiero, Alessandro; Trbojevic, Dejan; Keil, Eberhard; Johnstone, Carol et al.
Object Type: Article
System: The UNT Digital Library
Experimental investigation of burnup credit for safe transport, storage, and disposal of spent nuclear fuel. (open access)

Experimental investigation of burnup credit for safe transport, storage, and disposal of spent nuclear fuel.

This report describes criticality benchmark experiments containing rhodium that were conducted as part of a Department of Energy Nuclear Energy Research Initiative project. Rhodium is an important fission product absorber. A capability to perform critical experiments with low-enriched uranium fuel was established as part of the project. Ten critical experiments, some containing rhodium and others without, were conducted. The experiments were performed in such a way that the effects of the rhodium could be accurately isolated. The use of the experimental results to test neutronics codes is demonstrated by example for two Monte Carlo codes. These comparisons indicate that the codes predict the behavior of the rhodium in the critical systems within the experimental uncertainties. The results from this project, coupled with the results of follow-on experiments that investigate other fission products, can be used to quantify and reduce the conservatism of spent nuclear fuel safety analyses while still providing the necessary level of safety.
Date: April 1, 2004
Creator: Berry, Donald T.; Harms, Gary A.; Ford, John T.; Walker, Sharon Ann; Helmick, Paul H. & Pickard, Paul S.
Object Type: Report
System: The UNT Digital Library
Technetium-99 Behavior in Savannah River Site High Level Waste Sludges During Waste Processing (open access)

Technetium-99 Behavior in Savannah River Site High Level Waste Sludges During Waste Processing

This report presents results of an in-depth study of the behavior of technetium-99 (Tc-99) during waste processing operations at Savannah River Site. Tc-99 is a long lived (t1/2 equals 2.1E05 years) radioactive fission product of U-235. Its behavior during high level waste (HLW) processing is important to understand because Tc-99 can fractionate in the waste and appear in both the sludge and the salt tanks at Savannah River Site. Further it can also be soluble in groundwaters and thus is an important radionuclide that may dictate how much residual waste has to be removed from a waste tank to prepare it for permanent closure. Results are also presented for Pd-105, another important U-235 fission product. This fission product is stable, but it is important because it has a finite solubility in the sludge supernates in the HLW and is also used to calculate the concentration of the radionuclide Pd-107 that has to be reported in the Waste Acceptance Specifications to send HLW glass to a repository.
Date: April 1, 2004
Creator: Bibler, N. E.; Fellinger, T. L. & Hobbs, D. T.
Object Type: Report
System: The UNT Digital Library
Corrective Action Decision Document for Corrective Action Unit 204: Storage Bunkers, Nevada Test Site, Nevada, Rev. No. 0 (open access)

Corrective Action Decision Document for Corrective Action Unit 204: Storage Bunkers, Nevada Test Site, Nevada, Rev. No. 0

The six bunkers included in CAU 204 were primarily used to monitor atmospheric testing or store munitions. The ''Corrective Action Investigation Plan (CAIP) for Corrective Action Unit 204: Storage Bunkers, Nevada Test Site, Nevada'' (NNSA/NV, 2002a) provides information relating to the history, planning, and scope of the investigation; therefore, it will not be repeated in this CADD. This CADD identifies potential corrective action alternatives and provides a rationale for the selection of a recommended corrective action alternative for each CAS within CAU 204. The evaluation of corrective action alternatives is based on process knowledge and the results of investigative activities conducted in accordance with the CAIP (NNSA/NV, 2002a) that was approved prior to the start of the Corrective Action Investigation (CAI). Record of Technical Change (ROTC) No. 1 to the CAIP (approval pending) documents changes to the preliminary action levels (PALs) agreed to by the Nevada Division of Environmental Protection (NDEP) and DOE, National Nuclear Security Administration Nevada Site Office (NNSA/NSO). This ROTC specifically discusses the radiological PALs and their application to the findings of the CAU 204 corrective action investigation. The scope of this CADD consists of the following: (1) Develop corrective action objectives; (2) Identify corrective action alternative …
Date: April 1, 2004
Creator: Boehlecke, Robert
Object Type: Report
System: The UNT Digital Library
Characterization of Turbiditic Oil Reservoirs Based on Geophysical Models of Their Formation (open access)

Characterization of Turbiditic Oil Reservoirs Based on Geophysical Models of Their Formation

A hierarchy of models and results are presented for the simulation of the dynamics and deposition of concentrated turbidity currents. The turbidity flows are assumed to be two-dimensional due to a constant flux release of dense suspensions spreading over a nonerodible flat surface. The three models presented are the Suspension Balance Model (SBM), the Simplified Suspension Balance Model (SSBM) and the Vertically Averaged Simplified Suspension Balance Model (VASSBM). The SBM is computationally intensive. However, simulations of the SBM indicate that the only a subset of the terms in the equations for the SBM are significant. The VASSBM is significantly faster computationally, and it is shown here to be an accurate approximation of the SBM model. For all the models, the two parameters that determine the dynamics and deposition of a concentrated turbidity current due to a constant flux release are the inlet volume fraction and the buoyancy number, a ratio of the buoyancy forces to viscous forces acting on the current. A parameter study is conducted for a volume fraction ranging from 10 to 40% and buoyancy numbers ranging from 0.01 to 0.2, typical of many real concentrated turbidity flows. It is found that the length or extent of deposit …
Date: April 1, 2004
Creator: Bonnecaze, Roger T. & Lakshminarasimhan, Srivatsan
Object Type: Report
System: The UNT Digital Library
GridWise Standards Mapping Overview (open access)

GridWise Standards Mapping Overview

''GridWise'' is a concept of how advanced communications, information and controls technology can transform the nation's energy system--across the spectrum of large scale, central generation to common consumer appliances and equipment--into a collaborative network, rich in the exchange of decision making information and an abundance of market-based opportunities (Widergren and Bosquet 2003) accompanying the electric transmission and distribution system fully into the information and telecommunication age. This report summarizes a broad review of standards efforts which are related to GridWise--those which could ultimately contribute significantly to advancements toward the GridWise vision, or those which represent today's current technological basis upon which this vision must build.
Date: April 1, 2004
Creator: Bosquet, Mia L.
Object Type: Report
System: The UNT Digital Library
Advanced Compressor Engine Controls to Enhance Operation, Reliability and Integrity (open access)

Advanced Compressor Engine Controls to Enhance Operation, Reliability and Integrity

This document provides a mid-term update for the ''Advanced Compressor Engine Controls to Enhance Operation, Reliability, and Integrity'' project. SwRI is conducting this project for DOE in conjunction with Cooper Energy Services, under DOE contract number DE-FC26-03NT41859. The objective of this one-year project is to develop, evaluate, and demonstrate advanced engine control technologies and hardware, specifically, closed-loop NO{sub x} emissions control on a two-stroke integral reciprocating engine/compressor used for pipeline gas transmission service. This work uses a Cooper-Bessemer GMVH-6 laboratory engine owned by Cooper Energy Services (CES) and installed in a test facility at Southwest Research Institute (SwRI). The gas transmission industry operates over 4,000 integral engine compressors, the majority being two-stroke, with a median age of 45 years and a median size of 2000 horsepower. These engines have historically exhibited poor performance and high emissions, due in part to poor engine control. The end results are misfires and partial burns that lead to increased fuel usage and exhaust emissions. Many of the slow-speed integral engines in the gas compression industry utilize control systems that are outdated, slow, and suffer from poor resolution. Research into more advanced control systems for integral compressor engines has increased tremendously in recent years. The …
Date: April 1, 2004
Creator: Bourn, Gary D.
Object Type: Report
System: The UNT Digital Library
Neutralization of Plutonium and Enriched Uranium Solutions Containing Gadolinium as a Neutron Poison (open access)

Neutralization of Plutonium and Enriched Uranium Solutions Containing Gadolinium as a Neutron Poison

Materials currently being dissolved in the HB-Line Facility will result in an accumulated solution containing an estimated uranium:plutonium (U:Pu) ratio of 4.3:1 and an 235U enrichment estimated at 30 per cent The U:Pu ratio and the enrichment are outside the evaluated concentration range for disposition to high level waste (HLW) using gadolinium (Gd) as a neutron poison. To confirm that the solution generated during the current HB-Line dissolving campaign can be poisoned with Gd, neutralized and discarded to the Savannah River Site (SRS) high level waste (HLW) system without undue nuclear safety concerns the caustic precipitation of surrogate solutions was examined. Experiments were performed with a U/Pu/Gd solution representative of the HB-Line estimated concentration ratio and also a U/Gd solution. Depleted U was used in the experiments as the enrichment of the U will not affect the chemical behavior during neutralization, but will affect the amount of Gd added to the solution. Settling behavior of the neutralized solutions was found to be comparable to previous studies. The neutralized solutions mixed easily and had expected densities of typical neutralized waste. The neutralized solids were found to be homogeneous and less than 20 microns in size. Partially neutralized solids were more amorphous …
Date: April 1, 2004
Creator: Bronikowski, M. G.
Object Type: Report
System: The UNT Digital Library
MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED PHOTOACOUSTIC EFFECT TO MEASURE UNBURNED CARBON (open access)

MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED PHOTOACOUSTIC EFFECT TO MEASURE UNBURNED CARBON

Three test instruments are being evaluated to determine the feasibility of using photoacoustic technology for measuring unburned carbon in fly ash. The first test instrument is a single microwave frequency system previously constructed to measure photoacoustic signals in an off-line configuration. A second off-line instrument was constructed based in part on lessons learned with the first instrument, but which also expands the capabilities of the first instrument. Improvements include a control loop to allow more constant microwave power output and an ability to operate over a range of microwave frequencies. The third instrument, the on-line version of the fly ash monitor, has been designed, constructed, and initial efficiency tests have been conducted on the monitor's electrical components. Photoacoustic measurements were collected using the off-line MEPA spectrometer with different microwave frequencies in order to develop photoacoustic microwave spectra of several fly ash samples. Microwaves from 500 MHz to 1800 MHz were used. Modifications to the on-line thermal elastic fly ash monitor include the improving the operation of the agitator for the bottom hopper, and installing a second diaphragm assembly in the freeboard section of the fly ash monitor. This second diaphragm assembly can be used with a second MEMS-based accelerometer and …
Date: April 1, 2004
Creator: Brown, Robert C.; Weber, Robert J. & Sweterlitsch, Jeff
Object Type: Report
System: The UNT Digital Library
REALTIME MONITORING OF PIPELINES FOR THIRD-PARTY CONTACT (open access)

REALTIME MONITORING OF PIPELINES FOR THIRD-PARTY CONTACT

Third-party contact with pipelines (typically caused by contact with a digging or drilling device) can result in mechanical damage to the pipe, in addition to coating damage that can initiate corrosion. Because this type of damage often goes unreported and can lead to eventual catastrophic failure of the pipe, a reliable, cost-effective method is needed for monitoring and reporting third-party contact events. The impressed alternating cycle current (IACC) pipeline monitoring method consists of impressing electrical signals on the pipe by generating a time-varying voltage between the pipe and the soil at periodic locations where pipeline access is available. The signal voltage between the pipe and ground is monitored continuously at receiving stations located some distance away. Third-party contact to the pipe that breaks through the coating changes the signal received at the receiving stations. In this project, the IACC monitoring method is being developed, tested, and demonstrated. Work performed to date includes a technology assessment, development of an IACC model to predict performance and assist with selection of signal operating parameters, and experimental measurements on a buried pipe at a test site. Initial results show that simulated contact can be detected. Future work will involve further refinement of the method …
Date: April 1, 2004
Creator: Burkhardt, Gary L.; Crouch, Alfred E. & Fisher, Jay L.
Object Type: Report
System: The UNT Digital Library
History and testimony of competency-based development at Sandia National Laboratories. (open access)

History and testimony of competency-based development at Sandia National Laboratories.

More than ten years ago, Sandia managers defined a set of traits and characteristics that were needed for success at Sandia. Today, the Sandia National Laboratories Success Profile Competencies continue to be powerful tools for employee and leadership development. The purpose of this report is to revisit the historical events that led to the creation and adaptation of the competencies and to position them for integration in future employee selection, development, and succession planning processes. This report contains an account of how the competencies were developed, testimonies of how they are used within the organization, and a description of how they will be foundational elements of new processes.
Date: April 1, 2004
Creator: Burt, Rebecca A. & Narahara, Sheryl K.
Object Type: Report
System: The UNT Digital Library
Build up of electron cloud with different bunch pattern in the presence of solenoidal field (open access)

Build up of electron cloud with different bunch pattern in the presence of solenoidal field

We have augmented the code POSINST to include solenoid fields, and used it to simulate the build up of electron cloud due to electron multipacting in the PEP-II positron ring. We find that the distribution of electrons is strongly affected by the resonances associated with the cyclotron period and bunch spacing. In addition, we discover a threshold beyond which the electron density grows exponentially until it reaches the space charge limit. The threshold does not depend on the bunch spacing but does depend on the positron bunch population.
Date: April 1, 2004
Creator: Cai, Y.; Furman, M. A. & Pivi, M.
Object Type: Article
System: The UNT Digital Library
Drip shield Structural Response to Rock Fall (open access)

Drip shield Structural Response to Rock Fall

The objective of this calculation is to determine areas over the drip shield (DS) top plate and side-walls where the residual stress values exceed 50% of Ti-7 yield strength. These areas will also be referred to as the damaged areas throughout this document. The scope of this document is limited to reporting the calculation results in terms of the damaged areas based on a chosen set of stress components. This calculation is intended for use in support of the preliminary design activities for the license application design of the DS. This calculation is associated with the DS design and was performed by the Waste Package and Components. AP-3.12Q, ''Design Calculations and Analyses'' is used to perform the calculation and develop the document. The DS is classified as a safety category item. Therefore, this calculation is subject to the Quality Assurance Requirements and Description. The information provided by the sketches attached to this calculation is that of the potential design of the type of DS considered in this calculation and provides the potential dimensions and materials for the DS design. The finite element (FE) calculation was performed by using the commercially available LS-DYNA Version (V)960 (Software Tracking Number [STN] 10300-960.1106-00, Ref. …
Date: April 1, 2004
Creator: Ceylan, Z.
Object Type: Report
System: The UNT Digital Library
IMPACT OF DME-DIESEL FUEL BLEND PROPERTIES ON DIESEL FUEL INJECTION SYSTEMS (open access)

IMPACT OF DME-DIESEL FUEL BLEND PROPERTIES ON DIESEL FUEL INJECTION SYSTEMS

The objectives of this research program are to develop information on lubricity and viscosity improvers and their impact on the wear mechanisms in fuel injectors operating on blends of dimethyl ether (DME) and diesel fuel. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In the shuttle bus project, we have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. Our strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. In this project, we have sought to develop methods for extending the permissible DME content in the DME-diesel blends without experiencing rapid injector failure due to wear. Our activities have covered three areas: examination of the impact of lubricity additives on the viscosity of DME, development of a high-pressure lubricity test apparatus for studies of lubricity and …
Date: April 1, 2004
Creator: Chapman, Elana M.; Boehman, Andre; Wain, Kimberly; Lloyd, Wallis; Perez, Joseph M.; Stiver, Donald et al.
Object Type: Report
System: The UNT Digital Library
Cost-Effective Reciprocating Engine Emissions Control and Monitoring for E&P Field and Gathering Engines: Report 5 (open access)

Cost-Effective Reciprocating Engine Emissions Control and Monitoring for E&P Field and Gathering Engines: Report 5

During the fifth reporting period, the main goal for the team was to focus on collecting data to develop Oxygen Sensor Recording System (OSRS) parametric relationships for several rich-burn engines. An air/fuel ratio controller was intergraded with an O{sub 2} sensor. With the use of an Alternative Continuous Emissions Monitoring System (ACEMS) provided by Eastern Municipal Water District (EMWD), the performance will be observed during normal operation.
Date: April 1, 2004
Creator: Chapman, Kirby S. & Adriani, Allen
Object Type: Report
System: The UNT Digital Library
Protective coating on stainless steel interconnect for SOFCs:Oxidation kinetics and electrical properties (open access)

Protective coating on stainless steel interconnect for SOFCs:Oxidation kinetics and electrical properties

An effective, dense and well adherent coating was produced on 430SS that has the result of significantly reducing the oxidation rate of this alloy at elevated temperatures. The coating is essentially a Mn-Co-O spinel, applied in powder form, and compacted to improve its green density. A simplified model is presented that allows an assessment of the effects of the contact and scale geometries. For 850 C, an ASR can be predicted of approximately 0.5 cm2, after 50,000hrs in air, taking in to account a factor of 10 penalty for unfavorable contact geometries. The effect of the densified Mn-Co spinel coating is to reduce significantly Cr2O3 sub-scale formation, lower the thermal expansion mismatch, and increase the electronic conductivity of the scale. The findings point to several potential remedies for achieving coatings on 430 SS that allow for metal interconnects with a service life of 50,000 hrs or more. Considering contact geometries, such service life is unlikely to be possible above operating temperatures of about 700 C, unless highly specialized alloys are used, with potential processing and cost penalties.
Date: April 1, 2004
Creator: Chen, Xuan; Hou, Peggy Y.; Jacobson, Craig P.; Visco, Steven J. & De Jonghe, Lutgard C.
Object Type: Article
System: The UNT Digital Library
Forced Volume Magnetostriction in Composite Gd5Si2Ge2 (open access)

Forced Volume Magnetostriction in Composite Gd5Si2Ge2

A -1200 ppm forced volume magnetostriction has been obtained in a [0-3], resin binder, Gd{sub 5}Si{sub 2}Ge{sub 2} particulate composite. The strain is a result of a magnetically induced phase transformation from a high volume (high temperature, low magnetic field) monoclinic phase to a low volume (low temperature, high magnetic field) orthorhombic phase. The particles used in the composite were ball-milled from a bulk sample and were sieved to obtain a size distribution of {approx}> 600 {micro}m. Bulk Gd{sub 5}Si{sub 2}Ge{sub 2} was manufactured via arc melting and subsequently annealed at 1300 C for 1 hour to produce a textured, polycrystalline sample. The transformation temperatures of the bulk sample, as measured using a Differential Scanning Calorimeter (DSC), were M{sub s}= -9.3 C, M{sub f}=-14.6 C, A{sub s}=-4.4 C, and A{sub f}=-1.2 C. The composite and the bulk samples were magnetically characterized using a SQUID magnetometer, and found to undergo a paramagnetic to ferromagnetic transition during the phase transformation, consistent with published results. The bulk sample was also found to possess a maximum linear magnetostriction -2500 ppm.
Date: April 1, 2004
Creator: Choe, W; McCall, S K; Radousky, H B; Nersessian, N; Or, S W; Carman, G P et al.
Object Type: Article
System: The UNT Digital Library