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2007 Radiation & Climate GRC ( July 29-August 3, 2007) (open access)

2007 Radiation & Climate GRC ( July 29-August 3, 2007)

The theme of the fifth Gordon Research Conference on Radiation and Climate is 'Integrating multiscale measurements and models for key climate questions'. The meeting will feature lectures, posters, and discussion regarding these issues. The meeting will focus on insights from new types of satellite and in situ data and from new approaches to modeling processes in the climate system. The program on measurements will highlight syntheses of new satellite data on cloud, aerosols, and chemistry and syntheses of satellite and sub-orbital observations from field programs. The program on modeling will address both the evaluation of cloud-resolving and regional aerosol models using new types of measurements and the evidence for processes and physics missing from global models. The Conference will focus on two key climate questions. First, what factors govern the radiative interactions of clouds and aerosols with regional and global climate? Second, how well do we understand the interaction of radiation with land surfaces and with the cryosphere?
Date: June 1, 2008
Creator: Gray, William Collins Nancy Ryan
System: The UNT Digital Library
Accelerators and the Accelerator Community (open access)

Accelerators and the Accelerator Community

In this paper, standing back--looking from afar--and adopting a historical perspective, the field of accelerator science is examined. How it grew, what are the forces that made it what it is, where it is now, and what it is likely to be in the future are the subjects explored. Clearly, a great deal of personal opinion is invoked in this process.
Date: June 1, 2008
Creator: Malamud, Ernest & Sessler, Andrew
System: The UNT Digital Library
Analysis of Sub-Hourly Ramping Impacts of Wind Energy and Balancing Area Size (Poster) (open access)

Analysis of Sub-Hourly Ramping Impacts of Wind Energy and Balancing Area Size (Poster)

WindPower 2008 conference sponsored by AWEA held in Houston, TX on June 1-4 2008. This poster illustrates the data collected for an analysis of sub-hourly ramping impacts of wind energy and balancing area size.
Date: June 1, 2008
Creator: Milligan, M. & Kirby, B.
System: The UNT Digital Library
Analysis of Sub-Hourly Ramping Impacts of Wind Energy and Balancing Area Size: Preprint (open access)

Analysis of Sub-Hourly Ramping Impacts of Wind Energy and Balancing Area Size: Preprint

In this paper, we analyze sub-hourly ramping requirements and the benefit of combining Balancing Authority operations with significant wind penetrations.
Date: June 1, 2008
Creator: Milligan, M. & Kirby, B.
System: The UNT Digital Library
Analysis of Thermally Induced Changes in Fractured Rock Permeability during Eight Years of Heating and Cooling at the Yucca Mountain Drift Scale Test (open access)

Analysis of Thermally Induced Changes in Fractured Rock Permeability during Eight Years of Heating and Cooling at the Yucca Mountain Drift Scale Test

We analyzed a data set of thermally induced changes in fractured rock permeability during a four-year heating (up to 200 C) and subsequent four-year cooling of a large volume, partially saturated and highly fractured volcanic tuff at the Yucca Mountain Drift Scale Test, in Nevada, USA. Permeability estimates were derived from about 700 pneumatic (air-injection) tests, taken periodically at 44 packed-off borehole intervals during the heating and cooling cycle from November 1997 through November 2005. We analyzed air-permeability data by numerical modeling of thermally induced stress and moisture movements and their impact on air permeability within the highly fractured rock. Our analysis shows that changes in air permeability during the initial four-year heating period, which were limited to about one order of magnitude, were caused by the combined effects of thermal-mechanically-induced stress on fracture aperture and thermal-hydrologically-induced changes in fracture moisture content. At the end of the subsequent four-year cooling period, air-permeability decreases (to as low as 0.2 of initial) and increases (to as high as 1.8 of initial) were observed. By comparison to the calculated thermo-hydro-elastic model results, we identified these remaining increases or decreases in air permeability as irreversible changes in intrinsic fracture permeability, consistent with either inelastic …
Date: June 1, 2008
Creator: Rutqvist, J.; Freifeld, B.; Min, K.-B.; Elsworth, D. & Tsang, Y.
System: The UNT Digital Library
Applying SE Methods Achieves Project Success to Evaluate Hammer and Fixed Cutter Grinders Using Multiple Varieties and Moistures of Biomass Feedstock for Ethanol Production (open access)

Applying SE Methods Achieves Project Success to Evaluate Hammer and Fixed Cutter Grinders Using Multiple Varieties and Moistures of Biomass Feedstock for Ethanol Production

Applying basic systems engineering (SE) tools to the mission analysis phases of a 2.5-million dollar biomass pre-processing project for the U.S. Department of Energy directly assisted the project principal investigator understand the complexity and identify the gaps of a moving-target project and capture the undefined technical/functional requirements and deliverables from the project team and industrial partners. A creative application of various SE tools by non-aerospace systems engineers developed an innovative “big picture” product that combined aspects of mission analysis with a project functional flow block diagram, providing immediate understanding of the depth and breath of the biomass preprocessing effort for all team members, customers, and industrial partners. The “big picture” diagram became the blue print to write the project test plan, and provided direction to bring the project back on track and achieve project success.
Date: June 1, 2008
Creator: Zirker, Larry R.; Christopher T. Wright, PhD & Hamelin, R. Douglas
System: The UNT Digital Library
Arsenic and chromium partitioning in a podzolic soil contaminated by chromated copper arsenate (open access)

Arsenic and chromium partitioning in a podzolic soil contaminated by chromated copper arsenate

This research combined the use of selective extractions and x-ray spectroscopy to examine the fate of As and Cr in a podzolic soil contaminated by chromated copper arsenate (CCA). Iron was enriched in the upper 30 cm due to a previous one-time treatment of the soil with Fe(II). High oxalate-soluble Al concentrations in the Bs horizon of the soil and micro-XRD data indicated the presence of short-range ordered aluminosilicates (i.e. proto-imogolite allophane, PIA). In the surface layers, Cr, as Cr(III), was partitioned between a mixed Fe(III)/Cr(III) solid phase that formed upon the Fe(II) application (25-50%) and a recalcitrant phase (50-75%) likely consisting of organic material such as residual CCA-treated wood. Deeper in the profile Cr appeared to be largely in the form of extractable (hydr)oxides. Throughout the soil, As was present as As(V). In the surface layers a considerable fraction of As was also associated with a recalcitrant phase, probably CCA-treated woody debris, and the remainder was associated with (hydr)oxide-like solid phases. In the Bs horizon, however, XAS and XRF findings strongly pointed to the presence of PIA acting as an effective adsorbent for As. This research shows for the first time the relevance of PIA for the adsorption of …
Date: June 1, 2008
Creator: Nico, Peter; Hopp, Luisa; Nico, Peter S.; Marcus, Matthew A. & Peiffer, Stefan
System: The UNT Digital Library
Assembly and Test of a Support Structure for 3.6 m Long Nb3Sn Racetrack Coils (open access)

Assembly and Test of a Support Structure for 3.6 m Long Nb3Sn Racetrack Coils

The LHC Accelerator Research Program (LARP) is currently developing 4 m long Nb{sub 3}Sn quadrupole magnets for a possible upgrade of the LHC Interaction Regions (IR). In order to provide a reliable test bed for the fabrication and test of long Nb{sub 3}Sn coils, LARP has started the development of the long racetrack magnet LRS01. The magnet is composed of two 3.6 m long racetrack coils contained in a support structure based on an aluminum shell pre-tensioned with water-pressurized bladders and interference keys. For the phase-one test of the assembly procedure and loading operation, the structure was pre-stressed at room temperature and cooled down to 77 K with instrumented, solid aluminum 'dummy coils'. Mechanical behavior and stress homogeneity were monitored with strain gauges mounted on the shell and the dummy coils. The dummy coils were replaced with reacted and impregnated Nb{sub 3}Sn coils in a second assembly procedure, followed by cool-down to 4.5 K and powered magnet test. This paper report on the assembly and loading procedures of the support structure as well as the comparison between strain gauge data and 3D model predictions.
Date: June 1, 2008
Creator: Ambrosio, G.; Anerella, M.; Caspi, S.; Cheng, D. W.; Felice, H.; Hafalia, A. R. et al.
System: The UNT Digital Library
L-band RF gun with a thermionic cathode (open access)

L-band RF gun with a thermionic cathode

We present a conceptual design for an L-band (1.3 GHz) rf gun with a two-grid thermionic cathode assembly. The rf gun is designed to provide a 9 mA average beam current for 1 ms pulses at a 5 Hz rate. These parameters match the beam requirements for both the ILC and the Fermilab Project X test facilities. In our simulations we are able to attain a full bunch length of 20-30 degrees, while the output energy can vary from 2 to 4 MeV. Simulations as well as a preliminary design will be presented.
Date: June 1, 2008
Creator: Nagaitsev, S.; Andrews, R.; Church, M.; Lunin, A.; Nezhevenko, O.; Solyak, N. et al.
System: The UNT Digital Library
A Basic LEGO Reactor Design for the Provision of Lunar Surface Power (open access)

A Basic LEGO Reactor Design for the Provision of Lunar Surface Power

A final design has been established for a basic Lunar Evolutionary Growth-Optimized (LEGO) Reactor using current and near-term technologies. The LEGO Reactor is a modular, fast-fission, heatpipe-cooled, clustered-reactor system for lunar-surface power generation. The reactor is divided into subcritical units that can be safely launched with lunar shipments from Earth, and then emplaced directly into holes drilled into the lunar regolith to form a critical reactor assembly. The regolith would not just provide radiation shielding, but serve as neutron-reflector material as well. The reactor subunits are to be manufactured using proven and tested materials for use in radiation environments, such as uranium-dioxide fuel, stainless-steel cladding and structural support, and liquid-sodium heatpipes. The LEGO Reactor system promotes reliability, safety, and ease of manufacture and testing at the cost of an increase in launch mass per overall rated power level and a reduction in neutron economy when compared to a single-reactor system. A single unshielded LEGO Reactor subunit has an estimated mass of approximately 448 kg and provides approximately 5 kWe. The overall envelope for a single subunit with fully extended radiator panels has a height of 8.77 m and a diameter of 0.50 m. Six subunits could provide sufficient power generation …
Date: June 1, 2008
Creator: Bess, John Darrell
System: The UNT Digital Library
Benchmark Evaluation of Plutonium Hemispheres Reflected by Steel and Oil (open access)

Benchmark Evaluation of Plutonium Hemispheres Reflected by Steel and Oil

During the period from June 1967 through September 1969 a series of critical experiments was performed at the Rocky Flats Critical Mass Laboratory with spherical and hemispherical plutonium assemblies as nested hemishells as part of a Nuclear Safety Facility Experimental Program to evaluate operational safety margins for the Rocky Flats Plant. These assemblies were both bare and fully or partially oil-reflected. Many of these experiments were subcritical with an extrapolation to critical configurations or critical at a particular oil height. Existing records reveal that 167 experiments were performed over the course of 28 months. Unfortunately, much of the data was not recorded. A reevaluation of the experiments had been summarized in a report for future experimental and computational analyses. This report examines only fifteen partially oil-reflected hemispherical assemblies. Fourteen of these assemblies also had close-fitting stainless-steel hemishell reflectors, used to determine the effective critical reflector height of oil with varying steel-reflector thickness. The experiments and their uncertainty in keff values were evaluated to determine their potential as valid criticality benchmark experiments of plutonium.
Date: June 1, 2008
Creator: Bess, John Darrell
System: The UNT Digital Library
Bremstrahlung versus Monoenergetic Photons for Photonuclear Inspection Applications (open access)

Bremstrahlung versus Monoenergetic Photons for Photonuclear Inspection Applications

Bremsstrahlung sources have been utilized for various non-intrusive inspection or interrogation applications for over 100 years - with the primary focus being radiographic imaging. In the last several decades, it has become evident that photons of energy greater than 6 MeV can also provide useful photonuclear information that can extend the capabilities and information available from active inspections. These energetic inspection photons can be produced as a continuum of energies (i.e., bremsstrahlung distribution) or as a set of one or more discrete photon energies (i.e., monoenergetic distribution). This paper will discuss the photonuclear process and its energetic photon energy dependence, will discuss the photonuclear role in nuclear material detection, will present applicable photon sources along with their field deployment status, and highlight some advantages and disadvantages of bremsstrahlung and monoenergetic photons sources.
Date: June 1, 2008
Creator: Jones, Dr. James L.
System: The UNT Digital Library
Challenges and concepts for design of an interaction region with push-pull arrangement of detectors - an interface document (open access)

Challenges and concepts for design of an interaction region with push-pull arrangement of detectors - an interface document

Two experimental detectors working in a push-pull mode has been considered for the Interaction Region of the International Linear Collider [1]. The push-pull mode of operation sets specific requirements and challenges for many systems of detector and machine, in particular for the IR magnets, for the cryogenics and alignment system, for beamline shielding, for detector design and overall integration, and so on. These challenges and the identified conceptual solutions discussed in the paper intend to form a draft of the Interface Document which will be developed further in the nearest future. The authors of the present paper include the organizers and conveners of working groups of the workshop on engineering design of interaction region IRENG07 [2], the leaders of the IR Integration within Global Design Effort Beam Delivery System, and the representatives from each detector concept submitting the Letters Of Intent.
Date: June 1, 2008
Creator: Parker, B.; /Brookhaven; Herve, A.; Osborne, J.; /CERN; Mikhailichenko, A. et al.
System: The UNT Digital Library
Characterization of DECam focal plane detectors (open access)

Characterization of DECam focal plane detectors

DECam is a 520 Mpix, 3 square-deg FOV imager being built for the Blanco 4m Telescope at CTIO. This facility instrument will be used for the 'Dark Energy Survey' of the southern galactic cap. DECam has chosen 250 ?m thick CCDs, developed at LBNL, with good QE in the near IR for the focal plane. In this work we present the characterization of these detectors done by the DES team, and compare it to the DECam technical requirements. The results demonstrate that the detectors satisfy the needs for instrument.
Date: June 1, 2008
Creator: Diehl, H.Thomas; Angstadt, Robert; Campa, Julia; Cease, Herman; Derylo, Greg; Emes, John H. et al.
System: The UNT Digital Library
Co-Firing Oil Shale with Coal and Other Fuels for Improved Efficiency and Multi-Pollutant Control (open access)

Co-Firing Oil Shale with Coal and Other Fuels for Improved Efficiency and Multi-Pollutant Control

Oil shale is an abundant, undeveloped natural resource which has natural sorbent properties, and its ash has natural cementitious properties. Oil shale may be blended with coal, biomass, municipal wastes, waste tires, or other waste feedstock materials to provide the joint benefit of adding energy content while adsorbing and removing sulfur, halides, and volatile metal pollutants, and while also reducing nitrogen oxide pollutants. Oil shale depolymerization-pyrolysis-devolatilization and sorption scoping studies indicate oil shale particle sorption rates and sorption capacity can be comparable to limestone sorbents for capture of SO2 and SO3. Additionally, kerogen released from the shale was shown to have the potential to reduce NOx emissions through the well established “reburning” chemistry similar to natural gas, fuel oil, and micronized coal. Productive mercury adsorption is also possible by the oil shale particles as a result of residual fixed-carbon and other observed mercury capture sorbent properties. Sorption properties were found to be a function particle heating rate, peak particle temperature, residence time, and gas-phase stoichmetry. High surface area sorbents with high calcium reactivity and with some adsorbent fixed/activated carbon can be produced in the corresponding reaction zones that exist in a standard pulverized-coal or in a fluidized-bed combustor.
Date: June 1, 2008
Creator: Carrington, Robert A.; Hecker, William C. & Clayson, Reed
System: The UNT Digital Library
Construction and Test of 3.6 m Nb3Sn Racetrack Coils for LARP (open access)

Construction and Test of 3.6 m Nb3Sn Racetrack Coils for LARP

Development of high-performance Nb{sub 3}Sn quadrupoles is one of the major goals of the LHC Accelerator Research Program (LARP). As part of this program, long racetrack magnets were made in order to check the fabrication steps for long Nb{sub 3}Sn coils, that the changes in coil length that take place during reaction and cooldown are correctly accounted for in the quadrupole design, and the use of a long aluminum shell for the support structure. This paper reports the construction of the first long Nb{sub 3}Sn magnet with racetrack coils 3.6 m long. The magnet reached a nominal 'plateau' at 9596 A after five quenches. This is about 90% of the estimated conductor limit. The peak field in the coils at this current was 11 T.
Date: June 1, 2008
Creator: Wanderer, P.; Ambrosio, G.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S. et al.
System: The UNT Digital Library
Continuous time random walk analysis of solute transport in fractured porous media (open access)

Continuous time random walk analysis of solute transport in fractured porous media

The objective of this work is to discuss solute transport phenomena in fractured porous media, where the macroscopic transport of contaminants in the highly permeable interconnected fractures can be strongly affected by solute exchange with the porous rock matrix. We are interested in a wide range of rock types, with matrix hydraulic conductivities varying from almost impermeable (e.g., granites) to somewhat permeable (e.g., porous sandstones). In the first case, molecular diffusion is the only transport process causing the transfer of contaminants between the fractures and the matrix blocks. In the second case, additional solute transfer occurs as a result of a combination of advective and dispersive transport mechanisms, with considerable impact on the macroscopic transport behavior. We start our study by conducting numerical tracer experiments employing a discrete (microscopic) representation of fractures and matrix. Using the discrete simulations as a surrogate for the 'correct' transport behavior, we then evaluate the accuracy of macroscopic (continuum) approaches in comparison with the discrete results. However, instead of using dual-continuum models, which are quite often used to account for this type of heterogeneity, we develop a macroscopic model based on the Continuous Time Random Walk (CTRW) framework, which characterizes the interaction between the fractured …
Date: June 1, 2008
Creator: Cortis, Andrea; Cortis, Andrea & Birkholzer, Jens
System: The UNT Digital Library
Cooling the dark energy camera instrument (open access)

Cooling the dark energy camera instrument

DECam, camera for the Dark Energy Survey (DES), is undergoing general design and component testing. For an overview see DePoy, et al in these proceedings. For a description of the imager, see Cease, et al in these proceedings. The CCD instrument will be mounted at the prime focus of the CTIO Blanco 4m telescope. The instrument temperature will be 173K with a heat load of 113W. In similar applications, cooling CCD instruments at the prime focus has been accomplished by three general methods. Liquid nitrogen reservoirs have been constructed to operate in any orientation, pulse tube cryocoolers have been used when tilt angles are limited and Joule-Thompson or Stirling cryocoolers have been used with smaller heat loads. Gifford-MacMahon cooling has been used at the Cassegrain but not at the prime focus. For DES, the combined requirements of high heat load, temperature stability, low vibration, operation in any orientation, liquid nitrogen cost and limited space available led to the design of a pumped, closed loop, circulating nitrogen system. At zenith the instrument will be twelve meters above the pump/cryocooler station. This cooling system expected to have a 10,000 hour maintenance interval. This paper will describe the engineering basis including the thermal …
Date: June 1, 2008
Creator: Schmitt, R. L.; Cease, H.; /Fermilab; DePoy, D.; U., /Ohio State; Diehl, H. T. et al.
System: The UNT Digital Library
Corner Rounding in Photoresists for Extreme Ultraviolet Lithography (open access)

Corner Rounding in Photoresists for Extreme Ultraviolet Lithography

Deprotection blur in EUV resists fundamentally limits the smallest sized dense features that can be patterned in a single exposure and development step. Several metrics have recently been developed to explore the ways that different resist and process parameters affect the deprotection blur in EUV resists. One of these metrics is based on the imaging fidelity of a sharp corner on a large feature. As this metric has involved the close inspection of printing fidelity of corner features, it has brought attention to an interesting phenomena: corners print differently whether or not the remaining resist edge contains 270 degrees of resist or 90 degrees of resist. Here we present experimental data across a wide sampling of leading resists to show this effect is real and reproducible. They provide aerial image modeling results assuming thin and realistic mask models that show no corner bias between the aerial images in the 90-degree and 270-degree configurations. They also compare modeled patterning results assuming several resist models including the single blur, dual blur, and Prolith models, none of which reproduce the corner biasing that is observed experimentally.
Date: June 1, 2008
Creator: Anderson, Christopher N.; Naulleau, Patrick; Deng, Yunfei & Wallow, Thomas
System: The UNT Digital Library
Coupled Analysis of Change in Fracture Permeability during the Cooling Phase of the Yucca Mountain Drift Scale Test (open access)

Coupled Analysis of Change in Fracture Permeability during the Cooling Phase of the Yucca Mountain Drift Scale Test

This paper presents results from a coupled thermal, hydrological and mechanical analysis of thermally-induced permeability changes during heating and cooling of fractured volcanic rock at the Drift Scale Test at Yucca Mountain, Nevada. The analysis extends the previous analysis of the four-year heating phase to include newly available data from the subsequent four year cooling phase. The new analysis of the cooling phase shows that the measured changes in fracture permeability follows that of a thermo-hydro-elastic model on average, but at several locations the measured permeability indicates (inelastic) irreversible behavior. At the end of the cooling phase, the air-permeability had decreased at some locations (to as low as 0.2 of initial), whereas it had increased at other locations (to as high as 1.8 of initial). Our analysis shows that such irreversible changes in fracture permeability are consistent with either inelastic fracture shear dilation (where permeability increased) or inelastic fracture surface asperity shortening (where permeability decreased). These data are important for bounding model predictions of potential thermally-induced changes in rock-mass permeability at a future repository at Yucca Mountain.
Date: June 1, 2008
Creator: Rutqvist, Jonny; Freifeld, B.; Tsang, Y. W.; Min, K. B. & Elsworth, D.
System: The UNT Digital Library
Dark current model for ILC main linac (open access)

Dark current model for ILC main linac

In the ILC Main Linac, the dark current electrons, generated in SRF cavity can be accelerated to hundreds of MeV before being kicked out by quadrupoles and thus will originate electromagnetic cascade showers in the surrounding materials. Some of the shower secondaries can return back into vacuum and be re-accelerated again. The preliminary results of simulation of the dark current generation in ILC cavity, its dynamics in linac are discussing in this paper.
Date: June 1, 2008
Creator: Solyak, N.; Romanov, G.; Mokhov, N. V.; /Fermilab; Eidelman, Y.; /Novosibirsk, IYF et al.
System: The UNT Digital Library
The Dark Energy Survey CCD imager design (open access)

The Dark Energy Survey CCD imager design

The Dark Energy Survey is planning to use a 3 sq. deg. camera that houses a {approx} 0.5m diameter focal plane of 62 2kx4k CCDs. The camera vessel including the optical window cell, focal plate, focal plate mounts, cooling system and thermal controls is described. As part of the development of the mechanical and cooling design, a full scale prototype camera vessel has been constructed and is now being used for multi-CCD readout tests. Results from this prototype camera are described.
Date: June 1, 2008
Creator: Cease, H.; DePoy, D.; Diehl, H. T.; Estrada, J.; Flaugher, B.; Guarino, V. et al.
System: The UNT Digital Library
Decays of B_s Mesons and b Baryons: A Review of Recent First Observations and Branching Fractions (open access)

Decays of B_s Mesons and b Baryons: A Review of Recent First Observations and Branching Fractions

Recent rate measurements of B{sub s}{sup 0} mesons and {Lambda}{sub b}{sup 0} baryons produced in {radical}s = 1.96 TeV proton-antiproton and {Upsilon}(5S) electron-positron collisions are reviewed, including the first observations of six new decay modes: B{sub s}{sup 0} {yields} D{sub s}{sup +} K{sup -} (CDF), B{sub s}{sup 0} {yields} D{sub s}{sup -} D{sub s}{sup +} (CDF), B{sub s}{sup 0} {yields} D{sub s1}{sup -}(2536){mu}{sup +} {nu}{sub {mu}} X (DZero), B{sub s}{sup 0} {yields} {phi}{gamma} (Belle)< {Lambda}{sub b}{sup 0} {yields} p{pi}{sup -} (CDF), and {Lambda}{sub b}{sup 0} {yields} pK{sup -} (CDF). Also examined are branching-fraction measurements or limits for the B{sub s}{sup 0} {yields} D{sub s}{sup (*)} D{sub s}{sup (*)} modes (Belle, CDF, and DZero), the B{sub s}{sup 0} {yields} {gamma}{gamma} radiative penguin decay (Belle), and three two-body charmless B{sub s}{sup 0} meson decay channels (CDF). Implications for the phenomenology of electroweak and QCD physics, as well as searches for physics beyond the Standard Model, are identified where applicable.
Date: June 1, 2008
Creator: Warburton, Andreas
System: The UNT Digital Library
Density of Spray-Formed Materials (open access)

Density of Spray-Formed Materials

Spray Forming is an advanced materials processing technology that transforms molten metal into a near-net-shape solid by depositing atomized droplets onto a substrate. Depending on the application, the spray-formed material may be used in the as-deposited condition or it may undergo post-deposition processing. Regardless, the density of the as-deposited material is an important issue. Porosity is detrimental because it can significantly reduce strength, toughness, hardness and other properties. While it is not feasible to achieve fully-dense material in the as-deposited state, density greater than 99% of theoretical density is possible if the atomization and impact conditions are optimized. Thermal conditions at the deposit surface and droplet impact angle are key processing parameters that influence the density of the material. This paper examines the factors that contribute to porosity formation during spray forming and illustrates that very high as-deposited density is achieved by optimizing processing parameters.
Date: June 1, 2008
Creator: McHugh, Kevin M.; Uhlenwinkel, Volker & Ellendr, Nils
System: The UNT Digital Library