States

Control of a high beta maneuvering reentry vehicle using dynamic inversion. (open access)

Control of a high beta maneuvering reentry vehicle using dynamic inversion.

The design of flight control systems for high performance maneuvering reentry vehicles presents a significant challenge to the control systems designer. These vehicles typically have a much higher ballistic coefficient than crewed vehicles like as the Space Shuttle or proposed crew return vehicles such as the X-38. Moreover, the missions of high performance vehicles usually require a steeper reentry flight path angle, followed by a pull-out into level flight. These vehicles then must transit the entire atmosphere and robustly perform the maneuvers required for the mission. The vehicles must also be flown with small static margins in order to perform the required maneuvers, which can result in highly nonlinear aerodynamic characteristics that frequently transition from being aerodynamically stable to unstable as angle of attack increases. The control system design technique of dynamic inversion has been applied successfully to both high performance aircraft and low beta reentry vehicles. The objective of this study was to explore the application of this technique to high performance maneuvering reentry vehicles, including the basic derivation of the dynamic inversion technique, followed by the extension of that technique to the use of tabular trim aerodynamic models in the controller. The dynamic inversion equations are developed for …
Date: May 1, 2005
Creator: Watts, Alfred Chapman
Object Type: Report
System: The UNT Digital Library
Condition monitoring through advanced sensor and computational technology : final report (January 2002 to May 2005). (open access)

Condition monitoring through advanced sensor and computational technology : final report (January 2002 to May 2005).

The overall goal of this joint research project was to develop and demonstrate advanced sensors and computational technology for continuous monitoring of the condition of components, structures, and systems in advanced and next-generation nuclear power plants (NPPs). This project included investigating and adapting several advanced sensor technologies from Korean and US national laboratory research communities, some of which were developed and applied in non-nuclear industries. The project team investigated and developed sophisticated signal processing, noise reduction, and pattern recognition techniques and algorithms. The researchers installed sensors and conducted condition monitoring tests on two test loops, a check valve (an active component) and a piping elbow (a passive component), to demonstrate the feasibility of using advanced sensors and computational technology to achieve the project goal. Acoustic emission (AE) devices, optical fiber sensors, accelerometers, and ultrasonic transducers (UTs) were used to detect mechanical vibratory response of check valve and piping elbow in normal and degraded configurations. Chemical sensors were also installed to monitor the water chemistry in the piping elbow test loop. Analysis results of processed sensor data indicate that it is feasible to differentiate between the normal and degraded (with selected degradation mechanisms) configurations of these two components from the acquired …
Date: May 1, 2005
Creator: Kim, Jung-Taek (Korea Atomic Energy Research Institute, Daejon, Korea) & Luk, Vincent K.
Object Type: Report
System: The UNT Digital Library
Preparation and Reactions of Base-FreeBis(1,2,4-tri-tert-butylcyclopentadienyl)uranium Oxide, Cp'2UO (open access)

Preparation and Reactions of Base-FreeBis(1,2,4-tri-tert-butylcyclopentadienyl)uranium Oxide, Cp'2UO

Reduction of the uranium metallocene,[eta5-1,2,4-(Me3C)3C5H2]2UCl2 (1), Cp'2UCl2, in the presence of2,2'-bipyridyl and sodium naphthalene gives the dark green metallocenecomplex, Cp'2U(bipy) (6), which reacts with p-tolylazide orpyridine-N-oxide to give Cp'2U=N(p-tolyl) (7) or Cp'2U(O)(py) (8),respectively. The Lewis acid, BPh3, precipitates Ph3B(py) and gives thebase-free oxo, Cp'2UO (10), which crystallizes from pentane. Theoxometallocene 10 behaves as a nucleophile with Me3SiX reagents but itdoes not exhibit cycloaddition behavior with acetylenes, suggesting thatthe polar resonance structure, Cp'2U+-O- dominates the double bondresonance structure Cp'2U=O.
Date: May 25, 2005
Creator: Zi, Guofu; Werkema, Evan L.; Walter, Marc D.; Gottfriedsen,Jochen P. & Andersen, Richard A.
Object Type: Article
System: The UNT Digital Library
Estimating large-scale fracture permeability of unsaturatedrockusing barometric pressure data (open access)

Estimating large-scale fracture permeability of unsaturatedrockusing barometric pressure data

We present a three-dimensional modeling study of gas flow inthe unsaturated fractured rock of Yucca Mountain. Our objective is toestimate large-scale fracture permeability, using the changes insubsurface pneumatic pressure in response to barometric pressure changesat the land surface. We incorporate the field-measured pneumatic datainto a multiphase flow model for describing the coupled processes ofliquid and gas flow under ambient geothermal conditions. Comparison offield-measured pneumatic data with model-predicted gas pressures is foundto be a powerful technique for estimating the fracture permeability ofthe unsaturated fractured rock, which is otherwise extremely difficult todetermine on the large scales of interest. In addition, this studydemonstrates that the multi-dimensional-flow effect on estimatedpermeability values is significant and should be included whendetermining fracture permeability in heterogeneous fracturedmedia.
Date: May 17, 2005
Creator: Wu, Yu-Shu; Zhang, Keni & Liu, Hui-Hai
Object Type: Article
System: The UNT Digital Library
Radiological Instrumentation Assessment for King County Wastewater Treatment Division (open access)

Radiological Instrumentation Assessment for King County Wastewater Treatment Division

The King County Wastewater Treatment Division (WTD) have concern about the aftermath of a radiological dispersion event (RDE) leading to the introduction of significant quantities of radioactive material into its combined sanitary and storm sewer system. Radioactive material could come from the use of a radiological dispersion device (RDD). RDDs include "dirty bombs" that are not nuclear detonations but are explosives designed to spread radioactive material. Radioactive material also could come from deliberate introduction or dispersion of radioactive material into the environment, including waterways and water supply systems. Volume 2 of PNNL-15163 assesses the radiological instrumentation needs for detection of radiological or nuclear terrorism, in support of decisions to treat contaminated wastewater or to bypass the West Point Treatment Plant (WPTP), and in support of radiation protection of the workforce, the public, and the infrastructure of the WPTP. Fixed radiation detection instrumentation should be deployed in a defense-in-depth system that provides 1) early warning of significant radioactive material on the way to the WPTP, including identification of the radionuclide(s) and estimates of the soluble concentrations, with a floating detector located in the wet well at the Interbay Pump Station and telemetered via the internet to all authorized locations; 2) monitoring …
Date: May 19, 2005
Creator: Strom, Daniel J.; McConn, Ronald J. & Brodzinski, Ronald L.
Object Type: Report
System: The UNT Digital Library
2005 Habitat Evaluation Procedure (HEP) Report for the Priest River Project (open access)

2005 Habitat Evaluation Procedure (HEP) Report for the Priest River Project

On July 6, 2004, the Habitat Evaluation Procedure (HEP) was used to determine baseline habitat suitability on the Priest River property, an acquisition completed by the Kalispel Tribe of Indians in 2001. Evaluation species and appropriate models include bald eagle, black-capped chickadee, Canada goose, mallard, yellow warbler, and white-tailed deer. Habitat Suitability Index (HSI) values were visually estimated and agreed upon by all HEP team members. The Priest River Project provides a total of 140.73 Habitat Units (HUs) for the species evaluated. Conifer forest habitat provides 60.05 HUs for bald eagle, black-capped chickadee, and white-tailed deer. Grassland meadow habitat provides 7.39 HUs for Canada goose and mallard. Scrub-shrub vegetation provides 71.13 HUs for mallard, yellow warbler, and white-tailed deer. Open water habitat provides 2.16 HUs for Canada goose and mallard. The objective of using HEP at the Priest River Project and other protected properties is to document the quality and quantity of available habitat for selected wildlife species. In this way, HEP provides information on the relative value of the same area at future points in time so that the effect of management activities on wildlife habitat can be quantified. When combined with other tools, the baseline HEP will be …
Date: May 2005
Creator: Entz, Ray
Object Type: Report
System: The UNT Digital Library
Effective Supergravity from the Weakly Coupled HeteroticString (open access)

Effective Supergravity from the Weakly Coupled HeteroticString

The motivation for Calabi-Yau-like compactifications of the weakly coupled E{sub 8} {circle_times} E{sub 8} heterotic string theory, its particle spectrum and the issue of dilaton stabilization are briefly reviewed. Modular invariant models for hidden sector condensation and supersymmetry breaking are described at the quantum level of the effective field theory. Their phenomenological and cosmological implications, including a possible origin for R-parity, are discussed.
Date: May 1, 2005
Creator: Gaillard, Mary K.
Object Type: Article
System: The UNT Digital Library
New developments for the site-specific attachment of protein to surfaces (open access)

New developments for the site-specific attachment of protein to surfaces

Protein immobilization on surfaces is of great importance in numerous applications in biology and biophysics. The key for the success of all these applications relies on the immobilization technique employed to attach the protein to the corresponding surface. Protein immobilization can be based on covalent or noncovalent interaction of the molecule with the surface. Noncovalent interactions include hydrophobic interactions, hydrogen bonding, van der Waals forces, electrostatic forces, or physical adsorption. However, since these interactions are weak, the molecules can get denatured or dislodged, thus causing loss of signal. They also result in random attachment of the protein to the surface. Site-specific covalent attachment of proteins onto surfaces, on the other hand, leads to molecules being arranged in a definite, orderly fashion and uses spacers and linkers to help minimize steric hindrances between the protein surface. This work reviews in detail some of the methods most commonly used as well as the latest developments for the site-specific covalent attachment of protein to solid surfaces.
Date: May 12, 2005
Creator: Camarero, J A
Object Type: Article
System: The UNT Digital Library
CH-TRU Waste Content Codes (CH-TRUCON) (open access)

CH-TRU Waste Content Codes (CH-TRUCON)

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container. Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 …
Date: May 1, 2005
Creator: Westinghouse TRU Solutions LLC
Object Type: Report
System: The UNT Digital Library
Experimental Determination of Apery-Like Identities forZeta(2n+2) (open access)

Experimental Determination of Apery-Like Identities forZeta(2n+2)

We document the discovery of two generating functions forzeta(2n+2), analogous to earlier work for zeta(2n+1) and zeta(4n+3),initiated by Koecher and pursued further by Borwein, Bradley andothers.
Date: May 11, 2005
Creator: Bailey, David H.; Borwein, Jonathan M. & Bradley, David M.
Object Type: Article
System: The UNT Digital Library
An analytical and computational study of combined rate and size effects on material properties. (open access)

An analytical and computational study of combined rate and size effects on material properties.

The recent interests in developing multiscale model-based simulation procedures have brought about the challenging tasks of bridging different spatial and temporal scales within a unified framework. However, the research focus has been on the scale effect in the spatial domain with the loading rate being assumed to be quasi-static. Although material properties are rate-dependent in nature, little has been done in understanding combined loading rate and specimen size effects on the material properties at different scales. In addition, the length and time scales that can be probed by the molecular level simulations are still fairly limited due to the limitation of computational capability. Based on the experimental and computational capabilities available, therefore, an attempt is made in this report to formulate a hyper-surface in both spatial and temporal domains to predict combined size and rate effects on the mechanical properties of engineering materials. To demonstrate the features of the proposed hyper-surface, tungsten specimens of various sizes under various loading rates are considered with a focus on the uniaxial loading path. The mechanical responses of tungsten specimens under other loading paths are also explored to better understand the size effect. It appears from the preliminary results that the proposed procedure might …
Date: May 1, 2005
Creator: Fang, Huei Eliot; Chen, Zhen (University of Missouri-Columbia, Columbia, MO); Shen, Luming () University of Missouri-Columbia, Columbia, MO) & Gan, Yong (University of Missouri-Columbia, Columbia, MO)
Object Type: Report
System: The UNT Digital Library
Sphere-Pac Evaluation for Transmutation (open access)

Sphere-Pac Evaluation for Transmutation

The U.S. Department of Energy Advanced Fuel Cycle Initiative (AFCI) is sponsoring a project at Oak Ridge National Laboratory with the objective of conducting the research and development necessary to evaluate the use of sphere-pac transmutation fuel. Sphere-pac fuels were studied extensively in the 1960s and 1970s. More recently, this fuel form is being studied internationally as a potential plutonium-burning fuel. For transmutation fuel, sphere-pac fuels have potential advantages over traditional pellet-type fuels. This report provides a review of development efforts related to the preparation of sphere-pac fuels and their irradiation tests. Based on the results of these tests, comparisons with pellet-type fuels are summarized, the advantages and disadvantages of using sphere-pac fuels are highlighted, and sphere-pac options for the AFCI are recommended. The Oak Ridge National Laboratory development activities are also outlined.
Date: May 19, 2005
Creator: Icenhour, A.S.
Object Type: Report
System: The UNT Digital Library
Development and Validation of High-Resolution State Wind Resource Maps for the United States (Poster) (open access)

Development and Validation of High-Resolution State Wind Resource Maps for the United States (Poster)

A poster presentation for AWEA's WindPower 2005 conference in Denver, Colorado, May 15 -18, 2005 that provides an outline of the approach and process used for validating U.S. wind resource maps.
Date: May 1, 2005
Creator: Elliott, D. & Schwartz, M.
Object Type: Article
System: The UNT Digital Library
Laser Guiding at Relativistic Intensities and Wakefield ParticleAcceleration in Plasma Channels (open access)

Laser Guiding at Relativistic Intensities and Wakefield ParticleAcceleration in Plasma Channels

High quality electron beams with hundreds of picoCoulombs ofcharge inpercent energy spread above 80 MeV were produced for the firsttime in high gradient laser wakefield accelerators by guiding the drivelaser pulse.
Date: May 1, 2005
Creator: Geddes, C. G. R.; Toth, Cs.; van Tilborg, J.; Esarey, E.; Schroeder, C. B.; Bruhwiler, D. et al.
Object Type: Article
System: The UNT Digital Library
Transport of Radioactive Material by Alpha Recoil (open access)

Transport of Radioactive Material by Alpha Recoil

The movement of high-specific-activity radioactive particles (i.e., alpha recoil) has been observed and studied since the early 1900s. These studies have been motivated by concerns about containment of radioactivity and the protection of human health. Additionally, studies have investigated the potential advantage of alpha recoil to effect separations of various isotopes. This report provides a review of the observations and results of a number of the studies.
Date: May 19, 2005
Creator: Icenhour, A.S.
Object Type: Report
System: The UNT Digital Library
3D-Simulation Studies of SNS Ring Doublet Magnets (open access)

3D-Simulation Studies of SNS Ring Doublet Magnets

The accumulator ring of the Spallation Neutron Source (SNS) at ORNL employs in its straight sections closely packed quadrupole doublemagnets with large aperture of R=15.1 cm an relatively short iron-to-iron distance of 51.4 cm. These quads have much extended fringe field, and magnetic interferences among them in the doublet assemblies is not avoidable. Though each magnet in the assemblies has been individually mapped to high accuracy of lower than 0.01 percent level, the experimental data including the magnetic interference effect will not be available. We have performed 3D computing simulations on a quadrupole doublet model in order to assess the degree of the interference and to obtain relevant data for the SNS commissioning and operation.
Date: May 5, 2005
Creator: Wang, J. G.; N., Tsoupas & Venturini, M.
Object Type: Article
System: The UNT Digital Library
Macro-System Model (Poster) (open access)

Macro-System Model (Poster)

Poster presentation on Macro-System Model for the 2005 Hydrogen, Fuel Cells & Infrastructure Technologies Program Annual Review held in Arlington, Virginia on May 23-26, 2005
Date: May 1, 2005
Creator: Ruth, M.
Object Type: Article
System: The UNT Digital Library
Quantum Coherence Arguments for Cosmological Scale (open access)

Quantum Coherence Arguments for Cosmological Scale

Homogeneity and correlations in the observed CMB are indicative of some form of cosmological coherence in early times. Quantum coherence in the early universe would be expected to give space-like phase coherence to any effects sourced to those times. If dark energy de-coherence is assumed to occur when the rate of expansion of the relevant cosmological scale parameter in the Friedmann-Lemaitre equations is no longer supra-luminal, a critical energy density is immediately defined. It is shown that the general class of dynamical models so defined necessarily requires a spatially flat cosmology in order to be consistent with observed structure formation. The basic assumption is that the dark energy density which is fixed during de-coherence is to be identified with the cosmological constant. It is shown for the entire class of models that the expected amplitude of fluctuations driven by the dark energy de-coherence process is of the order needed to evolve into the fluctuations observed in cosmic microwave background radiation and galactic clustering. The densities involved during de-coherence which correspond to the measured dark energy density turn out to be of the electroweak symmetry restoration scale. In an inflationary cosmology, this choice of the scale parameter in the FL equations …
Date: May 27, 2005
Creator: Lindesay, James
Object Type: Report
System: The UNT Digital Library
Study of the $\tau^- to 3h^- 2h^+ \nu_\tau$ Decay (open access)

Study of the $\tau^- to 3h^- 2h^+ \nu_\tau$ Decay

The branching fraction of the {tau}{sup -} {yields} 3h{sup -} 2h{sup +} {nu}{sub {tau}} decay (h = {pi}, K) is measured with the BABAR detector to be (8.56 {+-} 0.05 {+-} 0.42) x 10{sup -4}, where the first error is statistical and the second systematic. The observed structure of this decay is significantly different from the phase space prediction, with the {rho} resonance playing a strong role. The decay {tau}{sup -} {yields} f{sub 1}(1285){pi}{sup -}{nu}{sub {tau}}, with the f{sub 1}(1285) meson decaying to four charged pions, is observed and the branching fraction is measured to be (3.9 {+-} 0.7 {+-} 0.5) x 10{sup -4}.
Date: May 4, 2005
Creator: Aubert, Bernard; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Object Type: Article
System: The UNT Digital Library
Investigation of Microwave Instability on Electron Storage Ring TLS (open access)

Investigation of Microwave Instability on Electron Storage Ring TLS

With the planned installation of a superconducting rf system, the new operation mode of TLS, the electron storage ring at NSRRC, is expected to double the beam intensity. Several accelerator physics topics need to be examined. Beam instability of single-bunch longitudinal microwave instability is one of these topics. We consider two approaches to measure the effective broad band impedance. We compare these measurement results with each other and to old data [Ref.1]. We calculate the threshold current of microwave instability with a mode-mixing analysis code written by Dr. K. Oide of KEK [Ref.2]. We also develop a multi-particle tracking code to simulate the instability. The results of simulation and measurement are compared and discussed. We conclude that doubling of beam current from 200 mA (1.5 mA/bunch) to 400 mA (3 mA/bunch) will not trigger the microwave instability even without a Landau cavity to lengthen the bunch. The benefit of Landau cavity is mainly for beam life time.
Date: May 17, 2005
Creator: Wang, M.-H. & Chao, A.
Object Type: Article
System: The UNT Digital Library
Preparation and Reactions of Base-FreeBis(1,2,4-tri-tert-butylcyclopentadienyl)uranium Methylimide, Cp'2U=NMe,and Related Compounds (open access)

Preparation and Reactions of Base-FreeBis(1,2,4-tri-tert-butylcyclopentadienyl)uranium Methylimide, Cp'2U=NMe,and Related Compounds

The uranium metallocenes, [eta5-1,3-(Me3E)2C5H3]2UMe2 (E =C, Si), react with NH3 to give the dimers{[eta5-1,3-(Me3E)2C5H3]2U}2(mu-NH)2 (E = C (1), Si (2)) but withp-toluidine to give the monomeric diamides,[eta5-1,3-(Me3E)2C5H3]2U(NH-p-tolyl)2 (E = C (3), Si (4)). The diamides[eta5-1,3-(Me3E)2C5H3]2U(NH-p-tolyl)2 (E = C (3), Si (4)) do noteliminate p- toluidine but sublime intact at 140oC in vacuum. The uraniummetallocene, [eta5-1,2,4-(Me3C)3C5H2]2UMe2, reacts with RNH2 to yield[eta5-1,2,4-(Me3C)3C5H2]2U(NHR)2 (R = Me (8), PhCH2 (9), p-tolyl (10)),which are isolated as crystalline solids. In benzene solution thesediamides are in equilibrium with [eta5-1,2,4-(Me3C)3C5H2]2U=NR, which maybe isolated pure when R is Me (11) or p-tolyl (12), and the primaryamine. The monomeric imide, [eta5-1,2,4-(Me3C)3C5H2]2U=NMe (11), reactswith R'=CR' to yield the cycloaddition products[eta5-1,2,4-(Me3C)3C5H2]2U[N(Me)C(R')=C(R')](R' = Me (15), Ph (16)),which react with excess MeNH2 to regenerate the diamide[eta5-1,2,4-(Me3C)3C5H2]2U(NHMe)2 (8) and MeN=C(R')CH(R'). Themethylimide, [eta5-1,2,4-(Me3C)3C5H2]2U=NMe (11), does not react withMe3SiX reagents; a model is proposed that rationalizes this reactivitypattern.
Date: May 27, 2005
Creator: Zi, Guofu; Blosch, Laura L.; Jia, Li & Andersen, Richard A.
Object Type: Article
System: The UNT Digital Library
Verification of high-order mixed FEM solution of transient Magnetic diffusion problems (open access)

Verification of high-order mixed FEM solution of transient Magnetic diffusion problems

We develop and present high order mixed finite element discretizations of the time dependent electromagnetic diffusion equations for solving eddy current problems on 3D unstructured grids. The discretizations are based on high order H(grad), H(curl) and H(div) conforming finite element spaces combined with an implicit and unconditionally stable generalized Crank-Nicholson time differencing method. We develop three separate electromagnetic diffusion formulations, namely the E (electric field), H (magnetic field) and the A-{phi} (potential) formulations. For each formulation, we also provide a consistent procedure for computing the secondary variables F (current flux density) and B (magnetic flux density), as these fields are required for the computation of electromagnetic force and heating terms. We verify the error convergence properties of each formulation via a series of numerical experiments on canonical problems with known analytic solutions. The key result is that the different formulations are equally accurate, even for the secondary variables J and B, and hence the choice of which formulation to use depends mostly upon relevance of the Natural and Essential boundary conditions to the problem of interest. In addition, we highlight issues with numerical verification of finite element methods which can lead to false conclusions on the accuracy of the methods.
Date: May 12, 2005
Creator: Rieben, R. & White, D. A.
Object Type: Article
System: The UNT Digital Library
How an antenna launches its input power into radiation: thepattern of the Poynting vector at and near an antenna (open access)

How an antenna launches its input power into radiation: thepattern of the Poynting vector at and near an antenna

In this paper I first address the question of whether theseat of the power radiated by an antenna made of conducting members isdistributed over the "arms" of the antenna according to $ - \bf J \cdotE$, where $\bf J$ is the specified current density and $\bf E$ is theelectric field produced by that source. Poynting's theorem permits only aglobal identification of the total input power, usually from a localizedgenerator, with the total power radiated to infinity, not a localcorrespondence of $- \bf J \cdot E\ d^3x $ with some specific radiatedpower, $r^2 \bf S \cdot \hat r\ d\Omega $. I then describe a modelantenna consisting of two perfectly conducting hemispheres of radius\emph a separated by a small equatorial gap across which occurs thedriving oscillatory electric field. The fields and surface current aredetermined by solution of the boundary value problem. In contrast to thefirst approach (not a boundary value problem), the tangential electricfield vanishes on the metallic surface. There is no radial Poyntingvector at the surface. Numerical examples are shown to illustrate how theenergy flows from the input region of the gap and is guided near theantenna by its "arms" until it is launched at larger \emph r/a into theradiation pattern …
Date: May 18, 2005
Creator: Jackson, J.D.
Object Type: Article
System: The UNT Digital Library
The effects of process parameters on injection-molded PZT ceramics part fabrication- compounding process rheology. (open access)

The effects of process parameters on injection-molded PZT ceramics part fabrication- compounding process rheology.

Solid solutions of lead-based perovskites are the backbone materials of the piezoelectric components for transducer, actuator, and resonator applications. These components, typically small in size, are fabricated from large sintered ceramic slugs using grinding and lapping processes. These operations increase manufacturing costs and produce a large hazardous waste stream, especially when component size decreases. To reduce costs and hazardous wastes associated with the production of these components, an injection molding technique is being investigated to replace the machining processes. The first step in the new technique is to compound an organic carrier with a ceramic powder. The organic carrier is a thermoplastic based system composed of a main carrier, a binder, and a surfactant. Understanding the rheology of the compounded material is necessary to minimize the creation of defects such as voids or cavities during the injection-molding process. An experiment was performed to model the effects of changes in the composition and processing of the material on the rheological behavior. Factors studied included: the surfactant of the organic carrier system, the solid loading of the compounded material, and compounding time. The effects of these factors on the viscosity of the material were investigated.
Date: May 1, 2005
Creator: Halbleib, Laura L.; Yang, Pin; Mondy, Lisa Ann & Burns, George Robert
Object Type: Report
System: The UNT Digital Library