bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Transfer and Flow on the Blade Tip of a Gas Turbine Equipped With a Mean-Camberline Strip
Authors: Ameri A. A.
Published: July 2002

Experimental and computational studies have been performed to investigate the detailed distribution of convective heat transfer coefficients on the first-stage blade tip surface for a geometry typical of large power generation turbines (>100 MW). In a previous work the numerical heat transfer results for a sharp edge blade tip and a radiused blade tip were presented. More recently several other tip treatments have been considered for which the tip heat transfer has been measured and documented. This paper is concerned with the numerical prediction of the tip surface heat transfer for radiused blade tip equipped with mean-camberline strip (or “squealer” as it is often called). The heat transfer results are compared with the experimental results and discussed. The effectiveness of the mean-camberline strip in reducing the tip leakage and the tip heat transfer as compared to a radiused edge tip and sharp edge tip was studied. The calculations show that the sharp edge tip works best (among the cases considered) in reducing the tip leakage flow and the tip heat transfer.
Stochastic System Identification for Operational Modal Analysis: A Review
Authors: Peeters Bart , De Roeck Guido
Published: July 2002

This paper reviews stochastic system identification methods that have been used to estimate the modal parameters of vibrating structures in operational conditions. It is found that many classical input-output methods have an output-only counterpart. For instance, the Complex Mode Indication Function (CMIF) can be applied both to Frequency Response Functions and output power and cross spectra. The Polyreference Time Domain (PTD) method applied to impulse responses is similar to the Instrumental Variable (IV) method applied to output covariances. The Eigensystem Realization Algorithm (ERA) is equivalent to stochastic subspace identification.
A Distributed Product Realization Environment for Design and Manufacturing
Authors: Gerhard Jonathan F. , Rosen David , Allen Janet K. , Mistree Farrokh
Published: July 2002

Geographically distributed engineers must collaboratively develop, build and test solutions to design-manufacture problems to be competitive in the global marketplace. Engineers operate in a distributed system in which separate entities communicate cooperatively—ideas and information requests are generated anywhere within the system, rapid turn-around is essential, and multiple projects must be handled simultaneously. In this paper we present a prototype platform-independent framework to integrate distributed and heterogeneous software resources to support the computationally intensive activities in the product realization process. This framework, PRE-RMI, is based on an experimental event-based communications model; it has been coded in Java and uses the RMI messaging system. We describe its usage in a distributed product realization environment, the Rapid Tooling TestBed. PRE-RMI is compared to a previous environment, called P2 that was based on Java Servlet technology. PRE-RMI is adaptable to different design processes, is modular and extensible, is robust to network and computing failures, and is far preferable to P2. Further, we demonstrate the successful integration of CAD, CAE, design, and manufacturing software tools and resources in this flexible distributed computing environment.
A Critical Reexamination of Classical Metal Plasticity
Authors: Wilson C. D.
Published: July 2002

P. W. Bridgman’s early work on flow and fracture in the presence of hydrostatic pressure showed no systematic effect on strain hardening. This experimental observation led to the conclusions that yielding does not depend on hydrostatic stress and that the yielded material is incompressible. Classical plasticity theory was largely built on these observations. New experiments and nonlinear finite element analyses of 2024-T351 aluminum notched round bars has quantified the effect of hydrostatic tensile stresses on yielding. Nonlinear finite element analyses using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions was performed. The von Mises results overestimated experimental load-displacement curves by 10–65 percent. The Drucker-Prager results essentially matched the experimental results. The only additional data requirement for the Drucker-Prager yield function is the compressive yield strength.
Modeling the Air-Cooled Gas Turbine: Part 2—Coolant Flows and Losses
Authors: Young J. B. , Wilcock R. C.
Published: July 2002

This paper is Part II of a study concerned with developing a formal framework for modeling air-cooled gas turbine cycles. It deals with the detailed specification of coolant flowrates and losses. For accurate performance assessment, it is necessary to divide the turbine expansion into individual stages with stator and rotor rows being treated separately. Particular care is needed when deriving the equations for the rotor, and it is shown how all required flow variables can be estimated from minimal data if design values are unavailable. Specification of the cooling flowrates is based on a modified Holland and Thake procedure, which can be formalized in terms of averaged parameters. Thermal barrier coatings can be included if present. The importance of allowing for fluctuations in combustor outlet temperature is stressed and procedures for dealing with end-wall and disk cooling are suggested. There is confusion in the literature concerning cooling losses, and it is shown how these may be defined and subdivided in a consistent way. The importance of representing losses in terms of irreversible entropy creation rather than total pressure loss is stressed. A set of models for the components of the cooling loss are presented and sample calculations are used to illustrate the division and magnitude of the loss.
Determination of Planck Mean Absorption Coefficients for HBr, HCl, and HF
Authors: Fuss S. P. , Hamins A.
Published: July 2002

The Planck mean absorption coefficient, ap, has been calculated for HBr, HCl, and HF over a temperature range from 300 K–2300 K using data from the 1996 edition of the HITRAN molecular database. Plots of ap versus temperature showed monotonically decreasing behavior over this temperature range, with peak values at 300 K of 45.9 (atm-m)−1, 5.3 (atm-m)−1, and 1.95 (atm-m)−1 for HF, HCl, and HBr, respectively. The magnitude of these values suggests that HBr, HCl, and HF can significantly impact calculations of radiative transfer in flames containing these species. Two sets of additional calculations were performed for CO to validate the methodology used for calculation of ap for HBr, HF, and HCl. In the first approach, which employed the narrow band model RADCAL, the calculation procedure was similar to that of the present calculations. The second approach utilized tabulated values of the integrated intensity for each CO band and an average value of the Planck function within each band. Results from the three methods showed general agreement. Polynomial expressions are provided as fits to ap as a function of temperature for HBr, HCl, HF, and CO.
An Active-Passive Piezoelectric Absorber for Structural Vibration Control Under Harmonic Excitations With Time-Varying Frequency, Part 2: Experimental Validation and Parametric Study
Authors: Morgan R. A. , Wang K. W.
Published: July 2002

In Part 1 of the paper, a new high-performance active-passive hybrid piezoelectric absorber concept was presented. This design is an attractive alternative to semi-active absorbers for the purpose of suppressing harmonic excitations with variable frequency. In this paper (Part 2), the effectiveness of the new absorber design is first demonstrated through experimental investigations. Parametric studies are then carried out to illustrate how the performance of the new design is affected by the design parameters and excitation characteristics. In these studies, two state-of-the-art control methods are used as baselines for comparison with the new absorber design, and it is shown that the proposed design offers superior performance and efficiency compared to these methods.
Averaging Models for Heterogeneous Viscoplastic and Elastic Viscoplastic Materials
Authors: Molinari Alain
Published: July 2002

Averaging models are proposed for viscoplastic and elastic-viscoplastic heterogeneous materials. The case of rigid viscoplastic materials is first discussed. Large deformations are considered. A first class of models is based on different linearizations of the nonlinear local response. A second class of models is obtained from approximate solutions of the nonlinear Eshelby problem. In this problem, an ellipsoid with uniform nonlinear properties is embedded in an infinite homogeneous matrix. An approximate solution is obtained by approaching the matrix behavior with an affine response. Using this solution of the nonlinear Eshelby problem, the average strain rate is calculated in each phase of the composite material, each phase being represented by an ellipsoid embedded in an infinite reference medium. By adequate choices of the reference medium, different averaging models are obtained (self-consistent scheme, nonlinear Mori Tanaka model…). Finally, elasticity is included in the modelling, but with a restriction to small deformations.
Strain Hardening at Large Strains as Predicted by Dislocation Based Polycrystal Plasticity Model
Authors: To´th La´szlo´ S. , Molinari Alain , Estrin Yuri
Published: July 2002

A recent strain hardening model for late deformation stages (Estrin, Y., To´th, L.S., Molinari, A., and Bre´chet, Y., Acta Materialia, 1998, “A dislocation-based model for all hardening stages in large strain deformation,” Vol. 46, pp. 5509-5522) was generalized for the 3D case and for arbitrary strain paths. The model is based on a cellular dislocation arrangement in which a single- phase material is considered as a composite of a hard skeleton of cell walls and soft cell interiors. An important point in the approach is the evolution of the volume fraction of the cell walls which decreases with the deformation and gives rise to a plateau-like behavior (Stage IV) followed by a drop-off (Stage V) of the strain hardening rate observed at large strains. The hardening model was implemented into the viscoplastic self-consistent polycrystal model to predict hardening curves corresponding to different proportional loading paths. The calculated curves were evaluated to elucidate the path dependence of hardening.
Aluminizing Behaviors of Vacuum Plasma Sprayed MCrAlY Coatings
Authors: Itoh Y. , Saitoh M. , Ishiwata Y.
Published: July 2002

The objective of this study is aluminide overlay coatings of MCrAlY sprayed by a vacuum plasma spraying (VPS) process for the protection against high-temperature corrosion and oxidation of gas turbine components. Diffusion coating processes have been applied for many years to improve similarly the environmental resistance by enriching the surface of nickel-based superalloys with chromium, aluminum, or silicon element. Recently, aluminizing of MCrAlY coatings is used for improving further the high-temperature oxidation resistance. However, the aluminizing properties of plasma-sprayed MCrAlY coatings, which have an important effect on the coating performance, have not been clarified. In this study, five kinds of plasma-sprayed MCrAlY (CoCrAlY, CoNiCrAlY, CoNiCrAlY+Ta, NiCrAlY, and NiCoCrAlY) coating were selected for pack-aluminizing tests. The as sprayed and the heat-treated (1393 K, 2 h, argon cooled and 1116 K, 24 h, argon cooled) MCrAlY specimens were Al-Cr-Al2O3-NH4Cl pack-aluminized at 1173, 1223, and 1273 K for 5, 10, and 20 h, respectively. The experimental results showed that the aluminizing process formed the aluminum rich layers of NiAl or CoAl phase. It also indicated that the thickness of the aluminum rich layer showed a parabolic time-dependence in all MCrAlY coatings. The order of reaction diffusion rate was NiCoCrAlY=NiCrAlY>CoNiCrAlY>CoNiCrAlY+Ta>CoCrAlY. There was a tendency that the reaction diffusion rate by aluminizing increased with increasing nickel content in the MCrAlY coatings and the reaction diffusion rate of as sprayed MCrAlY coatings is faster than that of the heat-treated MCrAlY coatings.
Measurement of Local Creep Deformation in Cross-Weld Specimen by Optical Fiber Marking and Remote Monitoring
Authors: Tu Shan-Tung , Gong Jian-Ming , Ling Xiang , He Xiao-Yuan
Published: July 2002

Creep deformation localization is a common occurrence generally found in high temperature components, typically at weldments and geometrical discontinuities. The deformation in a small region cannot be measured by a conventional displacement gage. A new technique for measuring long-term local creep deformation was developed. It uses quartz optical fiber marking, remote monitoring, and image processing. Long-term measurements of the creep deformations of base metal, weld metal, and heat-affected zone in cross-weld specimens were performed at high temperature, which verify the new technique. Strain distributions and evolutions in the weldments are obtained.
Biomechanical Factors Affecting the Peak Hand Reaction Force During the Bimanual Arrest of a Moving Mass
Authors: DeGoede Kurt M. , Ashton-Miller James A. , Schultz Albert B. , Alexander Neil B.
Published: July 2002

Fall-related wrist fractures are among the most common fractures at any age. In order to learn more about the biomechanical factors influencing the impact response of the upper extremities, we studied peak hand reaction force during the bimanual arrest of a 3.4 kg ballistic pendulum moving toward the subject in the sagittal plane at shoulder height. Twenty healthy young and 20 older adults, with equal gender representation, arrested the pendulum after impact at one of three initial speeds: 1.8, 2.3, or 3.0 m/sec. Subjects were asked to employ one of three initial elbow angles: 130, 150, or 170 deg. An analysis of variance showed that hand impact force decreased significantly as impact velocity decreased (50 percent/m/s) and as elbow angle decreased (0.9 percent/degree). A two segment sagittally-symmetric biomechanical model demonstrated that two additional factors affected impact forces: hand-impactor surface stiffness and damping properties, and arm segment mass. We conclude that hand impact force can be reduced by more than 40 percent by decreasing the amount of initial elbow extension and by decreasing the velocity of the hands and arms relative to the impacting surface.
Scaling of Sea Ice Fracture—Part II: Horizontal Load From Moving Ice
Authors: Bazˇant Z. P.
Published: July 2002

Continuing the analysis of fracture size effect in Part I, which was focused on the maximum force in vertical penetration of ice, Part II tackles the problem maximum force that can be applied by a moving ice plate on an obstacle presented by a fixed structure. Based on an asymptotic approach, approximate solutions for are obtained for the size effects of ice thickness, effective structure diameter and, in the case of a finite ice floe, the size of the floe.
Lattice models in micromechanics
Authors: Ostoja-Starzewski Martin
Published: July 2002

This review presents the potential that lattice (or spring network) models hold for micromechanics applications. The models have their origin in the atomistic representations of matter on one hand, and in the truss-type systems in engineering on the other. The paper evolves by first giving a rather detailed presentation of one-dimensional and planar lattice models for classical continua. This is followed by a section on applications in mechanics of composites and key computational aspects. We then return to planar lattice models made of beams, which are a discrete counterpart of non-classical continua. The final two sections of the paper are devoted to issues of connectivity and rigidity of networks, and lattices of disordered (rather than periodic) topology. Spring network models offer an attractive alternative to finite element analyses of planar systems ranging from metals, composites, ceramics and polymers to functionally graded and granular materials, whereby a fiber network model of paper is treated in considerable detail. This review article contains 81 references.
Enhanced Boiling of FC-72 on Silicon Chips With Micro-Pin-Fins and Submicron-Scale Roughness
Authors: Honda H. , Takamastu H. , Wei J. J.
Published: July 2002

Experiments were conducted to study the effects of micro-pin-fins and submicron-scale roughness on the boiling heat transfer from a silicon chip immersed in a pool of degassed and gas-dissolved FC-72. Square pin-fins with fin dimensions of 50×50×60μm3 (width×thickness×height) and submicron-scale roughness (RMS roughness of 25 to 32 nm) were fabricated on the surface of square silicon chip 10×10×0.5mm3 by use of microelectronic fabrication techniques. Experiments were conducted at the liquid subcoolings of 0, 3, 25, and 45 K. Both the micro-pin-finned chip and the chip with submicron-scale roughness showed a considerable heat transfer enhancement as compared to a smooth chip in the nucleate boiling region. The chip with submicron-scale roughness showed a higher heat transfer performance than the micro-pin-finned chip in the low-heat-flux region. The micro-pin-finned chip showed a steep increase in the heat flux with increasing wall superheat. This chip showed a higher heat transfer performance than the chip with submicron-scale roughness in the high-heat-flux region. The micro-pin-finned chip with submicron-scale roughness on it showed the highest heat transfer performance in the high-heat-flux region. While the wall superheat at boiling incipience was strongly dependent on the dissolved gas content, it was little affected by the liquid subcooling.
A Novel In-Vitro System for the Simultaneous Exposure of Bladder Smooth Muscle Cells to Mechanical Strain and Sustained Hydrostatic Pressure
Authors: Haberstroh Karen M. , Kaefer Martin , DePaola Natacha , Frommer Sarah A. , Bizios Rena
Published: July 2002

The novel hydrostrain system was designed in an effort to establish and maintain conditions that simulate the in-vivo mechanical environment of the bladder. In this laboratory system, ovine bladder smooth muscle cells on flexible, 10-cm-dia silastic membranes were exposed simultaneously to hydrostatic pressure (40 cm H2O, a pressure level currently associated with bladder pathologies) and mechanical strains (up to 25 percent) under standard cell culture conditions for 7 h. Under these conditions, Heparin Binding-Epidermal Growth Factor and Collagen Type III mRNA expression were significantly increased (p<0.01 and 0.1, respectively); however, no changes were observed in Collagen Type I mRNA expression. Decreases in the Collagen Type I:Type III ratio following simultaneous exposure of bladder smooth muscle cells to pathological levels of hydrostatic pressure and mechanical strain in vitro are in agreement with clinically observed increases in Collagen Type III with concomitant decreased human bladder compliance. The results of the present study, therefore, provide cellular/molecular level information relevant to bladder pathology that could have significant implications in the field of clinical urology.
Use of Surface Flow Visualization Methods in Centrifugal Pump Design
Authors: Hamkins Christopher P. , Bross Stephan
Published: July 2002

Surface flow patterns generated with oils or oil paint have been used in centrifugal pump design for many years. Here it is shown how modern image analysis methods allow quantitative predictions of the corresponding pressure distribution by analyzing surface flow patterns. Further, the surface flow patterns can be used to confirm computational fluid dynamics (CFD) results, improve their boundary conditions and determine their limits of validity. The authors see the need for a new type of boundary condition for CFD packages, in which a measured flow pattern could be used as “input.”
A Mathematical Model for the Strained Shape of a Large Scientific Balloon at Float Altitude
Authors: Baginski F. , Collier W.
Published: July 2002

A large scientific balloon is constructed from long flat tapered sheets of thin polyethylene film called gores which are sealed edge to edge to form a complete shape. The balloon is designed to carry a fixed payload to a predetermined altitude. Its design shape is based on an axisymmetric model that assumes that the balloon film is inextensible and that the circumferential stresses are zero. While suitable for design purposes, these assumptions are not valid for a real balloon. In this paper, we present a variational approach for computing strained balloon shapes at float altitude. Our model is used to estimate the stresses in the balloon film under various loads and for different sets of material constants. Numerical solutions are computed. [S0021-8936(00)02201-7]
Chondrocyte Translocation Response to Direct Current Electric Fields
Authors: Chao Pen-Hsiu Grace , Roy Rani , Mauck Robert L. , Liu Wendy , Valhmu Wilmot B. , Hung Clark T.
Published: July 2002

Using a custom galvanotaxis chamber and time-lapse digital video microscopy, we report the novel observation that cultured chondrocytes exhibit cathodal migration when subjected to applied direct current (DC) electric fields as low as 0.8 V/cm. The response was dose-dependent for field strengths greater than 4 V/cm. Cell migration appeared to be an active process with extension of cytoplasmic processes in the direction of movement. In some cells, field application for greater than an hour induced elongation of initially round cells accompanied by perpendicular alignment of the long axis with respect to the applied field. Antagonists of the inositol phospholipid pathway, U-73122 and neomycin, were able to inhibit cathodal migration. Cell migration toward the cathode did not require the presence of serum during field application. However, the directed velocity was nearly threefold greater in studies performed with serum. Studies performed at physiologic temperatures ∼37°C revealed a twofold enhancement in migration speed compared to similar studies at room temperature ∼25°C. Findings from the present study may help to elucidate basic mechanisms that mediate chondrocyte migration and substrate attachment. Since chondrocyte migration has been implicated in cartilage healing, the ability to direct chondrocyte movement has the potential to impact strategies for addressing cartilage healing/repair and for development of cartilage substitutes. [S0148-0731(00)00803-7]
A Design Method to Prevent Low Pressure Turbine Blade Flutter
Authors: Panovsky J. , Kielb R. E.
Published: July 2002

A design approach to avoid flutter of low pressure turbine blades in aircraft engines is described. A linearized Euler analysis, previously validated using experimental data, is used for a series of parameter studies. The influence of mode shape and reduced frequency are investigated. Mode shape is identified as the most important contributor to determining the stability of a blade design. A new stability parameter is introduced to gain additional insight into the key contributors to flutter. This stability parameter is derived from the influence coefficient representation of the cascade, and includes only contributions from the reference blade and its immediate neighbors. This has the effect of retaining the most important contributions to aerodynamic damping while filtering out terms of less significance. This parameter is utilized to develop a stability map, which provides the critical reduced frequency as a function of torsion axis location. Rules for preliminary design and procedures for detailed design analysis are defined. [S0742-4795(00)01401-0]
A Full Numerical Solution to the Mixed Lubrication in Point Contacts
Authors: Hu Yuan-Zhong , Zhu Dong
Published: July 2002

A full numerical solution for the mixed elastohydrodynamic lubrication (EHL) in point contacts is presented in this paper, using a new numerical approach that is simple and robust, capable of handling three-dimensional measured engineering rough surfaces moving at different rolling and sliding velocities. The equation system and the numerical procedure are unified for a full coverage of all the lubrication regions including the full film, mixed and boundary lubrication. In the hydrodynamically lubricated areas the Reynolds equation is used. In the asperity contact areas, where the film thickness is zero, the Reynolds equation is reduced to an expression equivalent to the mathematical description of dry contact problem. In order to save computing time, a multi-level integration method is used to calculate surface deformation. Sample cases under severe condition show that this approach is capable of analyzing different cases in a full range of λ ratio, from infinitely large down to nearly zero (less than 0.03). [S0742-4787(00)00101-6]
Detrimental Effects of Debris Dents on Rolling Contact Fatigue
Authors: Ne´lias D. , Ville F.
Published: July 2002

Debris dents produced by solid particles in suspension in oil or grease when they travel through an EHL contact may be at the origin of rolling bearing failures. A summary of an experimental investigation carried out to identify (i) the particle entry ratio, (ii) the mechanisms of particle fragmentation or deformation, (iii) the resulting indentation features, and (iv) the initiation site of subsequent surface damage is presented first. Afterwards, numerical simulations of a dent moving through an EHL contact are performed. A critical slide-to-roll ratio is found. Results of our numerical simulations are analyzed and discussed in relation to the concept of infinite life for rolling bearing applications. [S0742-4787(00)00901-2]
Modeling Shrouded Stator Cavity Flows in Axial-Flow Compressors
Authors: Wellborn S. R. , Tolchinsky I. , Okiishi T. H.
Published: July 2002

Experiments and computational analyses were completed to understand the nature of shrouded stator cavity flows. From this understanding, a one-dimensional model of the flow through shrouded stator cavities was developed. This model estimates the leakage mass flow, temperature rise, and angular momentum increase through the cavity, given geometry parameters and the flow conditions at the interface between the cavity and primary flow path. This cavity model consists of two components, one that estimates the flow characteristics through the labyrinth seals and the other that predicts the transfer of momentum due to windage. A description of the one-dimensional model is given. The incorporation and use of the one-dimensional model in a multistage compressor primary flow analysis tool is described. The combination of this model and the primary flow solver was used to reliably simulate the significant impact on performance of the increase of hub seal leakage in a twelve-stage axial-flow compressor. Observed higher temperatures of the hub region fluid, different stage matching, and lower overall efficiencies and core flow than expected could be correctly linked to increased hub seal clearance with this new technique. The importance of including these leakage flows in compressor simulations is shown. [S0889-504X(00)00501-8]
Technical Basis for Code Cases on Design of Ellipsoidal and Torispherical Heads for ASME Section VIII Vessels
Authors: Rana Mahendra D. , Kalnins Arturs
Published: July 2002

ASME Boiler and Pressure Vessel (B&PV) Code Committees have approved Code Cases 2260 and 2261 on the design of ellipsoidal and torispherical heads for Section VIII Division 1 and Division 2 vessels, respectively. Burst and low-cycle fatigue failure modes have been considered. A rationale is provided for including the foregoing referenced failure modes, and not including other failure modes such as dimensional changes, plastic collapse, knuckle yielding, etc. The basis for the specified design formulas to satisfy the burst and low-cycle fatigue criterion is discussed. The paper also discusses limitations and other requirements that have been imposed in the Code Cases. [S0094-9930(00)01401-3]
Vibro-Impact Dynamics of a Periodically Forced Beam
Authors: Knudsen Jakob , Massih Ali R.
Published: July 2002

The vibration and impact dynamics of a periodically forced loosely supported beam are analyzed. The wear work rates at impact points are evaluated. The considered beam is clamped at one end, and constrained against unilateral contact at contact sites, with or without friction, near the other end. In this work, the structure is modeled by a Bernoulli-type beam supported by springs using finite element method. Our model calculations are compared with measurements of contact forces and displacements made on a loosely supported rod that was subjected to harmonic loading. Furthermore, the dynamics of vibro-impacts are characterized by evaluating the impact velocity as a function of harmonic excitation frequency for two idealizations of the aforementioned structure. [S0094-9930(00)01002-7]
Epitaxial C60 Film on Si(111) by XPS
Authors: Vasquez Richard P. , Brain Ruth A. , Ross David , Yeh Nai-Chang
Published: July 2002

High resolution XPS measurements of the C 1s, including energy losses, and the valence band regions are presented for a high quality epitaxial film (average grain size ~70 nm) of C60 on a Si (111) substrate. Similar films have also been characterized with x-ray diffraction and transmission electron microscopy.
Copper by XPS
Authors: Miller A. C. , Simmons G. W.
Published: July 2002

High energy resolution spectra of high purity Cu foil that was scraped in situ are presented. The experimental width (16%–84% measurement) of the Fermi level of nickel obtained under identical experimental conditions was 0.32 ± 0.02 eV. The binding energy scale calibration is based on the position of the Au 4f7/2 line which is taken to be 83.98 eV [see M. T. Anthony and M. P. Seah, Surf. Interface Anal. 6, 95 (1984)]. The Auger spectra are presented primarily to provide information on the detailed structure of the line at high energy resolution and accurate measurements of the relative separations between the transitions contained within the line. Since the kinetic energy of a photoelectron depends upon the photon energy and the kinetic energy of an Auger electron does not, the position of the Auger electron on the binding energy scale is a function of the photon energy. For nonmonochromatic x-ray excitation, the positions of the photoelectron lines and Auger lines are fixed relative to one another because the natural x-ray line has a defined centroid. However, for monochromatic Al Kα radiation, the exact photon energy can deviate from the centroid energy by as much as 0.3 eV. Thus, there can be systematic deviations in the binding energies of the Auger lines as recorded with instruments using monochromatic radiation as compared to those using nonmonochromatic x-ray sources. Comparison of the L3M4,5M4,5 line position with other published work [see M. P. Seah, G. C. Smith, and M. T. Anthony, Surf. Interface. Anal. 15, 293 (1990)] suggests that our photon energy is 1486.73 eV, and that all of the Auger line positions recorded in the table are systematically displaced by 0.15 eV.
Copper Mg K
α XPS Spectra from the Physical Electronics Model 5400 Spectrometer
Authors: Mansour A. N.
Published: July 2002

Copper spectra were measured with the Physical Electronics Model 5400 x-ray photoelectron spectrometer (XPS) using unmonochromatized Mg Kα x rays and four pass energy settings corresponding to analyzer energy resolutions of 1.34, 0.54, 0.27, and 0.13 eV. The specimen was a high purity copper foil that was sputter-cleaned by 3 keV Ar ions. We present the survey spectrum (binding energy range of 0–1100 eV) measured at an analyzer energy resolution of 1.34 eV. Multiplexes of the Cu 2p (924–974 eV), Cu 3p (65–90 eV), Cu 3s (113–138 eV), valence band region (−5–10 eV), and Cu LVV Auger lines (305–355 eV) were measured at analyzer energy resolutions of 0.54, 0.27, and 0.13 eV.
Characterization of NiO by XPS
Authors: Mansour A. N.
Published: July 2002

We report x-ray photoemission spectra (XPS) of nickelous oxide (NiO). XPS spectra were measured with the Physical Electronics Model 5400 x-ray photoelectron spectrometer using unmonochromatized Mg Kα x rays at two pass energy settings corresponding to analyzer energy resolutions of 1.34 and 0.54 eV. We present the survey spectrum (binding energy range of 0–1100 eV) measured at an analyzer energy resolution of 1.34 eV. Multiplexes of the C, O, and Ni photoemission lines, valence band region, as well as the Ni LVV Auger line were measured at an analyzer energy resolution of 0.54 eV. The research grade high purity NiO sample was obtained commercially from Atomergic Chemetals Corporation.
Characterization of the Surface of α-FeOOH Powder by XPS
Authors: Mansour A. N. , Brizzolara Robert A.
Published: July 2002

We report x-ray photoemission spectra of the surface of iron (III) oxyhydroxide (α-FeOOH) particles. Research grade purity (99.0%) α-FeOOH sample was commercially obtained from Alfa/AESAR. The XPS spectra were measured with the Physical Electronics Model 5400 X-ray Photoelectron Spectrometer using unmonochromated Mg Kα x-rays at two pass energy settings corresponding to analyzer energy resolutions of 1.34 and 0.54 eV. We present the survey spectrum (binding energy range of 0–1100 eV) measured at an analyzer energy resolution of 1.34 eV. Multiplexes of the C 1s, O 1s and 2s, Fe 2p and 3p photoemission lines, valence band region as well as the Fe L3VV Auger line were measured at an analyzer energy resolution of 0.54 eV. The XPS spectra indicate that the surface of α-FeOOH powdered material consists mainly of its bulk chemistry with small quantities of oxidized carbon and hydrocarbon as contaminants.
Aluminum Phosphate by XPS
Authors: Rotole John A. , Sherwood Peter M. A.
Published: July 2002

The XPS spectra of aluminum phosphate were collected with a VSW HA150 using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the rich peak structure in the valence band of aluminum phosphate due to the absence of interfering x-ray satellites from the intense O 2s region. The valence band region shows the characteristic phosphate peaks at 13.79 eV and 10.69 eV. The valence band, survey, and the Al 2s, Al 2p, O 1s, and C 1s core levels are reported.
Mn2O3 by XPS
Authors: Stranick Michael A.
Published: July 2002

Manganese compounds have many applications in areas such as catalysis, electrochemistry, and metallurgy, among others. Distinguishing between the various chemical states of manganese is an important aspect of research in many of these areas. It has been shown that the different chemical states of manganese can be identified with XPS through the Mn 2p3/2 peak positions, Mn 2p1/2 satellite–Mn 2p1/2 peak separations, Mn 3s multiplet splittings, or Mn Auger parameters. To date, however, all of these values have not been available in a single reference. In this study, XPS has been used to obtain core level, Auger, and valence band spectra for a commercial, high purity Mn2O3 powder. This submission provides a reference that contains all of the Mn XPS data necessary for the identification of Mn2O3 and also provides information that may be useful for the analysis of other Mn compounds.
Transmission electron microscope investigation of SrBi2Ta2O9 memory capacitors on Si with silicon dioxide and silicon nitride as buffers
Authors: Ils A. , Cantoni M. , Sallese J.-M. , Fazan P. , Han J.-P. , Guo X. , Ma T. P.
Published: July 2002

Ferroelectric memory capacitors were made by deposition of SrBi2Ta2O9 (SBT) on Si with thin (∼40–90 Å) buffer layers of jet vapor deposition (JVD) silicon nitride and oxide. Transmission electron microscope analysis was carried out to compare the microscopic integrity of both films after subsequent processing steps. It was found that the thin SiO2 buffer layer failed to prevent further oxidation of the Si substrate and furthermore allowed the diffusion of the SBT towards the SiO2/Si interface. In contrast the silicon nitride layer deposited by the JVD process acted as a good barrier for the diffusion of SBT. It also stopped further oxidation of the Si substrate during subsequent annealing in oxygen. Electrical tests show that the capacitors have large memory windows and that the windows present only slight degradation after 1011 switching cycles. The use of JVD nitride as a buffer is encouraging for the further development of ferroelectric memory transistors.
Tantalum etching with a nonthermal atmospheric-pressure plasma
Authors: Tu V. J. , Jeong J. Y. , Schütze A. , Babayan S. E. , Ding G. , Selwyn G. S. , Hicks R. F.
Published: July 2002

Tantalum was etched in a downstream, atmospheric-pressure plasma. In this process, etching occurred without significant ion bombardment. An etching rate of 6.0±0.5 μm/min was achieved using 14.8 Torr oxygen, 22.4 Torr carbon tetrafluoride, 720±5 Torr helium, 685 W radio frequency power at 13.56 MHz, and a film temperature of 300 °C. The etching rate increased with the applied power, carbon tetrafluoride pressure, oxygen pressure, and residence time of the gas between the electrodes, indicating that the surface reaction depends on the density of reactive fluorine species generated in the plasma. X-ray photoemission spectroscopy revealed that the etched surface was covered with tantalum fluoride and to a lesser extent, tantalum oxide. Based on these observations, a mechanism for tantalum etching is proposed which involves the reaction between fluorine atoms and the adsorbed tantalum fluoride.
Structures and properties of vacuum vapor deposited coatings on steel substrates
Authors: Neirynck M. , Samaey W. , Van Poucke L.
Published: July 2002

An examination was made of the influence of some deposition parameters on coating structures and properties. The evaporated metals were aluminum and zinc. The deposition parameters were deposition rate and substrate temperature and roughness. The examined coating properties were appearance, adhesion, grain size, porosity, texture, and structure. The coatings were applied on steel sheets and wire pieces in a discontinuous way, and on wire in a continuous air-to-air installation. In testing the zinc coatings, the influence of both, the substrate temperature and the deposition rate on coating grain size and porosity, was most evident. Also the influence of the deposition rate on the re-evaporation temperature of the substrate was examined. During the examination of the aluminum coatings, an important influence of deposition rate and substrate temperature on structure, grain size, texture, and condensation mechanism was established.
Effect of ion bombardment during deposition on thick metal and ceramic deposits
Authors: Bland R. D. , Kominiak G. J. , Mattox D. M.
Published: July 2002

Energetic ion bombardment of metal and ceramic deposits during deposition is shown to affect the morphology, structure, stochiometry, and physical properties of the resulting deposit. The bombardment of the growing deposit tends to eliminate the columnar growth morphology normally encountered in thick-crystalline deposits. Generally, in metals it is found that internal stress, density, and gas content increase with increasing ion bombardment energy, but in some cases there is a decrease at high energies, possibly due to heating. In the case of sputter-deposited glass films, it is found that ion bombardment affects the stoichiometry, the coefficient of thermal expansion, and the strain point of the glass. Specific data are presented for thick (> 1 μ) rf sputter-deposited Corning 1720 glass and also sputter-deposited and electron-beam ion-plated chromium deposits with both a dc and a rf substrate bias.
Operating Parameters of a Quadrupole in a Grounded Cylindrical Housing
Authors: Denison D. R.
Published: July 2002

Quadrupole theory and design are based on the solution of Mathieu’s equations, which assume that zero potential, except for the symmetry axes between the electrodes, is infinitely far away. In practice, the quadrupole rods are mounted within a grounded housing not much larger than the electrode structure itself. This study determines the operating parameters and optimum electrode size for a quadrupole with electrodes of circular cross section located within a zero-potential cylindrical surface. It is found that the rod size is only weakly dependent on the location of the external, zero-potential surface and the optimum rod size is r=1.1468r0 for a cylinder radius of 3.54r0. Although the optimum rod size is only 1.15% smaller than the commonly used value of r=1.16r0, it is found that 43% higher sensitivity at a resolution of 400 (ΔM measured at half-height) results from using the optimum radius electrodes.
High-Capacity Lead—Tin Barrel Dome Production Evaporator
Authors: Kurtz J. A. , Rendon D. , Trahn K. A.
Published: July 2002

The deposition of 0.005 cm of lead-tin solder is required in the fabrication of flip-chip integrated circuits. Conventional bell jar techniques for coating masked wafers 214-in. (5.7-cm) diam severely limited the batch size. Consequently, a 142-position, 5-tier “ferris wheel” dome, rotated at 5 rpm, was used. A low-voltage radiation heated source was mounted within the dome and was masked experimentally to attain uniform deposition rates on each tier. The vacuum system for this arrangement is fairly novel for the semiconductor industry. Instead of the conventional bell jar a box coater, about 36-in. (0.9-m) on a side, with a full opening front door is used. This provides for extremely flexible design and easy operation. Specifically the “shoe horn” tooling so characteristic of bell jars is avoided. The lead-tin evaporation source is extremely rugged and reliable even though it evaporates 3 lb at a time. Thickness is within the range of 0.0046–0.006 cm and maintenance is minimal.
Hydrogen and Nitrogen Desorption Phenomena Associated with a Stainless Steel 304 Low Energy Electron Diffraction (LEED) and Molecular Beam Assembly
Authors: Horgan A. M. , Dalins I.
Published: July 2002

The rates of hydrogen desorption from the walls of a standard LEED stainless steel vacuum chamber isolated from the ion pump have been measured using an oxygen-free copper orifice of known conductance, which acts as the final focussing slit in a molecular beam assembly, and found unacceptably high for the maintenance of a clean metal single crystal surface. The causes are discussed and the rates of desorption are presented after the stainless steel apparatus had been subjected to vacuum degassing at 850–950 °C in a vacuum furnace at pressures ≤10−5 Torr. Desorption rates are decreased ∼130 times. Rates of desorption of nitrogen from Varian post-acceleration type two and three grid LEED optics screens (P-4 CR 422 phosphor) have been measured. Possible displacement reactions with residual hydrogen, small quantities of which are adsorbed during nitrogen desorption, are discussed. It is concluded that the two processes are independent of each other. Contamination of the single crystal samples with the nitrogen desorbed for the LEED screen is also discussed. Brief reference is made to the adsorption properties of stainless steel 304 with special reference to hydrogen and nitrogen.
High-Frequency Surface Conductivity and Magnetic-Field-Induced Surface States
Authors: Koch J. F.
Published: July 2002

We introduce the concept of magnetically induced surface states by analogy with the bound states produced by an electric field. The paper considers surface bound states in normal and super-conducting metals and explores their contribution to the high-frequency surface conductivity. We provide a brief compendium of significant experimental and theoretical results of research on magnetic surface levels.
Development of Continuous Sputtering Machines
Authors: Hanfmann A. M. , Kumagai H. Y. , Fletcher I. M.
Published: July 2002

New data have been gained since a comparison of the “open-end” and closed-end” machines was made in 1968 [A. M. Hanfmann and F. J. Viola, Proc. 4th Intern. Vacuum Congress (Physical Society, London, 1969), Part II, pp. 549–553]. The “open-end” machine remained a reliable tool for sputtering resistor film (nitrided or oxy-nitrided tantalum). Development of the “closed-end” machine was aimed at optimizing the properties of capacitor (beta-tantalum) film. Beneficial effects of the lowered substrate temperature on capacitor film properties were realized (a) by improved cooling of the machine and (b) by introduction of dc-enhanced ac sputtering (H. Y. Kumagai, U. S. Patent No. 3 616 402). The dependence of dielectric leakage on sputtering voltage and current was studied. A favorable operating region was defined and used in production.
The Effect of Water Vapor on the Sticking Coefficient of Lead on Silicon Monoxide
Authors: Bloore Ernest W. , Olson Ferron A.
Published: July 2002

Experiments have been conducted at a total pressure of 10−9−10−5 Torr while the partial pressure of water was varied from 10−10 to 10−6 Torr. A constant lead flux of 4.5×1014 atoms cm−2 sec−1 was utilized. Results indicated that a rapid decrease in the initial sticking coefficient reached an asymptote of approximately 0.6 as the partial pressure of the residual water vapor was increased. Also, the sticking coefficient did not approach unity as deposition continued but remained essentially constant. Competitive reactions between the lead and the water molecules with the surface are proposed as an explanation of this latter phenomenon. The sticking coefficient for this system can equal unity in a total pressure range of 10−6−10−5 Torr if the partial pressure of water is restricted to less than 1×10−8 Torr.
Fabrication of Framed Beryllium Windows by High Rate Physical Vapor Deposition Processes
Authors: Bunshah R. F. , Juntz Robert S.
Published: July 2002

Beryllium windows are used in radiation generators and detectors such as x-ray tubes, counters, etc., because of the low atomic number of beryllium. In current practice, thin foils of beryllium >0.001-in. thickness and brazed or welded into a frame which is then attached to the apparatus. This presents the problems of procurement of the thin foil and damage to it during the joining process. In our technique, beryllium is evaporated onto a substrate such as copper to the desired thickness and the window is produced by dissolving the substrate with concentrated nitric acid in the window area after masking off the area which forms the frame. Thus, a framed window of the different shapes can be produced. The principal problem is porosity in the deposit below 0.002-in. thickness.
A sputtering technique for coating the inside walls of through-holes in substrates
Authors: Vossen J. L.
Published: July 2002

By sputter-etching a substrate with through-holes while the substrate rests on a sputtering target, material from the target coats the inside walls of the through-holes without appreciably coating the plane surfaces. The deposition rate is greatest when the sputtering voltage is low (<1 kV), and the pressure- and target-sputtering yield are high. The rate is nearly independent of the hole aspect ratio (ratio of diameter to depth) for ratios greater than 0.3, but decreases rapidly for smaller ratios. The uniformity of the films thus deposited depends mainly on the smoothness of the through-hole walls.
The First Twenty Years of the American Vacuum Society
Authors: Schleuning H. W.
Published: July 2002

This year, 1973, is the twentieth anniversary of the formation of the American Vacuum Society, and it is thus appropriate to review the development and growth of the Society. This brief history describes the formation of the Society and the first year of its existence and lists the officers of the Society over the years and the location of annual symposia. Various activities of the Society are described such as the symposia, educational activities, publications divisions and sections, and scholarships and awards.