bluuebunny/crossref_metadata_2025 huggingface dataset:
Pumping Test Methods for Determining Aquifer Characteristics
Authors: Lang S. M.
Published: August 2009

Data describing the shape and manner in which the cone of depression forms about a well discharging at a constant rate are used with various formulas to determine the hydraulic characteristics of aquifer materials. The solutions to these formulas generally are graphical and may be used to detect the presence of hydraulic or geologic boundaries to the aquifer.
Apparatus for Measuring Hydraulic Conductivity of Undisturbed Soil Samples
Authors: Wit K. E.
Published: August 2009

Since undisturbed soil samples can be obtained to a depth of about 50 m, a laboratory apparatus for the determination of the hydraulic conductivity has been developed. The tests with this apparatus provide data on vertical hydraulic conductivity; horizontal conductivity; the presence of semipervious or pervious confining layers; and the correlation between hydraulic conductivity and granular composition, porosity, minor structures, etc. The data are used for comparison with data obtained from other methods and as a basis for computation of directionand intensity of flow under natural conditions. The permeameter consists of a container in which simultaneous tests of 50 samples are possible, with both the constant-head and the falling-head methods. The hydraulic head applied for the flow ranges from 2 to 20 mm, depending on structure and texture of the samples.
Abnormalities in Hydraulic Flow Through Fine-Grained Soils
Authors: Mitchell J. K. , Younger J. S.
Published: August 2009

Evidence for deviations from Darcy's law during hydraulic flow through fine-grained soils is reviewed. Abnormal water properties, electrokinetic coupling, fabric changes under the action of seepage forces, and experimental errors are considered as possible causes for the observed behavior. Data are presented to suggest deviations from Darcy's law in saturated kaolinite and in saturated, compacted silty clay. No evidence for a threshold gradient was found for these materials. The behavior of the compacted specimens was such as to indicate that particle migrations are more likely causes for non-Darcy flow than are abnormal water properties. Support for this conclusion was provided by the results of tests wherein pore pressure distributions along the length of specimens were determined during flow. In this way it was possible to determine the variations in hydraulic gradient with time at different points in the sample. The effects of non-Darcy flow behavior in soil mechanics problems are discussed. If high gradient tests are used in the laboratory, the results may bear little relationship to the behavior in the field where gradients seldom exceed unity. Data are presented illustrating the variation of excess pore pressure with time at several points throughout the height of a consolidating clay specimen. The results indicate, contrary to other evidence in the literature, that there could have not been a threshold gradient for flow. Because of the considerable experimental uncertainty associated with permeability measurements on fine-grained soils, laboratory test results must be interpreted with caution.
Field Determination of Permeability by the Infiltration Test
Authors: Schmid W. E.
Published: August 2009

The measurement of permeability by infiltration tests is discussed and formulas for infiltration wells terminating below and above the ground water table are derived. The validity of the formulae and the assumptions used are checked by model tank experiments and permeameter tests. For infiltration above the ground water table no comparable formula exists, but the values found by the proposed formula are about one order of magnitude smaller than those found by infiltration into the ground water. This may be caused by difference in the effective porosity that occurred due to trapped air. Nevertheless, the value obtained by the new formula may be considered as a lower bound value of the permeability.
Air and Water Permeability of Compacted Soils
Authors: Matyas E. L.
Published: August 2009

Specimens of a glacial till and a silty clay, compacted at molding water contents corresponding to optimum water content or greater, have been tested in triaxial apparatus. The migration of water, due to capillary forces acting between partially saturated samples placed at different molding water contents and densities, has been investigated experimentally, and typical results are reported. Experimental studies of air permeability in partially saturated soils and water permeability in both partially saturated and saturated soils are described. The air permeability is shown to range over five log cycles as the degree of saturation is increased and becomes negligible as the suction, μa − μw, approaches zero. The validity of Darcy's law is confirmed by performing water permeability tests at different back pressures. If the soil is completely saturated, there is no evidence of a “threshold gradient” or a nonlinear relationship between velocity and hydraulic gradient as reported by some investigators. Coefficients of permeability as determined by direct measurement are compared with values calculated from triaxial consolidation test data, and the lack of agreement is discussed briefly on a theoretical basis.
A Comparison of Atomic Absorption with Some Other Techniques of Chemical Analysis
Authors: Lewis L. L.
Published: August 2009

Since the introduction of atomic absorption spectrophotometry (AAS) ten years ago, over 20 million dollars have been invested in the 3000 AAS instruments in the United States. This wide acceptance and phenomenal growth have been accompanied by sound but haphazard progress. We have learned that, despite their apparent simplicity, AAS methods require careful laboratory technique, familiarity with the separations and reactions that are fundamental in analytical chemistry, and a thorough knowledge of potential sources of error and their control. The nature of AAS provides a genuine challenge in proper instrument operation, which is unlike the challenges in the chemical methods. The real problems begin in the interlaboratory testing of a new method, and it remains to be seen how AAS will compare with chemical methods in interlaboratory testing programs. As regards to ASTM, the real benefits from AAS depend on the completion of unfinished work on the critical evaluation of all of our methods, the sound appraisal of AAS methods through interlaboratory testing programs, and agreement on recommended practices in our AAS methods.
Determination of Trace Metals in Seawater by Atomic Absorption Spectrophotometry
Authors: Brewer P. G. , Spencer D. W. , Smith C. L.
Published: August 2009

The distribution of trace metals in seawater has been studied for a long time; however, poor analytical techniques and unrepresentative sampling have rendered much of the published data useless for understanding the role of these elements in the geochemical and biological cycles of the ocean. A solvent extraction method has been devised to recover copper, zinc, iron, cobalt, nickel, and lead from seawater and to transfer these metals into a solvent suitable for their direct analysis by atomic absorption spectrometry. These metals range in concentration from about 20 to 0.1 ppm in true solution, and in greater concentrations in the particulate matter suspended in the oceans. At these very low levels extreme care must be taken in the development of a suitable method of analysis and in manipulation of the sample. We have chosen the method of standard additions for our analytical scheme, and have paid particular attention to investigating interferences in the method and to establishing a “blank” determination for each and every sample. The nature of this blank will be discussed, and its effect on the analysis of each element will be described. A statistical treatment of the data has been developed, enabling us to use a computer program to process the raw data and to calculate confidence limits on each analysis.
Determination of Cobalt and Impurities in Gold Plating Solutions and Gold Plates by Atomic Absorption
Authors: Kapetan J. P.
Published: August 2009

Prior to atomic absorption, cobalt in gold plating solutions was determined by polarography; copper, iron, and lead by optical emmission. With atomic absorption, both methods were consolidated with a significant decrease in analytical time. For the determination of cobalt in the range of 50 to 200 ppm the gold plating solutions are diluted, and the cobalt concentration is determined from a calibration curve constructed from Fisher Scientific Standards. To determine iron, lead, and copper in the range of 1 to 30 ppm the plating solutions are not diluted. In the course of the investigation it was found that iron and cobalt standards are unstable when stored in glass volumetric flasks. Polyethylene bottles have been found satisfactory for storing these standards. For the determination of cobalt and impurities in gold plates on copper and bronze the sample is dissolved in 1:3 nitric acid. Citrate is added to the nitric acid to complex the tin of the bronze. The solution then is filtered, and the insoluble gold plate is washed thoroughly with distilled water. Up to 25 mg of gold is dissolved in 3 ml of aqua regia, and the volume is adjusted to 25 ml with distilled water. The cobalt and impurities then are determined from curves constructed from standards which also contain 3 ml of aqua regia per 25 ml of solution.
Load Transfer, Lateral Loads, and Group Action of Deep Foundations
Authors: Vesić A. S.
Published: August 2009

Keynote address containing a review of major developments in analysis of load transfer, behavior of piles and pile groups under lateral loads, and group action of pile foundations. Critical summaries of ten papers on this subject presented to this symposium are included.
Soil Behavior from Analysis of Tests of Uninstrumented Piles under Lateral Loading
Authors: Reese L. C. , Cox W. R.
Published: August 2009

The most up-to-date method for the design of laterally loaded piles is to solve numerically the differential equation describing pile behavior. Iterative solutions are necessary since there is a nonlinear relationship between soil resistance and pile deflection. Curves giving soil resistance as a function of pile deflection, called p-y curves, have been the subject of research for a number of years. The development of p-y curves normally requires that a test be performed on an instrumented laterally loaded pile. A curve showing bending moment in the pile needs to be obtained for each of the applied loads. This curve can be differentiated twice to obtain soil resistance, and it can be integrated twice to obtain pile deflection. Cross plots of these values can be made at desired depths to obtain the p-y curves. This paper shows that nondimensional curves, developed from the numerical solutions of the differential equation, can be used to estimate p-y curves if only the following easily obtainable information is reported; pile properties, magnitude of the individual lateral loads, point of load application, deflection of the top of the pile, slope of the top of the pile, and condition of restraint (if any) at the top of the pile. Thus, there needs to be no instrumentation of the pile except above ground. The procedure is illustrated by applying it to a test reported in the literature.
Energy Measurements for a Diesel Hammer
Authors: Davisson M. T. , McDonald V. J.
Published: August 2009

Measurements of pile force and deflection have been made at the head of a long concrete-filled pipe pile driven with a diesel hammer. The measurement techniques utilized are the first to allow calculation of energy transmitted to a pile. Energy transmitted to the pile was 73 percent of manufacturer's rated energy. Measurements, analyses, and logic regarding soil-pile behavior and the mechanics of diesel hammers allow several conclusions: (1) energy transmitted and peak pile force were linearly related for the near refusal driving conditions observed, (2) at combustion-impact diesel hammers contain more than twice manufacturer's rated energy, (3) at combustion-impact diesel hammers make approximately 100 percent of rated energy available for transmission to the pile, whereas steam hammers make only 80 to 85 percent available, and (4) analyses involving the one dimensional wave equation should be used instead of conventional dynamic formulas to estimate energy actually transmitted to the pile.
Vibratory Loading of Pile Foundations
Authors: Maxwell A. A. , Fry Z. B. , Poplin J. K.
Published: August 2009

This paper describes a unique investigation of the response of piles subjected to both dynamic and static loading, and presents findings relative to performance of pile foundations under these conditions. Preliminary load tests were conducted at NASA's Mississippi Test Facility prior to final design of massive static test firing stands for Saturn V rocket boosters. Friction-type, steel H-piles and point-bearing, concrete-filled pipe piles primarily supported by a dense sand layer overlain by fat clay and silty sand were loaded (a) statically up to 200 tons and (b) dynamically with combinations of 50, 100, and 200 tons dead load and a vertically directed, steady-state loading of dynamic force amplitudes ranging from 1 to 10 tons and frequencies ranging from 4 to 16 Hz. Also, a cluster of four H-piles was tested under combined loading. Typical data in the form of steady-state displacement and phase angle versus frequency plots indicated that resonance occurred at frequencies ranging from 5 to 10 Hz depending on the static load. The experimental data were compared with a single-degree-of-freedom analytical model with linear springs and viscous damping. At resonance, dynamic stiffness was greater than static stiffness for comparable piles, and damping was slight with computed damping ratios of 0.04 to 0.05 for single piles and about 0.10 for the four-pile cluster. Resonant frequencies could be predicted on the basis of static load-settlement curves, but resonant displacement could not be reliably extrapolated from test data at nonresonant frequencies. Permanent settlements occurred at resonance at higher dynamic force levels. Skin friction distribution along the pile length, as determined by strain gages, appeared similar in dynamic and static loading.
Introduction
Authors: Brothers A. J.
Published: August 2009

The purpose of this, the second symposium, sponsored by Subcommittee II on Fractography of ASTM Committee E-24 on Fracture Testing of Metals is to present the results of recent applications of microfractography. As the papers in this volume indicate, fractographic investigation has contributed both to the phenomenological study of the fracture mechanisms of cleavage, microvoid coalescence, stress corrosion, and fatigue, as well as providing quantitative measurement of microfractographic features associated with fracture processes. The successful attempts shown here to correlate measurement of fatigue and fracture features with the macroscopic parameters of current engineering analyses illustrate the value of application of these techniques. These results contribute directly to an understanding of the relationship between material phenomenological behavior and mechanical properties of fracture toughness, fatigue crack growth rate, and ductility of engineering alloys and polymers. It is believed that this, and future work of this nature, in time, will add both to the development of fractographic techniques as well as provide a useful link between fractographic features and mechanical properties of interest to material users.
Fractographic Studies of Crack-Tip Zones in a Structural Steel
Authors: Fegredo D. M.
Published: August 2009

Fatigue cracks increase the ductile-brittle transition temperature (dbtt) by about 20 C, and an evaluation was made of the contribution of the fine-radius fatigue crack tip to this increase by annealing specimens, partially cracked by fatigue, at 650 C for 3 h and comparing the dbtt of fatigued and annealed specimens. Transition temperatures (tt) were determined from impact tests, and the fatigue cracks were introduced by plane bending. Precracked specimens were aged (232 C for 1 h), and V-notched specimens were nitrided in ways that eliminated or retained shear lips. Precracked test specimens were nitrided only at the crack tip. Aging does not alter the tt appreciably, and V- notched and fatigue-cracked specimens that were similarly nitrided, possess the same energy absorbing properties with a higher tt than fatigued ones. Thus, the nitrided zone overrides the effect of notch sharpness and structure at the roots of notches. The elimination of shear lips causes a further rise in tt. Electron and optical microscopes were used, and the fractographic examination revealed how the ductile initiation zones (diz) at the roots of stress concentrators decreased in thickness with decreasing temperature and decreasing notch radius. Macro- and microfractographic features as a function of temperature are described. The results indicate semiquantitatively the energy absorbed in producing the diz and shear lips and thereby demonstrate their protective influence.
A Comparison of Elevated Temperature Tensile Fractures in Nonleaded and Leaded 4145 Steel
Authors: Zipp R. D. , Warke W. R. , Breyer N. N.
Published: August 2009

It has been found that a 4145 steel containing 0.3 percent lead suffers a loss in ductility when tension tested between 400 and 900 F. A visual analysis of the fractured surfaces from both leaded and nonleaded tension specimens was performed at various ultimate strength levels from 120 to 240 ksi, and the fractures were classified into five types. An electron microscope fractographic study was made on the five fracture types. Fractographs taken from Type A fractures (room temperature to 400 F) showed that fracture by microvoid coalescence (“dimpled rupture”) typified the entire fracture surface. Type B fractures (400 to 600 F) were characterized by a mixture of intergranular regions in an otherwise transgranular failure. Each group of intergranular grain facets contained an inclusion. For a Type C fracture (600 to 650 F) replicas taken from a cluster of small “fish eyes” showed both intergranular and transgranular modes of failure. Again, inclusions were present on the intergranular grain facets. Type D fracture (650 to 900 F) was almost 100 percent intergranular at the origin of the single flat fish eye. The percent intergranular decreased as the crack grew until it was 100 percent transgranular near the extremity of the fracture at the far side of the fish eye. Once again inclusions were present on the intergranular facets. Due to the fact that the Type E fracture occurs at high temperature (above 900 F), the surfaces were badly oxidized but appear to have been formed by a dimpled rupture process. The association of inclusions with the intergranular fracture regions was deemed significant since the lead was always found in an envelope surrounding the inclusions. The results of this study are compatible with a “liquid metal embrittlement” interpretation of the loss in ductility at elevated temperature.
Use of Electron Microfractography in Interpreting the Mechanisms of Fatigue Crack Propagation
Authors: Nair K. D. , Le May I.
Published: August 2009

Electron microfractography has been used in elucidating the mechanisms of fatigue crack propagation in two face-centered-cubic (fcc) sheet metals which had been treated to produce different preferred orientations or textures. Comparison of the striations on the fatigue fracture surfaces of cold-rolled material with those of the same material, annealed to give a different texture and a high ductility, showed the morphology of the striations to be dependent on ductility and texture. A qualitative mechanism is suggested for fatigue crack growth by the Stage II process, involving the formation of striations.
A Fractographic Study of Precipitation Hardened and Dispersion Strengthened Magnesium-Base Alloys
Authors: Calhoun C. D. , Stoloff N. S.
Published: August 2009

The fracture characteristics of Mg-3.7Th-0.4Zr and of Mg-0.6Zr have been investigated. The ternary is a precipitation hardenable system exhibiting a coherent transition precipitate, while the binary forms a stable dispersion of zirconium hydride when heated in an atmosphere of hydrogen. The ternary was investigated in four different heat treated conditions which provided two levels of yield stress. A solution treated alloy and an overaged alloy provided one yield stress, while the other yield stress level was attained by interrupting the heat treatment prior to optimum aging and by slightly overaging. The binary alloy was examined in the hydrided and solution treated conditions only. Specimens were fractured at —196, 23, and 210 C by tension testing. Further information concerning the influence of twins and the initiation of microvoids was acquired by differential temperature tests, where specimens were deformed at one temperature to a predetermined strain followed by deformation to fracture at another temperature. Electron fractography was accomplished on all fractured specimens in order to determine the mode of failure, the influence of precipitate and hydride dispersion on the size and distribution of dimples, and the amount of serpentine glide as a function of temperature and specimen condition. In aged specimens voids observed by light microscopy were up to two orders of magnitude larger than dimples sizes determined by electron fractography. It appeared that dimples are produced by overload failure of material bridging the voids.
Correlation of Fractographic Features with Fracture Mechanics Data
Authors: Bates R. C. , Clark W. G. , Moon D. M.
Published: August 2009

The fractographic features of failures produced in wedg-opening-loading type fracture toughness specimens tested under rising load and cyclic loading were evaluated for Ni-Mo-V and HP 9-4-25 alloy steels and aluminum alloys 5456-H321 and 7079-T6. Test variables included temperature and section size and, consequently, state of stress (plane strain versus nonplane strain). The characteristic fractographic features observed by means of electron microscopy then were compared with the fracture mechanics properties of the alloys. Correlations were found between: (1) fatigue striation spacing and cyclic stress intensity range, ΔK and (2) “stretched zones” (featureless area adjacent to the point where fast fracture initiated from a sharp defect) and the relative toughness of the material. These correlations can be used to provide failure analysis techniques capable of quantitatively evaluating the stress condition associated with failures from fractographic evidence alone.
The Influence of Microstructure on the Fracture Topography of Titanium Alloys
Authors: Williams J. C. , Boyer R. R. , Blackburn M. J.
Published: August 2009

A survey is presented of the fracture topography observed in titanium and titanium alloys. Ductile fracture by microvoid nucleation, growth, and coalescence is of widespread occurrence in these alloys. It is usually possible to qualitatively relate the dimple size to the macroscopic ductility of the alloy. Titanium alloys may be embrittled by alloying additions which in most cases lead to a fine dispersion of second phase particles. In α-phase alloys such brittleness is associated with cleavage fracture; however, β-phase alloys, which exhibit cleavage-like macroscopic behavior, microscopically show evidence of small dimples. Environment often has dramatic effects on fracture behavior of titanium alloys, producing low-energy cleavage-like failure in both α and β-phases which are normally ductile. We attempt to relate the observations of fracture behavior and topography to structural and environmental factors.
Gray Iron—A Unique Engineering Material
Authors: Krause D. E.
Published: August 2009

Gray iron is the most versatile of all foundry metals. The high carbon content is responsible for ease of melting and casting in the foundry and for ease of machining in subsequent manufacturing. The low degree or absence of shrinkage and high fluidity provide maximum freedom of design for the engineer. By suitable adjustment in composition and selection of casting method, tensile strength can be varied from less than 20,000 psi to over 60,000 psi and hardness from 100 to 300 BHN in the as-cast condition. By subsequent heat treatment, the hardness can be increased to HRc 60. If the service life of a gray iron part is considered to be too short, the design of the casting should be carefully reviewed before specifying a higher strength and hardness grade of iron. An unnecessary increase in strength and hardness may increase the cost of the casting as well as increase the cost of machining through lower machining rates. Although the relationship between Brinell hardness and tensile strength for gray iron is not constant, data are shown which will allow use of the Brinell hardness test to estimate the minimum tensile strength of the iron in a casting.
Introduction
Authors: Hillberry B. M.
Published: August 2009

The dynamic behavior of elastomers has led to their widespread application in the field of vibration control and isolation. Elastomeric components play a significant role in controlling vibration in the modern automobile through the use of elastomer body mounts, engine mounts, and suspension members. As this use increased and performance requirements increased, it became increasingly evident that the dynamic behavior of these components needed to be understood and controlled. Measurement methods were soon developed with the resonant beam test machine becoming one of the more widely used machines. TCAR Section 15B (later 11.65B) was organized to address itself to the problems of dynamic testing of elastomers and elastomeric components. With more and more laboratories becoming involved in dynamic testing, the problems of correlation of test results arose. The variation in the supplier and user test results created major concerns in the quality control of products. In general, the measurement of dynamic stiffness and damping of a material or component is very difficult. Any compliance of the test equipment tends to reduce the measured spring rate. Similarly, any damping in the fixtures or the machine will generally increase the measured damping. The normal variation of elastomer properties and its nonlinear behavior compounds the correlation problems. This requires careful control of the test parameters during the test. The members of TCAR have devoted considerable effort toward the correlation problem by examining “standard springs” and dashpots, conducting round-robin test programs and working toward a standard test method. At the September 1971 meeting of Section 11.65, the Committee took the official position that it would discourage the use of the resonent beam testing method and that a standard would be prepared based on the transmitted force method of testing. This action was prompted by a review of the work of A. S. Paul who had analytically studied the errors in the resonant beam test machine. His paper in this symposium describes these results in detail.
Dynamic Property Measurement of Elastomers and Elastomeric Mounts—Past, Present, and Future
Authors: Miller H. E.
Published: August 2009

This is a narrative account of the major events of the last 15 years as they relate to the activities of Section 11.65B, Subcommittee on the Dynamic Property Measurement of Elastomers and Elastomeric Mounts. Section 11.65B is a subcommittee of the Joint SAE-ASTM Technical Committee on Automotive Rubber (TCAR), often called “Tee-Car.” This is not a detailed history and the events are not necessarily in chronological order.
Application of Electrohydraulic Test Machines to Dynamic Testing of Elastomers
Authors: Owens J. Howell
Published: August 2009

Closed loop electrohydraulic servo-controlled test machines have gained rapid acceptance in the dynamic testing field. This paper describes the principles of a particular system designed for use in the Elastomer Test Laboratory. The paper will describe the basic principles of closed loop control, the techniques for calibration of instrumentation and scaling of signals, typical test operation and results, and a unique technique of readout for determining elastic spring rate and damping coefficient.
Computation and Direct Readout of Dynamic Properties: the Identifier
Authors: Hillberry B. M. , Goodson R. E. , Nachtigal C. L.
Published: August 2009

An instrumentation system is described which provides on-line computation and direct readout of C and K. The system relies on the measurement of force and displacement or velocity across the sample and is independent of the type of test machine. Errors introduced by unwanted phase shift in any instrumentation system are discussed. This is overcome in this measurement system by phase compensation. Calibration of the system is described in which an overall system accuracy can be determined independent of test machine or rubber sample. This system has been specifically designed for measurement of dynamic properties of rubber and provides the operator with direct readout of C and K scaled to engineering units, thereby reducing potential operator error.
An Application of Mini-Computers for the Determination of Elastomeric Damping Coefficients and Other Properties
Authors: Danko Donald M. , Svarovsky James E.
Published: August 2009

This paper describes a method for determining the dynamic properties of rubber compounds through the use of a dedicated mini-computer. Topics under discussion include the application of the Fast Fourier transform and its inverse as a rapid method of determining an array of nonlinear coefficients that describe the component force vectors. A discussion of the controlling algorithms in the determination of the dynamic spring rate, nonlinear damping coefficients, and hysteretic energy absorption through the implementation of the Fast Fourier transform is presented. The advantages of this method include relatively low cost, fast results, and simplicity of operation. The implementation of the mini-computer toward this application opens a new field for developing compounds with low damping coefficients where present methods of measurement may not yield consistent results. Test efficiency, repeatability, and reduction of development costs are the principal advantages. Added specialized algorithms can be introduced at minimum cost as the state-of-the-art develops.
Testing and Parameterization of Elastomers for Modeling of Linear Vibration Systems
Authors: Anderson A. D.
Published: August 2009

Representation of elastomers for use in modeling of linear systems requires great care in the acquisition of test data. Current industry-standard test techniques are not adequate for quantitative description of elastomers subjected to small amplitude sinusoidal excitation. Equally important to accurate dynamic testing of elastomers is parameterization of the test data for use in modeling of systems. The paper discusses testing and parameterization techniques used to describe elastomers for use in a linear, low-frequency vibration model of an automobile. Accuracy requirements of test instrumentation, selection of suitable linear elastomer models, and interpolating functions (used for equivalent linearization and ambient condition corrections) are discussed in some detail.
Factors Controlling the Dynamic Properties of Elastomeric Products
Authors: Sommer J. G. , Meyer D. A.
Published: August 2009

Selected compositional, processing, design, and testing factors are discussed with respect to their influence on the dynamic properties of elastomeric parts. Variations in rubbers, fillers, oils, and level of cross-linking produce specific changes in spring rate and damping coefficient. Processing factors such as mixing, curing, and storage are shown to have an important influence on dynamic properties. Design concepts relating material properties and the dynamic response of some simple shapes are reviewed, along with the effect of prestrain and strain history.
Welcoming Remarks from ASTM
Authors: Scace Robert I.
Published: August 2009

Good morning. On behalf of ASTM Committee F-l, the other sponsor of this meeting, I want to welcome you all. Spreading resistance measurements are only one of many measurement techniques with which Committee F-l is concerned. To give some perspective, let me describe a little of ASTM's background in electronics for you. ASTM is a large association of professional people who are engaged in developing standards on subjects ranging from railroad rails to surgical implants, and electronics is just one of over 120 such topics. Committee F-l was established in 1955, developing out of work on electron tube materials which had previously been in a committee on copper. One of our major efforts has been in the development of ways to measure the properties of semiconductor silicon. As Judson French has mentioned, NBS and ASTM have collaborated closely in this work, especially in resistivity measurements. Fifteen years ago we were lucky if two different people could measure the resistivity of a piece of silicon to within a factor of two, but now with the use of ASTM'methods it is possible to do this measurement to an accuracy of a couple of percent. Similar progress could be cited for many other measurements essential to good process control in our industry.
Keynote Address Symposium on Spreading Resistance Gaithersburg, Maryland June 13–14, 1974
Authors: Mazur Robert G.
Published: August 2009

This is the first symposium ever to be held on the subject of spreading resistance measurements. As I see it, the purpose in having this meeting is to gather together those who are currently using the spreading resistance measurement technique in their work on semiconductor processing problems along with others who would like to be able to do something about the same or similar problems, in the hope that, by sharing our knowledge and experience, we may all be better able to use the spreading resistance technique to our own advantage. I hope and believe that we will achieve this particular goal and that therefore in the future this meeting will be referred to as “The First Symposium on Spreading Resistance Measurements.” In deciding what I should talk about in a keynote speech for such an occasion, two related subjects came to mind. First, a number of individuals who haven't worked in the semiconductor industry from its earliest days have expressed an interest in the questions of where the technique came from as well as why and how it came about. Therefore, in the first part of my talk today I would like to relate the background of the spreading resistance technique as I know it. The second subject that came to mind is also in response to certain people that I've met over the years. These are the people who, when first exposed to the spreading resistance technique, rapidly developed a “hang-up” with respect to the mechanics of the contacts used. In an attempt to shed some light in this area, I will devote the second part of this morning's talk to what I know about the achievement of reproducible, known-geometry, metal-semiconductor, small-area pressure contacts. These contacts are what I have often referred to in past discussions as “conditioned” contacts.
The Physics of Spreading Resistance Measurements
Authors: Fonash Stephen J.
Published: August 2009

The spreading resistance method is uniquely suitable for the determination of electrical resistivities in a number of situations. However the technique does not simply measure the resistivity beneath the contacts. Considering the two probe configuration, what is actually measured is the ratio ΔV/I. Here ΔV is the difference between the Fermi levels of the probes necessary to maintain the sampling current I. This difference in the Fermi levels of the probes depends on the zero bias resistance of the probe - semiconductor contacts, the effective resistivity of the layers in a multilayer structure, and the configuration of the structure. The zero bias resistance depends on temperature and details of the metal-semiconductor contact including surface history. Effective resistivities enter into the measurement - and not the actual resistivities - because of the fact that the use of pressure probes creates a stress field under the contacts. This field falls off with a characteristic length of the order of the contact radius. Thus piezoresistivity effects - well known for Si - can be operative under the contacts. As a consequence of these various effects the interpretation of what ΔV/I is actually measuring is not straightforward. Practical application of the spreading resistance technique necessitates making certain simplifying assumptions. In light of the various phenomena involved in a spreading resistance measurement it is imperative that the implications of these assumptions to the accuracy of the measurement be understood.
On the Validity of Correction Factors applied to Spreading Resistance Measurements on Bevelled Structures
Authors: Pinchon P. M.
Published: August 2009

The correction factors in spreading resistance measurements are generally determined by using a plan-parallel model of a single or multi-layer structure. This paper will discuss the applicability of these factors to the profiling measurements on a bevel, and call attention to possible systematic errors which can appear in the case of an insulated layer or a low/high type of structure. After a short discussion on the spacial resolution of the spreading resistance probe, the case of a homogeneous isolated layer is examined in more detail. A simplified expression for the value of spreading resistance was calibrated against published data using fitting coefficients. It is then easy to show that the use of a correction derived for parallel structures is not correct for the case of a thin, isolated layer, when the measurement is made on a bevel. Indications are also given on the parameters which could minimise the problem The experimental part of this paper shows a series of profiles made with P-type epitaxial layers. After the application of the usual corrections, the various electrical boundaries or geometrical conditions are seen to affect the results in accordance with the discussion. An edge effect which is significant even at great distance from the edge, is also described. In the absence of a three dimensional theory for correction, the use of small spacing is recommended in conjunction with a small radius of contact and a shallow bevelling angle.
Spreading Resistance Correction Factors for (111) and (100) Surfaces
Authors: Murrmann H. , Sedlak F.
Published: August 2009

The effective contact radius for spreading resistance measurements on Si has been evaluated by comparision of S.R. for epitaxial layers limited by a pn-junction or by a well conducting buried layer for different crystal orientation. The contact radius on (100) surfaces showed to be greater by a factor of 1,26 than for a (111) plane. Furthermore measurements were made on samples for both (100) and (111) orientation in the resistivity range of 0,01 to 80 Ωcm with n and p-type doping. Data for spreading resistance and resulting from the predetermined contact radius for the resistivity dependent correction factor are given.
Comparison of the Spreading Resistance Probe with other Silicon Characterization Techniques
Authors: Schroen Walter H. , Lee Gregg A. , Voltmer Fred W.
Published: August 2009

Range and precision of doping concentration data in silicon materials gained by the spreading resistance technique are compared to values obtained by other characterization methods. They include junction and MOS capacitance-voltage techniques, mercury probe, four-point probe, incremental sheet resistance technique, ion microprobe, and optical methods. The comparison considers precision and resolution of each technique, range of silicon resistivities and layer thicknesses, experimental effort, analytical interpretation, and time and cost of data acquistion and evaluation. Examples are presented which demonstrate the range of applicability of each technique and how they can supplement each other so that they cover the total doping range of silicon devices.
A Direct Comparison of Spreading Resistance and MOS-CV Measurements of Radial Resistivity Inhomogeneities on PICTUREPHONE® Wafers
Authors: Edwards J. R. , Nigh H. E.
Published: August 2009

Small scale (∼ 50 µm) radial impurity concentration inhomogeneities in silicon wafers have been measured using both the MOS-CV method and the spreading resistance technique. The MOS-CV measurements were made using photolithographically defined 50 µm square capacitors placed on 75 µm centers and the spreading resistance measurements were made using a model 100 ASR probe on the same wafers after removal of the MOS capacitors. A direct comparison between these methods is presented for three specific types of ‹111› oriented silicon wafers with an impurity concentration range between 5 and 10 × 1014/cm3 In addition, a photograph showing the direct effect of radial resistivity variations on the dark field coring of a PICTUREPHONE® target is included.
Investigations on Local Oxygen Distribution in Silicon Single Crystals by Means of Spreading Resistance Technique
Authors: Vieweg-Gutberlet Fritz G.
Published: August 2009

By means of spreading resistance measurements subsequent to heat-treatments at approx. 450°C and 1100°C alternatively the local distribution of oxygen in the donor state in Silicon single crystals vas examined. Oxygen striations have not been found which is in correspondence to a distribution coefficient of ko = 1.25 ± 0.17 for oxygen in Silicon. The radial distribution of oxygen in the donor state is more or less uniform except for an edge area of about 1.5 mm where the oxygen content seems to be considerably lower. A very strong relationship between electrically activated oxygen (donor state) and swirls was found: in regions containing swirls a smaller amount of oxygen was activated to the donor state. This result fits De Kock's model describing swirls as consisting of vacancy-OXYGEN-clusters.
Effects of Oxygen and Gold on Silicon Power Devices
Authors: Assour Jacques
Published: August 2009

Several important features that make the two-probes spreading resistance technique a unique process control tool for designing and manufacturing silicon power devices are elucidated in terms of the effects of electrically active oxygen and gold centers on the characteristics of transistors, thyristors, and rectifiers. The effectiveness of the spreading resistance technique is compared to other commonly practiced techniques for the investigation of diffusion mechanisms of oxygen in homotaxial NPN transistors and of gold in fast switching rectifiers and thyristors.
The Experimental Investigation of Two-Point Spreading Resistance Correction Factors for Diffused Layers
Authors: Goldsmith N. , D'Aiello R. V. , Sunshine R. A.
Published: August 2009

Spreading resistance measurements have been made on a series of erfc and Gaussian phosphorus diffusions into n and p-type silicon. Conventional four point probe methods were used to obtain values of sheet resistance and surface concentration. Comparison between the two methods shows increasingly large disagreements as the diffusion depth is decreased. The Dickey formula for accounting for the presence of a junction is shown to work well for uniform (non-diffused) samples but to fail to correct fully and properly for diffusions less than 20 µm deep. Empiric curves for estimating errors on lapped surfaces used in this study are given for a wide variety of samples.
Improved Surface Preparation For Spreading Resistance Measurements on p-type Silicon
Authors: Ehrstein J. R.
Published: August 2009

The interpretation and the precision of spreading resistance measurements have been seen to be strongly dependent on specimen surface preparation. A bakeout at 150°C for 15 min. following specimen surface preparation with any aqueous polishing solution is considered here. It is shown both to improve the precision of the basic calibration curve for spreading resistance measurements and to significantly improve the correlation between resistivity values derived from spreading resistance measurements on a variety of specimens, and resistivity values derived from other measurement techniques. No bakeout appears to be necessary if specimen surface preparation is done with a non-aqueous polishing process.
Specular and Diffuse Reflectance Measurements of Aluminum Surfaces
Authors: Barkman E. F.
Published: August 2009

The appearance attributes of aluminum surfaces are measured using integrating sphere instruments commercially available. Total (TR) and diffuse reflectance (DR) values are obtained on the instrument. The specular reflectance (SR) is the difference: SR=TR−DR The term, “specularity” or “specular reflectance factor” (SRF), is calculated: SRF=100[SRTR] and is a numerical value of the visual “brightness” or mirror qualities of the surface. Examples of various appearance properties are given to illustrate the practical application of the method.
Notched-Bar Testing—Theory and Practice
Authors: Hoyt S. L.
Published: August 2009

This paper covers a few of the points thought to be especially significant in handling the practical phases of brittle fracture. When metallurgists and engineers were first confronted with the brittle fracture of steel, it was thought that impact must be the cause. But leading experimenters soon found this concept to be inadequate and, at the turn of the century, the notch was recognized in its true light and was introduced into formal tests of steel quality. At the same time, the energy absorbed in breaking the test bar was universally adopted as the measure of quality; this led to the simple device of breaking the test bar by means of a swinging pendulum. Doubtless due to the earlier notions, the test thus became commonly known as the “impact test” and so perpetuated the idea that brittle fracture was the result of impact. This was in spite of demonstrations to the contrary, such as the work of Considere, who found that increasing the strain rate simply raised the temperature at which brittle fracture occurred. Two other misconceptions impeded understanding of notch brittleness and delayed the general acceptance of notched-bar testing. First was the failure to fully recognize the rigidity or the stiffening effect, at the notch section, which is caused by the third dimensional stress. This is the stress, amplified by the stress concentration, which must exceed the cohesive or brittle strength for brittle fracture to result. Attention became centered on stress raisers, and the theory seems to have been that, since steel is ductile, a slight deformation at the root would relieve the stress, and that nothing more was important. An example which brings out the effect of rigidity is the failed forging, which while ductile with the single or standard-width test bar was brittle, with the same notch, when tested with the double-width bar. Another is the Navy Tear Test, which gives a much higher transition temperature than the Charpy keyhole test bar does with the same notch acuity. Another misconception has been that steels having the same tensile properties would all perform similarly in the presence of a notch. This was negated at an early date by a formal and authoritative series of tests conducted by the German Society for Testing Materials, the results of which were published in 1907. In more recent times, the fallacy of this assumption has been demonstrated many times.