bluuebunny/crossref_metadata_2025 huggingface dataset:
Feedback Flow and Permeation Systems for the Calibration of Very Low Gas Concentrations
Authors: Stedman DH , Kelly TJ , Shetter RE , Shetter JD , Cicerone RJ
Published: March 2009

The authors have developed two new absolute calibration techniques for low levels of atmospheric gases, using pure starting materials. The feedback flow system is a multistage dilution device with unreactive components, in which pure material is repetitively diluted with a single flow of zero gas, making available small flows of gas over the whole range from parts per trillion to percentages in one run. The permeation system is an extension of the work of Dietz et al, in which a sensitive low-cost system allows typical permeation rates to be measured in a few minutes.
Fire Research and Fire Safety: A Status Report on the Situation in the United States
Authors: Lyons JW
Published: March 2009

During the past century, efforts to control and reduce fire losses have concentrated successively on conflagrations destroying entire cities, large sections of cities, or large buildings, and, finally, on fires in the room of origin or in family residences. The first effort created effective fire departments, the second, the fire endurance concepts now an important part of the nation's building codes, and the third, now in full development, has produced research programs on interior finish, furnishings, and other consumer products. This current effort to protect occupants in the room of fire origin or in family residences is proving to be the most challenging and complex, technically and socially, of the three. These occupancies vary in materials used, configuration of the rooms, and placement of an infinite variety of movable contents.

To assess the level of fire safety, we must be able to compute or measure the time-temperature and time-gas concentration profiles at a number of points in the room. This requires, first, careful full-scale research and concommitant theoretical modeling. Second, it requires smaller, more economical tests which are correlated with the full-scale work. A series of such smaller tests will be necessary, including smoke and gas evolution, rate of heat release, and rate of fire spread over surfaces. Work on all of these is active now in many laboratories. The symposium will provide interesting progress reports on some aspects of these current efforts.
Ignition and Burning of Solids
Authors: Friedman R
Published: March 2009

This article reviews current knowledge of four stages of fire growth ignition, smoldering, flame spread, and burning of a fully ignited surface. Both cellulosic and thermoplastic combustibles are considered. In each case, the emphasis is that of the combustion scientist who seeks to identify controlling physicochemical mechanisms and ultimately to be able to make quantitative predictions of behavior based on understanding rather than empiricism. The present outlines of knowledge are traced, and problems particularly worthy of further research are identified. In view of the vastness of the subject, only a few highlights of the literature are discussed, 61 references are provided. Work in progress insofar as it is know to the author, is mentioned.
Development of a Room Fire Test
Authors: Benjamin IA
Published: March 2009

This paper has attempted to indicate the need for full-scale room and compartment tests at this time, indicating two possible uses of the compartment test (for approval, or for validating small-scale tests) and has discussed a few of the factors which affect the design of the tests, using the choice of ignition source as an example of the problems involved in the test design. Reference is made to the recommended practice developed by the task group of American Society for Testing and Materials Committee E-39.10.01.
Corona Discharge Processes in Voids
Authors: Bartnikas R
Published: March 2009

It has been well recognized in the past that one of the most common causes for insulation system failure occurs from void inclusions, which are usually introduced during the various manufacturing steps associated with the formation of the insulating materials themselves or the composite insulation systems used. For example, in the case of polyethylene cables, voids are generally introduced during the extrusion process. They may also occur due to the maintenance of a poor vacuum during the impregnation cycle as is often the case with epoxy cast instrument transformers or the oil-impregnated-paper insulating systems used in cables, capacitors, and transformers. Whether or not the presence of certain voids in a given insulation system can eventually lead to breakdown will depend primarily on whether or not the occluded voids undergo corona discharge under the operating voltage stress and on the intensity of the corona discharge process itself as well as on the degradation characteristics of the insulating materials involved. Obviously, voids, which do not discharge under the normal operating voltage conditions, are quite innocuous. In fact, discharge-free voids represent the near-ideal case of a loss-free dielectric.
Detection of Corona Discharges in Lumped Circuit Specimens
Authors: Starr WT
Published: March 2009

In tests carried out on lumped capacitance specimens, the assumption is made that the apparent corona pulse charge is given by the product of the capacitance of the specimen and the resultant change in voltage across the terminals of the specimen. It is the intent of this chapter to examine the factors that are involved in the precision of this relationship as well as the possible significance of the measured apparent charge with the prospective life of the lumped capacitance specimen. Recommendations are also to be made relative to the means available to improve the significance of the apparent charge measurements.
Corona Measurements Using Bridge Methods
Authors: Povey EH
Published: March 2009

Bridge methods are so important in the measurement art that it is not surprising to find them employed in the evaluation of corona or partial discharge activity. Bridges for this purpose must work at the high voltages at which discharge measurements are commonly made. In this chapter, consideration will be limited to bridges operating at high alternating voltages with frequencies in the power or audio range. Treated first is the evaluation of discharge activity from two bridge measurements, only one of which includes the discharge activity. Then a special bridge is described that uses an oscilloscope to produce a parallelogram-like trace from which more direct measurements of discharge activity may be obtained. The parallelogram trace technique has certain advantages in the sense that it may be effectively used to measure the energy loss due to pulse or pulseless type corona discharges. The measurement of the latter type of discharge can only be properly effected using the bridge approach. The term pulseless corona is commonly applied to the occurrence of true-glow and pseudo-glow discharges [I]. A conventional corona pulse detector fails to respond adequately to a true-glow discharge due to the absence of corona pulses within the glow region of the breakdown voltage wave (see Chapter 2); likewise, the pulse detector cannot respond to pulses whose rise times are unduly long such as produced by a pseudo-glow discharge. The concluding paragraphs deal with the use of the bridge method to facilitate measurement of pulses produced by corona or partial discharges.
Dynamic Strain-Aging and Neutron Irradiation in Mild Steel
Authors: Murty KL , Hall EO
Published: March 2009

“Blue brittle” or dynamic strain-aging studies were carried out on mild steel in vacuum-annealed, irradiated, and irradiated decarburized conditions. The effect of neutron damage is to decrease or eliminate the concentration of free interstitial impurity elements responsible for locking the dislocations. Progressively increasing the irradiation dose from ~ 1016 to ∼ 1019 nvt (> 1 MeV) resulted in a transition from “serrated” to “jerky” flow at and beyond ~ 1017 nvt. The activation energies for serrated and jerky flow were determined to be the same, ∼ 18 kcal/mol (75 kJ/mol), identifiable with the migration energy of carbon or nitrogen in iron. Thus neutron irradiation does not seem to affect the mechanism of dislocation locking.

Neutron irradiation was found to result in the following: (1) yield stress increases (hardening); (2) ductility decreases (embrittlement); (3) temperature of strainaging increases; (4) temperature region of unstable flow decreases; (5) degree of locking decreases; (6) Luders bands become relatively more diffuse; (7) the transition from serrated to jerky flow results in a complex temperature dependence of yield stress and Luders strain; (8) at temperatures below unstable flow, Luders strain increases and, at the highest doses (∼ 1019 nvt), fracture occurs during Luders extension; and (9) radiation hardening in mild steel is thermally activated.

There was no evidence of serrated flow in decarburized and irradiated decarburized material up to about 280°C (553 K). The effect of neutron damage was found to be similar to that of dry hydrogen treatment. In both cases a transition from serrated to jerky flow was observed. Both the appearance and disappearance of serrations were found to be dependent on the concentration of nitrogen in solution. These results imply that free nitrogen is primarily responsible for dynamic strain-aging in mild steel, both archive and irradiated.
Mechanical Properties of Fast Reactor Fuel Cladding for Transient Analysis
Authors: Hunter CW , Johnson GD
Published: March 2009

In order to determine mechanical behavior under various simulated reactor transient events, internally pressurized specimens of fast flux-irradiated 20 percent cold-worked Type 316 stainless steel fuel pin cladding were rapidly heated until they burst. Tests were conducted at heating rates of 10F°/s and 200°F/s with pressures of 2500 to 14 300 psi (17.2 to 98.6 MPa), resulting in failure temperatures from 1000 to 2000°F (811 to 1366 K). The specimens were taken from subassemblies irradiated in the Experimental Breeder Reactor-II at temperatures from 700 to 1300°F (644 to 978 K). Peak burnup and fluence levels ranged from 28 000 to 50 000 megawatt days per metric ton metal (MWd/MTM) and 2.5 to 4.0 × 1022 neutrons (n)/cm2 (E > 0.1 MeV), respectively.

Irradiation degraded both the failure strain and failure strength, when the transient test conditions resulted in intergranular fracture; intergranular fracture occurred above 1000 to 1200°F (811 to 922 K), depending on strain rate. Below these temperatures the fracture mode is transgranular, so that the failure strength is not reduced.

A correlation based on the ratio of irradiated material failure strain and failure strength was developed to describe the effects of irradiation on the mechanical properties of the cladding. The strain ratio correlation indicates that the failure strain does not further decrease beyond a fluence of 2 × 1022 n/cm2. The mechanical properties of cladding which had contained fuel during irradiation were degraded more than were the properties of unfueled material.
Neutron Energy Dependent Damage Functions for Tensile Properties of 20 Percent Cold-Worked Type 316 Stainless Steel
Authors: Simons RL
Published: March 2009

Material property measurements from test reactor irradiations cannot always be applied directly to design reactor irradiation conditions because of differences in neutron spectra. A semi-empirical damage function can be derived from the test reactor data for a particular property to describe the damage effectiveness of neutrons as a function of their energies. Such functions have been derived for strength and ductility parameters of 20 percent cold-worked Type 316 stainless steel for irradiation temperatures of 393, 493, and 593°C (740, 920, and 1100°F). Both fast and thermal reactor data were used in the analysis. Quantitative conclusions from this analysis were limited by the lack of data; however, damage functions for tensile properties of 20 percent cold-worked Type 316 stainless steel irradiated at 393 and 493°C (740 and 920°F) appear to be consistent with the displacement cross section for stainless steel. At 593 °C (1100°F) the ductility damage functions show substantial deviation from the displacement cross shape when both fast and thermal reactors are included in the analysis. The latter damage functions were found to be consistent with the correlation of ductility with the square root of the product of displacements and helium concentration. Examples of application to fast reactors and fusion reactors are given.
Swelling Behavior of Commercial Ferritic Alloys, EM-12 and HT-9, as Assessed by Heavy Ion Bombardment
Authors: Smidt FA , Malmberg PR , Sprague JA , Westmoreland JE
Published: March 2009

Ferritic alloys have some promise for duct and cladding applications for liquid metal fast breeder reactors (LMFBR) because of their favorable neutron absorption cross sections. Two alloys of the 10 to 12 percent chromium class, EM-12 and HT-9, have been selected for study in the National Alloy Development Program. Bombardment with 2.8 MeV 56Fe+ ions and transmission electron microscopy (TEM) observations were used to determine the temperature dependence of swelling at 150 displacements per atom (dpa) and the swelling rate at the peak swelling temperature up to 250 dpa. Both alloys were found to be more swelling resistant than Type 316 stainless steel, with EM-12 having a swelling rate of 0.011 percent/dpa at the peak swelling temperature of 550°C (1022°F) while HT-9 had a swelling rate of 0.017 percent/dpa at the peak swelling temperature of 500°C (932°F). An unusual feature of swelling in these materials was the formation of very large voids on precipitates along the grain boundaries.
Microstructure and Mechanisms of Ion-Simulated Irradiation-Induced Creep of Nickel
Authors: Michel DJ , Hendrick PL , Pieper AG
Published: March 2009

The microstructure of cold-worked, high-purity nickel has been investigated following ion-simulated irradiation-induced creep with 22-MeV deuterons and 70-MeV α-particles. The irradiations were conducted at 224°C (435°F), at stresses between 170 and 345 MPa, and at displacement rates between 13 and 30 × 10-8 displacements per atom per second (dpa/s). Transmission electron microscopy (TEM) procedures were used to prepare, observe, and photograph the microstructure of the ion-irradiated uniaxial creep specimens and companion unirradiated specimens. Examination of the ion-irradiated microstructure revealed no substantial differences between the deuteron and α-particle irradiated specimens. In all cases, a heterogeneous distribution of defect clusters or small dislocation loops and network dislocations, or both, were observed. A significant reduction in dislocation density from the unirradiated values was seen for the irradiated specimens. It was found that the small loops and defect clusters provided effective obstacles to dislocation motion as evidenced by the bowing of dislocations between adjacent defects.

The microstructural results were evaluated in terms of the theoretical mechanisms proposed for irradiation-induced creep and the previously reported creep simulation results for nickel by Hendrick et al. A model based on the climb-controlled glide of dislocations over dispersed obstacles was found to be consistent with the microstructural results and the experimental creep data.
Effect of Ion Irradiation on the Microstructure of an Iron-Nickel-Chromium Alloy
Authors: Sprague JA , Smidt FA , Westmoreland JE , Malmberg PR
Published: March 2009

Void and dislocation structures in an Fe-25Ni-15Cr alloy were studied following irradiation with 2.8 MeV58Ni+ ions at temperatures between 600 and 750°C (1112 and 1382°F) to maximum damage levels up to 80 displacements per atom (dpa). Void formation was observed at all the temperatures investigated, with the maximum swelling between 650 and 700 °C (1202 and 1292°F). The swelling versus dose relationships exhibited an incubation dose followed by swelling at a rate that increased with increasing damage level. These data were consistent with previous swelling results for austenitic alloys irradiated with charged particles, which indicate that the swelling should become linear with irradiation dose at higher damage levels. Tangled dislocation networks were observed to form at low doses and to be fairly stable up to the highest damage levels examined. With the assumption of the observed stable dislocation networks, the dose dependence of swelling could be explained by a general form of the chemical rate theory for swelling due to void growth.
Microstructural Changes in Ion-Irradiated Commercial Alloys
Authors: Bell WL , Lauritzen T , Darlin ES , Warner RW
Published: March 2009

The effect of heavy ion bombardment on the microstructural stability of several high-nickel superalloys was evaluated by transmission electron microscopy techniques. The work was intended to simulate the type and magnitude of radiation damage occurring with high-fluence exposure in a liquid metal fast breeder reactor (LMFBR) core.

Results revealed a general acceleration in precipitation kinetics in alloys with high titanium-to-aluminum ratios, over the temperature range 475 to 725 °C (887 to 1337°F). In the Inconel alloys 706 and 718, for example, bombardment produced the stable overaging precipitate η Ni3Ti at the expense of the preexisting phases γ', γ", and δ. Thermal control data over the same temperature range did not reveal the presence of η. Little or no changes in precipitate microstructure were observed in Nimonic PE16, an age-hardenable alloy with a titanium/aluminum ratio of unity.
Fracture Mechanics Characterization of the Trino Reactor Vessel Material
Authors: Mager TR , Davidson J , Galliani M
Published: March 2009

During preirradiation testing it became known that the Trino reactor vessel material exhibited a Charpy-V upper-shelf impact energy level of approximately 36 ft∙lb in a direction transverse to the plate rolling direction. Current U.S. practice is to require 75 ft∙lb impact energy for materials in the beltline region of the reactor vessel. It was proposed that fracture toughness properties be obtained on Trino reactor vessel Plate W6306-1 in terms of both fracture mechanics parameters and conventional Charpy-V impact energy. Concurrent with preirradiation testing of Plate W6306-1 an accelerated irradiation program was initiated in a test reactor.

To generate the fracture toughness data, compact tension specimens were tested both statically (KIc) and dynamically (Kid). The encapsulated specimens were irradiated at 550°F (288°C to a fluence of 3 × 1019 neutrons (n)/cm2 (E > 1 MeV).

The fracture toughness data obtained from the preirradiation testing indicated that Plate W6306-1 meets the intent of the ASME Appendix G, KIR curve. Postirradiation fracture toughness data (static and dynamic) from the accelerated radiation program indicated that the fracture toughness for transverse specimens was approximately 100 ksi (in.)½. The upper-shelf impact energy of the Trino vessel Plate W6306-1 decreased a maximum of 7 ft∙lb during the accelerated irradiation.

Based on the fracture toughness properties obtained during the evaluation, it was concluded that Plate W6306-1 exhibited adequate toughness to provide for continued safe operation of the Trino Vercellese Nuclear Power Plant.
Annealing of Irradiation Damage in High-Copper Ferritic Steels
Authors: Spitznagel JA , Shogan RP , Phillips JH
Published: March 2009

The postirradiation annealing response of one SA 302 Grade B plate material and two high-copper weld metals irradiated at 550 °F (288°C) was measured for annealing temperatures in the range 600°F (316°C) to 850 °F (454°C) and annealing times up to 1 week (168 h). Recovery of pre-irradiation microhardness was followed for all three steels. In addition, recovery of ductile-brittle transition temperature (DBTT) was measured for the SA 302 Grade B material. Optical and transmission electron microscopy (TEM) were utilized to characterize the microstructures of the irradiated and annealed SA 302 Grade B plate material. Small fracture specimens of all three steels were broken in an Auger spectrometer. Auger analyses were performed on the fracture surfaces, which were subsequently characterized with scanning electron microscopy (SEM). Microhardness measurements indicated that the weld metal with the highest copper content (0.31 weight percent) and lowest fluence (5.7 × 1018 neutrons (n)/cm2) was the most resistant to softening under postirradiation annealing. The recovery of ductility as measured by the DBTT shift of the SA 302 Grade B material paralleled the recovery as measured by microhardness. All three steels showed increased recovery with higher annealing temperatures and longer annealing times. No visible microstructural changes accompanied irradiation or annealing. Some evidence for a 5 to 10 percent increase in copper concentration at the fracture surfaces of irradiated specimens was obtained. No significant segregation of any element to the fracture surfaces, however, was observed to result from irradiation or postirradiation annealing. The measured annealing response of these steels agreed well with the values predicted by a previously developed theoretical model based on the dissolution of copper-vacancy aggregates.
Computer-Aided Structural Analysis and Design of Concrete Pipe
Authors: Wenzel TH , Parmelee RA
Published: March 2009

This paper describes the development of a finite-element computer program to simulate the structural behavior of a buried concrete pipe. The influence of the soil-structure interaction phenomenon is approximated by using appropriate material properties for the bedding and backfill, and by employing empirical hinging mechanisms which enable simulation of the progressive cracking behavior in the model of the concrete pipe. A second approximation, in which the pipe is represented as a linear frame, is introduced for the calculation of internal stress resultants. Various iteration techniques are employed to ensure deformation compatibility between the two pipe models. The results from full-scale experimentation are then used to validate the analytical models.

This model of the soil-pipe system was combined with appropriate serviceability and ultimate strength design criteria for reinforced concrete pipe to produce a comprehensive computer program for the design of buried concrete pipe. The resulting program, entitled NUPIPE, accounts for nonlinear soil-structure interaction, and permits the engineer to obtain the structural design of a given size pipe having a specified fill height and installed in any manner (that is, arbitrary bedding or backfill procedures or both).

The applicability of the new design method is demonstrated by designing various installations. The required steel areas for these installations are compared with those obtained by use of the current design method, and the differences are discussed.
Use of Laboratory Failure Simulation Exemplars to Study Intergranular Fracture Modes in 9Ni-4Co-0.20C Steel
Authors: Young JD , Kumar A
Published: March 2009

During structural spectrum load testing of the aft-fuselage structure of the B-1 aircraft, a 124-mm-long crack was detected in the 9Ni-4Co-0.20C steel primary structure. Review of the fracture location revealed that the crack path was adjunct to a production weld used in the fabrication of the 727-kg (1600-1b) forged and welded horizontal-vertical stabilizer support assembly. Upon removal and examination of the fracture on a scanning electron microscope, two distinct fracture modes were observed: (a) at the origin, a 0.5 to 1-mm intergranular fracture mode was observed, followed by (b) 123 mm of transgranular high-stress low-cycle fatigue crack propagation.

Fatigue crack growth rate analysis on the scanning electron microscope showed that the fatigue crack started propagation at the onset of testing, strongly suggesting a pre-existing crack which was corroborated by the observation of an intergranular fracture mode at the origin, which exhibited no evidence of cyclic growth.

A laboratory failure exemplar study program was conducted to establish standards for intergranular fracture mechanisms possible in 9Ni-4Co-0.20C steel, fabricated using the same environmental conditions as present during manufacturing. The salient features of the fractographs of known failure mechanisms were used to establish the cause of service failure intergranular cracking to be hydrogen embrittlement.
Case Histories Illustrating Fractographic Analysis Techniques
Authors: Meyn DA
Published: March 2009

The Naval Research Laboratory receives cracked and fractured parts ranging from the exotic to the mundane: for example, titanium alloy jet engine components, ultrahigh strength steel landing gear parts, aluminum alloy airframe sections, and galvanized mild steel radio antenna support frames. Failure analysis involving so many materials over such a wide range of applications demands great adaptability in the use of fractographic techniques. The use of all techniques from the unaided eye through low-power magnifiers to high-powered light microscopes and transmission and scanning microscopes, will be discussed, using actual case histories for illustration. The application of surface chemical analysis to failure analysis also will be mentioned.
Fractographic Observation of Stress-Corrosion Cracking of AISI 304 Stainless Steel in Boiling 42 Percent Magnesium-Chloride Solution
Authors: Mukai Y , Watanabe M , Murata M
Published: March 2009

The fracture surface of AISI 304 stainless steel in stress corrosion cracking (SCC) in boiling 42 percent magnesium-chloride (MgCl2) solution was investigated fractographically by scanning electron microscopy. To determine the orientation of fracture surface, etch pits were formed on fracture surface by the electroetching method in 1 N sulfuric acid (H2SO4) + 100 mg/litre ammonium thiocyanate (NH4SCN) solution. It was made clear from morphology of etch pit that fracture surface in SCC was almost everywhere on the {100} plane, namely, the path of the crack was determined by crystal orientation and direction of stress. In addition, a striation-like pattern was often found by careful observation on the flat surface.
Use of Microfractography in the Study of Fatigue Crack Propagation under Spectrum Loading
Authors: Abelkis PR
Published: March 2009

Use of electron microscope fractography in the study of fatigue crack propagation under spectrum loadings is based on the evaluation of 7075-T651 aluminum alloy specimens from an experimental program. Microscopically established crack propagation data by striation spacing measurements are shown to provide cycle-to-cycle evidence of crack propagation behavior under spectrum loading that normally cannot be established under macroscopic observation. Crack propagation rate retardation and acceleration is illustrated through fractographic striation measurements. Contribution and interaction of various loads of a transport wing loads spectrum are illustrated fractographically from the test program.
Role of Interface Chemistry in Failure of Materials
Authors: Joshi A
Published: March 2009

Properties of many materials are influenced strongly by small compositional changes that occur at interfaces such as phase and grain boundaries. Knowledge of the elements involved and whether they are segregated or present in a second phase provides a better understanding of the failure mechanism. In many instances of grain boundary failures, the chemistry provides the most comprehensive and useful information. Examples of such studies discussed here include temper embrittlement and other forms of impurity-induced low temperature embrittlement, weld-metal embrittlement, grain boundary corrosion, and intergranular stress corrosion cracking. Failures at phase boundaries and other more macroscopic interfaces such as encountered in fiber/metal matrix composites, interparticle interfaces in powder metallurgy materials and bonded (thermal compression, solder, or diffusion bonded) interfaces also can be understood by close examination of chemistry of these interfaces.

In many of these examples, the zone of segregation at boundaries is very small, only a few angstroms, the same as the boundary width. The interface chemistry has been studied successfully in a scanning Auger microprobe by Auger electron spectroscopic analysis of grain boundary fracture surfaces obtained inside the vacuum system.
Effects of Shot-Peening Residual Stresses on the Fracture and Crack-Growth Properties of D6AC Steel
Authors: Elber W
Published: March 2009

The fracture strength and cyclic crack-growth properties of surface-flawed, shot-peened D6AC steel plate were investigated. For short crack lengths (up to 1.5 mm) simple linear elastic fracture mechanics—based only on applied loading—did not predict the fracture strengths. Also, Paris' Law for cyclic crack growth did not correlate the crack-growth behavior. To investigate the effect of shot-peening, additional fracture and crack-growth tests were performed on material which was precompressed to remove the residual stresses left by the shot-peening. Both tests and analysis show that the shot-peening residual stresses influence the fracture and crack-growth properties of the material. This report presents the analytical method of compensating for residual stresses and the fracture and cyclic crack-growth test results and predictions.
More on Specimen Size Effects in Fracture Toughness Testing
Authors: Kaufman JG , Nelson FG
Published: March 2009

A new study of the effect of specimen size on the results of plane-strain fracture toughness tests of a relatively tough aluminum alloy, 2219-T851, suggests that an increase in specimen size requirements may be necessary to assure size-independent test results. Specifically, it appears that the crack length limit should be increased to 5(KIc/σYS)2, which has the effect of keeping the maximum nominal net-section stress below two thirds of the yield strength. The current limit on thickness could be maintained at 2.5 (KIc/σYS)2, although there is some evidence that it might be relaxed further. Additional work is needed to check the generality of these suggestions for other materials, as well as the possibility that if W/B=2 and a=B ⋝ 5(KIc/σYS)2, Kmax, may be useful as an engineering estimate of KIc.
Dynamic Compact Tension Testing for Fracture Toughness
Authors: Paris PC , Bucci RJ , Loushin LL
Published: March 2009

Within this paper it is demonstrated that dynamic fracture toughness evaluation may be made by adherence to the ASTM Test for Plane-Strain Fracture Toughness of Metallic Materials (E 399-72) procedure with the single exception of test speed. The test procedure, specimen, fixturing, and instrumentation are otherwise identical to ASTM E 399-72. This makes possible direct comparisons of static, KIc values with the results of these dynamic tests.

The additional equipment required for these tests, over the normal servocontrolled hydraulic test machine typically used for KIc testing, is only the provision of a high flow and high response servo-valve with hydraulic accumulators and the capability of dynamic data storage (digital) for convenient playback into the usual X-Y recording unit.

Employing the test technique developed, dynamic fracture toughness evaluation was demonstrated on two steel alloys (302 B and A516-70) tested at room and -50° F temperatures.
Further Aspects of Fracture Resistance Measurement on Thin Sheet Material: Yield Stress and Crack Length
Authors: Sullivan AM , Stoop J
Published: March 2009

The fracture resistance value, Kc, has been determined for a number of alloys of aluminum, titanium, and steel and found to depend inversely upon the material yield stress. During this investigation various initial crack lengths, 2ao, were employed.

Analysis of the data has disclosed that the amount of crack extension, that is, final crack length, 2ac, appears to be influenced by the initial crack length. Plotted on a log-log scale of (ao/ac) versus β=[1B(cKybσ)2], statistical analysis justifies a relationship conforming to the equation ln⁡10(ao/ac)=A-Bln⁡10β which can be transformed to (aoac)=AβB

The development of these relationships can be of real assistance in the design of a standard initial screening test for Kc.
Further Studies of Crack Propagation Using the Controlled Crack Propagation Approach
Authors: Weitzmann RH , Finnie I
Published: March 2009

In a previous paper, a new fracture-toughness-measuring technique was presented which made it possible to evaluate the functional relationship between load and cracklength at the moment of crack initiation or arrest. It was demonstrated that this relationship is directly relatable to the strain energy release rate and experimental results were presented for a 7075-T6 aluminum alloy.

This paper presents the results of additional exploratory work as the concept is applied to more 7075-T6 aluminum, a 250 grade maraging steel, and AZ31B magnesium plate.
Double Torsion Technique as a Universal Fracture Toughness Test Method
Authors: Outwater JO , Murphy MC , Kumble RG , Berry JT
Published: March 2009

A method of measuring the fracture toughness of materials is described that is both simple and universal. A specimen is failed in double torsion so that a crack is driven down the center of a rectangular specimen. The energetics of failure are such that the load causing the crack remains constant as the crack deepens and this load is directly related to the fracture toughness. This enables a simple specimen to be used and obviates the difficulties associated with crack depth or compliance measurements or both. Results are shown for aluminum alloys to supplement earlier work on glass and polymers.
Measurement of KIc on Small Specimens Using Critical Crack Tip Opening Displacement
Authors: Robinson JN , Tetelman AS
Published: March 2009

A method is described whereby on-load values of crack tip crack opening displacement (COD) can be measured at the midsection of precracked three-point bend specimens by infiltration of silicone rubber. A calibration curve relating midsection COD to clip gage displacement was derived from measurements on the silicone rubber “castings.” This calibration curve can be used to calculate midsection COD from on-load clip gage displacement and specimen geometry only, without further infiltration measurements. These values of COD have been shown to be simply related to the stress intensity factor, independent of material, as theoretically predicted.

The central region of a Charpy specimen in three-point bend has been found to remain in plane strain until well after general yield. Thus, plane strain values of COD at fracture initiation, (COD)c, can be determined from small specimens. Two initiation detection methods are described whereby (COD)c can be determined. These values of (COD)c can be used to accurately predict KIc values which agree with data obtained on larger, more expensive valid ASTM KIc specimens.
Erosive Wear Testing
Authors: Hammitt FG
Published: March 2009

Fluid-induced erosion, single and multiphase flow induced, is considered according to the various phenomena involved. The basic damage mechanisms are considered and described. The various types of erosion testing devices are described and compared.
Wear Debris as an Indicator of Valid Simulation in Wear Tests
Authors: Ludema KC
Published: March 2009

Wear testing is often unreliable because wear is a complex process. There are several wear modes for each material, and often a small change in operating condition produces a drastic change in wear rate. Uncertainty in developing wear tests may be reduced by examination of wear debris from both the wear tester and the full scale machine being simulated. If the debris from both are similar, the wear test is worthy of further use.
Locus of Failure and Its Implications for Adhesion Measurements
Authors: Good RJ
Published: March 2009

The extreme importance of correctly establishing the locus of separation in an adhering system, such as a film on a solid, is pointed out. Two theories as to the level of possibility that true interfacial separation will occur are described and both are criticized. A logically rigorous formulation which draws upon both these theories is given.
Problems in Adhesion Measurement
Authors: Bikerman JJ
Published: March 2009

Clinging of preformed films to other solids can be measured unequivocally, and the two most common causes of it are outlined. The real adhesion of films, applied as a liquid and then solidifed on the substrate, cannot be measured because mechanical separation of the film from the substrate exactly along their interface is almost impossible. Recent confirmations of this impossibility are reviewed. In the tests intended for measuring this adhesion, very often the tensile strength of the film material is determined, albeit in an indirect manner. In many other systems, the experimental breaking stress depends on a layer spread along the above interface. The use of the term adhesion for the strength of coatings is not advisable.
Experimental Methods to Determine Locus of Failure and Bond Failure Mechanism in Adhesive Joints and Coating-Substrate Combinations
Authors: Baun WL
Published: March 2009

The strength of an adhesive bond is assessed by means of several physical tests in which a load is placed on the joint until failure occurs. The durability of adhesive joints is evaluated by still other techniques where the bond is tested, usually under load, in salt spray, high humidity and temperature, or other environments deleterious to the bond. Regardless of the strength of the joint, a complete description of joint performance must include how and where the bond failed.

Ion scattering spectrometry (ISS) and secondary ion mass spectrometry (SIMS) combined with scanning electron microscopy (SEM) are capable of determining the true locus of failure in an apparent interfacial bond separation. Methods using an electron beam, such as Auger electron spectroscopy (AES), are useful for analyzing evaporated metal films and the metal or alloy surface in adhesive bonds but are of limited use for examining the adhesive side of a failure, because of heating, which rapidly destroys the specimen surface. X-ray photoelectron spectroscopy (XPS), sometimes called electron spectroscopy for chemical analysis (ESCA), provides not only elemental analysis but also gives information on how the elements are combined in the adhesive, adherend, and interfacial regions. Results using these and other techniques are discussed for failure surfaces obtained by lap shear, peel test, and wedge test methods. Advantages and limitations of various methods are discussed.
Adhesion of Thin Plasma Polymer Films to Plastics
Authors: Crane LW , Hamermesh CL
Published: March 2009

To date, no comprehensive study of the adhesion of plasma-polymerized films on plastics has been made. In the present work, 1400-Å films produced by the radio frequency discharge plasma polymerization of styrene and acrylonitrile were deposited on polyethylene, polystyrene, polypropylene, poly(ethyleneterephthalate) (Mylar), polytetrafluoroethylene (Teflon), polycarbonate (Lexan), polyimide (Kapton), poly(methyl methacrylate) (Lucite), polyamide (Nylon 6), poly(oxymethylene) (Delrin), and poly(vinyl fluoride) (Tedlar) substrates. Adherence of these films was then measured by applying a ½ by 2 in. (1.27 by 5 cm) piece of Scotch No. 810 tape to the film and then removing the tape in a 90-deg peel. This provides a lower limit of 190 g/in. for the adhesion of the polymer film to the substrate. It was found that both plasma polystyrene and plasma polyacrylonitrile were removed by this procedure from poly(oxymethylene), polypropylene, poly(methyl methacrylate), and polycarbonate. Both films remained adhered to the other seven plastics during this test. These results can be explained on the basis of molecular structure and can be correlated with literature data on bond strength results for activated gas-treated substrates. It was also concluded, considering the divergent properties of the two plasma polymers, that adhesion to any substrate is not dependent on the structure of the plasma polymer. Soaking films of plasma-deposited polyacrylonitrile on Mylar in solvents of varying polarity for long periods of time did not reduce the adhesion of the film to the substrate. It would seem that the film-substrate bond is either a physical one of a very high order or more likely a true chemical bond.
Threshold Adhesion Failure: An Approach to Aluminum Thin-Film Adhesion Measurement Using the Stylus Method
Authors: Oroshnik J , Croll WK
Published: March 2009

A detailed study of the scratch test was undertaken to determine its sensitivity, reproducibility, and soundness as a means of measuring the adhesion of aluminum films on fused quartz substrates. The complete-removal failure criterion was found to be quite subjective and often ambiguous, finally leading to the threshold adhesion failure (TAF) concept. Using the TAF approach, it was found that the scratch test is sensitive enough to discriminate between failure and nonfailure within 0.1 g of stylus loading at both low- and high-load levels. Also, the reproducibility of the mean TAF loads is excellent. In addition to the expected TAF load dependence on stylus tip radius of curvature and film thickness, it was also found that any one stylus has its own scribing characteristics which are reflected in the TAF load. The mean TAF loads are, therefore, relative measurements.

The occurrence of crescent fractures in the substrate at high-stylus loads puts an upper bound on acceptable testing loads. TAF loads are almost always well below the crescent fracture load level, but critical loads determined by the complete removal criterion (being so much higher) may have doubtful meaningfulness.

It appears that the TAF approach is measuring the lower limits, while the critical load approach is measuring the upper limits of film adherence. In either case, one obtains an estimate of the quality of film adherence, but not an unequivocal measurement of the adhesive forces.
Adhesion of Thick Films to Ceramic and Its Measurement by Both Destructive and Nondestructive Means
Authors: Morey RL
Published: March 2009

Techniques for the measurement of adhesion of thick films to alumina have been evaluated. One method is to solder a connection into a thick film pad and measure strength using a force gage. By this method it is not possible to differentiate between inherent adhesion problems and soldering effects. Another method is to use a wire peel test, but it requires optimized procedures or the effects of soldering can mask the adhesion characteristics. Metallurgical sectioning with use of a scanning electron microscope (SEM) and energy dispersive X-ray (EDAX) attachment is an invaluable aid for examining the interface and determining the characteristics of glass and metal components. Bondability tests are also a means of evaluating adhesion but are affected by bonding technique and wire size. Standardized methods are needed for adhesion measurements which, coupled with a comprehensive quality-assurance procedure, can give full process control.
Evaluation of Methods for Performing Adhesion Measurements of Thick-Film Terminations on Chip Components
Authors: Ewell GJ
Published: March 2009

The nailhead lead tension test is shown to be a very useful method of measuring the adhesion strength of thick film, solderable end terminations on chip resistors, and multilayer monolithic ceramic capacitors. Alternative test concepts are considered and detailed comparisons are presented. Specimen preparation and test parameters are defined, and the effects of variation in termination configuration are illustrated. It was found that attachment parameters must be well defined and followed so as not to introduce other variables in measured strengths. The test criteria defined in this paper can be applied to other specific devices, but limits for their use must be individually established. The data provide application limits for some commonly used chip components.
Adherence Measurements and Evaluation of Thick-Film Platinum-Gold
Authors: Schroter S
Published: March 2009

The fabrication of thick-film hybrid circuits using the solder system consists of screen printing conductor and resistor networks on alumina substrates and attaching other circuit elements (capacitors, discrete semiconductors etc.) to the conductor using tin-lead solder. The difficulty encountered with this technique has been that, although components are rigidly attached at the time of assembly, deterioration of the solder bonds occurs.

The objective of the investigation was to develop a suitable test method for testing incoming materials, optimizing process variables, and in-process quality control of the product.

After review of methods of conductor adherence testing, a method, pull-peel at 90 deg, was chosen which represented the worst case in actual module application. In order to hold the variables to a minimum, one standard test module was chosen for all experimental work. Part of this test module was incorporated into the design of production modules so that quality control of the product could be directly correlated with the initial testing results and with any process variables. Tests were conducted under controlled conditions which optimized all the assembly steps. Four areas have been found to have marked influence on conductor adhesion: the initial thickness of screened material, the preparation of substrate before soldering, the amount of solder used to make a joint, and the rate of cooling of the soldered joint. Implementing these controls results in a product with improved conductor adhesion.
Methods for Evaluating Adhesion of Photoresist Materials to Semiconductor Devices
Authors: Deckert CA
Published: March 2009

A technique has been developed for making comparative evaluations of the adhesion of photoresists to various types of substrates. The technique is based on the use of a fluoride-containing etchant which exaggerates the rate of undercutting of photoresist on silicon dioxide (SiO2) surfaces and thus permits direct microscopic measurement of the relative rates of undercutting that result with various types of SiO2 surfaces and with various types of photoresist materials. Using the special etchant, the benefits of adhesion promoters such as hexamethyldisilazane are readily demonstrated. An empirical equation is given which approximately describes the shape of the undercut oxide edges, thus allowing a numerical measure of the relative adhesion (that is, resistance to etchant undercutting) of photoresist/SiO2 composites.

A variation of this test can be used to detect nonuniform adhesion across a wafer surface. A photomask with a very-fine-geometry, highly recurrent pattern is used to define the photoresist, after which the wafer is etched. By using an optical microscope, the resultant dielectric/silicon substrate can be inspected very rapidly for localized adhesion variation because of the distinct color difference between areas which have or have not been undercut.
Measuring the Temperature Dependence of the Strength of Metal-Polymer Joints
Authors: Egorenkov NI , Belyi VA
Published: March 2009

The method of measuring the temperature dependence of adhesion characterized by peel strength, which is based on the application of the temperature gradient in the plane of adhesive contact, is discussed. The foil is peeled in the direction of the temperature gradient. In this case the adhesiogram is the temperature dependence of peel strength. The method determines in a simple way the dependence of the strength of adhesive metal-polymer joints on the test temperature for a wide temperature range. The gradient method has been employed to study the effect of the test temperature (250 to 390 K) on the adhesion of amorphous and crystalline polymers to aluminum. The temperature dependence of adhesion in the case of amorphous polymers to the metal is described by a curve with the maximum at 15 to 35 K higher than the polymer glass transition temperature. The strength of adhesion in the case of crystalline polymers is lower than that of amorphous ones, and decreases with increasing test temperature.