bluuebunny/crossref_metadata_2025_split huggingface dataset:
X-Ray Diffraction and TEM Studies of the Delamination of Copper Thin Films from Glass and Silica Substrates
Authors: Fox Alan G. , Cannon Rowland M. 
Published: March 2011

AbstractThe events associated with fractures along interfaces between copper thin films and glass substrates were investigated by X-ray diffraction and transmission electron microscopy (TEM). In the as-bonded films the Bragg diffraction lines were shifted and broadened (relative to pure strain-free copper) due to residual in-plane tensile strains arising from the differences in thermal contraction between the copper and the substrates; TEM studies of these films in cross-section showed that the residual stresses had been relieved somewhat by dislocation densities as high as 1010 lines/cm2 in Cu/SiO2 films.The passage of a crack along the Cu/glass interfaces led to a significant reduction in the line shift and a slight reduction in the line broadening. Thus dislocations generated by the fracture events ‘plastically relaxed’ the residual stresses present in the as-bonded Cu by superposing a compressive component onto the pre-existing in-plane tensile strains. This dislocation generation was confirmed by TEM studies. In addition, it was found that the greater the strength of an interface, the greater was the reduction in mean strain due to the fracture; this is consistent with a larger crack-tip plastic zone and the generation of greater numbers of dislocations in the Cu films by fracture along interfaces of higher toughness (i.e. bond strength).
Oxidation of PB-SN and PB-SN-in Alloys: Bulk VS. Grain boundary regions
Authors: Sluzewski D. A. , Chang Y. A. , Marcotte V. C. 
Published: March 2011

AbstractAir oxidized Pb-Sn and Pb-Sn-In single phase alloys have been studied with scanning Auger microscopy. Line scans across grain boundaries combined with argon ion sputter etching revealed grain boundary oxidation. In the Pb-Sn samples, tin is preferentially oxidized with the grain boundary regions having a much higher percentage of tin oxide than the bulk surface oxide. In the Pb-Sn-In alloys, both tin and indium are preferentially oxidized with the grain boundary regions being enriched with tin and indium oxides.
Organic Die Coat Materials for Plastic Packages
Authors: Padmanabhan R. 
Published: March 2011

AbstractThe role of organic materials in electronic packages is constantly being expanded. A fairly recent application is the use of these materials for encapsulating high lead count IC dice, like TAB chips that are bonded directly to the board or housed in plastic packages. Since these packages are non-hermetic, some special constraints are placed in the selection of these die coat materials. Reliability issues that have to be addressed include compatibility with the underlying dielectric medium, chemical resistance, low moisture absorption, corrosion protection and resistance to thermal stresses. This paper discusses some of these concerns and reviews the suitability of different categories of die coat materials for this application.
Leaching Characteristics of Fly Ash after Four Years of Natural Weathering
Authors: Andrade A. , Coenegracht Y. M. A , Hollman G. G. , Janssen-Jurkovicova M. , Pietersen H. S. , Vriend S. P. , Schuiling R. D. 
Published: March 2011

AbstractThe natural weathering process of fly ashes was studied in artificial fly ash beds. The ashes were previously classified according to their total alkali content into acid, neutral and alkaline. After 4 years the effects of weathering are minor. The formation of concretions due to local cementation by calcite is observed in alkaline fly ash. Small brown pellets, highly enriched in some heavy metals, are present in the acid fly ash beds. Under natural conditions leaching is mainly confined to the alkaline fly ash. Elements which are leached most are sulphur and some alkalis as well as minor amounts of some trace elements.Shake- and column experiments of the weathered fly ashes with acids of pH 1 and 4, the latter also in combination with complexing agents, were carried out in order to check if the natural leaching process may be accelerated artificially. Strong acids (pH= 1) were most effective, but relatively large quantities of major elements were also leached. Experiments with the weak acids, combined with complexing agents, resulted in leaching percentages which did not significantly differ from experiments without these agents. This indicates that a major part of the elements are present in an immobile form; because of the use of sulphuric acid, it is likely that they are in some cases precipitated as sulphates (e.g. barium, calcium).
The Practitioners View of Fly Ash Utilisation
Authors: Mills Ronald H. 
Published: March 2011

AbstractPartial substitution of Portland cement (PC) with fly ash (FA) offers the practitioner expanded scope for optimal utilisation of materials. This method requires careful evaluation of the resulting blended cement beyond the basic age-strength relationship. For the construction practitioner, workability, rate of strength gain, and inherent variability are major factors in meeting strength requirements and determining costs. A blend may be characterised by a mass efficiency factor which is the mass ratio of PC to FAwhich will yield the same target strength at fixed maturity and workability. Alternatively, the maturity efficiency factor may be determined as the ratio of log maturity values for the cements to reach a given target strength. Both efficiency factors incorporate important economic parameters of interest to the practitioner.Because of its glassy character, FA attracts calcium hydroxide as well as sodium and potassium ions released into solution by the PC component. The risk of alkali-aggregate reaction may therefore be reduced. This characteristic may prove to be of such over-riding importance that a new approach to mix design may become necessary. The essence of such an approach would be the provision of sufficient FA to absorb reactive species released by the PC. This might involve increased PC+FA and water, with concomitant reduction in aggregate and in fineness modulus.Dimensional changes such as shrinkage and creep affect the distribution of load between steel and concrete in columns, the deflection of beams and slabs, and cracking where displacements are restrained. In the case of PC concrete, both creep and shrinkage depend on the volume ratio of hydration products and the movement of pore water caused by drying and by mechanical load. In general the magnitude of creep and shrinkage varies with Vp, the volume proportion of cement paste, and reduces with wo*. Part substitution of PC with FA generally results in increase of Vp, but this is compensated by decrease in wo*. The nature of the hydration products varies with PCiFA ratio, and thus quantities such as the internal surface area, the hydraulic mean radius of pores and the effective modulus—the ratio of stress to total strain—must be evaluated.In general the data required by the practitioner is not available in the literature and he must have recourse to ad hoc tests in order to establish basic workability-time-temperature-strength data. This is, potentially, a fruitful area of research.
Performance of a Fly Ash Stabilized Pavement
Authors: Laguros Joakim G. , Hayes Curt 
Published: March 2011

AbstractAn expansive shale roadbase, stabilized with a Class C (high-calcium) fly ash received an 11–inch full–depth asphaltic concrete surface layer and the highway was opened to traffic six years ago. Periodic sampling and visual observations indicate that the performance of the pavement test sections are above average.Analyses of field samples showed that fly ash was effective in ameliorating the texture and plasticity of the shale and imparting strength to it on a long term basis. Pavement deflections and the extent of cracking have not increased beyond acceptable levels during the six year period.X-ray diffraction studies show a reduction of the areas under the peaks and the SEM observations reveal a dense degree of packing and reduction of the void areas. These modifications occur during the first two years of service and any changes beyond that period appear to be minor.
Evaluating the Use of Ponded Fly Ash in a Roadway Base Course
Authors: Hunsucker David Q. , Graves R. Clark 
Published: March 2011

AbstractThis paper summarizes findings of laboratory and field trial evaluations of ponded fly ash used as a component in a stabilized aggregate base course. Ponded fly ash is the fine portion of pond ash which is a by-product of a coal burning process and is disposed by sluicing to a disposal pond.Three stabilized aggregate base mixtures containing various proportions of dense graded aggregate, ponded fly ash, and hydrated lime were evaluated in the laboratory relative to maximum dry density, optimum moisture content, unconfined compressive strength, and static chord modulus of elasticity. The mixture that was selected for field trial evaluation had the highest unconfined compressive strength and consisted of 84% dense graded aggregate, 11% ponded fly ash, and 5% hydrated lime.A 750 foot section of a 22 foot wide roadway was constructed in May 1988. Approximately 88 tons of ponded fly ash were utilized in constructing the experimental base. Prior to construction, in-place California Bearing Ratio tests, moisture content determinations and Road Rater deflection tests were performed on the prepared subgrade. The stabilized aggregate base was placed in one 8 inch lift. During construction, relative compaction and moisture content of the base material were monitored by means of nuclear devices. Post construction evaluations included Road Rater deflection tests and coring to obtain samples for laboratory evaluation.To date, the section containing the stabilized aggregate base is performing very well in comparison to the conventionally paved section.
Environmental Assessment of Botitom Ash and Fly Ash Used in Road Stabilization
Authors: Atalay Asmare , Laguros Joakim G. 
Published: March 2011

AbstractFly ash and bottom ash are being used extensively for stabilization of roads. Unpaved county roads in rural areas are often being resurfaced with bottom ash to improve their stability. A preliminary, uncontrolled examination was conducted to assess the environmental problems that may result from the use of fly ash and bottom ash on highways. To do this, soil, plant and run–off water samples were collected from county roads and highways in Oklahoma that were constructed using either of the two ash forms. These samples were analyzed for fourteen elements of which eight are under the USEPA regulation list of priority pollutants for solid waste and drinking water. The results indicated that the allowable limits for six out of the eight elements were exceeded in the run-off water samples. Compared with the control, fly ash, bottom ash, coal and soil-core samples all contained significantly higher levels of all elements; however, except for barium all were below the regulatory levels. The concentrations of As, Sb, Pb, Ni, Se, and TI in the run-off water samples are high enough to be of concern, although they are below the allowable limits for drinking water. These six elements are found at much higher levels in the fly ash and bottom ash than in the input coal. More Ba is released into the run–off water when the roads were under heavy traffic. Although there was no visual damage observed on the collected plant samples, much higher than normal levels of most metals, were obtained in the tissues.
Analysis of Coal Fly Ash by Bulk and Surface Characterization Techniques
Authors: Bellotto M. , Boni C. , Caridi A. , Cereda E. , Chemelli C. , Marcazzan G. M. Braga , Parmigiani F. , Scagliotiti M. , Bellagamba B. 
Published: March 2011

AbstractThe application of different characterization techniques to the study of coal fly ash formation and of its behaviour in particulate control devices is discussed. Particle Induced X-ray Emission (PIXE) and Proton Induced Gamma-ray Emission (PIGE) are used for bulk elemental analyses, while X-Ray Photoelectron and Auger Spectroscopies are used for surface elemental analyses. Structural characterization is carried out by powder X-Ray Diffraction and Raman Microfocus Spectroscopy. The effect of different collection efficiencies of electrostatic precipitators on emitted fly ash characteristics is addressed. Furthermore size fractionated fly ash is analyzed to investigate the mechanisms of particle growth.
Microstructure, Mass Transport and Densification of Slag Cement Pastes
Authors: Feng Q. L. , Glasser F. P. 
Published: March 2011

AbstractThe kinetics and mechanism of the hydration reactions in slag cements were explored in blends containing either 40 or 50 wt% ground granulated blast furnace slag, made to a water:solid ratio of either 0.50 or 0.60 and aged 7d to 885d at 20°C. The microstructure of the slag rapidly differentiates into zonal structures. Analytical electron microscopy has been used to analyze the composition and indirectly determine the mineralogy of the zones. It is shown that considerable chemical matter is transported out of the slag grains, resulting in porosification of the former slag grains and densification of the cement hydrate matrix. This is supported by mass balance calculations. The driving force for these migrations is accounted for by the existence of a chemical potential gradient of water; hydrophyllic species such as Ca, Si, etc. migrate into regions of high chemical potential for water. The densification of the phase matrix is probably responsible for the low permeabilities of matured slag-cement blends.
A Statistical Investigation on Particle to Particle Variation of Fly Ash Using SEM-AIA-EDAX Technique.
Authors: Barta L. E. , VÁmos G. , Toqan M. A. , Teare J. D. , BeÉr J. M. , Sarofim A. F. 
Published: March 2011

AbstractDue to the particle to particle variation of coal mineral properties and random coalescence of mineral particles during coal burnout, fly ash particle properties change from particle to particle. The variations of particle properties (e.g. SiO2 content, viscosity) can be mathematically described by random variables. Since bulk analysis of fly ash gives only the mean values of chosen random variables, it is considered insufficient to describe the fly ash behavior either in boiler slagging/fouling or in different concrete structures. SEM-AIA-EDAX technique was used to supply raw data for estimating the distribution functions of particle size and chemical compounds in Texas lignite minerals and fly ash and Eagle Butte fly ash. To determine the volume based size distributions of these samples from their area-based size distributions, Abelian transformation was used. To estimate the distribution functions of CaO and SiO2 contents of the samples, particle area fractions were used. The confidence limits were also calculated for the estimated parameters. By determining the distribution functions of particle viscosity and chemical composition, it was shown that in the case of Texas lignite the coal burnout does not cause significant changes in the mineral matter properties. It was observed that the properties of fly ash depended solely on the mineral matter properties. However, in the Eagle Butte case the coal burnout has a major effect on the fly ash size distribution and its chemical composition.
The Chemistry Of MDF Cements Produced From Polyacrylamide-Cement-Water Pastes
Authors: Silsbee M. R. , Roy D. M. , Adair J. H. 
Published: March 2011

AbstractIt is becoming more generally accepted that the role of the polymers in these MDF (macro-defect-free) cement systems is more complex than simply acting as a processing aid or a filler. The polymer interacts in some way with the cations released from the cement to form a metal cross-linked polymer gel. Studies on complex formation in polymer gels have shown that there is often an unusual specificity in the ions, resulting in the highest degree of complexation. In addition, gel formation often occurs only within a narrow pH regime. Hence, the results shown here will attempt to examine the effects of altering the cement chemistry on strength development in calcium silicate-based systems.
Alkali Activated Slag And Portland/Slag Ultrafine Cement
Authors: Clarke William J. , Helal Maan 
Published: March 2011

AbstractUltrafine Alkali Activated Slag (AAS) and Portland/Slag (P/S) cements have been commercially available in the United States for 2 and 5 years, respectively. Ultrafine cements have been the subject of research at Northwestern University for 6 years.Particle size of the ultrafine slag cement is characterized by 98% passing at 7 microns and a D50 at 3 microns in contrast to the ultrafine portland/slag cement which has 98% passing at 10 microns and a D50 at 4 microns.The chemical composition of the slag used in these cements is 35% SiO2, 16% Al2O3, and 43% CaO. The composition of the portland/slag cement, which is a 25/75 blend, is therefore between the bulk composition of portland cement and the slag.Both of the ultrafine cements permeate fine sands when formulated at high
water-to-cement ratios. Viscosity plays an important part in the permeation mechanism, and both cements exhibit viscosities below 10 cps at water-to-cement ratios of 2. This low viscosity is obtained through the use of superplasticizing with naphthalene sulfonate and acrylic acid polymers.Applications of the ultrafine cements include dam grout curtain rehabilitation, consolidation grouting, and nuclear and hazardous waste containment. One hundred and twenty metric tonnes of the portland/slag cement have been used for hazardous waste containment at Niagara Falls, New York.
Low-Temperature (<300°C) Phosphate Ceramics from Reactive Aluminas
Authors: Silsbee M. R. , Steinke R. A. , Roy D. M. , Agrawal D. K. , Roy R. 
Published: March 2011

AbstractReactive aluminas, including rapidly calcined gibbsites, offer exciting potential for forming ceramic materials at low temperatures. New x-ray amorphous aluminas will react with water at room temperatures to form compacts with 10–50 MPa tensile strengths, via viscous slurries. The cementious behavior of these materials has been examined. The results of TGA, x-ray diffraction, SEM, mechanical properties, and other characterization techniques, as applied to these systems, will be discussed.
High-Temperature Processing and Applications of Silica-Modified Portland Cement CBC Composites
Authors: Wise Sean , Kevan R. 
Published: March 2011

AbstractSilica-modified portland cement-based Chemically Bonded Composites (CBCs) have been prepared and cured to elevated temperatures. It has been found that when cementitious composites with calcium-to-silica (C/S) ratios of 0.83 are thoroughly hydrated through hydrothermal curing, followed by careful dehydration, mortars of exceptional strength are produced. The bulk of this strength is maintained to over 600°C. X-ray diffraction studies of binder samples dried at 200°C and 500°C show only slight differences in mineral product contents. Above 600°C, a drop in strength is noted, and a substantial portion of the binder converts to wollastonite. Even so, these CBC composites retain as much as 40% of their peak compressive strength to temperatures up to 800°C. Applications of these materials in high-temperature industrial processes are presented.
Temperature Dependence of Stress for Copper, Copper-Silver and Copper-Tin Films
Authors: Haynes Richard 
Published: March 2011

1. IntroductionIn VLSI processing and other applications such as printed circuit boards thin films of copper, usually used as conductors, undergo thermal cycling. This thermal cycling can cause loss of adhesion and mechanical failures thus decreasing reliability of the devices[l–7]. Understanding thermally induced stress due to mismatch of thermal expansion may assist in generating designs, processes and material replacement for increased reliability. This paper reports studies of the temperature dependence of stresses for plated and sputtered copper and plated copper-silver and copper-tin alloys. Studies of thermally annealed plated copper and copper-tin alloys are also reported.
Mechanical Properties of Carbon-Implanted Niobium
Authors: Zinkle S. J. , Huang J. S. 
Published: March 2011

ABSTRACTPolycrystalline niobium specimens were implanted with either 200 keV carbon ions or a combination of 50, 100, and 200 keV carbon ions to peak concentrations of 0.6 to 50 at. %. Microindentation techniques were used to measure the hardness and elastic modulus of the implanted layer. Both the hardness (H) and modulus (E) showed dramatic increases due to the carbon implantation. The measured peak hardness and modulus following uniform implantation with 16 at. % C were 15× and 3× that of niobium, respectively, which is comparable to the literature values for NbC. The peak hardness and modulus for the implanted specimens were observed at an indent depth of ˜40 nm, which is about one-eighth of the depth of the implanted carbon layer. The decrease in the indentation mechanical properties at deeper indent depths is due to the interaction of long-ranging strain fields underneath the indenter with the niobium substrate.
Measurement of Stress Relaxation in Thin Aluminum Metallizations by Continuous Indentation and X-Ray Techniques
Authors: Korhonen M. A. , LaFontaine W. R. , Paszkiet C. A. , Black R. D. , Li Che-Yu 
Published: March 2011

ABSTRACTThin aluminum films deposited on silicon substrates are representative of materials systems used in integrated circuit technology. Large stresses in such systems usually arise from thermal expansion mismatch between the thin film and the substrate, and constitute an important reliability concern.X-ray and continuous indentation testing were used to measure post-heat treatment stresses in a 0.3 μm thick aluminum film on a silicon substrate. The sample was heat treated at 450°C for one hour in an inert atmosphere, after which the stress relaxation was followed as a function of time. The stress data gathered by the two techniques agree very closely during a time span of about 100 hours.
Deflection Shapes Due to Intrinsic Stress in Thin Films
Authors: Masters Christine B. , Salamon N. J. , Fahnline D. E. 
Published: March 2011

ABSTRACTThe curvatures of thin film/substrate systems are obtained for a nonlinear plate deflection model using a Galerkin minimization procedure proposed by Hyer. A fifth order polynomial involving the curvatures is given. The results show that the linear models of Stoney and Brenner and Senderoff apply only at low stress states and that stable and unstable configurations develop at higher stresses even for isotropic systems.
Mechanical Properties of Carbon Films for Thin Film Disks
Authors: White Richard L. , Doerner Mary F. , Walker George W. 
Published: March 2011

ABSTRACTCarbon overcoat films are used extensively in thin film disk applications to provide wear resistance. A nano-indentation technique and wafer curvature measurements have been used to study the mechanical properties of carbon films sputtered under various processing conditions. Specifically, the effects of substrate/target spacing, power, pressure, and substrate bias have been studied for films sputtered in an argon plasma. The relationship of these properties to contact start-stop performance of hydrocarbon lubricated disks is further described. The frictional performance during the test can be related to film hardness, while the durability can be affected by the residual film stress.
Experiments on, and a Two-Component Model for, the Behavior of Water Nano-Films on Metals
Authors: Gao Chao , Kuhlmann-Wilsdorf D. 
Published: March 2011

ABSTRACTBy means of the hoop apparatus, contact resistance and coefficient of friction of fiber bundles on a solid substrate have been determined in air at different humidities. The results can be explained by a two-component model, comprising (i) a double molecular layer of adsorbed water at contact spots and (ii) a zone about each contact spot within which excess adsorbed moisture which has been squeezed out from the load-bearing area bypasses the spot.