The main objective in this work was to learn how the instrument, the Interfacial Shear Rheometer (ISR400), worked and to investigate how the rheological properties, storage modulus (elasticity), G' and loss modulus (viscous), G'', changes when the surface pressure at the air-liquid interphase changes. The second objective were to examine the different kind of magnetic needles used in the experiments and to conclude which type of needle is best for its specific field of analysis. It was concluded that the relative heavy needle with mass 70.6 mg and length 50 mm was best for systems where the viscous and elastic components are significantly large, where the inertia of the needle is not dominant. It also worked of using the heavier needle for a system of phospholipids. For the hydroxystearic acid (HSA) experiment that were tested on NaCl sub-phase there was a clear improvement after switching from the heavy needle (mass 41.5 mg; length 51 mm) to the relative lighter needle (mass 6.94 mg; length 34.7 mm). The values for the dynamic modulus therefore had a better agreement with reference literature. A spread layer of class II hydrophobins (HFBII) could be compressed to a surface pressure of 46 mNm-1. The G' and G'' values from the frequency sweep were discarded because the monolayer turned into a very viscous-like liquid, and the oscillating needle, after compression, was kind of stuck in the sub-phase and moved very staggering during a frequency sweep. The needle comparison experiment with silica particles 10 wt% Bindzil CC30 (BCC30), at pH 3.5 was done to see if there was any difference in the sensitivity for the needles at the interface which consisted of a pure 10 mM NaCl solution or a 10 mM NaCl solution with BCC30 added to it. The differences were negligible in terms of surface tension but there was a clear difference between the heavy needle and the light needle, when oscillating at higher frequencies (>≈6 rad/s). With this study, the understanding of ISR400 has increased largely. Several issues have been addressed and the results provide a good basis for further studies within the many areas the instrument can be used for. Despite the project's time limit, and the fact that the instrument was new and untested where the project was carried out, focus areas were prioritized so good results could be achieved within reasonable goals. / Huvudmålet med detta arbete var att lära sig hur instrumentet ytskiktsreometern (ISR400) fungerade och undersöka hur de reologiska egenskaperna, elasticitetsmodulen G' och viskositetsmodulen G'', kommer att förändras när det sker en förändring för yttrycket vid gränsskiktet mellan luft och vätska. Det sekundära målet var att undersöka vilken typ av magnetiska nålar som är bäst att använda för respektive gränsskiktssystem. Av att använda den tyngre nålen med massan 70.6 mg och längden 50 mm kunde man dra slutsatsen att den är bäst att använda för system där de viskösa och elastiska komponenterna är signifikant stora, där nålens tröghet inte är dominant. Den fungerade även att mäta med i ett fosfolipidsystem. I experimentet med 12-hydroxy-stearinsyra (HSA) som utfördes på en subfas av NaCl, syntes en klar förbättring efter att byta från en tyngre nål (massa 41.5 mg; längd 51 mm) till en lättare (massa 6.94 mg; längd 34.7 mm). Värdena för dynamiska modulen stämde därför bättre överens med referenslitteraturen. Det utspridda lagret av klass II hydrophobins (HFBII) kunde komprimeras upp till yttrycket 46 mNm-1. Värdena för G' och G'' förkastades därför att monolagret förvandlades till en väldigt viskösliknande vätska, och den oscillerande nålen, efter kompressionen, satt fast i denna tröga vätska och rörde sig väldigt hackigt och oregelbundet under tiden ett frekvenssvep utfördes. Då en jämförelse av olika typer av nålar genomfördes med kiseldioxidpartiklar (10 % (viktsprocent) Bindzil CC30 med pH 3.5), för att se om det är någon skillnad i känslighet för nålarna vid gränssnittet, som bestod av en ren 10 mM NaCl-lösning eller en 10 mM NaCl-lösning med tillsatt BCC30. Skillnaderna var försumbara gällande ytspänningen, men det var en klar skillnad mellan den tunga nålen och den lätta nålen vid oscillering vid höga frekvenser (>≈6 rad/s). I och med detta arbete så har förståelsen för hur ISR400 fungerar förbättrats mycket sedan starten. Flera frågeställningar har behandlats och resultaten ger en bra grund för fortsatta studier inom de många områden som utrustningen kan användas till. Trots projektets tidsbegränsning, och det faktum att instrumentet var nytt och oprövat på platsen där detta arbete utfördes, så prioriterades fokusområden så att goda resultat kunde uppnås inom rimliga mål.

The design, fabrication, and characterization of polymer-carbon nanotube (CNT) composites have generated a significant amount of attention in the fields of materials science and polymer chemistry. The challenge in fabricating composites that exploit the unique properties of the CNT and the ideal processing ability and low cost of the polymer is in achieving a uniform dispersion of the filler in the polymer matrix. This body of work focuses on (1) techniques employed to disperse CNTs into a polymer matrix and (2) the effects of CNTs on the mechanical and electrical properties of the polymer. Poly (methyl methacrylate) (PMMA), an amorphous polymer, and poly (4-methyl-1-pentene) (P4M1P), a semi crystalline polymer, were chosen as the matrices. Non-functionalized single-walled carbon nanotubes and soot (unpurified carbon nanotubes) were chosen as the filler material. In the first study, single-walled carbon nanotubes (SWNTs) were sonicated in methyl methacrylate monomer and initiated via thermal energy, UV light, and gamma radiation. Composite films with increased dielectric constants and unique optical transparency were produced. Samples were characterized using differential scanning calorimetry, dielectric analysis, and dynamic mechanical analysis. Refractive Indices were obtained and correlated to the dielectric constant using Maxwells relationship. PMMA/soot composites were fabricated in the second study. Dispersion was accomplished by way of sonication and melt compounding. The PMMA/soot composites were exposed to gamma radiation, with a 137Cs gamma source, in order to investigate how the filler affects the polymers ability to resist radiation. Samples were characterized by differential scanning calorimetry, dielectric analysis, and dynamic mechanical.

Successful field waterflood is a crucial prerequisite for improving the performance before EOR methods, such as ASP, SP, and P flooding, are applied in the field. Excess water production is a major problem in mature waterflooded oil fields that leads to early well abandonment and unrecoverable hydrocarbon. Gel treatments at the injection and production wells to preferentially plug the thief zones are cost-effective methods to improve sweep efficiency in reservoirs and reduce excess water production during hydrocarbon recovery. There are extensive experimental studies performed by some researchers in the past to investigate the performance of gels in conformance control and decreasing water production in mature waterflooded reservoirs, but no substantial modeling work has been done to simulate these experiments and predict the results for large field cases. We developed a novel, 3-dimensional chemical compositional and robust general reservoir simulator (UTGEL) to model gel treatment processes. The simulator has the capability to model different types of microgels, such as preformed particle gels (PPG), thermally active polymers (TAP), pH-sensitive microgels, and colloidal dispersion gels (CDG). The simulator has been validated for gel flooding using laboratory and field scale data. The simulator helps to design and optimize the flowing gel injection for conformance control processes in larger field cases. The gel rheology, adsorption, resistance factor and residual resistance factor with salinity effect, gel viscosity, gel kinetics, and swelling ratio were implemented in UTGEL. Several simulation case studies in fractured and heterogeneous reservoirs were performed to illustrate the effect of gel on production behavior and water control. Laboratory results of homogeneous and heterogeneous sandpacks, and Berea sandstone corefloods were used to validate the PPG transport models. Simulations of different heterogeneous field cases were performed and the results showed that PPG can improve the oil recovery by 5-10% OOIP compared to waterflood. For recovery from fractured reservoirs by waterflooding, injected water will flow easily through fractures and most part of reservoir oil will remain in matrix blocks unrecovered. Recovery from these reservoirs depends on matrix permeability, wettability, fracture intensity, temperature, pressure, and fluid properties. Chemical processes such as polymer flooding (P), surfactant/polymer (SP) flooding and alkali/surfactant/polymer (ASP) flooding are being used to enhance reservoir energy and increase the recovery. Chemical flooding has much broader range of applicability than in the past. These include high temperature reservoirs, formations with extreme salinity and hardness, naturally fractured carbonates, and sandstone reservoirs with heavy and viscous crude oils. The recovery from fractured carbonate reservoirs is frequently considered to be dominated by spontaneous imbibition. Therefore, any chemical process which can enhance the rate of imbibition has to be studied carefully. Wettability alteration using chemicals such as surfactant and alkali has been studied by many researchers in the past years and is recognized as one of the most effective recovery methods in fractured carbonate reservoirs. Injected surfactant will alter the wettability of matrix blocks from oil-wet to water-wet and also reduce the interfacial tension to ultra-low values and consequently more oil will be recovered by spontaneous co-current or counter-current imbibition depending on the dominant recovery mechanism. Accurate and reliable up-scaling of chemical enhanced oil recovery processes (CEOR) are among the most important issues in reservoir simulation. The important challenges in up-scaling CEOR processes are predictability of developed dimensionless numbers and also considering all the required mechanisms including wettability alteration and interfacial tension reduction. Thus, developing new dimensionless numbers with improved predictability at larger scales is of utmost importance in CEOR processes. There are some scaling groups developed in the past for either imbibition or coreflood experiments but none of them were predictive because all the physics related to chemical EOR processes (interfacial tension reduction and wettability alteration) were not included. Furthermore, most of commercial reservoir simulators do not have the capability to model imbibition tests due to lack of some physics, such as surfactant molecular diffusion. The modeling of imbibition cell tests can aid to understand the mechanisms behind wettability alteration and consequently aid in up-scaling the process. Also, modeling coreflood experiments for fractured vuggy carbonates is challenging. Different approaches of random permeability distribution and explicit fractures were used to model the experiments which demonstrate the validity and ranges of applicability of upscaled procedures, and also indicate the importance of viscous and capillary forces in larger scales. The simulation models were then used to predict the recovery response times for larger cores.

No description available.

The rapid progress of complementary-metal-oxide-semiconductor (CMOS) integrated circuit technology became feasible through continuous device scaling. The implementation of high-k/metal gates had a significantcontribution to this progress during the last decade. However, there are still challenges regarding the reliability of these devices. One of the main issues is the escalating 1/fnoise level, which leads to degradation of signal-to-noise ratio (SNR) in electronic circuits. The focus of this thesis is on low-frequency noise characterization and modeling of various novel CMOS devices. The devices include PtSi Schottky-barriers  for source/drain contactsand different high-kgatestacksusingHfO2, LaLuO3 and Tm2O3 with different interlayers. These devices vary in the high-k material, high-k thickness, high-k deposition method and interlayermaterial. Comprehensive electrical characterization and low-frequency noise characterization were performed on various devices at different operating conditions. The noise results were analyzed and models were suggested in order to investigate the origin of 1/f noise in these devices. Moreover, the results were compared to state-of-the-art devices. High constant dielectrics limit the leakage current by offering a higher physical dielectric thickness while keeping the Equivalent Oxide Thickness (EOT) low. Yet, the 1/f noise increases due to higher number of traps in the dielectric and also deterioration of the interface with silicon compared to SiO2. Therefore, in order to improve the interface quality, applying an interfacial layer (IL) between the high-k layer and silicon is inevitable. Very thin, uniform insitu fabricated SiO2 interlayers with HfO2 high-k dielectric have been characterized. The required thickness of SiO2 as IL for further scaling has now reached below 0.5 nm. Thus, one of the main challenges at the current technology node is engineering the interfacial layer in order to achieve both high quality interface and low EOT. High-k ILs are therefore proposed to substitute SiOx dielectrics to fulfill this need. In this work, we have made the first experiments on low-frequency noise studies on TmSiO as a high-k interlayer with Tm2O3 or HfO2 on top as high-k dielectric. The TmSiO/Tm2O3 shows a lower level of noise which is suggested to be related to smoother interface between the TmSiO and Tm2O3. We have achieved excellentnoise performancefor TmSiO/Tm2O3 and TmSiO/HfO2 gate stacks which are comparableto state-of-the-art SiO2/HfO2 gate stacks. / <p>QC 20151130</p>

Polymer Nanocomposites (PNC) are a new class of materials characterized by their large interfacial areas between the host polymer and nanofiller. This unique feature, due to the size of the nanofiller, is understood to be the cause of enhanced mechanical, electrical, optical, and barrier properties observed of PNCs, relative to the properties of the unfilled polymer. This interface can determine the miscibility of the nanofiller in the polymer, which, in turn, influences the PNC's properties. In addition, this interface alters the polymer's structure near the surface of the nanofiller resulting in heterogeneity of local properties that can be expressed at the macroscopic level. Considering the polymer-nanoparticle interface significantly influences PNC properties, it is apparent that some atomistic level of detail is required to accurately predict the behavior of PNCs. Though an all-atom simulation of a PNC would be able to accomplish the latter, it is an impractical approach to pursue even with the most advanced computational resources currently available. In this contribution, we develop (1) an equilibrium coarse-graining method to predict nanoparticle dispersion in a polymer melt, (2) a dynamic coarse-graining method to predict rheological properties of polymer-nanoparticle melt mixtures, and (3) a numerical approach that includes interfacial layer effects and polymer rigidity when predicting barrier properties of PNCs. In addition to the above, we study how particle and polymer characteristics affect the interfacial layer thickness as well as how the polymer-nanoparticle interface may influence the entanglement network in a polymer melt. More specifically, we use a mean-field theory approach to discern how the concentration of a semiflexible polymer, its rigidity and the particle's size determine the interfacial layer thickness, and the scaling laws to describe this dependency. We also utilize molecular dynamics and simulation techniques on a model PNC to determine if the polymer-nanoparticle interaction can influence the entanglement network of a polymer melt. / text

The progress of the silicon-based complementary-metal-oxide-semiconductor (CMOS) technology is mainly contributed to the scaling of the individual component. After decades of development, the scaling trend is approaching to its limitation, and there is urgent needs for the innovations of the materials and structures of the MOS devices, in order to postpone the end of the scaling. Atomic layer deposition (ALD) provides precise control of the deposited thin film at the atomic scale, and has wide application not only in the MOS technology, but also in other nanostructures. In this dissertation, I study rapid thermal processing (RTP) treatment of thermally grown SiO2, ALD growth of SiO2, and ALD growth of high-k HfO2 dielectric materials for gate oxides of MOS devices. Using a lateral heating treatment of SiO2, the gate leakage current of SiO2 based MOS capacitors was reduced by 4 order of magnitude, and the underlying mechanism was studied. Ultrathin SiO2 films were grown by ALD, and the electrical properties of the films and the SiO2/Si interface were extensively studied. High quality HfO2 films were grown using ALD on a chemical oxide. The dependence of interfacial quality on the thickness of the chemical oxide was studied. Finally I studied growth of HfO2 on two innovative interfacial layers, an interfacial layer grown by in-situ ALD ozone/water cycle exposure and an interfacial layer of etched thermal and RTP SiO2. The effectiveness of growth of high-quality HfO2 using the two interfacial layers are comparable to that of the chemical oxide. The interfacial properties are studied in details using XPS and ellipsometry.

A study is carried out into fracture behavior of steel/steel laminates both experimentally and through finite element analysis (FEM). The laminates produced by hot pressing consisted of low carbon and medium carbon steels with two volume fractions / 0.41 and 0.81. Fracture toughness, JIC has been measured using partial unloading technique assuming a critical value of crack extension. The technique is initially applied to monolithic material and then to the laminates in crack divider orientation. Evaluation of fracture toughness of laminates indicates that there is a substantial improvement of JIC with increase in the volume fraction. The systems under study were also evaluated by FEM modeling with the use MARC package program. To evaluate JIC, the problem has been evaluated in several steps / first two-dimensional plane strain problem is considered. This is followed by three-dimensional case and then by an artificially layered system, all for monolithic materials. Values of JIC derived were close to one another in all cases. Following this verification, the method, as implemented in layered monolithic system, was applied to laminates. This has shown that JIC of laminates can be predicted using FEM analysis, including the delamination. Values of JIC varied in the same manner as the experiment verifying that fracture toughness in the current system increases with increase in volume fraction. It has been concluded that modeling as implemented in this work can be used for useful composite systems incorporating hard/brittle reinforcements both in crack divider and crack arrester orientation.

abstract: With the increasing focus on developing environmentally benign electronic packages, lead-free solder alloys have received a great deal of attention. Mishandling of packages, during manufacture, assembly, or by the user may cause failure of solder joint. A fundamental understanding of the behavior of lead-free solders under mechanical shock conditions is lacking. Reliable experimental and numerical analysis of lead-free solder joints in the intermediate strain rate regime need to be investigated. This dissertation mainly focuses on exploring the mechanical shock behavior of lead-free tin-rich solder alloys via multiscale modeling and numerical simulations. First, the macroscopic stress/strain behaviors of three bulk lead-free tin-rich solders were tested over a range of strain rates from 0.001/s to 30/s. Finite element analysis was conducted to determine appropriate specimen geometry that could reach a homogeneous stress/strain field and a relatively high strain rate. A novel self-consistent true stress correction method is developed to compensate the inaccuracy caused by the triaxial stress state at the post-necking stage. Then the material property of micron-scale intermetallic was examined by micro-compression test. The accuracy of this measure is systematically validated by finite element analysis, and empirical adjustments are provided. Moreover, the interfacial property of the solder/intermetallic interface is investigated, and a continuum traction-separation law of this interface is developed from an atomistic-based cohesive element method. The macroscopic stress/strain relation and microstructural properties are combined together to form a multiscale material behavior via a stochastic approach for both solder and intermetallic. As a result, solder is modeled by porous plasticity with random voids, and intermetallic is characterized as brittle material with random vulnerable region. Thereafter, the porous plasticity fracture of the solders and the brittle fracture of the intermetallics are coupled together in one finite element model. Finally, this study yields a multiscale model to understand and predict the mechanical shock behavior of lead-free tin-rich solder joints. Different fracture patterns are observed for various strain rates and/or intermetallic thicknesses. The predictions have a good agreement with the theory and experiments. / Dissertation/Thesis / Ph.D. Mechanical Engineering 2011

Suite à la demande constante de réduire la taille des transistors et celle des dispositifs électroniques, guidée par la loi de Moore, l'intégration 2D n'est plus adaptée à cette demande croissante. Cela a conduit à l'intégration 3D des dispositifs actifs à l'aide de piliers Cu/Ni recouverts d'alliages de brasage à base de Sn. Dans les années à venir, les applications qui demandent des interconnexions à haute densité (optoélectroniques, microdisplays, les détecteurs IR, MEMS) nécessiteront l’utilisation de pas d'interconnexions inférieurs à 10 µm. Cependant, les piliers Cu/Ni/alliage de brasure base Sn n'ont jamais été étudiés en profondeur pour un si petit pas d'interconnexion. Avec la réduction de la dimension d'interconnexion, le diamètre des piliers Cu/Ni/alliage de brasure est réduit également. De ce fait, la formation des intermétalliques, qui joue un rôle primordial dans la bonne tenue de la jonction, peut poser des problèmes majeurs en raison de la réduction des dimensions du pilier de Cu et de l’alliage de brasure.Le travail de cette thèse est consacré à l'étude métallurgique et à la caractérisation d’interconnections de très petites dimensions (diamètre de 5 µm et pas de 10 µm) avec comme objectif principal l’étude des mécanismes physicochimiques des interactions entre les alliages de soudure Sn-Ag et les couches de Ni ou Ni/Au. Les mécanismes des interactions à l'état solide entre Sn et Ni ainsi que l’évolution du joint vers la transformation totale en intermétallique Ni3Sn4 (Solid-Liquid-Intercondiffusion - SLID processus), ont été étudiés pour la première fois dans de tels systèmes de dimensions micrométriques. De plus, les propriétés mécaniques et électriques ainsi que la stabilité thermique de ces interconnexions ont été étudiées. L’observation pour la première fois de la formation de la phase Ni3Sn2 à l’interface Ni/Sn à 200°C lors des vieillissements thermiques présente un intérêt pratique de grande importance. / With the constant demand for reducing the feature size of transistors and that of the devices, which is guided by Moore’s law, 2D integration is no longer fit to adapt the growing demand. This has led to 3D integration of active devices with the help of Cu/Ni pillars capped with Sn based solder alloys. In the coming years, applications which demand high density interconnects (optoelectronic, microdisplays, IR-detectors, MEMS) will require an interconnect pitch of 10 µm and below. However, Cu/Ni/solder pillars have never been investigated in depth for such a small interconnection pitch. With reduction of interconnect dimension, the diameter of Cu/Ni pillar and solder alloy also reduces. Thus, it is feared that the intermetallic formation, which is the key phenomenon responsible for the bonding, may be problematic due to the reduction in size of Cu pillar capped with solder alloy.The thesis is dedicated to the metallurgical study and its characterization for very small interconnects (5 µm) at 10 µm pitch, where the main focus is given on the physio-chemical mechanisms of soldering between Sn-Ag solder alloy and Ni or Ni/Au layers. For the first time, the mechanism of solid-state interactions between Sn and Ni is studied in depth and also for the first time the Ni3Sn4 SLID (Solid-Liquid-lnterdiffusion) system as an interconnect has been investigated at these dimensions. Moreover, the mechanical and electrical properties as well as the thermal stability of these interconnects are studied. Interestingly, during the latter part of this study, Ni3Sn2 layer is observed during aging of the Ni/Ni3Sn4 system for low temperature (200°C).