Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 18 of 18 for “"Long-term Aging"”.
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Impact of laboratory simulated aging on asphalt concrete flexibility
The aging of asphalt materials is considered an important factor contributing to the deterioration of asphalt concrete (AC) pavements. Asphalt binder aging is a combination of various complex mechanisms that affect its rheological properties causing AC to become stiffer and more brittle. As a …
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The effect of mica on the aging of asphalt binder
… of mica on asphalt materials subjected to aging. A total of five different concentrations of mica in fines are examined using X-ray diffraction (XRD) technology. These mica-fines are combined with two asphalt binders to make mastics. Mastics are aged at four different levels and examined …
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Development of Antioxidant Treatments for Asphalt Binders and Mixtures
… binders were subjected to accelerated laboratory aging using the Rolling Thin Film Oven to simulate short-term aging and the Pressure Aging Vessel to simulate long-term aging. Rheological measurements using the Dynamic Shear Rheometer and the Bending Beam Rheometer were used to screen those …
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Microstructure evolution in Alloy 709 at 550 and 650 °C
… stainless steel is studied after thermal aging at 550°C and 650°C. The microstructure is characterized using variety of techniques. The alloy shows excellent thermal stability at its working temperature 550°C, while its microstructure evolves rapidly at 650°C with complex precipitation …
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Wideband characterization of aluminum nitride substrates and high power-high frequency thick film applications
… of <i>AIN</i> are addressed, and short and long term aging effects on several circuit parameters are studied. To evaluate the performance of <i>AIN</i> in high power and high frequency applications, two circuits; an impulse generator and a power converter, are realized, tested and compared …
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High temperature aging study on long-term aged Alloy 617 and Alloy 230
… degradation process of these materials, long-term (up to 10000 hours) aging experiments have been carried out to investigate the microstructural evolution and mechanical property development for both alloys. In the present study, focus is placed on the alloys aged for 10000 hours. Tensile …
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Evaluation of Warm Mix Additives for Use in Modified Asphalt Mixtures: Phase I
… mix additives with typical polymer-modified and terminal blend tire rubber asphalt mixtures from Nevada and California. The research effort is broken into three phases that are intended to evaluate the impacts of warm mix additives with typical polymer-modified and terminal blend tire rubber …
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BULK NANOSTRUCTURED STEELS FOR NUCLEAR REACTOR AND EXTREME ENVIRONMENT APPLICATIONS
… FeCrAl alloys suffer from embrittlement after long-term aging around 475 C, due to separation of Cr-enriched α’, which is further accelerated in a nuclear environment because of irradiation induced point defects enhancing diffusion. Nanostructured materials have been shown to have better …
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Microstructural responses of a nickel-base cast IN-738 superalloy to a variety of pre-weld heat-treatments
… manifested extensive intergranular cracking and aging contraction stresses. Aging resulted in coarsening of primary and secondary $\gamma\prime$ particles, degeneration and dissociation of primary carbide particles to form secondary $\gamma\prime$ particles andfine $\rm M\sb{23}C\sb6$ carbide …
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Durability study of proton exchange membrane fuel cells via experimental investigations and mathematical modeling
… tensile observations, combining the concepts of elongated polymer aggregates, proton conduction channels as well as states of water. The rationale focuses on the polymer bundle rotation/interphase chain readjustment before yielding and polymer aggregates disentanglement/ reorientation after …
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Viscoelastic Modeling of Straight and Modified Binders at Intermediate and High Temperatures
… and three modified binders were tested at intermediate and high service temperatures. Short-term and long-term aging were simulated by the rolling thin film oven test and the pressure aging vessel test, respectively. A dynamic shear rheometer with parallel plate configuration was used to …
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Model development and validation of bituminous-based crack sealants
… monitored after each winter for three years to determine a performance index (PI) consisting primarily of adhesive, cohesive, and overband wear. Field samples were collected from the sites to conduct laboratory testing and validate the sealant grading system. According to the field results, most …
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Optimizing asphalt binder chemistry and rheology to control potential flexible pavement cracking
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-12-01
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Mechanisms of Microbial Formation and Photodegradation of Methylmercury in the Aquatic Environment
… (influenced by environmental conditions) in determining the reactivity of mercury in these biological and photochemical reactions was the focus of this research.</p><p>Methylmercury production in the aquatic environment is primarily mediated by anaerobic bacteria in surface sediments, …
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Thermal Stability of Al₂O₃/Silicone Composites as High-Temperature Encapsulants
… in high-density and high-temperature packaging. There are high-temperature materials such as encapsulants on the market that are claimed for capability of continuous operation at or above 250°C. With an objective of identifying encapsulants suitable for packaging wide-bandgap devices, some …
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Elevated temperature mechanical properties of line pipe steels
… were also tested at elevated temperatures after aging at 200, 275, and 350 °C for 100 h under a tensile load of 419 MPa. The presence of serrated yielding depended on temperature and strain rate, and the upper bound of the temperature range where serrated yielding was observed was independent of …
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HIGH STRENGTH COLD ROLLED ASPHALT SURFACE COURSE MIXTURES
… not favourable to the application of cold BEM in terms of the long curing process and low early strength. Decreasing wastes from aggregate production processes, reducing land-filling and reducing CO2 emissions during hot bituminous mixture production and laying are the main target schemes for the …
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Microstructural evolution and mechanical behavior in nickel based alloys for very high temperature reactor
… performance during a high-temperature and long-term service life, various material tests and experiments were conducted to investigate the fundamental deformation mechanisms of the alloys and their long-term degradation process during thermal aging. First, mechanical properties of both …