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Results for “impurity”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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First-principles study of carbon impurity effects in the pseudo-hexagonal Ta2O5
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The effects of crystal orientation and common coal impurities on electronic conductivity in copper–carbon composites
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The role of impurities and degradation on the thermal conductivity of carbon fiber and amorphous carbon
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Helium impurities and interactions in lithium
Here we investigate helium interactions with lithium using density functional theory. Like other body-centered cubic (bcc) metals, the lowest-energy site for interstitial helium is a tetrahedral site. However, helium in lithium shows a higher substitutional formation energy than either the tetrahedral or octahedral interstitial formation energies, which is unique. The calculated migration energies of helium in lithium are also very low ( ~ 1 meV), an order of magnitude lower than those in other bcc metals. We find an increase in the binding energy to a vacancy as the number of helium atoms bound to it increases. The extremely low migration energies suggest that helium transport in lithium will be very fast.
High temperature oxidation of steels in CO 2 containing impurities
Future power systems require steels that resist corrosion in high temperature CO 2 containing combustion products/impurities. Here we evaluate the corrosion behavior of several commercial steels exposed to 95% CO 2 -4 % H 2 O-1 % O 2 , with/without 0.1 % SO 2 , at 550 °C and 1 atm. High-Cr steels formed thin Cr-rich oxides and low-Cr steels thick Fe-rich oxides during SO 2 -free exposures. Additions of SO 2 had little effect on low-Cr steels but enhanced corrosion of high-Cr steels, where S within the chromia scale led to its failure and subsequent Fe-rich oxide nodule growth. Ultimately, the results are rationalized by considering the thermodynamic and kinetic factors controlling the reaction.
Impurity driven corrosion behavior of HAYNES® 230® alloy in molten chloride Salt
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General model for calcite growth kinetics in the presence of impurity ions
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Properties of impurity-bearing ferrihydrite II: Insights into the surface structure and composition of pure, Al- and Si-bearing ferrihydrite from Zn(II) sorption experiments and Zn K-edge X-ray absorption spectroscopy
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Properties of impurity-bearing ferrihydrite III. Effects of Si on the structure of 2-line ferrihydrite
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