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Results for “PRECIPITATION”
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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H-phase precipitation and its effects on martensitic transformation in NiTi-Hf high-temperature shape memory alloys
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Impact of elevated CO2 concentrations on carbonate mineral precipitation ability of sulfate-reducing bacteria and implications for CO2 sequestration
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The relationships between insoluble precipitation residues, clouds, and precipitation over California’s southern Sierra Nevada during winter storms
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Upscaling calcium carbonate precipitation rates from pore to continuum scale
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A microstructure-based modeling approach to predict the mechanical properties of Zr alloy with hydride precipitates
In nuclear reactors, hydrides can form in fuel cladding due to hydrogen absorption in ZIrcaloy and cause embrittlement. This work presents a microstructure-based finite element model to predict the stress-strain response of Zircaloy containing hydrides. Quantitative microstructural details extracted from scanning electron microscopy (SEM) images were used to generate heterogeneous microstructures including the morphology and spatial distribution of hydrides. The constitutive material model for zircaloy in this study is based on crystal plasticity theory which considers the hexagonal close-packed (HCP) atomic structure of Zircaloy material. The hydrides were modeled as brittle material along with a damage model. Hydride formation inside the zircoloy matrix results in residual stress. This phenomenon is also captured in this model. A parametric study has been conducted to understand the effect of volume fraction, orientation, and lamellae thickness of the hydride phase on the mechanical properties of the overall material.
Experimental and numerical study of permeability reduction caused by asphaltene precipitation and deposition during CO2 huff and puff injection in Eagle Ford shale
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Dissolved sulfide-catalyzed precipitation of disordered dolomite: Implications for the formation mechanism of sedimentary dolomite
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Precipitation pathways for ferrihydrite formation in acidic solutions
In this study, iron oxides and oxyhydroxides form via Fe 3+ hydrolysis and polymerization in many aqueous environments, but the pathway from Fe 3+ monomers to oligomers and then to solid phase nuclei is unknown. In this work, using combined X-ray, UV–vis, and Mössbauer spectroscopic approaches, we were able to identify and quantify the long-time sought ferric speciation over time during ferric oxyhydroxide formation in partially-neutralized ferric nitrate solutions ([Fe 3+ ] = 0.2 M, 1.8 < pH < 3). Results demonstrate that Fe exists mainly as Fe(H 2 O) 6 3+ , μ-oxo aquo dimers and ferrihydrite, and that with time, the μ-oxo dimer decreases while the other two species increase in their concentrations. No larger Fe oligomers were detected. Given that the structure of the μ-oxo dimer is incompatible with those of all Fe oxides and oxyhydroxides, our results suggest that reconfiguration of the μ-oxo dimer structure occurs prior to further condensation leading up to the nucleation of ferrihydrite. The structural reconfiguration is likely the rate-limiting step involved in the nucleation process.
Stable nitride precipitation in additively manufactured nickel superalloys
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Rainfall frequency analysis for ungauged regions using remotely sensed precipitation information
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