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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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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Anomalous density and elastic properties of basalt at high pressure: Reevaluating of the effect of melt fraction on seismic velocity in the Earth's crust and upper mantle

Independent measurements of the volumetric and elastic properties of Columbia River basalt glass were made up to 5.5 GPa by high-pressure X-ray microtomography and GHz-ultrasonic interferometry, respectively. The Columbia River basalt displays P and S wave velocity minima at 4.5 and 5 GPa, respectively, violating Birch’s law. These data constrain the pressure dependence of the density and elastic moduli at high pressure, which cannot be modeled through usual equations of state nor determined by stepwise integrating the bulk sound velocity as is common practice. We propose a systematic variation in compression behavior of silicate glasses that is dependent on the degree of polymerization and arises from the flexibility of the aluminosilicate network. Likewise, this behavior likely persists into the liquid state for basaltic melts resulting in weak pressure dependence for P wave velocities perhaps to depths of the transition zone. By modeling the effect of partial melt on P wave velocity reductions it is suggested that melt fraction determined by seismic velocity variations may be significantly overestimated in the crust and upper mantle.

58 GEOSCIENCES↗
DOE OSTI2016

Measurements of CO 2 ‐brine relative permeability in Berea sandstone using pressure taps and a long core

Abstract We measured CO 2 ‐brine relative permeability by performing five steady‐state primary drainage experiments in a 116 mD Berea sandstone core at 20°C and 10.34 MPa. We used a long (60.8 cm) core and four pressure taps to study and minimize end effects that can plague CO 2 ‐brine relative permeability measurements, and we obtained in situ saturation profiles using a medical X‐ray Computed Tomography (CT) scanner. We found that entrance and exit effects propagated ∼5 cm into the core, but the center sections of the core had uniform saturation. From the saturations and pressure drops, we obtained both CO 2 and brine relative permeability in the center sections. We also obtained CO 2 relative permeability at the entrance section where the brine saturation was lower and not uniform. The 15‐cm long exit section of the core had non‐uniform saturation and a measured pressure drop that was on the order of the capillary pressure and hence was unreliable for calculating relative permeability. We found that the CO 2 and brine relative permeabilities determined in five experiments were consistent with each other and followed two simple Corey‐type models that are similar to those seen in oil‐brine relative permeability measurements. We discuss why end effects are much greater in the CO 2 ‐brine system than in oil‐brine systems, and how this is a possible explanation of the low CO 2 relative permeabilities recently reported for the CO 2 ‐brine systems. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd.

Chen, Xiongyu↗
DOE OSTI2023

The stress state in bismuth to 298 GPa and its use as a pressure transmitting medium and pressure marker at multi-megabar pressures

We have conducted diffraction studies of bismuth (Bi) to 298 GPa using both conventional and toroidal diamond anvil cells (DACs) to investigate its suitability as a pressure-transmitting medium (PTM) to such pressures. Using microfocused x-ray beams, we have determined the pressure dependence of the uniaxial stress component (⁠t⁠) in cubic Bi-V from 7 to 298 GPa and find that at 298 GPa, t < 0.5 GPa. Bi-V, therefore, cannot support significant shear stresses, making it an excellent PTM. We have also measured the compressibility of Bi-V against that of copper (Cu) and gold (Au), allowing it to be used as a pressure marker as well as a PTM.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1979

The relation of the yield stress of high-pressure anvils to the pressure attained at yielding and the ultimate attainable pressure

A sensitive microprofilometer was used to determine the onset of yielding in the anvils of a supported opposed anvil device for the case of 3% cobalt-cemented tungsten carbide as the anvil material. In addition, it is shown how the commencement of yielding in boron carbide pistons, the yield strength being known, can be used to obtain the transition pressure to a conducting phase in gallium phosphide. The transition pressures of bismuth and gallium phosphide are obtained and it is found that these transitions are extremely close to the maximum attainable pressure in, respectively, a maraging steel and a 3% cobalt-cemented tungsten carbide.

Panda, P. C.↗
DOE OSTI2013

The influence of pressure on the phase stability of nanocomposite Fe{sub 89}Zr{sub 7}B{sub 4} during heating from energy dispersive x-ray diffraction

Nanocomposite materials consisting of small crystalline grains embedded within an amorphous matrix show promise for many soft magnetic applications. The influence of pressure is investigated by in situ diffraction of hammer milled Fe{sub 89}Zr{sub 7}B{sub 4} during heating through the {alpha}{yields}{gamma} Fe transition at 0.5, 2.2, and 4.9 GPa. The changes in primary and secondary crystallization onset are described by diffusion and the energy to form a critical nucleus within the framework of classical nucleation theory.

36 MATERIALS SCIENCE↗