Permanent densification of silica glass for pressure calibration between 9 and 20 GPa at ambient temperature

2019 ◽  
Vol 39 (1) ◽  
pp. 117-130 ◽  
Author(s):  
Michael Guerette ◽  
Alexandra Poltorak ◽  
Yingwei Fei ◽  
Timothy A. Strobel
Keyword(s):  
Ambient Temperature ◽  
Silica Glass ◽  
Pressure Calibration ◽  
Permanent Densification

Ab initio simulation of permanent densification in silica glass

2017 ◽  
Vol 96 (5) ◽  
Author(s):  
Emina Ryuo ◽  
Daisuke Wakabayashi ◽  
Akihide Koura ◽  
Fuyuki Shimojo
Keyword(s):  
Ab Initio ◽  
Silica Glass ◽  
Ab Initio Simulation ◽  
Permanent Densification

Permanent densification of compressed silica glass: a Raman-density calibration curve

2012 ◽  
Vol 25 (2) ◽  
pp. 025402 ◽  
Author(s):  
T Deschamps ◽  
A Kassir-Bodon ◽  
C Sonneville ◽  
J Margueritat ◽  
C Martinet ◽  
...  
Keyword(s):  
Calibration Curve ◽  
Silica Glass ◽  
Permanent Densification

Designing Glasses with Tunable Structure and Properties by Computer Simulation

2009 ◽  
Vol 1229 ◽  
Author(s):  
Liping Huang ◽  
Fenglin Yuan ◽  
Qing Zhao
Keyword(s):  
Silica Glass ◽  
Structural Transition ◽  
Materials Science ◽  
Dynamics Simulation ◽  
Structure And Properties ◽  
Mechanical Behaviors ◽  
Conceptual Foundation ◽  
High Pressure And Temperature ◽  
Tunable Structure ◽  
Permanent Densification

AbstractA normal solid becomes stiffer when squeezed and softer when heated. In contrast, silica glass behaves the opposite way: its elastic moduli decrease upon compression and increase upon heating. Silica glass is also known to densify under compression and radiations. These have been long-standing mysteries in materials science. Using molecular dynamics simulation, we uncovered the structural origins of the anomalous thermo-mechanical behaviors and mechanisms of permanent densification in silica glass. Accordingly, these anomalies can be attributed to localized structural transitions, analogous to those that occur in the crystalline counterparts. The irreversible densification in silica glass is achieved through structural transition involving bond breaking and re-formation under a combination of high pressure and temperature. We further revealed that the anomalous thermo-mechanical behaviors are inherently connected to the ability of the glass to undergo permanent densification. Our computer simulations demonstrate that by processing in ways that gradually eliminates anomalous thermo-mechanical behaviors, degree of the glass to undergo densification can be eventually eradicated. This provides the conceptual foundation for the bottom-up design of new glasses with tunable structure and properties.

SEM of non-coated hepatocellular cytoskeleton of perfused livers

1984 ◽  
Vol 42 ◽  
pp. 306-307
Author(s):  
S.W. French ◽  
N.C. Benson ◽  
C. Davis-Scibienski
Keyword(s):  
Ambient Temperature ◽  
Critical Point ◽  
Protease Inhibitors ◽  
Metal Deposition ◽  
Heat Damage ◽  
Detergent Extraction ◽  
Cytoskeletal Elements ◽  
Triton X ◽  
Excised Tissue

Previous SEM studies of liver cytoskeletal elements have encountered technical difficulties such as variable metal coating and heat damage which occurs during metal deposition. The majority of studies involving evaluation of the cell cytoskeleton have been limited to cells which could be isolated, maintained in culture as a monolayer and thus easily extracted. Detergent extraction of excised tissue by immersion has often been unsatisfactory beyond the depth of several cells. These disadvantages have been avoided in the present study. Whole C3H mouse livers were perfused in situ with 0.5% Triton X-100 in a modified Jahn's buffer including protease inhibitors. Perfusion was continued for 1 to 2 hours at ambient temperature. The liver was then perfused with a 2% buffered gluteraldehyde solution. Liver samples including spontaneous tumors were then maintained in buffered gluteraldehyde for 2 hours. Samples were processed for SEM and TEM using the modified thicarbohydrazide procedure of Malich and Wilson, cryofractured, and critical point dried (CPD). Some samples were mechanically fractured after CPD.

Formation of Dislocation Channels in Neutron Irradiated Molybdenum

1972 ◽  
Vol 30 ◽  
pp. 672-673
Author(s):  
S. Mahajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Channel Formation ◽  
Early Stages ◽  
Transmission Electron ◽  
Three Stages ◽  
Two Stages ◽  
Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

Crystallographic Characterization of Dislocation Loops in Irradiated Tungsten

1968 ◽  
Vol 26 ◽  
pp. 290-291
Author(s):  
Robert C. Rau
Keyword(s):  
Electron Microscope ◽  
Ambient Temperature ◽  
Dislocation Loops ◽  
Polycrystalline Specimen ◽  
Post Irradiation ◽  
Neutron Fluences

Previous work has shown that post-irradiation annealing, at temperatures near 1100°C, produces resolvable dislocation loops in tungsten irradiated to fast (E > 1 MeV) neutron fluences of about 4 x 1019 n/cm2 or greater. To crystallographically characterize these loops, tilting experiments were carried out in the electron microscope on a polycrystalline specimen which had been irradiated to 1.5 × 1021 n/cm2 at reactor ambient temperature (∼ 70°C), and subseouently annealed for 315 hours at 1100°C. This treatment produced large loops averaging 1000 Å in diameter, as shown in the micrographs of Fig. 1. The orientation of this grain was near (001), and tilting was carried out about axes near [100], [10] and [110].

Voids in Quenched Nickel

1968 ◽  
Vol 26 ◽  
pp. 266-267
Author(s):  
J. J. Laidler
Keyword(s):  
Electron Beam ◽  
Ambient Temperature ◽  
Cooling Rate ◽  
Three Dimensional ◽  
Cooling Curve ◽  
Polycrystalline Nickel ◽  
Quenching Temperature ◽  
Long Tail ◽  
Diffusion Pump

The presence of three-dimensional voids in quenched metals has long been suspected, and voids have indeed been observed directly in a number of metals. These include aluminum, platinum, and copper, silver and gold. Attempts at the production of observable quenched-in defects in nickel have been generally unsuccessful, so the present work was initiated in order to establish the conditions under which such defects may be formed.Electron beam zone-melted polycrystalline nickel foils, 99.997% pure, were quenched from 1420°C in an evacuated chamber into a bath containing a silicone diffusion pump fluid . The pressure in the chamber at the quenching temperature was less than 10-5 Torr . With an oil quench such as this, the cooling rate is approximately 5,000°C/second above 400°C; below 400°C, the cooling curve has a long tail. Therefore, the quenched specimens are aged in place for several seconds at a temperature which continuously approaches the ambient temperature of the system.

Sign in / Sign up

Export Citation Format

Share Document