Investigation of Micro-Sized Capsules at High Pressure by PALS Method

2017 ◽  
Vol 373 ◽  
pp. 284-287
Author(s):  
Bożena Zgardzińska ◽  
Maciej Tydda ◽  
Jan Wawryszczuk
Keyword(s):  
High Pressure ◽  
Solid Phase ◽  
Boundary Region ◽  
Argon Atmosphere ◽  
Phase Changes ◽  
Filling Material ◽  
Polymer Shell ◽  
Positron Annihilation Lifetime ◽  
The Core ◽  
Phase Pressure

The positron annihilation lifetime spectroscopy (PALS) was applied to investigate the properties of capsules composed of n-alkanes (filling material) and polymer (shell) in the broad range of pressures up to 450 MPa. These microcapsules aggregate into the grains having about 200 μm in diameter. Their properties were investigated as a function of pressure (p) at several selected temperatures: when the filling material is in liquid, rotator and solid phase. Pressure experiments were performed without gas access to the sample and in an argon atmosphere. Two o-Ps components were found, the longer-lived correspond to the filler material, and the shorter-lived one – to the shell. These components change with p; even a small pressure (6 MPa) reduces considerably the o-Ps lifetimes (τ). At 303 K the o-Ps lifetime in the core changes non-monotonically, and at 60 MPa τ is higher than at 20 MPa. The increase of pressure induces the phase changes in the filling material, and also produces the deformation of microcapsule aggregates and crash of small capsules at the grain boundary region. Internal structure of the microcapsules was observed by SEM.

scholarly journals O2volumes at high pressure from KClO4decomposition: D″ as a siderophile element pump instead of a lid on the core

2002 ◽  
Vol 3 (11) ◽  
pp. 1-26 ◽  
Author(s):  
D. Walker ◽  
S. M. Clark ◽  
L. M. D. Cranswick ◽  
M. C. Johnson ◽  
R. L. Jones
Keyword(s):  
High Pressure ◽  
The Core

Simultaneous sintering of low-melting-point Mg with high-melting-point Ti via a novel one-step high-pressure solid-phase sintering strategy

2021 ◽  
Vol 858 ◽  
pp. 158344
Author(s):  
Xuecheng Cai ◽  
Shuaijun Ding ◽  
Zhongjie Li ◽  
Xin Zhang ◽  
Kangkang Wen ◽  
...  
Keyword(s):  
High Pressure ◽  
Melting Point ◽  
Solid Phase ◽  
High Melting ◽  
High Melting Point ◽  
One Step

scholarly journals In situ observation of phase changes of a silica-supported cobalt catalyst for the Fischer–Tropsch process by the development of a synchrotron-compatible in situ/operando powder X-ray diffraction cell

2018 ◽  
Vol 25 (6) ◽  
pp. 1673-1682 ◽  
Author(s):  
Adam S. Hoffman ◽  
Joseph A. Singh ◽  
Stacey F. Bent ◽  
Simon R. Bare
Keyword(s):  
High Pressure ◽  
Elevated Pressure ◽  
Phase Changes ◽  
In Situ Observation ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
X Ray ◽  
And Performance ◽  
Co Nanoparticles

In situ characterization of catalysts gives direct insight into the working state of the material. Here, the design and performance characteristics of a universal in situ synchrotron-compatible X-ray diffraction cell capable of operation at high temperature and high pressure, 1373 K, and 35 bar, respectively, are reported. Its performance is demonstrated by characterizing a cobalt-based catalyst used in a prototypical high-pressure catalytic reaction, the Fischer–Tropsch synthesis, using X-ray diffraction. Cobalt nanoparticles supported on silica were studied in situ during Fischer–Tropsch catalysis using syngas, H2 and CO, at 723 K and 20 bar. Post reaction, the Co nanoparticles were carburized at elevated pressure, demonstrating an increased rate of carburization compared with atmospheric studies.

Natural Convection Inside a Bidisperse Porous Medium Enclosure

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Arunn Narasimhan ◽  
B. V. K. Reddy
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Natural Convection ◽  
Volume Fraction ◽  
Solid Phase ◽  
Darcy Number ◽  
The Core ◽  
Side Walls ◽  
Porous Blocks ◽  
Rayleigh Numbers

Bidisperse porous medium (BDPM) consists of a macroporous medium whose solid phase is replaced with a microporous medium. This study investigates using numerical simulations, steady natural convection inside a square BDPM enclosure made from uniformly spaced, disconnected square porous blocks that form the microporous medium. The side walls are subjected to differential heating, while the top and bottom ones are kept adiabatic. The bidispersion effect is generated by varying the number of blocks (N2), macropore volume fraction (ϕE), and internal Darcy number (DaI) for several enclosure Rayleigh numbers (Ra). Their effect on the BDPM heat transfer (Nu) is investigated. When Ra is fixed, the Nu increases with an increase in both DaI and DaE. At low Ra values, Nu is strongly affected by both DaI and ϕE. When N2 is fixed, at high Ra values, the porous blocks in the core region have negligible effect on the Nu. A correlation is proposed to evaluate the heat transfer from the BDPM enclosure, Nu, as a function of Raϕ, DaE, DaI, and N2. It predicts the numerical results of Nu within ±15% and ±9% in two successive ranges of modified Rayleigh number, RaϕDaE.

The Structure of Cosmic Ray Air Showers

1949 ◽  
Vol 2 (2) ◽  
pp. 184
Author(s):  
CBO Mohr
Keyword(s):  
High Pressure ◽  
Sea Level ◽  
Cosmic Ray ◽  
Low Density ◽  
Air Showers ◽  
Ionization Chambers ◽  
Single Chamber ◽  
Transition Effect ◽  
The Core ◽  
Rate Frequency

The structure of cosmic ray air showers at sea-level has been studied by an investigation of the burst rate frequency and the transition effect in lead, for cosmic ray bursts occurring simultaneously in two high-pressure ionization chambers with varying separation. Although extensive showers were responsible for all the coincidences observed with the larger chamber separations, they accounted for less than 3 per cent, of the bursts observed with a single chamber. Of the remaining 97 per cent., somewhat more than one-half appear to be due to nuclear disintegrations and the rest either to narrow showers of approximate radius 30 cm. or to the core of an extensive shower of low density. The extensive shower frequency was about 10 times that predicted by theory. The bearing of these results on present views of the origin and development of air showers is discussed.

Solid phase changes in chemically and biologically leached copper smelter slag

2017 ◽  
Vol 106 ◽  
pp. 97-101 ◽  
Author(s):  
Anna H. Kaksonen ◽  
Silja Särkijärvi ◽  
Jaakko A. Puhakka ◽  
Esa Peuraniemi ◽  
Saku Junnikkala ◽  
...  
Keyword(s):  
Solid Phase ◽  
Copper Smelter ◽  
Phase Changes ◽  
Smelter Slag

Features of metal destruction under pulse laser and beam-plasma exposure

2020 ◽  
Vol 10 ◽  
pp. 34-47
Author(s):  
V. A. Gribkov ◽  
◽  
S. V. Latyshev ◽  
V. N. Pimenov ◽  
S. A. Maslayev ◽  
...  
Keyword(s):  
High Pressure ◽  
Laser Radiation ◽  
Solid Phase ◽  
Ion Beam ◽  
Pulsed Laser ◽  
Average Energy ◽  
Destructive Effect ◽  
Pulsed Laser Radiation ◽  
Beam Plasma ◽  
Metal Materials

The features of the destructive effect of high-pressure generated under comparable conditions, namely, upon irradiation of target samples with pulsed laser radiation and beam-plasma flows created in Plasma Focus (PF) devices, on metal materials were studied. In both cases, close parameters of radiation-heat treatment were provided: power density q ~ 1010–1011 W/cm2 and pulse duration τ ~ 10 –100 ns. It have been shown that the double exposure of laser radiation to thin samples of vanadium and molybdenum with a thickness of 0.3 mm and 0.1 mm, respectively, leads to the formation of molten zones in the materials, inside which there were deep craters. The craters extended over the entire thickness of the samples, on the reverse side of which the recesses end with holes of ~ 0.1 mm for V and 0.2 mm for Mo. In a tungsten sample 0.2 mm thick, the depth of the craters in the molten zone was less than its thickness and there were microcracks on the back of the sample. Based on numerical estimates of the process under study, it was suggested that the observed effects are associated with the creation of high pressure zones of ~ 1 – 10 GPa in the irradiated targets, localized in microregions of radius r ~ 0.1 mm. In these zones, the behavior of the solid phase of the target materials, for which the tensile strength σB ≤ 1 GPa (V, Mo, W), under high pressure became close to the behavior of the liquid. The pseudo-liquid phase of the material was displaced from the center of the crater, where the pressure was maximum, to its periphery to the region of low pressure with the subsequent release of matter from the target through the irradiated surface at a speed of ~ 103 m/s. In experiments using the PF, the mechanism responsible for the formation of craters when a powerful pulsed laser radiation is applied to the target is not realized due to the different nature of the distribution of the absorbed energy density in the surface layer of the irradiated sample. The region in which the energy absorbed during the of particles implantation into the material was determined mainly by the average energy and the diameter of the ion beam (Еi ≈ 100  keV, d ~ 2 – 10 mm) and exceeds by one or two orders of magnitude the corresponding volume under laser irradiation.

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