Pore formation during dehydration of a polycrystalline gypsum sample observed and quantified in a time-series synchrotron X-ray micro-tomography experiment

Abstract. We conducted an in-situ X-ray micro-computed tomography heating experiment at the Advanced Photon Source (USA) to dehydrate an unconfined 2.3 mm diameter cylinder of Volterra Gypsum. We used a purpose-built X-ray transparent furnace to heat the sample to 388 K for a total of 310 min to acquire a three-dimensional time-series tomography dataset comprising nine time steps. The voxel size of 2.2 μm3 proved sufficient to pinpoint reaction initiation and the organization of drainage architecture in space and time. We observed that dehydration commences across a narrow front, which propagates from the margins to the centre of the sample in more than four hours. The advance of this front can be fitted with a square-root function, implying that the initiation of the reaction in the sample can be described as a diffusion process. Novel parallelized computer codes allow quantifying the geometry of the porosity and the drainage architecture from the very large tomographic datasets (20483 voxels) in unprecedented detail. We determined position, volume, shape and orientation of each resolvable pore and tracked these properties over the duration of the experiment. We found that the pore-size distribution follows a power law. Pores tend to be anisotropic but rarely crack-shaped and have a preferred orientation, likely controlled by a pre-existing fabric in the sample. With on-going dehydration, pores coalesce into a single interconnected pore cluster that is connected to the surface of the sample cylinder and provides an effective drainage pathway. Our observations can be summarized in a model in which gypsum is stabilized by thermal expansion stresses and locally increased pore fluid pressures until the dehydration front approaches to within about 100 μm. Then, the internal stresses are released and dehydration happens efficiently, resulting in new pore space. Pressure release, the production of pores and the advance of the front are coupled in a feedback loop.

Download Full-text

Pore formation during dehydration of polycrystalline gypsum observed and quantified in a time-series synchrotron radiation based X-ray micro-tomography experiment

Solid Earth Discussions ◽

10.5194/sed-3-857-2011 ◽

2011 ◽

Vol 3 (2) ◽

pp. 857-900 ◽

Cited By ~ 4

Author(s):

F. Fusseis ◽

C. Schrank ◽

J. Liu ◽

A. Karrech ◽

S. Llana-Fúnez ◽

...

Keyword(s):

Time Series ◽

Pore Space ◽

Three Dimensional ◽

Internal Stresses ◽

Micro Computed Tomography ◽

X Ray ◽

Computer Codes ◽

Micro Tomography ◽

Effective Drainage

Abstract. We conducted an in-situ X-ray micro-computed tomography heating experiment at the Advanced Photon Source (USA) to dehydrate an unconfined 2.3 mm diameter cylinder of Volterra Gypsum. We used a purpose-built X-ray transparent furnace to heat the sample to 388 K for a total of 310 min to acquire a three-dimensional time-series tomography dataset comprising nine time steps. The voxel size of 2.2 μm3 proved sufficient to pinpoint reaction initiation and the organization of drainage architecture in space and time. We observed that dehydration commences across a narrow front, which propagates from the margins to the centre of the sample in more than four hours. The advance of this front can be fitted with a square-root function, implying that the initiation of the reaction in the sample can be described as a diffusion process. Novel parallelized computer codes allow quantifying the geometry of the porosity and the drainage architecture from the very large tomographic datasets (6.4 × 109 voxel each) in unprecedented detail. We determined position, volume, shape and orientation of each resolvable pore and tracked these properties over the duration of the experiment. We found that the pore-size distribution follows a power law. Pores tend to be anisotropic but rarely crack-shaped and have a preferred orientation, likely controlled by a pre-existing fabric in the sample. With on-going dehydration, pores coalesce into a single interconnected pore cluster that is connected to the surface of the sample cylinder and provides an effective drainage pathway. Our observations can be summarized in a model in which gypsum is stabilized by thermal expansion stresses and locally increased pore fluid pressures until the dehydration front approaches to within about 100 μm. Then, the internal stresses are released and dehydration happens efficiently, resulting in new pore space. Pressure release, the production of pores and the advance of the front are coupled in a feedback loop. We discuss our findings in the context of previous studies.

Download Full-text

Development of synchrotron X-ray micro-tomography under extreme conditions of pressure and temperature

Journal of Synchrotron Radiation ◽

10.1107/s1600577516016623 ◽

2017 ◽

Vol 24 (1) ◽

pp. 240-247 ◽

Cited By ~ 8

Author(s):

M. Álvarez-Murga ◽

J. P. Perrillat ◽

Y. Le Godec ◽

F. Bergame ◽

J. Philippe ◽

...

Keyword(s):

High Pressure ◽

Structural Changes ◽

Three Dimensional ◽

Crystallographic Structure ◽

Three Dimensional Imaging ◽

X Ray ◽

Wide Range ◽

Micro Tomography ◽

Non Destructive

X-ray tomography is a non-destructive three-dimensional imaging/microanalysis technique selective to a wide range of properties such as density, chemical composition, chemical states and crystallographic structure with extremely high sensitivity and spatial resolution. Here the development of in situ high-pressure high-temperature micro-tomography using a rotating module for the Paris–Edinburgh cell combined with synchrotron radiation is described. By rotating the sample chamber by 360°, the limited angular aperture of ordinary high-pressure cells is surmounted. Such a non-destructive high-resolution probe provides three-dimensional insight on the morphological and structural evolution of crystalline as well as amorphous phases during high pressure and temperature treatment. To demonstrate the potentials of this new experimental technique the compression behavior of a basalt glass is investigated by X-ray absorption tomography, and diffraction/scattering tomography imaging of the structural changes during the polymerization of C60 molecules under pressure is performed. Small size and weight of the loading frame and rotating module means that this apparatus is portable, and can be readily installed on most synchrotron facilities to take advantage of the diversity of three-dimensional imaging techniques available at beamlines. This experimental breakthrough should open new ways for in situ imaging of materials under extreme pressure–temperature–stress conditions, impacting diverse areas in physics, chemistry, geology or materials sciences.

Download Full-text

In-Situ X-Ray Tomography on Permeability Evolution of C/SiC Porous Ceramic for Hypersonic Vehicles

10.21203/rs.3.rs-557941/v1 ◽

2021 ◽

Author(s):

Bo Zhang ◽

Haiming Huang ◽

Shengchuan Wu ◽

Weijie Li ◽

Jie Huang ◽

...

Keyword(s):

Cooling System ◽

Pore Space ◽

Porous Ceramic ◽

Three Dimensional ◽

Hypersonic Vehicles ◽

Permeability Evolution ◽

X Ray ◽

Tomography System ◽

X Ray Imaging

Abstract Transpiration cooling system in hypersonic vehicles still remains a challenge due to the limitations of observing permeability and microstructure evolution of porous medium filled with coolant. To tackle this problem, a novel compression-permeation device is designed with high-resolution X-ray tomography system, and then an investigation on permeability evolution mechanism of a C/SiC porous ceramic under pressure is performed using in-situ X-ray imaging and the compression-permeation device. The experimental results indicate that the pore-space fluid flow is displayed in terms of three-dimensional streamlines, making the permeability mechanism clear. Meanwhile the porosity along the thickness of ceramic under pressure has been obtained by synchrotron tomography testing, and it is also verified that the porosity of C/SiC ceramic fabricated in our research group is basically uniform (>95.4%) along the thickness. Furthermore, we have found the evolution rule for permeability of porous ceramic with water, which depends on the variation of its microstructure under different loads.

Download Full-text

Assessment of Geometrical and Transport Properties of a Fibrous C/C Composite Preform Using x-ray Computerized Micro-tomography: Part I. Image Acquisition and Geometrical Properties

Journal of Materials Research ◽

10.1557/jmr.2005.0311 ◽

2005 ◽

Vol 20 (9) ◽

pp. 2328-2339 ◽

Cited By ~ 32

Author(s):

Olivia Coindreau ◽

Gérard L. Vignoles

Keyword(s):

Pore Space ◽

Three Dimensional ◽

Internal Surface ◽

Carbon Composite ◽

Internal Surface Area ◽

X Ray ◽

Geometrical Properties ◽

Original Algorithm ◽

Micro Tomography

Raw and partially infiltrated carbon–carbon composite preforms have been scanned by high-resolution synchrotron radiation x-ray computerized micro-tomography. Three dimensional high-quality images of the pore space have been produced at two distinct resolutions and have been used for the computation of geometrical quantities: porosity, internal surface area, pore sizes, and their distributions, as well as local and average fiber directions. Determination of the latter property makes use of an original algorithm. All quantities have been compared to experimental data with good results. Structural models appropriate for ideal families of cylinders are shown to represent adequately the actual pore space.

Download Full-text

Morphology and Mechanical Properties of Fossil Diatom Frustules from Genera of Ellerbeckia and Melosira

Nanomaterials ◽

10.3390/nano11061615 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1615

Author(s):

Qiong Li ◽

Jürgen Gluch ◽

Zhongquan Liao ◽

Juliane Posseckardt ◽

André Clausner ◽

...

Keyword(s):

Fracture Behavior ◽

Three Dimensional ◽

Mechanical Tests ◽

Fracture Force ◽

Thickness Change ◽

X Ray ◽

Transmission Electron ◽

Percentage Concentration ◽

Morphology Characterization

Fossil frustules of Ellerbeckia and Melosira were studied using laboratory-based nano X-ray tomography (nano-XCT), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Three-dimensional (3D) morphology characterization using nondestructive nano-XCT reveals the continuous connection of fultoportulae, tube processes and protrusions. The study confirms that Ellerbeckia is different from Melosira. Both genera reveal heavily silicified frustules with valve faces linking together and forming cylindrical chains. For this cylindrical architecture of both genera, valve face thickness, mantle wall thickness and copulae thickness change with the cylindrical diameter. Furthermore, EDS reveals that these fossil frustules contain Si and O only, with no other elements in the percentage concentration range. Nanopores with a diameter of approximately 15 nm were detected inside the biosilica of both genera using TEM. In situ micromechanical experiments with uniaxial loading were carried out within the nano-XCT on these fossil frustules to determine the maximal loading force under compression and to describe the fracture behavior. The fracture force of both genera is correlated to the dimension of the fossil frustules. The results from in situ mechanical tests show that the crack initiation starts either at very thin features or at linking structures of the frustules.

Download Full-text

In Situ Three-Dimensional Synchrotron X-Ray Nanotomography of the (De)lithiation Processes in Tin Anodes

Angewandte Chemie International Edition ◽

10.1002/anie.201310402 ◽

2014 ◽

Vol 53 (17) ◽

pp. 4460-4464 ◽

Cited By ~ 72

Author(s):

Jiajun Wang ◽

Yu-chen Karen Chen-Wiegart ◽

Jun Wang

Keyword(s):

Three Dimensional ◽

X Ray

Download Full-text

A microscopic approach to investigate bacteria under in situ conditions in sea-ice samples

Annals of Glaciology ◽

10.3189/172756401781818275 ◽

2001 ◽

Vol 33 ◽

pp. 304-310 ◽

Cited By ~ 76

Author(s):

Karen Junge ◽

Christopher Krembs ◽

Jody Deming ◽

Aaron Stierle ◽

Hajo Eicken

Keyword(s):

Sea Ice ◽

Pore Space ◽

Three Dimensional ◽

Epifluorescence Microscopy ◽

Microbial Populations ◽

Microbial Life ◽

Dimensional Network ◽

In Situ Conditions ◽

Fluorescent Stain

AbstractMicrobial populations and activity within sea ice have been well described based on bulk measurements from melted sea-ice samples. However, melting destroys the micro-environments within the ice matrix and does not allow for examination of microbial populations at a spatial scale relevant to the organism. Here, we describe the development of a new method allowing for microscopic observations of bacteria localized within the three-dimensional network of brine inclusions in sea ice under in situ conditions. Conventional bacterial staining procedures, using the DNA-specific fluorescent stain DAPI, epifluorescence microscopy and image analysis, were adapted to examine bacteria and their associations with various surfaces within microtomed sections of sea ice at temperatures from −2° to −15°C. The utility and sensitivity of the method were demonstrated by analyzing artificial sea-ice preparations of decimal dilutions of a known bacterial culture. When applied to natural, particle-rich sea ice, the method allowed distinction between bacteria and particles at high magnification. At lower magnifications, observations of bacteria could be combined with those of other organisms and with morphology and particle content of the pore space. The method described here may ultimately aid in discerning constraints on microbial life at extremely low temperatures.

Download Full-text