On the Causes of Natural Cementation in Sensitive Soils

1972 ◽  
Vol 9 (1) ◽  
pp. 117-119 ◽  
Author(s):  
Dwight A. Sangrey
Keyword(s):  
Mechanical Behaviour ◽  
Chemical Weathering ◽  
Unique Characteristic ◽  
X Ray Diffraction ◽  
Secondary Products ◽  
X Ray ◽  
Cemented Soils ◽  
Fresh Rock

A unique characteristic of many naturally cemented sensitive soils is that they are made up of finely ground fresh rock debris, "rock flour", much of which is very susceptable to chemical weathering or decomposition. Many of these minerals can be identified by X-ray diffraction. The decomposition of these minerals produces secondary products which can act as effective natural cements. A process is outlined whereby the sequence of deposition, weathering and cementation can account for the observed mechanical behaviour of naturally cemented soils.

Study of the mechanical behaviour of zirconium 702αin correlation with the texture determined by X-ray diffraction

2003 ◽  
Vol 100 (12) ◽  
pp. 1179-1183
Author(s):  
H. Francillette ◽  
A. Gavrus ◽  
J-L. Béchade
Keyword(s):  
Mechanical Behaviour ◽  
X Ray Diffraction ◽  
X Ray

Influence of Sterilization with γ-Irradiation in the Degradation of Plasma Sprayed Hydroxyapatite Coatings

2006 ◽  
Vol 514-516 ◽  
pp. 1054-1058 ◽  
Author(s):  
Tânia Costa ◽  
Ana Paula Serro ◽  
Eduardo Pires ◽  
Rogerio Colaço
Keyword(s):  
Mechanical Behaviour ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
Γ Irradiation ◽  
Water Contact ◽  
X Ray ◽  
Angle Measurements ◽  
Hydroxyapatite Coatings ◽  
Plasma Sprayed ◽  
Irradiation Process

The influence of sterilization with γ-irradiation in the properties of plasma sprayed hydroxyapatite (HAp) coatings used for medical implants is investigated in this work. HAp coatings were applied on titanium alloy substrates by plasma spraying and then submitted to 1 and 10 cycles of sterilization with γ-irradiation. As-applied HAp coatings were used as control samples. Afterwards, the modifications on the samples, induced by the irradiation process, were evaluated by X-ray diffraction and X-ray photoelectron spectroscopy (XPS). Water contact angle measurements as well as adhesion tests were also carried out in order to evaluate the influence of the irradiation process on the wettability and mechanical behaviour of the HAp coatings. No microstructural modifications were detected by X-ray diffraction after sterilization. However, the results show that sterilization with γ-irradiation originates modifications of the surface of HAp, as detected by a change of color of the coatings and by the XPS analysis. Nevertheless, these modifications do not result in significant changes in the wettability and mechanical behaviour of the HAp coatings.

Weathering evolution in lutites of the K/Pg transition red beds of the Tremp Group (Tremp-Isona Basin, south Pyrenees)

Clay Minerals ◽  
2017 ◽  
Vol 52 (1) ◽  
pp. 107-126
Author(s):  
J. Bastida ◽  
R. Linares ◽  
A.M. López Buendía ◽  
M.C. Osácar ◽  
J. Rosell ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Hierarchical Analysis ◽  
X Ray Diffraction ◽  
Red Beds ◽  
Anova Analysis ◽  
X Ray ◽  
South Central ◽  
Dry Seasons ◽  
Mineralogical Compositions ◽  
Maximum Development

AbstractThe Tremp–Isona basin (south-central Pyrenees, Lleida, Spain) shows maximum development of the Tremp Group (early Maastrichtian to late Paleocene) covering a wide geological record across the Cretaceous–Paleogene (K/Pg) boundary in continental facies. The mineralogy and geochemistry of lutites were used to assess the evolution of weathering from the Maastrichtian to the Eocene, and particularly for the red beds of the Lower Red and Upper Red Units (pre- and post-K/Pg, respectively). Chemical weathering decreased initially in the Maastrichtian (Gray Unit to Lower Red Unit), increasing subsequently from the Paleocene (Upper Red Unit) to Eocene units. ANOVA analysis of mineralogical compositions and cluster hierarchical analysis have been useful tools to select convenient lutites for assessment of weathering evolution by the chemical alteration index and by broadening of the 001 X-ray diffraction line of illite after ethylene glycol solvation. The lesser chemical weathering found in the Upper Red Unit (Danian) is interpreted in the context of relative warming and aridification, in climates of contrasting seasons and pronounced dry seasons.

The mechanism of bending in a plastically flexible crystal

2020 ◽  
Vol 56 (84) ◽  
pp. 12841-12844
Author(s):  
Subhrajyoti Bhandary ◽  
Amy J. Thompson ◽  
John C. McMurtrie ◽  
Jack K. Clegg ◽  
Peuli Ghosh ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Mechanical Behaviour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fluorine Interactions

The mechanism of plastic deformation in crystals of a trifluoromethylated benzamide derivative has been determined with micro-focused X-ray diffraction. Fuorine–fluorine interactions are propose to mediated the observed mechanical behaviour.

(U-Th-Sm)/He dating of supergene Fe duricrusts in NE French Guiana: implications of a multiproxy approach

2020 ◽  
Author(s):  
Beatrix Heller ◽  
Silvana Bressan Riffel ◽  
Cécile Gautheron ◽  
Thierry Allard ◽  
Guillaume Morin ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
French Guiana ◽  
X Ray Diffraction ◽  
X Ray ◽  
Weathering Processes ◽  
Erosion Rates ◽  
Large Dispersion ◽  
Icp Ms ◽  
Physical Erosion ◽  
Geochemical Analyses

<p>Laterites are developing under intense chemical weathering and low physical erosion rates. Despite their large extension at the Earth’s surface, there is still a lack of time constraints for their formation, evolution and relation with climatic change. Nevertheless, several chronological studies show that they represent a geological record at least all along the Cenozoic Era. Indeed, laterite samples often contain several coexisting generations of iron oxides and oxyhydroxides that indicate successive weathering processes due to the dissolution of previously formed phases followed by reprecipitation. This study focuses on the condition and chronology of weathering in Northeastern French Guiana which generated pedogenic iron crusts on Paleoproterozoic mafic and intermediate rocks. It offers the opportunity to document the evolution of this part of the Guyana Shield, known as a tectonically stable area since the Cretaceous. The two sampling sites, Kaw and Baduel, are paleosurfaces at 300m and 100m elevations, respectively, that have been dated previously by paleomagnetism, providing Eocene ages for both sites, albeit with some substantial uncertainties and dispersion [1].</p><p>Since the duricrust (top layer) of the lateritic profile is enriched in hematite and goethite, we aim to date those mineral phases using the (U-Th-Sm)/He method. Older ages are from Oligocene and Miocene epochs for the Kaw and Baduel sites, respectively, with a large dispersion in the age values, as expected from the presence of several generations of Fe-minerals. Identification of petrological relationship between these different generations is hindered by their intimate mixing. In order to overcome this difficulty and to identify the episodes of weathering and mineral precipitation, we coupled a number of mineralogical and geochemical analyses, namely through powder and single grain X-ray diffraction, energy dispersive X-ray spectrometry (SEM-EDS) and solution- and LA-ICP-MS. Data on formation ages of secondary iron phases will be discussed by reference to literature, in terms of geodynamic and paleoclimatic forcing.</p><p>[1] Théveniaut, H., and Freyssinet, P. (2002): Timing of lateritization on the Guiana Shield: synthesis of paleomagnetic results from French Guiana and Suriname. Palaeogeography, Palaeoclimatology, Palaeoecology (178) 91-117</p>

Modelling of mechanical behaviour of polyamide nanocomposite fibres using a three-phase Halpin-Tsai model

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Emilia Garofalo ◽  
Giovanna Maria Russo ◽  
Luciano Di Maio ◽  
Loredana Incarnato
Keyword(s):  
Mechanical Behaviour ◽  
Analytical Techniques ◽  
Elongational Flow ◽  
Polyamide 6 ◽  
Morphological Parameters ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
X Ray ◽  
Three Phase ◽  
Fibre Spinning

AbstractThe aim of the present study is to correlate the features of the elongational flow-induced morphology to the mechanical properties of polyamide based nanocomposite fibres. Particular attention was paid to modelling the mechanical behaviour of the hybrids which were produced by fibre spinning technique and collected at different draw ratios.Tensile properties of as-spun and stretched fibres were investigated and correlated to their nanostructure through analytical techniques sensitive to different aspects of the hybrids morphology, such as X-Ray diffraction and TEM analysis. In particular, the TEM images of the nanocomposite systems showed intercalated/exfoliated morphology in all hybrids. For this reason, a three-phase Halpin-Tsai model, based on polyamide-6 matrix, exfoliated clay platelets and nanolayer intercalated clusters, was used to fit the experimental data.This method was applied to calculate the Young’s modulus of nanocomposite fibres both as-spun and stretched ones. Moreover, the model was used for predicting the effect of various morphological parameters including the exfoliation degree, clay layer and cluster aspect ratio.

scholarly journals Understanding the thermo-mechanical behaviour of solid oxide fuel cell anodes using synchrotron X-ray diffraction

2018 ◽  
Vol 314 ◽  
pp. 156-164 ◽  
Author(s):  
T.M.M. Heenan ◽  
J.B. Robinson ◽  
X. Lu ◽  
B. Tjaden ◽  
A. Cervellino ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Mechanical Behaviour ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fuel Cell Anodes
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