Search results for "Ceramic"
showing 10 items of 2129 documents
Synthesis and characterization of praseodymium-containing ZrSiO4 solid solutions from gels
2011
Abstract The preparation and characterization of a series of praseodymium–zircon solid solution (Prx–ZrSiO4) materials with increasing nominal amounts of Pr is reported. Pr-doped zircon gels were prepared by gelling mixtures of zirconium n-propoxide, praseodymium acetylacetonate and tetraethylorthosilicate, and annealed over the range of temperature up to the formation of Pr–zircon solid solutions. The reaction sequence was followed by X-ray powder diffraction (XRD), ultraviolet–visible diffuse reflectance (DR) and infrared spectroscopy (IR). The first crystalline phase detected on annealing gels was a tetragonal praseodymium-containing ZrO2 phase (t-Pr–ZrO2). On further annealing, the subs…
A physical-based constitutive model for surface integrity prediction in machining of OFHC copper
2017
International audience; Due to the rising interest in predicting machined surface integrity and sustainability, various models for metal cutting simulation have been developed. However, their accuracy depends deeply on the physical description of the machining process. This study aims to develop an orthogonal cutting model for surface integrity prediction, which includes a physical-based constitutive model of Oxygen Free High Conductivity (OFHC) copper. This constitutive model incorporates the effects of the state of stress and microstructure on the work material behavior, as well as a dislocation density-based model for surface integrity prediction. The coefficients of the constitutive mod…
Flash microwave synthesis and sintering of nanosized La0.75Sr0.25Cr0.93Ru0.07o3–δ for fuel cell application.
2009
International audience; Perovskite-oxide nanocrystals of La0.75Sr0.25Cr0.93Ru0.07O3–δ with a mean size around 10 nm were prepared by microwave flash synthesis. This reaction was performed in alcoholic solution using metallic salts, sodium ethoxide and microwave autoclave. The obtained powder was characterised after purification by energy dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), BET adsorption technique, photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM). The results show that integrated perovskite-type phase and uniform particle size were obtained in the microwave treated samples. At last the synthesised powder was directly used in a sin…
γ-ray induced GeODC(II) centers in germanium doped α-quartz crystal
2011
International audience; Main luminescence of α-quartz crystal doped with germanium results from the luminescence of a self-trapped exciton (STE) near germanium. In as grown Ge-doped α-quartz crystal, the luminescence associated with the twofold coordinated Ge center (GeODC) in amorphous silica glass doped with germanium, was never observed. In this work, we performed experiments to investigate if a GeODC like luminescence could appear after a γ-irradiation of a Ge-doped α-quartz crystal. The answer is positive: under excitation with pulsed light of an ArF laser (193 nm): a new luminescence with two bands -- a blue one associated to a time constant of about 100 μs appears and another one wit…
Raman investigation of the drawing effects on Ge-doped fibers
2011
International audience; We have investigated the Raman activity of various germanosilicate fibers and their associated preforms. Our data indicate an enhancement in small rings' (3-member rings) concentration in the silica-based matrix of the fibers during the drawing process. The generation of such rings appears compatible with an increase of the sample density and fictive temperature. The data regarding the drawing effects on the fiber stress appear less clear, and it is possible to suggest that in some cases the drawing could lower the tensile stress. Finally we have also provided evidence that changing the drawing conditions within the usual range of application leads to no significant …
Radiation-induced defects in fluorine-doped silica-based optical fibers: Influence of a pre-loading with H2
2009
International audience; We investigated the effects of 10-keV X-ray radiation on the transmission properties of F-doped optical fibers in the 200–850 nm range of wavelengths (1.5–6 eV). We also studied the influence of pre-loading this kind of fibers with hydrogen on its radiation sensitivity. Our results showed that, for our experimental conditions (pre-treatment with H2 several months before irradiation with diffusion of all the H2 out the fiber core and cladding before X-ray exposure), this pre-treatment increases the radiation-induced attenuation in the ultraviolet part (200–300 nm) of the spectrum. A previous H2-loading has no influence at greater wavelengths. The nature of the radiati…
Interaction between armenian-clay-based ceramics and model wines
2022
The use of ceramics for the transformation or conservation of wine has existed since the origins of wine, but the impact of ceramics on wine has not received much attention.However, in contact with the wine, ceramics are generally not neutral materials and the constituent minerals of ceramics are led to dissolve. This work mainly aims to study the migration of elements from ceramics to wine.To our knowledge, this question has so not been addressed so far, at least with our chosen approach.This study required the prior characterization of the materials and the ceramics produced in the laboratory.The analyzes (XRF, XRD, and SEM/EDX) revealed that the natural material used for the manufacture …
Entanglements, transmission processes and social identities. The technical traditions of ceramics in the Three-Lakes region and its margins (3600-300…
2019
In Western Europe, the second half of the 4th millennium is a turning point. On the Swiss Plateau, this phase is characterized by the end of Middle Neolithic cultures (Cortaillod and Pfyn) around 3550 BCE, and the emergence of Horgen after 3250 BCE. The transition between these two phases is now better documented thanks to Port-Conty type and Pfyn/Horgen settlements dated around 3400 BCE. This work aims to identify the cultural substract at the origin of the Horgen by characterizing the technical identities and entanglements at the end of the 4th millennium, then by identifying over time the transmission or abandonment of certain ways of making pots in order to determine the share of local …
-3400 autour du lac de Bienne
2015
La question du substrat culturel à l’origine du Néolithique récent reste, pour la Suisse occidentale, toujours ouverte. Ces changements viennent-ils plutôt du fond Cortaillod (de type Port-Conty) local, ou bien de la culture de Pfyn, présente en Suisse orientale. De plus, est-il possible de mettre en évidence des phénomènes de diffusion de l’émergence du Néolithique récent vers l’Ouest, en comparant notamment avec le Horgen du Jura français, ou le Néolithique récent du Bassin parisien.Ce poster présente les résultats préliminaires d'un mémoire de recherche de Master 2. Il concerne l'étude technologique des poteries issues de trois sites voisins et contemporains : Sutz-Lattrigen Riedstation,…
LE SITE CAMPANIFORME DE LUX LA PERROUZE (SAÔNE-ET-LOIRE)
2014
Le site de Lux La Perrouze (Saône-et-Loire) apporte de nouvelles données sur le Campaniforme bourguignon par la découverte d’une petit ensemble céramique remarquablement homogène, contenu dans le remplissage de quatre structures en creux. Cet ensemble se compose essentiellement de céramique commune, mais quelques gobelets décorés sont également à signaler. L’étude de ce mobilier permet de souligner la remarquable homogénéité des productions du groupe campaniforme bourguignon-jurassien tant pour leur chronologie que pour leurs affinités culturelles. The site of Lux La Perrouze (Saône-et-Loire) has provided new data on the Bell Beaker culture of Burgundy by the discovery of a small and remark…