Tesi sul tema "Frittage à l'état solide"
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Martin, Sylvain. "Contribution à la modélisation du frittage en phase solide". Thesis, Compiègne, 2014. http://www.theses.fr/2014COMP2144/document.
This thesis deals with the simulation of the sintering of nuclear fuel on a pellet scale. The goal is to develop numerical tools which can contribute to a better understandingof the physical phenomena involved in the sintering process. Hence, a multi scale approach is proposed. First of all, a Discrete Element model is introduced. It aims at modeling the motion of particles on a Representative Elementary Volume scale using an original Discrete Element Method. The latter is a Non Smooth Method called Contact Dynamics. Recently, there have been numerous papers about the simulation of sintering using Discrete Element Method. As far as we know, all these papers use smooth methods. Different studies show that the results match well experimental data. However, some limits come from the fact that smooth methods use an explicit scheme which needsvery small time steps. In order to obtain an acceptable time step, the mass of particles have to be dramatically increased. The Non Smooth Contact Dynamics uses an implicit scheme, thus time steps can be much larger without scaling up the mass of particles. The comparison between smooth and non smooth approaches shows thatour method leads to a more realistic representation of rearrangement. An experimental validation using synchrotron X-Ray microtomography is then presented, followedby a parametric study on the sintering of bimodal powders that aims at showing the capacity of this model.The second part presents a mechanical model on the sub-Granular scale, using a Finite Element method. This targets a better understanding of the behavior of twograins in contact. The model is currently being developped but the first results already show that some parameters like the shape of the surface of the neck are very sensitive.In the future, the Non smooth Contact Dynamics model of sintering may be improvedusing the results obtained by the sub-Granular scale mechanical model
Deplancke, Tiana. "Approche des mécanismes de frittage du UHMWPE : étude du comportement mécanique à l'état solide et à l'état fondu". Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-01018639.
Cumbunga, Judice. "Modeling and optimization of the thermomechanical behavior of metal partsobtained by sintering : Numerical and experimental approach". Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCA006.
The pressureless solid-state sintering process is a thermal treatment applied to improve or adjust material properties according to its field of application, given its ability to handle parts with complex geometries, high dimensional accuracy, small dimensions and suitability for soft and hard materials. However, modeling this type of process proves to be a difficult task, as an appropriate model needs to take into account various aspects, namely the multi-scale and multi-physics character of the problem, the high non-linearity of the material, the complexity of the geometries and, last but not least, the type of boundary conditions. From an industrial point of view, the appropriate heat treatment parameters are mainly obtained by trial and error. Numerical simulation makes it possible to reduce the cost of these tests and to provide more useful predictions or recommendations for actual production, than sintering tests themselves. Numerous research projects have been devoted to the development of mathematical and numerical models with approaches adapted to different levels or scales, such as the small scale (atomic level), the meso-scale (particle, grain and pore level), and the continuum scale (component level). The ability to predict the evolution of microstructure has put the mesoscopic model (at particle, grain and pore level) ahead of the others.In research terms, the question posed would therefore be "Given a untreated part obtained by MExAM, how can we numerically simulate the evolution of the microstructure (from an initial microstructural state) to control changes in thermomechanical properties during the solid-state sintering process ?"A robust computational model, based on a multiphysics and multi-scale approach, has been developed, tested and validated. It enables us to predict the evolution of the material's microstructure, thermal and mechanical properties. The model is based on the finite element method, and progressively takes into account the multiphysical couplings (thermal, mechanical and microstructure) that influence the material's behavior. Special considerations have been given to the integration of non-linear phenomena. The results of the various simulations have shown that the model developed is capable of predicting the behavior of the sintering process with correct accuracy. The special case of material behavior for MExAM was presented, as well as how to use the model to optimize its thermomechanical properties. Optimization was achieved by coupling the results of the various simulations with the Taguchi method. It should be noted that the results obtained from the analysis of material properties confirm the successful application of the model, both in predicting the microstructural and thermomechanical behavior of the material, and in optimizing its properties
Cordeiro, Cavalcanti Fabiano. "Caractérisation thermique de produits de l'état liquide à l'état solide". Lyon, INSA, 2006. http://theses.insa-lyon.fr/publication/2006ISAL0006/these.pdf.
The aim of this work is to propose a new experimental set-up that allows the thermal characterization of an industrial product (water, paraffin and n-hexadecane) undergoing phase change, i. E. Solidification/fusion. The considered properties are the thermal conductivities and heat capacities in the liquid and solid states, the phase change temperature and the latent heat. These properties are identified simultaneously by using Levenberg-Marquardt's method. Transient measurements of temperature at the extremities of the sample are used to solve the parameter estimation problem. A sensitivity coefficient analysis is realized and we use this study to present the optimal methodology of identification
Blidi, Abdelkader. "Frittage et réactivité des solides : réexamen des modèles cinétiques de l'étape initiale du frittage et des lois de variation isotherme de surface". Dijon, 1988. http://www.theses.fr/1988DIJOS015.
Chapelier, Alhan. "Modifications radioinduites dans les protéines à l'état solide". Paris 11, 2001. http://www.theses.fr/2001PA112351.
In this study four proteins were irradiated in the solid state at ambient temperature. Thioredoxine, lysozyme and a-lactalbumine were irradiated in the lyophilised state, human insulin was irradiated in the hexameric crystalline state. For all proteins and whatever the irradiation atmosphere is, irradiation seems to lead to only small changes. For doses lower than 5 kGy, all methods lead to the same conclusion : the percent of degradation is lower than 5 %. Irradiation affect all levels of organisation. As for primary structure, we did not detect any sequence or residue that would be specially sensitive. We have evidences for oxidative degradation pathway, specially on aromatic residues and this conclusion seems general. As for the secondary structure, insulin appears more sensitive than other proteins. Two different kinds of degradation appear, since we get more compact and more released proteins. .
Bowen, Martin. "Transport tunnel polarisé en spin à l'état solide". Paris 11, 2003. https://tel.archives-ouvertes.fr/tel-00003921v5.
This experimental Thesis investigates spin-polarized solid state tunneling between two ferromagnetic layers separated by an ultrathin insulating barrier, with an aim to bridge the gap between theory, which is based on ideal systems, and experiments dominated by junctions with amorphous barriers. The nearly total tunneling spin polarization of La(0. 7)Sr(0. 3)MnO3, when integrated into partially or fully epitaxial magnetic tunnel junctions, offers insight into the relationship between an insulating material's electronic structure and tunneling magnetotransport. In addition to transport experiments through epitaxial SrTiO3, Ce(0. 69)La(0. 31)O(l. 845), TiO2, MgO, and amorphous Al2O3, barriers, we have performed XMCD experiments on Al2O3 and MgO barriers to probe the theoretical underpinnings of our transport results. The half-metallic nature of La(0. 7)Sr(0. 3)MnO3 is then utilized in La(0. 7)Sr(0. 3)MnO3/SrTiO3/La(0. 7)Sr(0. 3)MnO3 and La(0. 7)Sr(0. 3)MnO3/SrTiO3/Co junctions to quantitatively confirm the spectroscopic nature of spin-dependent solid state tunneling between ferromagnetic electrodes. These bias-dependent studies underscore the influence of interfacial spin wave generation on the ferromagnetic order of the manganate/insulator interface near its Curie point. Finally, we utilize electromigration to modify both the density of states and the potential profile of the interfaces. We show how harnessing this effect may lead to a device with bistable magnetotransport properties; and we examine within the Fowler-Nordheim tunneling regime the incidence of such junction modifications on the formation of quantized energy states within the barrier, and the evolution of interlayer exchange coupling between the ferromagnetic electrodes
Caron, Vincent. "Mécanosynthèse et vitrification à l'état solide d'alliages moléculaires". Lille 1, 2006. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2006/50376-2006-Caron.pdf.
Popa, Ana Maria. "Frittage en phase solide de composites : cas de W-Cu". Grenoble INPG, 2001. http://www.theses.fr/2001INPG0078.
Harfouche, Lina. "Criblage de l'état solide chiral et diagrammes de phases". Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR007.
Many active pharmaceutical ingredients are chiral compounds. The two enantiomers of the corresponding molecules exhibit identical chemical and physical properties, but the desired biological activity is often provided by only one enantiomer. The strict regulations forced the pharmaceutical industry to develop new ways to produce pure enantiomers. Among separation methods, Preferential Crystallization (PC), is a technique with relatively high productivity and low cost. It consists of the out-of-equilibrium alternative crystallization of both enantiomers. It is thought that the application of PC is only possible when the enantiomers crystallize as a conglomerate, i.e. a physical mixture of homochiral particles. Yet, only ca 5-10% of the racemic species crystallize as a conglomerate, which strongly limits the applicability of PC. The work investigates how to perform PC in the remaining 90-95% of cases, for enantiomers crystallizing as racemic compounds, i.e. a 1:1 stoichiometric compound made with both enantiomers. Following an adequate screening procedure based on physico chemical and molecular considerations, one racemic chiral molecule was selected as model compound, namely “proxyphylline” (PXL). After the construction of the binary phase diagram between the enantiomer of PXL reveals a rich polymorphism (double polymorphism for enantiomer and racemic), PXL has been resolved by two approaches: (a) via an unforeseen metastable conglomerate, by inhibiting the spontaneous crystallization and growth of the undesired forms and by achieving a wide metastable zone width due to the selection of a suitable solvent. The obtained results extend the applicability of PC to the racemic forming system with specific thermodynamic (melting temperature) and kinetic (wide metastability) characteristics. (b) via a stable monohydrated conglomerate prepared by cocrystallization with salicylic acid. It was resolved by PC from a water/ethanol mixture with high productivity. This may be the first report of PC applied to such a cocrystal system
Nguyen, Trong Giang. "Modélisation du comportement rhéologique d'alliages à l'état semi-solide". Grenoble INPG, 1991. http://www.theses.fr/1991INPG0122.
Waysek, Edward H. "Caractérisation de caroténoi͏̈des à l'état solide dans des matrices organiques". Université Louis Pasteur (Strasbourg) (1971-2008), 2001. http://www.theses.fr/2001STR13111.
Hu, Bingwen. "Manipulations des interactions dipole-dipole en RMN de l'état solide". Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10062/document.
This thesis deals with the recoupling and decoupling of dipolar homonuclear and heteronuclear interactions in solid-state NMR.First, two kinds of techniques for establishing the through-space correlations between quadrupolar nuclei and spin 1/2 nuclei are presented. One is MPCP (Multiple-pulse Cross-Polarization) recoupling sequence and the other one is D-HMQC (Dipolar assisted- Heteronuclear Multiple Quantum Coherence) sequence. We evaluate different kinds of dipolar recoupling techniques such as SFAM, SR41², that are used in our D-HMQC. Second, we propose a new 1H homonuclear dipolar decoupling technique labeled SAM (Smooth Amplitude Modulation). This method that is a symmetry-based sequences, works mainly at fast or ultra-fast Magic Angle Spinning (MAS) rates (vR > 25 kHz) and is complementary to previous methods, such as DUMBO, FSLG/PMLG. Third, a novel symmetry-based homonuclear recoupling method (SPIP) that excites double-quantum (DQ) coherences between spin-1/2 nuclei, such as 1H, is presented. Compared to previous 1H DQ-recoupling techniques, this pulse sequence requires moderate rf field, even at ultra-fast MAS speed. Furthermore, it displays higher robustness to both chemical shift anisotropy and spreads in resonance frequencies.Fourth, a new processing scheme, called covariance, is employed in solid state NMR to produce homo-nuclear correlation (HOMCOR) 2D spectra. It can accommodate signal truncation much better than the usual 2D-FT data treatment, without any previous knowledge of the positions and line-widths of the resonances. Besides, covariance methods can be applied to HETCOR NMR data to generate two HOMCOR indirect-covariance spectra
Amharar, Youness. "De l'origine moléculaire de la discrimination chirale à l'état solide". Rouen, 2011. http://www.theses.fr/2011ROUES014.
This manuscript is devoted to the study of the molecular origins of chiral discrimination in the solid state. Several angles of this topic have been treated: The first part of this work deals with the study of chiral discrimination during the crystallization of host-guest supramolecular complexes formed between permethylated β-cyclodextrin and the enantiomers of 1-(p-fluorophényl)ethanol. The detailed analysis of this system revealed unusual stoichiometries and remarkable features. The combination of structural analysis, physical characterization of solid phases and molecular modeling has conducted to an original mechanism of chiral recognition based on two contributions: a molecular inclusion and a lattice inclusion. The second part of this work relates the study of the dehydration of the original racemic monohydrate of 5-methyl-5-(4’-ethylphenyl)hydantoin (18H). The mechanisms of the different transformations as well as the relationships between homo- and heterochiral phases could be established from structural data and form the physical behavior of solid phases. The major role played by residual water molecules during the dehydration and the impact of the molecular mobility on the spontaneous resolution could be highlighted. Finally, a methodology was developed and exemplified with the study of the binary system formed between the enantiomers of Diprophylline
Jouan, Gauthier. "Le frittage flash (SPS) : de la réactivité à l'assemblage de batteries "tout solide"". Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1724/.
The Spark Plasma Sintering technique has known a significant growth since 2004 at a national level. Characterized by very short heat treatment duration, it has recently shown interesting possibilities as a new synthesis route and one-step realizations of assembled devices, such as "all inorganic solid state batteries". The aim of this thesis is to determine the "machine" and "materials" parameters that govern interfaces phenomena during the densification and their influence on the behavior of obtained objects. The study of the behavior of different powder mixtures of Cu/V2O5 confirms the significant increase in the reaction kinetics by using the SPS. This effect is related to the application of a constant pressure during treatment ; the rapid rise in temperature mode by current pulses does not appear significant. In contrast, the study of less reactive mixtures indicates that the rapid thermal processing allows the production of dense composites and opens the door to the one-step assembly of "all inorganic solid state batteries". Such accumulators allow significant improvements in safety, operation at high temperatures and the use of high potential electrode materials (limited to 4. 5 V in liquid). The study of the making of various components of "all inorganic solid state batteries", enables to extract the generals criteria guaranteeing an optimum assembly by Spark Plasma Sintering, was perform on a model system (copper), known to have a solid electrolyte with high conductivity at room temperature. The powders microstructure and sintering parameters have a crucial role on the quality of electrode/electrolyte interfaces and therefore on the electrochemical performances. These interfaces were controlled in Cu-metal and Cu-ion batteries configurations. While in the first case, the growth of dendrites at the negative electrode generates important and irreversible losses of contact at Cu/electrolyte interface, the Cu-ion batteries show good reversibility on thirty cycles confirming the low degradation of electrode/electrolyte interfaces. Extending these results to the potentially more interesting Li-ion system highlights the existence of inherent materials limitations in terms of ionic conduction. The shaping optimization, by reducing the thickness of the electrolyte layer, has overcome these limitations permitting the assembly of Li-ion "all inorganic solid state batteries" and allowing the use of materials with high potential (LiCoPO4), paving the way for the realization of more efficient new electrochemical generators
Ajdour, Mounia. "Développement d'un code de calcul pour la simulation du frittage en phase solide". Saint-Etienne, EMSE, 2006. http://www.theses.fr/2006EMSE0039.
This work concerns a numerical study for the simulation of the evolution of two grains during solid state sintering. In a first step, a bibliographical study of sintering with the various numerical and analytical models is presented. This study allowed the development of a model, which takes into account the various mechanisms of diffusion (volume diffusion, grain boundary and surface diffusion), with like terms sources the gradient of chemical potential, therefore by considering the radii of curvatures the driving forces of sintering. The mechanical behavior of the grains is considered elastic in all the temperature range of the cycle of sintering. The discretization of the whole of the physical equations of the problem was made by the finite element method (3D) for elasticity, and by the method of the finite volume (2D) for the problem of the interfaces. Finally the first 3D simulations of two grains of identical size were carried. These simulations raised discussions and proposals for the improvement of certain points, which will allow the complete validation of this computer code
Vuillaume, Pascal. "Comportement thermique et structural à l'état solide de polyamphiphiles en peigne". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/NQ54034.pdf.
Bouhki, Mohamed. "Amorphisation par réaction à l'état solide dans les multicouches NI/TI". Nancy 1, 1993. http://www.theses.fr/1993NAN10005.
Belamri, Bachir. "Structures et réactivité à l'état solide de composés éther couronne-phénol". Lyon 1, 1988. http://www.theses.fr/1988LYO10161.
Camus, Lydie. "Caractérisation par résonance magnétique nucléaire à l'état solide de silices hybrides". Paris 6, 2003. http://www.theses.fr/2003PA066415.
Boukadir, Saïd. "Caractérisation par résonance magnétique nucléaire des noyaux quadrupolaires à l'état solide". Lille 1, 1989. http://www.theses.fr/1989LIL10100.
Gantillon, Barbara. "Préparation du poly(éthylène téréphtalate) à l'état solide en milieu dispersé". Lyon 1, 1999. http://www.theses.fr/1999LYO10272.
Delville, Jérôme. "Films d'amidon photoréticulé à l'état solide. Etudes des relations stucture-propriétés". Reims, 2001. http://www.theses.fr/2001REIMS009.
Demol, Franck. "Etude en solution et à l'état solide d'un pseudo-fullerène réduit". Lille 1, 1998. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1998/50376-1998-283.pdf.
Haxaire, Katia. "Conformation du hyaluronane et interactions en solution et à l'état solide". Université Joseph Fourier (Grenoble ; 1971-2015), 2000. http://www.theses.fr/2000GRE10156.
Tsutsumi, Kazuo. "Energie de surface et distribution en énergie des sites superficiels de solides minéraux". Mulhouse, 1985. http://www.theses.fr/1985MULH0007.
STELLMACHER, MAX. "Propriétés physiques des matériaux III - V A non stoechiométrie controlée". Palaiseau, Ecole polytechnique, 1999. http://www.theses.fr/1999EPXX0045.
Boulahbak, Mustapha. "Etude de la transférabilité des pseudopotentiels de l'état solide à l'état liquide : application au calcul de la structure des métaux liquides". Metz, 1996. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1996/Boilahbak.Mustapha.SMZ9650.pdf.
Pseudopotentials were originally introduced to simplify electronic structure calculations by eliminating the need to include the atomic core states and the strong potentials responsible for binding them. These potentials were then screened using a linear dielectric function method via local-field correction, G(q). In this work, we study the structure and thermodynamical properties of liquid metals by means of integral equation theory as well as molecular dynamics. It is developed around two main ideas. In the first part, we examine the extend to which the first principles pseudopotenitals can be transferred successfully from the solid state to other environments. We used both Bachelet et al. (BHS) and Fiolhais' model potentials. The latter appears to describe correctly the structure as well as the thermodynamical properties of each alkali metal. We clearly point out that the BHS's pseudopotential is not transferable except for Na. The second idea is a study of the effet of exchange and correlation in the theory of simple metals. It appears that the alkali, with one valence electron per atom, have relatively high rs valus. For this reason, the structure is quite insensitive to the form of G (q) while the thermodynamic quantities depend on it. On the contrary, for polyvalent metals, with small rs values, G (q) has a great influence already on the structure factor
Maury, Gisèle de. "Comportement thermique de quelques stéroïdes et de leur interaction à l'état solide". Montpellier 1, 1987. http://www.theses.fr/1987MON13506.
Chandrappa, Ravi Kumar. "Caractérisation de formulations pharmaceutiques par RMN de l'état solide : polymorphisme et déformulation". Versailles-St Quentin en Yvelines, 2011. http://www.theses.fr/2011VERS0058.
This thesis reports on the use of solid-state NMR in the quality control of pharmaceutical formulations. Polymorphism structural studies were done on two active principle components of pharmaceutical drugs, Xaliproden and Irbesartan. A process of deformulation is proposed and validated, aiming at controlling drug quality and detecting counterfeits. The effects of processing on the stability of the drugs and the individual ingredients are followed and described by use of high-resolution NMR techniques. Finally, the quantitative aspects of the NMR measurements by 13C CPMAS techniques are investigated. Common techniques are evaluated for 13C enriched or naturally abundant samples, and another method is proposed in view of these applications
Loué, Willem Richard. "Evolution microstructurale et comportement rhéologique d'alliages Al-Si à l'état semi-solide". Grenoble INPG, 1992. http://www.theses.fr/1992INPG0115.
Grillon, Nathanaël. "Etude de la fiabilité de microbatteries à l'état tout solide au lithium". Thesis, Tours, 2015. http://www.theses.fr/2015TOUR4022.
To meet the requirements of microelectronic devices miniaturization, innovative energy storage systems are emerging and are able to cross the large scale industrialization phase. The goal of this thesis is to achieve a comprehensive reliability study of LiCoO2 based microbatteries developed by an « all-solid » approach. From the performance analysis of the operating system, aging of the microbatteries was characterized in storage and electrochemical cycling modes. Through an adapted exponential function from the Weibull failure probability law, the aging of the microbatteries has been modeled. Finally, a mathematical tool dedicated to the lifetime prediction of the devices in application has been developed. Otherwise, with the help of the electrochemical characterization of the different layers and interfaces of the system and a reading methodology of galvanostatic discharge curves, the main failure source has been identified. The convergence of results made it possible to highlight the leading role of the LiCoO2 positive electrode on the mechanisms leading to aging of the microbatteries. Thenceforth, a failure scenario and reliability performance improvement opportunities have been proposed
Burel, Antoine. "Discrimination à l'état solide durant la cristallisation : application à l'ultrapurification du phénanthréne". Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR102/document.
Crystallization is a process during which molecules self assembly from a disordered (liquid, amorphous or gaseous) phase. The miscibility in the solid state between a component of interest and its impurity depends on: (i) their molecular structures, (ii) the crystal structure of the host lattice (namely, that of the component of interest). When no solid solution exists, the impurity can be completely eliminated from the target product after optimization of the crystallization conditions.The present thesis intends to demonstrate that, when two compounds present similar molecular structures with low-density crystal structures, solid solution formation can occur which prevents from their complete separation. Conversely, in case of sufcient dissimilarity, no solid solution is stable and their separation is possible thanks to a large discrimination in the solid state. The phenanthrene system – a model compound used as base for the synthesis of morphine derivatives – was chosen to illustrate this thesis. Several crystallization methods (zone melting, co-crystallization, solvent assisted crystallization and sublimation-condensation) were investigated and permitted, after optimization and combination, to obtain 99.999(9) mole % purity phenanthrene (which is above the ultrapure grade of 99.9 mole %)
Martin, Christophe. "Rhéologie et structure d'un alliage modèle Sn-Pb à l'état semi-solide". Grenoble INPG, 1995. http://www.theses.fr/1995INPG0128.
Papillon, Anthony. "Frittage de composites Cu-Cr pour l'élaboration de matériaux de contact d'ampoules à vide". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI099.
Cu-Cr composites are commonly used as contact materials for medium voltage circuit breakers vacuum bottles. Solid state sintering process of Cu-Cr composites is widespread but has been relatively little studied. Optimizing the process requires understanding the sintering mechanisms. This study was focused on two important aspects of sintering: the redox reactions associated to oxides on the powder surface and the competition between densification and swelling mechanisms during sintering.The redox reactions were studied by thermogravimetric analysis coupled to various spectroscopic techniques, first on isolated Cu and Cr, then on Cu-Cr composites. Interfaces analyses obtained by FIB clarified the location of the oxide inside the sintered materials. Oxygen transfer takes place between copper and chromium powders. This phenomenon strongly depends on the reducing character of the sintering atmosphere.Densification was analyzed by dilatometry on Cu, Cr and Cu-Cr composites. This analysis was supported by microstructural observations, including X-ray tomography .The effect of process parameters (atmosphere, heating rate, powders ...) was studied. The results show the relationship between sintering and copper oxide reduction. The swelling phenomenon of copper compacts is explained by high temperature degassing of copper during pore closure. This swelling does not occur in Cu-Cr composites as chromium delays pore closing and entraps the gases released by copper. Sintering atmosphere, chromium morphology and chromium particle size affect densification. Vacuum sintering reduces porosity. Chromium particles with spherical shape limit its inhibiting effect on densification. For small particle sizes, chromium participates to densification, leading to better densification of the material. These results open the route for optimizing the sintering of Cu-Cr composites.Cu-Cr composites were tested for short circuit performance in vacuum interrupters. The result of these tests showed the importance of reducing the chromium oxide amount. The effect of impurities commonly encountered on the powders copper and chromium powders was also determined
Hanouneh, Ahmad. "Synthèse asymétrique d'amines en phase solide". Montpellier 2, 1993. http://www.theses.fr/1993MON20211.
Cappella, Andrea. "Caractérisation thermique à haute température de couches minces pour mémoires à changement de phase depuis l'état solide jusqu'à l'état liquide". Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14500/document.
This thesis is devoted to the thermal characterization of molten materials, namely chalcogenide glass-type tellurium alloys, at the micrometer scale. An experimental setup of Photothermal Radiometry (PTR), formerly developed for solid state measurements, has been adapted for this purpose. Using MOCVD technique, a random lattice of sub-micrometric tellurium alloy structures is grown on a thermally oxidized silicon substrate. These structures are then embedded in a protective layer (silica or alumina) to prevent evaporation during melting. Measurements are then performed from room temperature up to 650°C. SEM and XRD measurements performed after annealing show that these samples withstand thermal stress only up to 300°C. The coating’s thermal boundary resistance is estimated by a heat transfer model based on the thermal impedance formalism. Moreover, the thermal conductivity and thermal boundary resistance of thin amorphous alumina by low temperature ALD are measured from the room temperature to 600°C
Charmont, Patrick. "Contributions à l'amélioration de la résolution en résonance magnétique nucléaire à l'état solide". Lyon, École normale supérieure (sciences), 2001. http://www.theses.fr/2001ENSL0187.
Chausse, Claire. "Etude du frittage en phase solide d'un alliage base tungstène. Influence du broyage des poudres". Limoges, 1994. http://www.theses.fr/1994LIMO0038.
Rabbani-Haghighi, Hadi. "Nouveaux matériaux et architectures de dispositifs pour les lasers organiques à l'état solide". Phd thesis, Université Paris-Nord - Paris XIII, 2011. http://tel.archives-ouvertes.fr/tel-00643467.
Hoang, Ha. "Modélisation numérique de la plasticité des transformations de phase diffusives à l'état solide". Thesis, Rouen, INSA, 2008. http://www.theses.fr/2008ISAM0019.
During the solid-solid phase transformation of a steel, the interaction between new phase and parent phase, each having its own properties, leads to accommodation stresses in the vicinity of the interface between phases. Dislocations are thus produced in the parent phase, the one which has the lowest yield stress. If an external loading stress -even small- is exerted during the transformation, dislocations result to a permanent strain at the macroscopic scale, in the direction of the load. This strain is called transformation plasticity or TRIP (TRansformation Induced Plasticity); only dedicated models can predict it. This plasticity may also be observed without any external load during the transformation, if the austenitic phase as been pre-hardened just before the transformation. In this latter case, current transformation plasticity models do not always provide correct predictions as compared to experimental observations. A numerical modelling of the mechanical consequences of diffusive transformations is proposed in this work. It is meant to identify the mechanisms which are responsible for the plasticity induced by such transformations for all cases of loading. The finite elements method is used to solve the problem of the mechanical interaction between phases at any instant of the transformation. This gives access to a local description of the stress and strain fields due to this interaction. In a first approach of the modelling inspired from most current transformation plasticity models, a single growing particle interacting with its mother phase is considered. This allows to analyse the hypothesis on mechanical fields according to which analytical formulations of transformation plasticity can be obtained. This approach has then been extended to the case of a homogeneous medium in which nuclei appear randomly in time and space, with prescribed distribution laws. With this improved approach, the importance of the spatial density of nuclei and of the rate of nucleation on TRIP predictions could be evidenced. Besides, this approach provides the basis of a modelling of diffusive transformation in a crystalline heterogeneous material, where the effective properties are determined by ensemble averaging over multicrystals. With both approaches, a correct qualitative agreement with experimental measures could be obtained, in the classical case of constant load during the transformation as well as concerning the consequences of a pre-hardening
Bavoux, Claude. "Organisation cristalline et réactivité à l'état solide d'ensemble moléculaires organiques : application aux dichlorophénols". Lyon 1, 1986. http://www.theses.fr/1986LYO19010.
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Lacoste, Jean-François. "Élaboration de fibres de poly(éthylène téréphtalate) à propriétés thermomécaniques améliorées par modification chimique à l'état fondu et à l'état solide". Lyon 1, 2004. http://www.theses.fr/2004LYO10045.
The aim of this thesis is to enhance the thermomechanical properties of PET fibers trialkoxysilane end-group crosslinking (hydrolysis-condensation) after the functionalization the alcohol and acid PET end-groups with bifunctional reagents. OH groupes were reacted with anhydride or isocyanate and COOH groups with epoxide. Reaction kinetics were studied by NMR on end-group model compounds. During melt modification many degradation and side reactions were observed and crosslinking occurred after hydrolysis-condensation. Thus we preferred to study the solid-state functionalization by diffusion of reagents at temperatures below 256°C. After solid-state modification, crosslinking finally occured giving maximum gel contents of 70°C. Mechanical properties of partially crosslinked samples were maintained up to 320°C
Bounhoure, Valérie. "Frittage en phase solide des alliages WC-Co : influence du rapport C/W et de l'ajout de Cr". Grenoble INPG, 2008. http://www.theses.fr/2008INPG0115.
This work aims at understanding the effect of the C/W ratio and of Cr addition on the solid-state sintering of WC-Co cemented carbides. Four alloys with low or high C-content and with or without Cr were studied from the macroscopic to the atomic scale. A macroscopic study was done to determine the different steps of sintering, the evolution of the phases in the alloys and the effect of the C/W ratio and of a Cr addition on the densification. Qualitative and quantitative microscopic observations were performed at three important stages of the densification of the alloys. They were linked to the shrinkage behaviour of the alloys. Finally, the influence of the C/W ratio on the beginning of the densification was explained through a detailed study of the WC/Co interface structure related to interface-energy calculations coming from literature. The orientation between Co and WC was determined and the interfaces were characterized at the atomic scale