Dissertations / Theses on the topic 'Elasticité et Conductivité Thermique'
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Abidi, Sonia. "Matériaux composites à haute tenue thermique : influence de la micro-nanostructure sur les transferts moléculaires, électroniques et thermiques." Thesis, Toulon, 2014. http://www.theses.fr/2014TOUL0019/document.
Fire protection materials are widely used to ensure the safety of users of the infrastructure. Standards of fire protection regularly operating, the materials must be more efficient. These are generally composed of refractory mortar and insulating oxides. The objective of this work is to develop a firewall composite 4 h applied by projecting but also to determine the thermal and mechanical properties.In the first part, this study describes the various stages of the development of a fire protection material, after the presentation of the approach that has guided the development of our materials, we are interested especially in the chemical composition of the matrix and that of the cement. Their thermal and mechanical properties have been reviewed.The raw materials for the preparation of mortar were selected. The evolution respectively of thermal conductivity, diffusivity, porosity, specific heat and the mechanical properties of mortars chosen according to the nature and amount of the fillers incorporated in the matrix has been studied. A description of the various analytical and numerical models for the representation of the thermal conductivity and Young's modulus of the materials led to the development of a model able to predict the thermal and mechanical behavior of composites based on the nature and amount of charges added.In a second part, the kinetics of the hydration reaction of gypsum to control setting time and to facilitate the production of the composite in the industrial chain was studied. The influence on the kinetics of hydration, of the chemical composition of the gypsum, particle size distribution and the addition of adjuvant commonly used in the plaster industry, has also been treated.At the end of this study, two formulations of composites applied by projection were developed
Du, Kou. "Modélisation micromécanique de géomatériaux en prenant en compte des anisotropies microstructurale et matricielle." Electronic Thesis or Diss., Université de Lorraine, 2021. http://docnum.univ-lorraine.fr/public/DDOC_T_2021_0254_DU.pdf.
The mechanical properties of heterogeneous geomaterials are evaluated by simultaneously taking into account the microstructural anisotropy as well as the one of matrix. To this end, the microstructural anisotropy is represented by the complexity of porous shape which is considered in the present work as concave or convex by particular attention to the superspherical and the axisymmetrical superspheroidal pores. The concentration and contribution tensors are numerically computed using Finite Element Method (FEM), which are next approximated by analytical expressions for the case of the concavity parameter being p<1, to evaluate the associated effective properties, such as effective elastic and thermal responses. Specifically, to solve the 2nd Eshelby problem (Eshelby (1961)) in the case of 3D non-ellipsoidal inhomogeneities, we make use of a recently developed adapted boundary condition (Adessina et al. (2017)) based on far-field solution (Sevostianov and Kachanov (2011)) to incorporate the matrix anisotropy and to correct the bias induced by the bounded character of the mesh domain, which allows to accelerate the computation convergence without sacrificing its accuracy. Simultaneously by complying with the numerical homogenization technique, the compliance/resistivity contribution tensors are computed for different forms of pores (particular attention of superspheroidal and superspherical ones) embedded in a transversely isotropic matrix. The proposed numerical method is shown to be efficient and accurate after several appropriate assessments and validation by comparing its predictions, in some particular cases, with analytical results and some available numerical ones. On the basis of these "3D" Finite Element Modeling, approximate relations of the property contribution tensors in the two aforementioned reference concave cases, supersphere and axisymmetric superspheroid, are developed for both elastic and thermal problems. Note here that the spherical pore (i.e. concavity parameter p=1) and circular crack (i.e. aspect ratio γ → 0), which can be considered as two particular cases, are also numerically studied. This allows to assess and validate the proposed method in the present work. Moreover, in the frame of homogenization, application to the typical porous geomaterials with transversely isotropic matrix such as clay rocks is presented to illustrate the impact of the concavity parameter and the matrix anisotropy on overall properties through several micromechanical homogenization schemes such as non-interaction approximation, Mori-Tanaka-Benveniste scheme and Maxwell scheme. The methodology of evaluation of the elastic and thermal properties of heterogeneous material aforementioned is proposed based on micromechanical homogenization via multiscale modeling. The overall properties of composites with regular pores are also predicted using direct finite element approaches and then compared against micromechanical modeling. The effect of microstructure is analyzed by considering periodic RVEs containing random arrangements of pores formed by transversely isotropic phases
Chen, Fengjuan. "Modélisation micromécanique de milieux poreux hétérogènes et applications aux roches oolithiques." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0134/document.
Focusing on the effect of shape factor on the overall effective properties of heterogeneous materials, the 1st and the 2nd Eshelby problem related to 3-D non-ellipsoidal inhomogeneities with a specific application to oolitic rocks have been discussed in the current work. Particular attention is focused on concaves shapes such as supersphere and superspheroid. For rocks, they may represent pores or solid mineral materials embbeded in the surrounding rock matrix. In the 1st Eshelby problem, Eshelby tensor interrelates the resulting strain about inclusion and eigenstrain that would have been experienced inside the inclusion without any external contraire. Calculations of this tensor for superspherical pores– both concave and convex shapes – are performed numerically. Results are given by an integration of derivation of Green’s tensor over volume of the inclusion. Comparisons with the results of Onaka (2001) for convex superspheres show that the performed calculations have an accuracy better than 1%. The current calculations have been done to complete his results. In the 2nd Eshelby problem, property contribution tensors that characterizes the contribution of an individual inhomogeneity on the overall physical properties have been numerically calculated by using Finite Element Method (FEM). Property contribution tensors of 3D non ellipsoidal inhomogeneities, such as supersphere and superspheroid, have been obtained. Simplified analytical relations have been derived for both compliance contribution tensor and resistivity contribution tensor. Property contribution tensors have been used to estimate effective elastic properties and effective conductivity of random heterogeneous materials, in the framework of Non-Interaction Approximation, Mori-Tanaka scheme and Maxwell scheme. Two applications in the field of geomechanics and geophysics have been done. The first application concerns the evaluation of the effective thermal conductivity of oolitic rocks is performed to complete the work of Sevostianov and Giraud (2013) for effective elastic properties. A two step homogenization model has been developed by considering two distinct classes of pores: microporosity (intra oolitic porosity) and meso porosity (inter oolitic porosity). Maxwell homogenization scheme formulated in terms of resistivity contribution tensor has been used for the transition from meso to macroscale. Concave inter oolitic pores of superspherical shape have been taken into account by using resistivity contribution tensor obtained thanks to FEM modelling. Two limiting cases have been considered: ‘dry case’ (air saturated pores) and ‘wet case’ (water liquid saturated pores). Comparisons with experimental data show that variations of effective thermal conductivity with porosity in the most sensitive case of air saturated porosity are correctly reproduced. Applicability of the replacement relations, initially derived by Sevostianov and Kachanov (2007) for ellipsoidal inhomogeneities, to non-ellipsoidal ones has been investigated. It it the second application of newly obtained results on property contribution tensors. We have considered 3D inhomogeneities of superspherical shape. From the results, it has been seen that these relations are valid only in the convex domain, with an accuracy better than 10%. Replacement relations can not be used in the concave domain for such particular 3D shape
Lachance, Olivier. "Conductivité thermique et perméabilité intrinsèque de la neige compactée." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30712/30712.pdf.
Lachance, Olivier, and Olivier Lachance. "Conductivité thermique et perméabilité intrinsèque de la neige compactée." Master's thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25083.
La perméabilité intrinsèque et la conductivité thermique de la neige sont deux paramètres essentiels pour effectuer l'analyse numérique du comportement thermique de milieux poreux. Plusieurs mesures de ces paramètres ont été effectuées successivement sur des échantillons de neiges compactées recueillis à l'Université Laval. La mesure de la conductivité thermique a été effectuée selon la méthode du fil chaud. Pour la perméabilité intrinsèque, un perméamètre à air à double mur fût conçu pour des expériences en laboratoire. La perméabilité intrinsèque et la conductivité thermique variaient respectivement de 1.1 x 10-8 à 8.0 x 10-11 m2 et de 0.09 à 0.48 W/mK pour des échantillons de neige ayant des porosités s'étalant entre 0.32 et 0.75. Les résultats se comparent bien avec ceux trouvés dans la littérature. Des modèles de prédiction des propriétés ont été examinés pour chacune des propriétés avec la porosité et le diamètre des grains.
Rigacci, Arnaud. "Élaboration d'aérogels de silice monolithiques et étude des relations entre leur structure et leur conductivité thermique équivalente." ENSMP, 1998. http://www.theses.fr/1998ENMP0836.
Lory, Pierre-François. "Dynamique de réseau et conductivité thermique dans les alliages métalliques complexes." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY042/document.
Complex metallic alloys are long range ordered materials, characterized by large cells, comprising several hundreds of atoms and cluster building blocks. A key property of CMAs is the low lattice thermal conductivity (1.3 W/m. K), which suggests a potential application for CMAs for thermoelectricity. Despite recent advances structure determination, the nature of the phonons modes remains an open question: do the clusters playing a role? Are there critical modes? To tackle this problem, my PhD project aims to understand the vibrational modes at atomic scale and the relation to lattice thermal conductivity in o-Al13Co4 which is an approximant of the quasicrystal, decagonal phase AlNiCo and the clathrate Ba8Ge40.3Au5.25. In this worked we have used Inelastic Neutron and X-ray Scattering experiments and atomic scale simulations, based on density functional theory and empirical pair potentials.A detailed analysis of the results of inelastic scattering experiments on monocrystals for the acoustic branches have shown, for the first time, a finite lifetime for acoustic phonons when they interact with the low-lying dispersion-less excitations due to atoms in the cluster. In both systems, we observe that when an acoustic branch flattens near the zone boundary, the phonon lifetime is a few picoseconds. The phonon lifetime is approximately independent of temperature like the lattice thermal conductivity. Lattice and molecular dynamics simulations with DFT and empirical, oscillating pair potentials show that the finite phonon lifetime is an anharmonic effect, due to structural disorder, explaining the weak temperature of the phonon lifetime. For o-Al13Co4, we have calculated the thermal conductivity with the Green-Kubo method based on equilibrium MD simulations. For Ba8Ge40.3Au5.25 we have developed a phenomenological model based on individual phonon modes. In conclusion, we have demonstrated how structural complexity affects thermal conductivity through the lattice dynamics
Lenain, Alexis. "Conductivité thermique des alliages métalliques amorphes en conditions cryogéniques et applications." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI100.
Bulk metallic glasses possess an amorphous structure without any atomic longrange ordering unlike their crystalline counterparts. They exhibit particularproperties due to this amorphous structure, which is very promising for futureindustrial applications. In particular, their thermal conductivity is very low compared to other metallic materials due to the absence of crystalline lattice. Thus, these alloys show some insulating properties, leading to low heat losses. This PhD work focuses on understanding the mechanisms that occur in thermal conductivity of bulk metallic glasses in order to identify suitable compositions. Several optimization methods have been carried out to minimize the thermal properties and resulted in the development of an optimized composition showing low thermal conductivity. Secondly, their joining ability has been studied with the aim to implement these alloys in an industrial device. Two different joining techniques have been faced to provide a short and a long term solution. Eventually, two patents which protect the use of beneficial compositions developed in this work have been filed. Besides, prototypes have been produced using the two processes studied in this work and show enhanced performances compared to the current solution
Duverger, Eric. "Etude sous pression partielle d'oxygène et à haute température de l'évolution de la conductivité dans les structures pérovskites : application à l'étude de BaTiO3 pur et dopé en accepteur." Dijon, 1992. http://www.theses.fr/1992DIJOS031.
Azizi, Smail. "Conductivité thermique des matériaux poreux humides : mesure par méthode flash et interprétation." Vandoeuvre-les-Nancy, INPL, 1988. http://www.theses.fr/1988NAN10014.
Fillion, Marie-Hélène. "Mesure de la conductivité thermique et de la perméabilité intrinsèque d'assemblages de cailloux." Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25911/25911.pdf.
Jadal, Mariam. "Conception et caractérisation d'un échangeur-stockeur composé d'un matériau à changement de phase dopé en conductivité." Thesis, Nantes, 2020. http://www.theses.fr/2020NANT4008.
The recovery of thermal waste is an important factor to improve the efficiency and economy of energy. Latent heat storage appears to be a promising solution of this problem and to synchronize the production and consumption of energy. We are interested in industrial applications with short thermal cycles. However, Phase Change Materials have low thermal conductivity. A concept based on paraffin and Expanded Natural Graphite (ENG) was manufactured and characterized. PCM has crystallization kinetics with two different transformations. The crystallization kinetics function of each transformation has been identified. The planar thermal conductivity, and the thermal contact resistance was identified in solid and liquid phases, using an experimental device coupled with a numerical model developing an inverse method. A phase change study of a plate and of an encapsulated aluminum cylinder was carried out using three energy conservation methods (enthalpy method, apparent specific heat, and crystallization kinetics), and experimentally validated. A 2D finite element simulation, associated with an analytical method was used for a tubular exchanger composed of a network of plate. Finally, an aging study of a single plate and encapsulated cylinders was carried out. The study confirms the thermal stability of the composite material
Filali, Mohamed. "Conductivité thermique apparente des milieux granulaires soumis à des contraintes mécaniques : modélisation et mesures." Phd thesis, Toulouse, INPT, 2006. http://oatao.univ-toulouse.fr/7454/1/filali.pdf.
Ben, amor Aymen. "Investigations expérimentales du transport thermique et électronique dans des nanofils hétérostructurés 3C/2H." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0113.
This research project presents an experimental exploration of thermal, electrical and thermoelectric properties of 3C/2H heterostructured Si and Ge nanowires. These studied nanowires are made by the Center for Nanosciences and Nanotechnologies of the University of Paris-Saclay, thanks to an original method which allows the creation of phase transformations in these nanowires. This results in a 3C/2H heterostructures along the nanowires with abrupt interfaces, giving hope for a significant reduction in their thermal conductivity without significantly altering their electronic properties. First, we showed the strong diameter dependence on thermal transport in such heterostructured nanowires. On the other hand, the annealing temperature during the phase transformation, which influences the size and the number of 2H domains, can constitute an effective parameter for reducing thermal conductivity. This study constitutes the first experimental evidence of reduced thermal conductivity in such types of nanowires. Then, with the aim of evaluation the electrical and thermoelectric properties of nanowires, an original prototype was developed during this thesis. This prototype allows simultaneous and real-time imaging of thermal and electrical conductivities and the Seebeck coefficient at the nanometric scale
Ruellan, Jérémie. "Conception, fabrication et caractérisation d'un capteur de conductivité thermique à base de nanofils de silicium." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY025/document.
Semiconducting nanowires are nowadays the topic of numerous research for their interesting physical properties. Relying more specifically on the thermal properties of nanostructures, the purpose of this thesis is to demonstrate the feasibility of a thermal conductivity detector based on silicon nanowires for pressure sensing (Pirani gauge) or gas detection. The work presented herein addresses the questions raised by the reduction of the objects size such as the increase of the noise or the thermal conduction in a rarefied gas and tries to bring a solution to those problematics. This work deals with all the steps required for the realization of such devices. That is, the design and simulation of the sensor, based on a detailed study of the physical behavior of the objects, the fabrication of such devices on 200mm wafers by the CEA-Leti cleanroom using standard microelectronics processes and finally their characterization as a pressure sensor and gas detector. The work presented here is part of a wider project that aims at developing of a portable gas detection system for air or water analysis
Vergne, Bruno. "Mise en forme de composites nanotubes de carbone/alumine et modélisation de leur conductivité thermique." Limoges, 2007. https://aurore.unilim.fr/theses/nxfile/default/a8757fd1-fa58-4fb7-aa6b-b7e8f1f46286/blobholder:0/2007LIMO4032.pdf.
Due to the very high thermal conductivity and aspect ratio of Carbon NanoTubes (CNT), their introduction in alumina matrices, even in low amounts, is expected to improve the thermal conductivity of the resulting composites. Such composites could then be used to manufacture thermal sinks for high power electronic circuits, provided that the coefficient of thermal expansion keeps a value close to that of alumina in order to get an intimate contact between the substrate and its sink. Researches on the formulation of alumina/CNT suspensions were carried out and led, after shaping and sintering, to quite homogeneous composites. In comparison with pure alumina, although a great improvement of the electrical conductivity of composites was recorded as early as a few vol. % of CNT were added, an opposite trend was observed for the thermal conductivity. We showed that the decrease of the thermal conductivity can not be caused only by the lowering of the relative density of the material. The refinement of simple computing model, taking into account the thermal resistances at the CNT/matrix and CNT/CNT interfaces, allowed to predict almost quantitatively this thermal conductivity loss
Jeancolas, Antoine. "Étude expérimentale et modélisation micromécanique du comportement de composites hybrides : optimisation de la conductivité thermique." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0285/document.
The increase of electronic components in the integrated circuits and the required electrical power set the question of the dissipation of the heat generated. The electrical box must favor the heat dissipation while maintaining electrical insulation. The solution chosen to transfer the heat is to develop composite materials whose reinforcements by their structure will improve the thermal conductivity. Polymer-based composite materials were chosen for their building ability. Thermal conductivity and electrical insulation are insured by ceramic reinforcements. The homogenization methods allow to improve the composites’ design according to the properties of their constituents, their geometry and their distribution. They thus provide an optimized formulation of materials satisfying the characteristics emanating from the industrial partner (‘Institut de Soudure’). The expected thermal conductivity of the composites imposes a high volume fraction of reinforcements to counterbalance the insulating polymer matrix. Homogenization methods have been developed to provide predictions of effective thermal conductivity for high (greater than 20%) reinforcement rates and high thermal conductivity contrasts. The presence of an interphase resulting from strong physico-chemical incompatibilities between the components must also be modeled
Jeancolas, Antoine. "Étude expérimentale et modélisation micromécanique du comportement de composites hybrides : optimisation de la conductivité thermique." Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0285.
The increase of electronic components in the integrated circuits and the required electrical power set the question of the dissipation of the heat generated. The electrical box must favor the heat dissipation while maintaining electrical insulation. The solution chosen to transfer the heat is to develop composite materials whose reinforcements by their structure will improve the thermal conductivity. Polymer-based composite materials were chosen for their building ability. Thermal conductivity and electrical insulation are insured by ceramic reinforcements. The homogenization methods allow to improve the composites’ design according to the properties of their constituents, their geometry and their distribution. They thus provide an optimized formulation of materials satisfying the characteristics emanating from the industrial partner (‘Institut de Soudure’). The expected thermal conductivity of the composites imposes a high volume fraction of reinforcements to counterbalance the insulating polymer matrix. Homogenization methods have been developed to provide predictions of effective thermal conductivity for high (greater than 20%) reinforcement rates and high thermal conductivity contrasts. The presence of an interphase resulting from strong physico-chemical incompatibilities between the components must also be modeled
Djeran-Maigre, Irini. "Etude des diffusions thermique et hydraulique dans une argile soumise à un champ de température." Marne-la-Vallée, ENPC, 1991. http://www.theses.fr/1991ENPC9108.
The thermal conductivity of clays is the fondamental parameter which governs the thermal diffusion and the pore pressure of the rock mass under thermal loading. Experiments have been untertaken in a reduced model, respecting representative boundary conditions. They show that the thermal conductivity depends on temperature in an unfavorable sense to the decrease of heat. On the other hand, the outflow of pore water, from the source to the exterior, has a low amplitude. A simple model of porous medium allows the observations and illustrates the effects of the variation of conductivity on the behaviour of rock mass. Finally, thanks to the numerical formulations specially developed, we examine the incident of the particularities of proposed models on the thermohydromechanical behaviour of geometricallysimple structures subjected to a given thermal loading
Dominguez, Bethencourt Cristina. "Formation, microstructure et propriétés de l'hexaluminate de calcium." Lyon, INSA, 2000. http://www.theses.fr/2000ISAL0026.
The aim of this work is to supply a general analysis of calcimn hexaluminate, as regard both formation and properties. Materials were prepared by reaction sintering. This way allows, sometimes, the formation of platelet grains. A model is proposed for the formation of CA6 grains. This model is based on the fact that hibonite needs enough space to develop with high aspect ratio. The growth mechanism of CA6 grains is the welding of neighbor platelets when they are disposed with their preferential growth planes parallel. This mechanism allows the formation of more equiaxed grains and is responsible for the subgrains formation when fired at high temperature. In general, calcium hexaluminate has properties similar to alumina. The differences manifested as lower thermal conductivity, Young modulus and thermal chock resistance and higher crack propagation resistance. Its particular microstructure has a key influence on its properties. The preferential crack propagation through subgrains or basal planes leads to high crack deviation. Dislocation movement through subgrains governs creep. Hot pressed calcium hexaluminate is highly oriented with basal planes perpendicular to pressing direction. This is the material with higher mechanical properties (excepting crack propagation resistance). It shows a considerable difference between the directions parallel and perpendicular to pressing direction
Fournier, Richard. "Optimisation et modélisation du procédé RTM." Phd thesis, École Nationale Supérieure des Mines de Paris, 2003. http://tel.archives-ouvertes.fr/tel-00266940.
Fèvre, Mathieu. "Etudes microstructurales d'oxydes désordonnés et modélisation de leurs propriétés thermiques." Paris 11, 2003. http://www.theses.fr/2003PA112252.
This thesis is devoted to the modelling of disordered oxides by Monte Carlo and Molecular Dynamics simulations, in relation with short-range order investigations by neutrons and X-rays diffuse scattering measurements. In zirconia based oxides the kinetics of cations is very slow, whereas it is very fast for anions. These materials are ionic systems. Thus, the largest contribution to the energy of the system is given by long-range electrostatic interactions (1/r). Local order measurements have shown that chemical species are not randomly placed in the crystal structure. Due to the presence of structural vacancies, created by a charge compensation mechanism, lattice distortions are also important. Thus, the chemical ordering is strongly correlated to the atomic displacements. The Non Equilibrium Molecular Dynamics technique has been used to compute the thermal conductivity from atomic configurations. However, this method can only reproduce the movement of particles during several nanoseconds. Therefore, in order to ameliorate the description of micro structural properties and to analyze the influence on the conductivity of the local order, we developed a code based on a Monte Carlo approach, which is adapted to ionic systems and which can describe the strong elastic effects as well as the chemical effects. The short-range order reproduced in the Monte Carlo simulations is very closed to the one measured. We also show that Molecular Dynamics simulations cannot reproduce the correct local order between defects, observed at high doping concentrations. Moreover, the thermal conductivity computations have shown a good agreement with the experimental data. Indeed, the error between simulations and measurements are below 20%. Finally, this study also discusses the influence of the short-range order on the conductivity behaviour using numerical results, diffuse scattering investigations and thermal conductivity measurements
Leclercq, Bérangère. "Etude de la conductivité thermique de matériaux à base de zircone : Relation avec la composition et la microstructure dans des systèmes binaires et ternaires." Limoges, 2002. http://www.theses.fr/2002LIMO0018.
Chamroune, Nabil. "Matériaux composites Aluminium/Carbone : architecture spécifique et propriétés thermiques adaptatives." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0140/document.
Many carbon/metal composites are currently used in several applications. One of them concerns their use as heat sinks in microelectronics. Concerning this application, two conditions are required: a high thermal conductivity (TC) in order to evacuate the heat generated by the electronic chip and a coefficient of thermal expansion (CTE) similar to the used material type of the electronic device (2-8×10-6 /K).Therefore, graphite flakes (GF; TC: 1000 W/m.K and CTE: -1×10-6 /K in the graphite plane) reinforced aluminum matrix (Al; TC: 217 W/m.K and CTE: 25×10-6 /K) composites were fabricated. These composite materials were fabricated by Powder Metallurgy (PM) and Flake Powder Metallurgy (FPM). This process, which consist to use a flattened metallic powder, helped to improve the in-plane orientation (perpendicular to the pressure direction) of GF under uniaxial pressure. Moreover, this process provided a better Al-C interface thanks to a planar contact between the matrix and the reinforcements. This resulted in an improvement of the CT from 400 W/m.K to 450 W/m.K for a reinforcement content of 50 vol.%. Nevertheless, regarding thermal dilation, CTEs of 21.8×10-6 /K and 21.7×10-6 /K were obtained by MP and FPM respectively, which is incompatible with the intended application.To overcome this problem, composite materials with multiple reinforcement were developed by solid-liquid phase sintering. Then, carbon fibers (CF) have been added to aluminum and graphite flakes. The addition of CF to GF reinforcement reduced significantly the CTE of the Al/(GF+CF) composites with a small proportion of CF, while preserving a high TC. In addition, the Al/(GF+FC) composite materials have significantly lower CTEs than the Al/CF composites with a equivalent vol.% of CF. Therefore, Al/(GF+CF) composite materials were developed by solid-liquid phase sintering to obtain a TC of 400 W/m.K (comparable to the TC of copper) and a CTE of 8×10-6 /K (comparable to the CTE of alumina). In addition, the lightweight of aluminum gives composite materials Al/C a low density (d = 2.4 g/cm3). Therefore, the composite materials developed in this study are promising as a lightweight heat sink in microelectronic industries
Petitjean, Sébastien Jean Denis. "Rôle de la conductivité thermique des radioéléments et du solidus dans l'origine et la stabilité des cratons archéens." Toulouse 3, 2005. http://www.theses.fr/2005TOU30148.
Brigaud, Frédéric. "Conductivité thermique et champ de température dans les bassins sédimentaires : à partir des données de puits." Montpellier 2, 1989. http://www.theses.fr/1989MON20176.
Camirand, Christian. "Étude de la chaleur spécifique et de la conductivité thermique des hydrures métalliques par calorimétrie différentielle." Thèse, Université du Québec à Trois-Rivières, 2000. http://depot-e.uqtr.ca/3139/1/000668315.pdf.
Bernard, Benjamin. "Barrières thermiques par projection plasma de suspensions : développement et caractérisation de microstructures à faible conductivité thermique." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0212/document.
The increase of operating temperature of gas turbine engines is an issue of interest for the aeronautic industry. A solution is the enhancement of thermal insulation properties of thermal barrier coatings (TBCs). The present work is related to suspension plasma spraying process (SPS) that allows to consider significant improvements for the next generation of TBC systems, compared to the currently used process, namely electron beam physical vapor deposition (EB-PVD). Indeed, SPS process can produce columnar microstructures able to provide high thermo-mechanical compliance. A microstructural study led to identify parameters which impacted the coating morphology (column size, distribution, and compaction). Two optimized yttria-stabilized zirconia (YSZ) microstructures were carefully characterized to highlight SPS process advantages. Low thermal conductivities (< 1 W.m-1.K-1) were obtained within a large temperature range (25 °C – 1100 °C), compared to EB-PVD YSZ coatings (1,3 – 1,5 W.m-1.K-1). Thermal lifetime was estimated thanks to thermal cyclic fatigue tests. A similar level of thermal lifetime was reached with SPS coatings compared to EB-PVD one. Some SPS columnar coatings even showed more than 2000 cycles to failure. The ability of SPS to perform multifunctional systems, including a YSZ columnar structure with a homogeneous Gd2Zr2O7 coating on the top, was investigated. This architecture must provide a chemical protection to CMAS (CaO–MgO–Al2O3–SiO2) aggressions. These contaminants would impede the increase of temperature in next generation of gas turbine engines. The anti-CMAS behavior was assessed for SPS Gd2Zr2O7 coatings until 1300 °C
Bourret, Julie. "Élaboration de céramiques alvéolaires à base de kaolin : propriétés thermiques et mécaniques." Limoges, 2012. https://aurore.unilim.fr/theses/nxfile/default/feab8bd8-27be-4c21-839a-aaaa32034cba/blobholder:0/2012LIMO4058.pdf.
Candidate materials for thermal insulation combine a solid phase of low thermal conductivity (<1 W. M⁻¹. K⁻¹) with a high pore volume fraction. This work concerns the preparation of ceramic foams exhibiting such characteristics using kaolin clay as the starting material. Processing involves a surfactant to stabilize the foam while remaining low cost and environmentally friendly. The properties of a clay-based material are sensitive to the orientation of the clay particles and, with thermal treatment, mineralogical transformations. Measurements of thermal conductivity and Young's modulus were made on textured kaolonite/muscovite samples obtained by extrusion, uniaxial or isostatic pressing and cut in different directions. An initial study revealed anisotropy at the macroscopic scale up to a factor of 3 related to the forming conditions and the amount of muscovite. However, with thermal treatment, this factor is progressively removed by transformations such as dehydroxylation and formation of mullite. In the last part, the pore volume fraction (Vp) was varied in the kaolin based foam by modifying the incorporated clay amount in the starting mixture. After thermal treatment at 1100̊ C, measurements of the thermal conductivity revealed a decrease from 0. 23 W. M⁻¹. K⁻¹ at Vp=0. 57 to 0. 054 W. M⁻¹. K⁻¹ at Vp=0. 95 in close agreement to predictions by the Hashin-Shtrikman upper bound, a cubic pore model and numerical simulation. The effective Young's modulus, obtained from mechanical compression tests, also decreases with pore volume fraction as described by Ashby's relation. However, the mechanical strengh was sufficient for handling even the more porous kaolin based foams
France-Lanord, Arthur. "Transport électronique et thermique dans des nanostructures." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS566/document.
The perpetual shrinking of microelectronic devices makes it crucial to have a proper understanding of transport mechanisms at the nanoscale. While simple effects are now well understood in homogeneous materials, the understanding of nanoscale transport in heterosystems needs to be improved. For instance, the relationship between current, resistance, and heat flux in nanostructures remains to be clarified. In this context, the subject of the thesis is centered around the development and application of advanced numerical methods used to predict electronic and thermal conductivities of nanomaterials. This manuscript is divided into three parts. We begin with the parameterization of a classical interatomic potential, suitable for the description of multicomponent systems, in order to model the structural, vibrational, and thermal transport properties of both silica and silicon. A well-defined, reproducible, and automated optimization procedure is derived. As an example, we evaluate the temperature dependence of the Kapitza resistance between amorphous silica and crystalline silicon, and highlight the importance of an accurate description of the structure of the interface. Then, we have studied thermal transport in graphene supported on amorphous silica, by evaluating the mode-wise decomposition of thermal conductivity. The influence of hydroxylation on heat transport, as well as the significant role played by collective excitations of phonons, have come to light. Finally, electronic transport properties of graphene supported on quasi-two-dimensional silica, a system recently observed experimentally, have been investigated. The influence on transport properties of ripples in the graphene sheet or in the substrate, which often occur in samples and whose amplitude and wavelength can be controlled, has been evaluated. We have also modeled electrostatic gating, and its impact on electronic transport
Nait-Ali, Benoît. "Elaboration, caractérisation et modélisation de matériaux poreux : Influence de la structure poreuse sur la conductivité thermique effective." Limoges, 2005. http://www.theses.fr/2005LIMO0038.
Marcq, Fabien. "Élaboration, caractérisation et vieillissement d'adhésifs conducteurs hybrides époxy-microparticules d'argent-nanotubes de carbone." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1750/.
The aim of this PhD work was the development of electrically and thermally conductive adhesives for space applications. It begins with the manufacturing by CCVD of double-walled carbon nanotubes (DWCNTs). These DWCNTs or commercial MWCNTs are dispersed by solvent route with micrometric silver flakes (µAg) in an epoxy matrix (EP). A characterization of resulting composites (EP + µAg + DWCNTs and EP + µAg + MWCNTs) follows: study of the microstructure, the electrical and thermal conductivities and the mechanical properties. Two types of reliability tests show lastly stable electrical properties over the time and higher mechanical properties than commercial thermally conductive adhesives currently in use in space industry
Goutorbe, Bruno. "Le régime thermique des marges continentales passives : méthodologie, observations et modélisation." Paris, Institut de physique du globe, 2007. http://www.theses.fr/2007GLOB0008.
In order to gain insights into the thermal regime of divergent continental margins, we successively developed a methodological part, estimated new heat flow values and performed numerical modelings. So as to use efficiently data from oil exploration, which is active on a number of continental margins, we set up a new method based on the neural network technique, relating a set of geophysical well logs to the thermal conductivity. We then performed an inter-comparison of several methods to correct bottom-hole temperatures from oil exploration, using a comprehensive data set from boreholes in Australia. We applied this methodology on several old margins, in eastern Canada, South Africa and Australia. The results we obtained suggest that mantle heat flow is higher on the margins than on the adjacent continent -- and possibly that on the adjacent ocean -- thereby contradicting the classical model of thermal evolution of continental margins. Heat flow measurements performed during a scientific cruise on a young margin, in the Gulf of Aden, are also significantly more elevated than the predictions of the classical models. These results are in agreement with numerical modelings that set the continental margins at the scale of the mantle convection, and show systematically an increase of heat flow towards the border of the continent on a minimum distance of 200 km, which remains permanently. The findings of this PhD work could bring new perspectives on the mechanisms of deformation of continental margins and the evolution of petroleum systems
Mohaine, Siyimane. "Etude des propriétés thermiques et mécaniques des bétons isolants structurels incorporant des cénosphères." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0030/document.
In the field of building thermal insulation, regulatory (RT2012) and standards (NF BPE: Béton à Propriétés Thermiques, September 2016) evolutions are encouraging the use of insulating structural concrete (BIS). The control of their thermal conductivity is essential. It is possible, in addition to using lightweight aggregates, to modify the composition of the cement paste by using hollow inclusions (fly ash cenospheres) to bring an additional thermal insulating potential. In a context of improved workability, to these properties is added the criterion of self-compacting concrete. The validation of these new formulas required the characterization of materials at different scales (from inclusion scale to building scale) by implementing experimental and numerical approaches. Their properties at fresh and hardened state were analyzed. The measured thermal conductivities place these new concretes in the Category of Structural Insulating Concrete in the sense of the new standard. The developed numerical model allowed approaching the experimental measurements correctly. The effect of cenospheres’ incorporation into cement paste on several durability indicators was also characterized
Azzopardi, Alban. "Evolution microstructurale à haute température de barrières thermiques déposées par évaporation : influence sur la conductivité thermique et le module d'élasticité." Paris 6, 2003. http://www.theses.fr/2003PA066010.
Fabien, Marcq. "Elaboration, caractérisation et vieillissement d'adhésifs conducteurs hybrides époxy / microparticules d'argent / nanotubes de carbone." Phd thesis, Université Paul Sabatier - Toulouse III, 2012. http://tel.archives-ouvertes.fr/tel-00723854.
Sassi, Selma. "Synthèse, caractérisation physico-chimique et propriétés de transport des composés homologues (PbSe)5 (Bi2Se3)3m (m = 1, 2, 3)." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0135/document.
The homologous series of compounds of general chemical formula (PbSe)5(Bi2Se3)3m with m = 1, 2 et 3 is characterized by a lamellar crystal structure where PbSe layers alternate with m Bi2Se3 layers. These compounds, that can be found as minerals, have recently focused attention for thermoelectric applications owing to their remarkable ability to poorly conduct heat. In order to evaluate their thermoelectric performances, the present work dealt with their synthesis by powder metallurgy techniques followed by measurements of their transport properties not only at low temperatures (2 – 300 K) with the aim to identify the basic mechanisms governing the transport but also at high temperatures (300 – 723 K) to determine their optimum temperature range. A detailed study of their crystalline structure has been carried out by a combination of X-ray diffraction on high-quality single crystals and high-resolution transmission electron microscopy. Measurements of their transport properties have confirmed the potential of these materials for power generation applications at mid temperatures. Numerous substitutions have been studied to optimize further their thermoelectric performances. The elements in substitution have been chosen to either increase (m = 1) or decrease (m= 2 and 3) the electron concentration. This work has demonstrated for the first time the possibility to dope these materials with various elements such as iodine, sodium, silver or tellurium. Moreover, a detailed study of the thermal properties of these compounds has been performed by means of powder inelastic neutron scattering in order to unveil the microscopic origin of the very low lattice thermal conductivity values measured
Sarthou, Julia. "Etude et caractérisation de céramiques transparentes fluorées pour lasers de forte puissance moyenne." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066534/document.
This PHD work is aiming at getting a better understanding of the structure-properties relationships of Yb:CaF2 transparent ceramics obtained with a wet-route fabrication process, with a special focus on thermal properties. At first, we introduce the assets of Yb:CaF2 transparent ceramics in the frame of high-power laser applications. The wet-route fabrication process is then described in a second chapter. The results of several analysis and characterizations performed along different steps of the ceramics synthesis are also presented, leading to an optimized fabrication process. The third chapter then focuses on an experimental study of the thermal properties of our ceramics, which shows in particular an important similarity with single crystals properties. This study is complemented with a modelization work described in chapter four. Two predictive models of thermal conductivity are investigated and compared. They bring a theoretical explanation to the tendencies experimentally observed. We thereby confirm the hypothesis according to which the grain boundaries impact on thermal conductivity is negligible with respect to that of the doping element introduction. Finally, in the fifth and last chapter, several hypothesis are investigated in order to bring an explanation to the ceramics overheating observed in laser conditions, which is superior to single crystals
Dorion, Fabrice. "Etude optique du comportement critique des propriétés de transport thermique conductif au voisinage de transition de phases dans les cristaux liquides et les microémulsions." Bordeaux 1, 1985. http://www.theses.fr/1985BOR10640.
Arab, Mohamed Raed. "Reconstruction stochastique 3D d'un matériau céramique poreux à partir d'images expérimentales et évaluation de sa conductivité thermique et de sa perméabilité." Phd thesis, Université de Limoges, 2010. http://tel.archives-ouvertes.fr/tel-00514461.
Reine, Bénédicte. "Étude et simulation de la conductivité thermique de matériaux composites à matrice organique chargée et renforcée de fibres de carbone PITCH." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2540/.
This thesis was a part of our on-going research in the frame of the THEOREM project leaded by THALES Systèmes Aéroportés. This project was a collaborative work between industrial and academic partners. The purpose was to develop a hybrid composite material made of a polymeric matrix filled with micro and nanoparticles and reinforced with PITCH carbon fibres. The ultimate material should exhibit high thermal conductivity like aluminum (~ 300 W/m/K). Two main lines are developed: one line on doped matrix and another one on reinforcements. On the matrix line numerical models of random dispersion of fillers in a predefined R. V. E. Were developed to obtain homogenized properties of the doped matrix. On the reinforcement line the influence of different fibre architectures on heat flux in the three directions of space was highlighted. Effective properties of the ultimate composite were numerically deduced from the gathering of those two lines. Different numerical models were correlated with different experimental measurements
Arab, Mohamed-Raed. "Reconstruction stochastique 3D d'un matériau céramique poreux à partir d'images expérimentales et évaluation de sa conductivité thermique et de sa perméabilité." Limoges, 2010. https://aurore.unilim.fr/theses/nxfile/default/2578ac4a-0866-4b80-b236-3397ae428fff/blobholder:0/2010LIMO4013.pdf.
The three-dimensional reconstructionof a representative sample of a biphasic ceramic material from a 2D structural image is proposed. The algorithm is of stochastic nature and is based on the minimization by a simulated annealing scheme. The statistical method of Lattice Boltzmann is presentedto simulate the phenomena of mass transport in order to estimate the permeability of the sample by a model LB D3Q19. The “effective” thermal conductivity in the 3D space is evaluated by the finite difference method by a Dufort-Frankel scheme. The tests show the ability of the reconstruction tool associated with the tools for simulations of phenomena of heat and mass transfer to digitally synthesize heterogeneous or porous materials and determine its physical parameters
Roux, Philippe. "Etude de l'influence de la contrainte, du champ magnétique et de la température sur le Pouvoir Thermoélectrique des matériaux métalliques." Lyon, INSA, 2008. http://theses.insa-lyon.fr/publication/2008ISAL0118/these.pdf.
The sensitivity of Thermoelectric Power (TEP) to many parameters and the interest of its non-destructive property, constitute a promising characterization technique in metal studies. Regardless of the simplicity of this method, the interpretation and understanding of TEP value for a given material is difficult, because the TEP depends on multiple factors. This PhD aims at determining what are the influences of different parameters (stress, magnetic field and temperature) on the TEP of metals. It has been shown that the TEP of metals vary linearly with stress in most cases. However when considering steels, the TEP follows a hysteretic behaviour as a function of stress. This special evolution may be changed by varying some metals characteristics. Nevertheless, a detailed study of the magnetic field influence on the TEP of steel has clearly demonstrated that the magnetic properties are at the origin of the hysteretic form. A new TEP device for low temperatures measuring (4,2-400 K) was also developed during this PhD work. It will enable major progresses with regard to the deconvolution of different parameters influencing the TEP
Martias, Céline. "Synthèse et caractérisation de matériaux composites à base de sulfate de calcium destinés à la protection incendie." Phd thesis, Toulon, 2011. http://tel.archives-ouvertes.fr/tel-00769952.
Cabrero, Julien. "Amélioration de la conductivité thermique des composites à matrice céramique pour les réacteurs de 4ème génération." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13877/document.
Azerou, Boussad. "Conception, réalisation et mise en œuvre de fluxmètres thermiques passif et dynamique à base de couches minces." Nantes, 2013. http://archive.bu.univ-nantes.fr/pollux/show.action?id=446c55ae-b122-4c56-bb72-917575e91ebc.
Heat flux sensors are very useful for the measurement of thermal properties and interfacial or superficial parameters (thermal contact resistance, heat transfer coefficient …. ). The objective of this work is to design, realize and test two new types of heat flux sensor based on thin film resistance temperature detector. The benefits sought are lower heat flux biases and a much lower manufacturing time. As a first step we have investigated the effect of processing conditions on the electrical resistivity and temperature coefficient of metallic thin films. Then, two types of heat flux sensors were considered : passive and dynamic. In the first case, the classical heat flux sensors with normal or tangential gradient figure out to be intrusive as they are located on surfaces perpendiculary to the main heat flux direction. Heat flux sensor with wire microthermocouples implemented within the wall offers much lower thermal disturbances, however their fabrication is time consuming and there is some uncertainty on the thermocouple locations. In our work, new heat flux sensors were realized using thin film thermoresistances deposited on polyimide substrate ant it appeared that they could offer less bias than classical heat flux sensor. The second type of heat flux sensor (dynamic) is a device composed of a micro heater and a temperature sensor. The interest is the measurement of several parameters such as the heat transfer coefficient and the equivalent temperature, one application being the characterization of microclimatic variations on the wall radiative-convective heat transfer in buildings. Such heat flux sensor was realized using thin films thermoresistances and tested with success using a wind tunnel
Coulson, MiKe. "Conductivité, diffusivité, émissivité thermiques de composites poly (EtherKetoneKetone) - charges carbonées : fibres continues et particules." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30215.
: The aim of this research is the improvement of the laser depositing fiber placement process, applied to Poly (EtherKetoneKetone) / continuous carbon fiber composites. The optimization of deposit parameters implies the investigation of the stability of the matrix and of the thermal behavior of composites. Thermal conductivity, diffusivity, and optical emissivity, are the key parameters for understanding the behavior of volume and surface conduction of composites. PEKK / carbon particle composites have been processed to study the effect of carbon morphology on thermal parameters. The emissivity of the PEKK / continuous fiber composites was measured by comparing the radiation emitted by the material with the one emitted by a black body at the same temperature. Thermal conductivity and diffusivity, which are intrinsic parameters of the composite, increase with the rate of charge and the temperature. These two parameters have been studied as a function of temperature, in the case of PEEK / continuous fibers composites and PEKK / carbon particles composites for various charge rates
Hadaoui, Abdellah. "Effets de taille et de concentration sur les propriétés thermiques et rhéologiques des nanofluides." Phd thesis, Université d'Orléans, 2010. http://tel.archives-ouvertes.fr/tel-00769934.
Jensen, Colby. "Rejoindre les nano et macro mondes : la mesure des propriétés thermiques utilisant la microscopie thermique et la radiométrie photothermique." Thesis, Reims, 2014. http://www.theses.fr/2014REIMS002.
In nuclear applications, material properties can undergo significant alteration due to destructive interaction with irradiating particles at microstructural levels that affect bulk properties. One of the challenges associated with studies of ion-Irradiated materials is that the affected layer, or penetration depth, is typically very thin (~0.1-100 μm). This study expands the current knowledge base regarding thermal transport in ion-Irradiated materials through the use of a multiscaled experimental approach using thermal wave methods. In a manner not previously explored, four thermal wave methods are used to characterize the proton-Irradiated layer in ZrC including scanning thermal microscopy (SThM), spatial-Scanning front-Detection photothermal radiometry (PTR), lock-In IR thermography (lock-In IRT), and tomographic, frequency-Based PTR. For the first time, the in-Depth thermal conductivity profile of an irradiated sample is measured directly. The profiles obtained by each of the spatial scanning methods are compared to each other and the numerical prediction of the ion-Damage profile. The complementary nature of the various techniques validates the measured profile and the measured degradation of thermal conductivity in the ZrC sample
Valalaki, Aikaterini. "Etude des propriétés thermoélectriques et d’isolation thermique du Si poreux et Si nanocristallin." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT031/document.
This thesis is devoted to the thermal conductivity and other thermoelectric properties of porous silicon (PSi) and thin polycrystalline Si films (thickness: 100-500 nm).PSi is a complex material composed of a Si skeleton of interconnected nanowires and dots, separated by voids. When it is highly porous, its thermal conductivity is very low, even below that of the amorphous Si. This makes it a good material for use as a thermal isolation platform on the Si wafer. In addition, its Seebeck coefficient is much higher than that of bulk c-Si.We studied k of PSi layers with different morphologies and porosities, in the temperature range 4.2-350K. The measurements below 20K are the first reported in the literature. A plateau-like dependence on temperature was observed for T below 20K, while above this temperature a monotonic increase with T is observed. The observed behaviour was interpreted using known theoretical models, based mainly on the fractal nature of PSi. PSi was characterized as a fractal material by calculating its fractal dimension using SEM images and the box counting algorithm.Two different methods were used to determine porous Si thermal conductivity: the DC method combined with FEM analysis and the 3ω method. Concerning the 3ω method, two improved approaches were proposed for extracting k from the 3ω voltage as a function of frequency: the first uses a fitting of the experimental data to the asymptotic solution of the Cahill’s integral formula, and the second is based on the analysis of the experimental data by combining them with a solution of the transient heat transfer equation using FEM analysis. The results in this second case were more accurate and in very good agreement with the DC method.We also measured the Seebeck coefficient (S) of PSi membranes with porosities 40-84% using a home-built setup, which was fabricated, calibrated and tested within this thesis. A value as high as 1mV/K was obtained for the 51% porosity sample. An anomalous porosity dependence of S was obtained, which was attributed to the interplay between energy filtering, phonon scattering and phonon drag effects. The results were explained by combining them with PL and TEM measurements, used for the determination of nanocrystal sizes. We concluded that, despite of the extremely low k and the high S of PSi, the material with the studied high porosities is not adequate for use as a “good thermoelectric” material, because of its significantly low electrical conductivity, which decreases with increasing porosity, resulting from carrier depletion during formation.We also studied the thermoelectric properties of thin, boron-doped, polycrystalline silicon films, which are much more attractive for use as Si-based thermoelectrics than porous Si. Their thermoelectric performance is improved by decreasing film thickness, due to a decrease in polysilicon grain size. Thin films with thickness between 100-500nm were investigated. We measured their thermal conductivity, resistivity and Seebeck coefficient and extracted their thermoelectric figure of merit, which showed threefold increase by reducing film thickness down to 100nm. A value as high as 0.033 was achieved, which is the highest reported in the literature so far for boron-doped polysilicon films at room temperature. This increase is attributed to a decrease in the grain size of the material. The obtained value shows the interest of nanocrystalline Si films for integration in efficient Si-based thermoelectric generators, compatible with CMOS processing