De nos jours, l’industrie de la microélectronique cherche à développer des composants toujours plus performants tout en réduisant la consommation d’énergie. Les solutions planaires ayant atteint leurs limites, desstructures 3D furent développées afin d’empiler verticalement les circuits. Cela nécessite une parfaite maitrise des différents procédés d’assemblage au sein desquels le collage direct de couches minces d’oxyde de silicium déposées par PECVD constitue une alternative intéressante en ce sens qu’elle permet l’élaboration à basse température de structures intégrant des couches isolantes composées d’oxyde de silicium.Le collage direct d’oxyde de silicium obtenu par voie thermique fut largement étudié par le passé. Cependant, l’utilisation d’oxyde de silicium obtenu par voie de dépôt PECVD fut jusqu’ici peu répandu dans les structures collées. L’objet de notre étude fut d’évaluer les particularités de l’oxyde de silicium déposé dans le cadre du collage direct ainsi que les mécanismes spécifiques mis en jeu lors du scellement de l’interface de collage. Le collage direct s’effectuant par la mise en contact de ces surfaces à température ambiante, puis étant généralement suivi d’un recuit de consolidation, des mécanismes particuliers auront lieu dans le volume de l’oxyde ainsi qu’à l’interface de collage permettant de différencier le comportement des oxydes déposés en collage.Dans cette étude, nous avons assemblés différentes configurations d’oxydes et montré l’influence primordiale de l’eau sur le collage direct. Il est apparu que, dès la température ambiante, cette dernière impactait déjà le collage en modifiant les propriétés physicochimiques et mécaniques de la subsurface de l’oxyde. A plus haute température, l’eau migre du volume de l’oxyde vers l’interface de collage permettant la fermeture de l’interface de collage en exacerbant les propriétés de l’oxyde précités. L’eau résultant de la fermeture de l’interface de collage est alors soit stockée à l’intérieur de cavités se formant à l’interface de collage, soit évacuée dans la subsurface de l’oxyde suivant la typologie de celui-ci. Il a également été montré que l’oxydedéposé disposait d’un profil de concentration d’eau relativement équilibré et qu’il pouvait contenir une quantité importante d’eau. Ces constations ont permis l’élaboration de structures bicouches optimisées pour le collage direct. La compréhension de ces différents mécanismes apporte un nouvel éclairage dans l’utilisation des procédés de collage direct pour les applications du futur. / Nowadays, the microelectronics industry is seeking to develop ever more efficient components while reducing energy consumption. Planar solutions having reached their limits, 3D structures were developed to vertically stack the circuits. This requires a perfect control of the different assembly processes in which the direct bonding of thin layers of silicon oxide deposited by PECVD constitutes an interesting alternative in the sense that it allows the elaboration at low temperature of structures integrating insulating layers composed of silicon oxide.The direct bonding of silicon oxide obtained by thermal oxidation has been widely studied in the past. However, the use of deposited PECVD silicon oxides has not been so far widespread in bonded structures. The purpose of our study was to evaluate the particularities of the silicon oxide deposited in the direct bonding framework as well as the specific mechanisms involved during sealing of the bonding interface. Since direct bonding takes place by bringing these surfaces into contact at room temperature and then generally followed byconsolidation annealing, special mechanisms will take place in the oxide volume and at the bonding interface to differentiate the behaviour of the PECVD deposited silicon oxides in bonding.In this study, we assembled different oxide configurations and showed the primordial influence of water on direct bonding. It appeared that, from the ambient temperature, the water was already impacting the bonding by modifying the physicochemical and mechanical properties of the oxide subsurface. At higher temperatures, the water migrates from the oxide volume to the bonding interface allowing the closing of the bonding interfaceby exacerbating the above oxide properties. The water resulting from the closing of the bonding interface is then either stored inside cavities forming at the bonding interface or discharged into the oxide subsurface dependingon the type of oxide. It was also shown that the deposited oxide had a relatively balanced water concentration profile and could contain a significant amount of water. These findings have led to the development of two-layerstructures optimized for direct bonding. Understanding these different mechanisms provides new insights into the use of direct bonding processes for future applications.

Orientador: Eugênio José Zoqui / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-20T11:43:58Z (GMT). No. of bitstreams: 1 VilasBoas_Bruna_M.pdf: 42430697 bytes, checksum: 87567412122ac22fa1c23e2b330933f0 (MD5) Previous issue date: 2012 / Resumo: Esta dissertação tem como finalidade avaliar a tixoconformabilidade das ligas Al- 4wt%Si-5wt%Zn, Al-5wt%Si-5wt%Zn, Al-6wt%Si-5wt%Zn. Para tanto, essas ligas foram submetidas a um tratamento térmico de globularização pelos tempos de 0s, 30s, 90s e 210s, na fração sólida de 45%, para assim, ocorrer o tixoforjamento em prensa excêntrica e em prensa pneumática. Posteriormente, foi feita a caracterização micro e macroestrutural das peças tixoconformadas. Em seguida, foram analisadas as propriedades mecânicas da peça tixoforjada através do ensaio de tração, e da análise da porosidade do material. Como resultado principal destaca-se que as três ligas apresentaram boas propriedades mecânicas após a tixoconformação e que as peças tixoconformadas na prensa pneumática apresentou melhores propriedades mecânicas do que a prensa excêntrica / Abstract: This dissertation aims to evaluate the thixoconformability of Al-4% Si-5% Zn, Al- 5% Si-5% Zn, Al-6% Si-5% Zn alloys. For this, these alloys were subjected to a heat treatment of globularization by the following periods of times 0s, 30s, 90s and 210s in the solid fraction of 45%, so that it can occurs the thixoforging in the eccentric press and the pneumatic press. Later on, it was made the characterization of micro and macrostructural thixoforged pieces. Next, we analyzed the mechanical properties of thixoforged pieces through tensile testing, and analysis of the porosity of the material. As a main result, it stands out that the three alloys showed good mechanical properties after thixoforming and thixoforged pieces in pneumatic press showed better mechanical properties than the eccentric press / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-08T11:32:05Z No. of bitstreams: 1 sabrinamascarenhasvargas.pdf: 12731626 bytes, checksum: b1c5ae34c05edd5e0970eb9289e25f3d (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T13:25:40Z (GMT) No. of bitstreams: 1 sabrinamascarenhasvargas.pdf: 12731626 bytes, checksum: b1c5ae34c05edd5e0970eb9289e25f3d (MD5) / Made available in DSpace on 2016-07-13T13:25:40Z (GMT). No. of bitstreams: 1 sabrinamascarenhasvargas.pdf: 12731626 bytes, checksum: b1c5ae34c05edd5e0970eb9289e25f3d (MD5) Previous issue date: 2016-04-04 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Visto que o esmalte dentário é um tecido não inervado e avascular, que está constantemente sob a in uência de carregamento cíclico (funcional ou parafuncional) e que o mesmo não tem capacidade de regeneração, torna-se importante o estudo sobre as propriedades mecânicas desse tecido. Possui uma microestrutura única, que o faz apresentar propriedades mecânicas excelentes, porém o mesmo se apresenta frágil, com pouca capacidade de suportar deformação plástica antes da sua fratura. Alguns testes experimentais de indentação tentam entender o comportamento mecânico desse compósito, porém a complexidade desse comportamento e as diferenças de técnicas fazem com que os módulos de elasticidade para a hidroxiapatita, a matriz orgânica e o módulo efetivo do esmalte dentário tenham resultados muito variados na literatura. O mesmo se dá para as simulações multiescala de modelos para o esmalte dentário. Diante disso, esse estudo tem como o objetivo utilizar a modelagem multi-escala em 2D para a determinação dos tensores de propriedades mecânicas efetivas do esmalte dentário, através da técnica de homogeneização por expansão assintótica (HEA). Dentre as conclusões do trabalho têm-se que: 1- O esmalte dentário pode ser representado por um meio homogêneo equivalente, uma célula unitária representativa repetitiva; 2- Os modelos propostos nesse estudo têm comportamento ortotrópico; 3- Embora haja limitações relacionadas às simpli cações mecânicas e geométricas adotadas, os resultados obtidos encorajam aplicações mais realistas e estudos mais aprofundados acerca da microestrutura do material em questão. / Whereas tooth enamel is not an innervated neither vascular tissue which is constantly under the in uence of cyclical loading (functional or parafuncional) and that its tissue has no capacity for regeneration, it becomes important to study the mechanical properties of the enamel. It has an unique microstructure, which makes it exhibit excellent mechanical properties, but it appears fragile, with little ability to withstand plastic deformation prior to fracture. Some experimental indentation tests attempt to understand the mechanical behavior of this composite, but the complexity of its behavior and the di erent techniques imply in the modulus of elasticity for the hydroxyapatite, the organic matrix and the e ective modulus of dental enamel showing very di erent results in the literature. The same occurs for multiscale simulations of dental enamel models. Thus, this study aims 2D multi-scale modeling by Asymptotic Expansion Homogenization (AEH) technic to determine the mechanical properties e ective tensor of dental enamel. The conclusions of this study shows: 1- The enamel can be represented by an equivalent homogeneous medium, a repetitive representative unit cell; 2- The models proposed in this study present orthotropic behavior; 3- Although there are some limitations due to the mechanical and geometric simpli cations adopted, the results suggest more realistic applications and further studies on the microstructure of the material in question.

Les EPDM (Ethylène Propylène Diène Monomère) sont employés comme isolants des câbles électriques des centrales nucléaires. En raison de l’environnement radioactif, ils se dégradent plus rapidement qu’en environnement classique. La détermination de leur durée de vie est donc un enjeu industriel important. Pour y parvenir, ce travail a d’abord consisté à déterminer l’influence de la composition des EPDM sur leurs cinétiques de dégradation. Ainsi, deux EPDM de composition chimique différente ont été irradiés sous rayonnement en présence d’oxygène. Les suivis de la fraction soluble et de la densité de chaines actives en fonction de la dose, ont permis de mettre en évidence une dégradation par réticulation et coupures de chaines. A partir de modèles statistiques, les cinétiques de ces deux processus ont pu être estimées : la réticulation dépend de la proportion en ENB résiduels tandis que les coupures de chaines sont indépendantes de la composition chimique et du degré de réticulation initial. De plus, au - delà d’une certaine dose, les nœuds de réticulation semblent progressivement détruits. Nous nous sommes ensuite intéressés aux conséquences de l’irradiation sur les propriétés mécaniques et ce, d’abord à 80°C, pour s’affranchir de la présence de cristallites. Si dans tous les cas, l’irradiation conduit à une décroissance de la contrainte à la rupture, nos matériaux montrent une déformation à rupture qui augmente avec la dose contrairement aux matériaux de Planès et al. Pour s’affranchir du rôle des hétérogénéités sur l’initiation de fissure, les propriétés mécaniques d’éprouvettes entaillées ont ensuite été étudiées. L’énergie de déchirement est corrélée à l’énergie de rupture des matériaux entaillés et peut être décrite par le modèle de Lake et Thomas, à condition de prendre en compte la longueur réelle entre nœuds de réticulation des matériaux irradiés. Aussi, les propriétés en rupture de tous les matériaux sont améliorées quand ils sont étudiés à 25°C et la présence de cristallites masque les conséquences de la dégradation ; cet effet est ici très marqué en raison d’une importante chimie - cristallisation. Des EPDM chargés ATH ont alors été étudiés. Nos résultats confirment une accélération de la dégradation par les ATH, dépendant de la surface spécifique des charges. La compréhension des propriétés en rupture des composites s’avère complexe car la rupture peut être entrainée par divers processus en compétition. L’évolution des propriétés mécaniques des composites testés à 25°C est, comme pour la matrice pure, dépendante de l’évolution de la cristallinité et des propriétés de la phase amorphe. Enfin, ce travail remet en cause la pertinence des critères de durée de vie actuellement utilisés dans l’industrie. Les énergies de rupture étant plus directement corrélées aux paramètres microstructuraux, ne faudrait-il pas plutôt considérer ce paramètre comme critère? / EPDM (EThylene Propylene Diene Monomer) are used as insulation for electrical cables in nuclear plants. Because of the radiative environment, the degradation of these cables is accelerated and a strong industrial challenge consists in the prediction of the cables lifetime. To address this crucial industrial concern, we first looked into the influence of the chemical composition of EPDM on their kinetics of degradation. To do so, two EPDM with different chemical compositions have been irradiated under radiations and in the presence of oxygen. The soluble fraction and the active chain density have been monitored as a function of the irradiation dose, and revealed the degradation by cross-linking and chain scissions. Furthermore, the kinetics of these mechanisms have been estimated based on statistical models: the cross-linking kinetics depends on the residual ENB content while the chain scission kinetics vary neither with the chemical composition nor the initial cross-linking degree. Moreover, beyond an irradiation dose, the cross-links are progressively broken. The mechanical performances were then studied at 80°C to prevent crystallinity. If the irradiation induces a decrease of the stress at break, the materials show an increase of the strain at break conversely to the EPDM systems studied by Planès et al. The mechanical properties of notched samples have then been employed in order prevent heterogeneities driven crack initiation. The tearing energy measured was correlated with the failure energy of notched samples andcan be described by the Lake and Thomas model with account for the real length between cross-links. The same study has then been performed at 25°C where the properties at break are seen to improve. Such improvements despite irradiation confirm that crystallites attenuate the degradation. This effect is more pronounced for the current set of materials because of a strong chemi-crystallisation. The addition of ATH fillers has been studied as well, showing an acceleration of the matrix degradation with the specific surface of the fillers. The understanding of the mechanical properties at break of filled materials seems complex because the failure can be obtained by various competing processes. Nevertheless, the matrix chemical nature can be mentioned as an important factor since the difference between the matrix mechanical properties and the matrix-filler interface properties will trigger the creation of macro-defects at the origin of failure. As for the neat matrix, the evolution of the composites mechanical properties tested at 25°C depends on the evolutions of both the crystallinity and the amorphous phase. More generally, this work questions the relevance of the actual lifetime criterion used in the industry. The energies at break are more directly correlated to the microstructural parameters and thus could correspond to a relevant criteria for predicting these systems lifetime.