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1
Ward, William F. "A theoretical investigation into the inelastic behavior of metal-matrix composites." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/17244.
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Hsu, Sheng-yuan. "On the prediction of compressive strength and propagation stress of aligned fiber-matrix composites /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Benethuilière, Thibaut. "Phénomènes physico-chimiques aux interfaces fibre/matrice dans des composites SMC structuraux : Du mouillage à l'adhésion." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI151.
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Gabrion, Xavier. "Contributions à la caractérisation d'un matériau composite thermoplastique thermostable : Application à des structures cylindriques sous sollicitations multiaxiales." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2012.
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Ce travail de thèse, en partenariat avec l’entreprise ALSTOM, s’inscrit dans une logique de remplacement de pièces industrielles en alliage métallique par des pièces composites pour l’allègement des structures. L’objectif est de contribuer à l’écriture de règles de dimensionnement permettant au partenaire industriel de certifier des pièces structurales annulaires réalisées en composite à matrice thermoplastique thermostable (TPTS) renforcée par des fibres de carbone pour des applications embarquées sur machine tournante. Il s’agit plus exactement de déterminer la durée de vieen fatigue de ces pièces, en particulier en présence d’endommagement, et lorsque celles -ci sont soumises aux chargements inertiels et thermiques de service.Au cours de ce travail de thèse, une méthodologie a été développée afin de répondre à cette demande. La stratégie a consisté à reproduire,à l’échelle d’éprouvettes de laboratoire, l’état de contrainte multi-axial et l’endommagement auxquels la structure industrielle est soumise, et ce en développant et optimisant un essai de traction sur des éprouvettes annulaires entaillées. Les essais multi axiaux plus classiques mettant en œuvre des sollicitations par pression interne présentent effectivement de nombreux problèmes techniques et sécuritaires lorsqu’ils doivent être mis en œuvre à chaud.Une fois la configuration d’essai sur anneau optimisé par simulation numérique, des essais ont été réalisés afin de confirmer l’apparition des endommagements escomptés à l’aide de techniques de contrôle non-destructif. Les essais cycliques réalisés dans cette configuration ont montré une excellente résistance du matériau en fatigue, en particulier pour un ratio de chargement R de 0.5, proche des conditions de service. Les résultats ont également soulignés le fort potentiel restant de ces structures, même après un grand nombre de cycles de chargementThe objective of this thesis work, in partnership with ALSTOM Company, is to contribute to the writing of design rules in order to qualify and certify annular structures made of thermostable thermoplastic matrix composite reinforced by carbon fibre. These structures are used in rotating machines for embedded applications.This work proposes an innovative methodology to achieve this goal. It consists in reproducing, at the scale of a laboratory specimen, the multiaxial stress and damage states to which the industrial structure is subjected in-service byoptimizing a tensile test on annular notched specimen. More conventional multiaxial tests, based on internal pressureand tensile loading are particularly unsafe and difficult to be performedwhen implemented at elevated temperature.After the optimisation of the ring configuration by numerical simulation, experimental tests were performed to validatethe appearance of the expected damage under loading. Damage was characterized using non-destructive techniques suchas acoustic emission and infrared thermography. The cyclic tests achieved using this configuration showed high fatiguestrength of this material, in particular for a ratio R of 0.5 (equivalent to thein-service ratio). The results also highlight thegreat remaining strength and rigidity of these structures, even after a large number of cycles
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Ellerby, Donald Thomas. "Processing and mechanical properties of metal-ceramic composites with controlled microstructure formed by reactive metal penetration /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/10583.
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Breunig, Thomas M. "Nondestructive evaluation of damage in SiC/Al metal matrix composite using x-ray tomographic microscopy." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/19999.
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Wright, Richard J. "Bolt bearing creep behavior of highly loaded polymer matrix composites at elevated temperatures." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17362.
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Elouaer, Abdelmonem. "Contribution à la compréhension et à la modélisation du comportement mécanique de matériaux composites à renfort en fibres végétales." Thesis, Reims, 2011. http://www.theses.fr/2011REIMS003/document.
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L’industrie des matériaux composites ne cesse d’évoluer et de croître en mettant en place de nouveaux matériaux et de nouvelles technologies. En substitution des matériaux d’origine fossile que les matériaux d’origine naturelles (et surtout végétales) commencent à voir le jour. C’est dans ce contexte que notre travail de recherche est proposé. Il s’intéresse à la caractérisation du comportement mécanique d’un composite à matrice Polypropylène, renforcé avec des fibres de Chanvre et du bois de Chanvre (Chènevotte). Les différents moyens et techniques de caractérisation, utilisés par la présente étude, ont montré que ces nouveaux matériaux sont dotés de propriétés, en particulier mécaniques, de haut niveau, qui viennent rivaliser avec celles des autres composites classiques à base de fibres de verre et de carbone.Les essais expérimentaux en statique et de fatigue, ont révélé beaucoup de détails en comparaison avec d’autres matériaux composites. Ces informations ont permis de créer une sorte de base de données qui pourra servir de référence pour d’autres composites de la même famille à base de fibres végétales. Ainsi, des mécanismes d’endommagement ont été mis en évidence grâce aux essais mécaniques (traction monotone, charge-décharge, …) associés à des observations microscopiques (Microscope Electronique à Balayage), et à des outils de détection du dommage basés sur l’émission acoustique. Par le biais de cette technique, nous avons pu apprécier la qualité et l’importance de l’interface fibre/matrice qui est un paramètre fondamental pour la présente étude et pour la détermination de la loi de comportement du composite.La modélisation micromécanique a été intégrée dans ce travail de thèse, grâce au modèle de Mori-Tanaka. Le comportement des matériaux à l’endommagement n’a pas été pris en considération ; seule l’élasticité a été étudiée. A l’aide de ce modèle, nous avons pu remonter aux propriétés intrinsèques des constituants (le module d’élasticité longitudinale des renforts: Chanvre et Chènevotte)The composites industry continues to evolve and grow by developing new materials and new technologies. Replacing fossil materials by materials with natural origin (especially vegetable) seems to be one of the most promising. In this context our research is proposed. It is interested to characterize the mechanical behavior of a polypropylene matrix composite reinforced with fibers of Hemp and Wood of Hemp (Chenevotte). The various means and characterization techniques used in this study showed that these new materials have interesting mechanical properties, coming rival those of other conventional composites based on carbon and glass fibers.The experimental static and fatigue tests have revealed many details in comparison with other composite materials. The information help creates a database that can serve as reference for other composites of the same family and vegetable fibers. Mechanisms of damage have been highlighted through mechanical tests (tensile monotonous charge-discharge …) associated with microscopic observations (Scanning Electron Microscope), and tools for damage detection based on emission acoustics. Thanks to this technique, we could improve the quality of the interface fiber / matrix which is a basic parameter for this study and for determining the behavior of composite.Micromechanical modeling has been integrated in this thesis, through the Mori-Tanaka model. The behavior of materials during damage has not been taken into account: only the elasticity has been studied. Using this model, we were able to trace the intrinsic properties of the constituents (the longitudinal modulus of elasticity of the reinforcements: Hemp and Chenevotte)
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Wang, Xufeng Materials Science & Engineering Faculty of Science UNSW. "Application of single-part adhesives as healing agent in self-healing composites." Awarded by:University of New South Wales. Materials Science and Engineering, 2007. http://handle.unsw.edu.au/1959.4/32233.
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The aim of this study was to develop a new single-part healing system for self-healing composites. The self-healing approach to composite repair has been developed in the last two decades and means that a damaged area can be repaired by material already housed within the structure. The background and development of self-healing has been reviewed. The two main self-healing mechanisms are discussed. To date only two part self healing systems have been examined. These require diffusion of the separate constituents to a single location in order to effect cure and restore strength. Single part adhesives do not have this disadvantage and are therefore very attractive. Several candidate single-part adhesive or resin systems were considered and discussed according to the critical requirements of a self-healing system. A series of experiments was undertaken to evaluate the possibility of candidate adhesive systems being effective for self-healing by focusing on the determination of storage stability and bonding efficiency. The results of storage stability testing showed that the stability of cyanoacrylate and polyurethane adhesives was poor. However silane and polystyrene cements showed good storage stability. Very low bonding efficiency was achieved with polystyrene cement but a 22% strength recovery was obtained with the silane 3-[tris(trimethylsiloxy)silyl]-propylamine. Suggestions for further research into single-part healing systems are also given.
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Sacks, Serena. "Effects of thermal aging on the mechanical behavior of K3B matrix material and its relationship to composite behavior." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/18865.
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Bulsara, Vatsal N. "Effects of fiber spatial distribution and interphase on transverse damage in fiber-reinforced ceramic matrix composites." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/21429.
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Drury, William James. "Quantitative microstructural and fractographic characterization of AE-Li/FP metal matrix composite." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/19958.
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Delcamp, Adrien. "Protection de fibres base SiC pour composites à matrice céramique." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13729/document.
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Les composites à matrice céramique (CMC) sont des matériaux constitués d’une matrice céramique renforcée par des fibres céramiques continues (généralement à base de SiC ou de C). Le travail de thèse présenté, réalisé en collaboration avec Snecma Propulsion solide et l’Agence De l’Environnement et de la Maîtrise de l’Energie, a pour objectif d’introduire des matériaux CMC au sein de pièces de moteurs d’avions civils, concurrençant ainsi les alliages métalliques actuellement utilisés. Pour ce faire, les matériaux CMC devront répondre aux exigences propres à l’aéronautique civil, à savoir qu’ils devront présenter une longue durée de vie en atmosphère oxydante dans une gamme de basse température (400-600°C) et avoir un coût compétitif. Dans ce contexte, des matériaux CMC constitués de fibres SiC de première génération, de coût moins élevé, sont étudiés, mais leur inconvénient majeur est leur plus grande sensibilité à l’oxydation. Des matrices auto-cicatrisantes multicouches à base de Si, B, et C ont été développées ces dernières années afin d’assurer une tenue à l’oxydation des fibres, mais elles ne sont pas opérantes dans la gamme de température imposée. Compte tenu d’études précédemment réalisées et des exigences requises pour l’application visée, l’objectif du travail présenté dans ce mémoire est de proposer des solutions pour améliorer la tenue à l’oxydation de renforts fibreux à base de fibres de SiC de première génération, dans la gamme de température 400-600°C, en évitant un surcoût de production trop importantContinuous fiber-reinforced ceramic matrix composites (CFCCs) are an important class of materials for structural applications at elevated temperatures because of their improved flaw tolerance, large fracture resistance, improved toughness by crack deflection and crack bridging mechanism, low density and noncatastrophic mode of failure comparing with metallic materials. Fibers play a critical role in both the processing and performance of CFCCs. SiC-based fibers are considered leading candidate materials in the aerospace application, such as engine turbines. However, the major shortcoming of SiC-based fibers is their oxidative embrittlement and degradation, which is caused by the oxygen ingression from the micro cracks and interstitials in the composites, is the dominant life-limiting phenomenon of non-oxide composites. This study carried out with the financial supply of both Snecma Propulsion Solide and Agence De l’Environnement et de la Maîtrise de l’Energie has for objective to integrate SiC-based as reinforcement in CFCCs for civil aircraft engine application. In order to reach this objective, it is imperative to find a novel approach to diminish the oxygen ingression by developing protective fiber coatings
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Edrees, Hamza J. "Sialon ceramic matrix composites." Thesis, University of Strathclyde, 1990. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21383.
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The present study has been performed on β'-sialon matrix reinforced with either carbon fiber, metals or TiN components. The study describes the optimum methods of fabrication of these composites and also investigates their mechanical and electrical properties. In carbon fiber/sialon system, reaction between the fiber and the matrix has been identified and overcomed by applying high densification rate and low temperature sintering. Samples containing 10-20V% fiber was hot pressed to almost theoretical density at temperatures 1500-1550°C. In metal reinforced sialon matrix composites there is always a reaction between the metal and the sialon to form metal silicide liquid at relatively low temperatures, which is found to be helpfull in decreasing the maximum densification temperature. Sialon reinforced by 15V% Ni powder is pressureless sintered to over 95 % of the theoretical density at temperature of 1450°C. Reaction in such composites can be controlled by increasing the sintering heating rate and the amount of silicon metal dissolveed into the metal particles (which strongly influences the composites mechanical properties) can be controlled by a two stage heat treatment sintering particularly in the stainless steel/sialon system. The addition of TiN to sialon matrix resulted in processing with no troubles of chemical incompatibility and composites with attractive mechanical properties. Density of almost theoretical was achieved in the addition of 10-30V%TiN to sialon. The crack type investigations on sialon and sialon matrix composites shows that the cracks are of Palmqvist type. The indentation fracture toughness of the composites mentioned above is dependant on the reinforced phase type, volume fraction and sintering temperature. In fiber/sialon composites fracture toughness of 4 7.9 MNm⁻³/² was achived by hot pressing 15V% carbon fiber/sialon composites. In metal/sialon composites, however, fracture toughness of 13 MNm⁻³/² is achieved, whilst the indentation fracture toughness of 30V%TiN reinforced sialon composites is 8.9 MNm⁻³/². The electrical conductivity of these composites is strongly dependant on the reinforced phase volume fraction and most importantly on the particles size of the conductive phase. However, resistivity of 0.5 Ω. cm is achieved in the addition of 20V% carbon to the sialon matrix. In metal/sialon systems resistivity of 3.37 Ω. cm is achieved in 20V% Ni/sialon composite whilst 30V%TiN is required to create a resistivity of 443 Ω. cm in such composites.
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Chamberlain, A. "Novel silicate matrix composites." Thesis, University of Warwick, 1994. http://wrap.warwick.ac.uk/107576/.
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Within this study, a novel matrix selection principle, within the MAS glass ceramic system, has been developed with emphasis placed on the use of this matrix in a ceramic fibre reinforced composite. Matrix selection was applied in order to develop a diphasic microstructure to allow tailoring of the matrix thermal expansion coefficient via a phase mixture. The phases selected were a-cordierite and enstatite, with a Nicalon fibre reinforcement. Initial studies centred on the use of chopped fibre systems in order to develop a processing methodology giving the correct phase structure, microstructure and interface development between the matrix and the fibre. It was found that variations in process route including the use of window I and window II pressing regimes (below and above the maximum crystallisation rate) caused large differences in the matrix microstructure. During this part of the study the effects of added nucleants were investigated (P2O5 at 2wt%, and Ti02 at 10wt%), the results indicating that, with the use of glass frit, the added nucleant was not necessary. Initial studies upon composite fabrication indicated the criticality of pressure application during processing indicated by a fall in the elastic modulus of the composite from the rule of mixtures calculation. A pre-preg methodology was developed to produce high quality green state composite, including a T-piece traverse head arrangement for the fibre tow infill, 'walls' on the winding cage and rollering the pre-preg sheets. Following this, a refined process route for hot pressing was developed with application of pressure during heating in a 'process-window' identified using DTA. Composites were fabricated using the NL-607 fibre type with optimised properties reaching a matrix microcracking stress of cmm = 665±75MPa, ultimate flexure strength of oUBS = 1168±41MPa and E = 157±12GPa (within the rule of mixtures calculation). TEM analysis indicated an interface width of 25-70nm. with carbon enrichment occurring. Measurement of the micromechanical properties of the interface used an indentation technique giving the interfacial debond energy 2T = 12.4±5.4Jnv2, and shear sliding resistance T = 48±15MPa. Tensile studies indicated that two regions could be identified associated with microcracking in the 90° and 0° plies by a modulus drop and acoustic emission. Thermal aging in air (lOOhrs) indicated that channelled oxidation via fibre / matrix interfaces was occurring at intermediate temperatures (450° - 700°C) and partial silica bridging of the interface at higher temperatures in this interval. Micromechanical property measurements indicated that for 450°C aging 2T = 13.6±4.4Jnr2 with T = 108±54 MPa, whereas for 700°C aging 2T = 35.6±29.2Jnr2 with T = 248±120MPa. At higher temperatures (1000°C), rapid silica bridging of the interface caused plugging to occur and the retention of as-fabricated mechanical properties for the bulk material. Fibres in the bulk of the composite had micromechanical properties similar to as fabricated materials, whereas fibres ~ 30pm from the edge of the sample had very high micromechanical properties indicative of fully silica bridged interfaces. Above 1000°C microstructural degradation was observed with the formation of a surface layer on the composites (60-80pm at 1000°C, 80- 140pm at 1200°C). Tensile creep studies indicated, for the conditions utilised within this work ( 1000°-1150°C and 50-90MPa), that fibre creep properties dominated, with the observed creep rate being - 1.6 x 10 8-s1. For all the creep studies conducted, nonsteady state creep was observed, with a continuously decreasing creep rate with time.
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Schuler, Sabine. "Modelling consolidation of matrix-coated fibre metal matrix composites." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284419.
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Arenburg, Robert Thomas. "Analysis of metal matrix composite structures using a micromechanical constitutive theory." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/49918.
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The nonlinear behavior of continuous-fiber-reinforced metal-matrix composite structures is examined using a micromechanical constitutive theory. Effective lamina and laminate constitutive relations based on the Aboudi micromechanics theory are presented. The inelastic matrix behavior is modeled by the unified viscoplasticity theory of Bodner and Partom. The laminate constitutive relations are incorporated into a first-order shear deformation plate theory. The resulting boundary value problem is solved by utilizing the finite element method. · Computational aspects of the numerical solution, such as the temporal integration of the inelastic strains and the spatial integration of bending moments are addressed. Numerical results are presented which illustrate the nonlinear response of metal matrix composites subjected to extensional and bending loads. Experimental data from available literature are in good agreement with the numerical results.Ph. D.
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Franklin, Jennifer. "In-situ Synthesis of Piezoelectric-Reinforced Metal Matrix Composites." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/10141.
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The in-situ synthesis of piezoelectric-reinforced metal matrix composites has been attempted with a variety of target matrix and reinforcement materials using reaction synthesis and high energy ball milling. Zinc oxide (ZnO) and barium titanate (BaTiO₃) have been successfully synthesized within copper and iron matrices in a range of volume percentages using reaction synthesis. The microstructures of these composites have been analyzed and found to partially consist of an interpenetrating microstructure. After considering experimental findings and thermodynamic issues involved with synthesis, ideal reaction system parameters have been identified that promote the creation of a composite with ideal microstructure and formulated composition. Reactive high energy ball milling has been used to create copper matrix composites reinforced with zinc oxide and copper matrix composites reinforced with lead titanate (PbTiO₃). The microstructures and compositions of each volume percentage formulation of the composite powders have been analyzed. In this work, several promising piezoelectric-reinforced metal matrix composite systems have been identified as having potential to be synthesized in an in-situ manner.Master of Science
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Mariappan, L. "In-Situ Synthesis Of A12O3_ZrO2_SiCw Ceramic Matrix Composites By Carbothermal Reduction Of Natural Silicates." Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/215.
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This thesis outlines the work done on in-situ synthesis of Al2O3-ZrO2-SiCw ceramic composites and their property evaluation. The introductory chapter deals with the literature survey on ceramic matrix composites, properties desirable for structural applications and toughening mechanisms associated with these composites. The role of whisker toughening in ceramic matrix composites, the growth mechanisms involved in whisker growth and the conditions that favour or hamper the whisker growth are also discussed. The advantages and disadvantages of in-situ synthesis of composites as compared to physical mixing are also dealt with. The objective and scope of the work undertaken are outlined at the end.
The second chapter describes the experimental techniques associated with carbothermal synthesis and characterisation of reaction products as well as properties of hot pressed bulk composites. The equipments used for this work are described here.
The third chapter focuses on the results obtained by the carbothermal reduction of mixtures of kaolin, sillimanite and zircon taken in various proportions. The formation of the product phases with respect to variations in temperature, variations in composition and effect of catalyst is analysed with the help of XRD while their morphology is analysed using SEM. The conditions favouring the formation of tetragonal zirconia without the addition of stabilizers is also enumerated here.
The fourth chapter deals with the compaction of these composite powders and the evaluation of some physical, thermal and mechanical properties. Density and porosity, coefficient of thermal expansion, modulus of rupture and fracture toughness of the composite specimens are evaluated and compared with binary and ternary composites made by other methods.
Finally the thesis concludes by summarizing the work done and briefly projecting the areas for future work.
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Mariappan, L. "In-Situ Synthesis Of A12O3_ZrO2_SiCw Ceramic Matrix Composites By Carbothermal Reduction Of Natural Silicates." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/215.
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This thesis outlines the work done on in-situ synthesis of Al2O3-ZrO2-SiCw ceramic composites and their property evaluation. The introductory chapter deals with the literature survey on ceramic matrix composites, properties desirable for structural applications and toughening mechanisms associated with these composites. The role of whisker toughening in ceramic matrix composites, the growth mechanisms involved in whisker growth and the conditions that favour or hamper the whisker growth are also discussed. The advantages and disadvantages of in-situ synthesis of composites as compared to physical mixing are also dealt with. The objective and scope of the work undertaken are outlined at the end.
The second chapter describes the experimental techniques associated with carbothermal synthesis and characterisation of reaction products as well as properties of hot pressed bulk composites. The equipments used for this work are described here.
The third chapter focuses on the results obtained by the carbothermal reduction of mixtures of kaolin, sillimanite and zircon taken in various proportions. The formation of the product phases with respect to variations in temperature, variations in composition and effect of catalyst is analysed with the help of XRD while their morphology is analysed using SEM. The conditions favouring the formation of tetragonal zirconia without the addition of stabilizers is also enumerated here.
The fourth chapter deals with the compaction of these composite powders and the evaluation of some physical, thermal and mechanical properties. Density and porosity, coefficient of thermal expansion, modulus of rupture and fracture toughness of the composite specimens are evaluated and compared with binary and ternary composites made by other methods.
Finally the thesis concludes by summarizing the work done and briefly projecting the areas for future work.
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Tsotra, Panagiota. "Electrically conductive epoxy matrix composites /." Kaiserslautern : IVW, 2004. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015387627&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Davies, Christopher Huw John. "Production of aluminium matrix composites." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46737.
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Antti, Marta-Lena. "All-oxide ceramic matrix composites." Doctoral thesis, Luleå, 2001. http://epubl.luth.se/1402-1544/2001/34/index.html.
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Ling, Paul Keh Yiing. "Creep of metal matrix composites." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240496.
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Chaplin, Adam. "Novel matrix resins and composites." Thesis, University of Surrey, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259908.
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Hihara, Lloyd Hiromi. "Corrosion of aluminum-matrix composites." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14332.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1989.Videocassette is VHS format. Vita.
Includes bibliographical references.
by Lloyd Hiromi Hihara.
Ph.D.
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Boufaida, Zakariya. "Analyse des propriétés mécaniques de composites taffetas verre/matrice acrylique en relation avec les propriétés d’adhésion des fibres sur la matrice." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0108/document.
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Cette thèse est essentiellement consacrée à la caractérisation et à l’analyse des propriétés mécaniques de matériaux composites constitués d’un renfort taffetas verre et d’une résine acrylate (Elium®). Avant l’apparition de la résine Elium® sur le marché en 2013, les polymères acrylates n’étaient pas utilisés dans l’industrie des composites fibres longues. Dans le volet expérimental de la thèse, nous nous intéressons principalement à l’influence de l’ensimage (traitement de surface appliqué aux fibres pour favoriser l’adhésion de la matrice) sur le comportement mécanique de nos composites. En complément de différents essais mécaniques macroscopiques « classiques » (traction, flexion etc.), nous avons utilisé des techniques d’analyse locales fines (mesures de champ cinématique, microtomographie X, Microscopie Électronique à Balayage, nanoindentation…) qui nous ont permis de caractériser et d’étudier certains mécanismes locaux de déformation et d’endommagement. L’influence de l’ensimage sur les propriétés en fatigue a été mise en évidence grâce à des mesures d’autoéchauffement pour lesquelles nous avons développé un traitement original des données. A l’issue de nos investigations, nous avons pu quantifier le bénéfice qui résulte de l’utilisation d’un ensimage spécifiquement conçu pour favoriser l’adhésion d’un polymère acrylate sur des fibres de verre. Dans le volet « simulation numérique » de la thèse, nous avons modélisé le comportement mécanique de nos composites taffetas verre/matrice acrylate grâce au solveur spectral CraFT (Composite response and Fourier Transforms). Le détail des champs de contrainte et de déformation a été obtenu à l’échelle de la mésostructure et révèle une structuration périodique induite par la présence du renfort tissé. Une analyse quantitative a permis de vérifier que les champs de déformation qui ont été obtenus grâce au solveur CraFT sont en très bon accord avec des mesures réalisées par corrélation d’images. A partir du champ de contrainte, nous avons mis en évidence les régions de la mésostructure qui subissent les plus fortes sollicitations mécaniques. En visualisant par microtomographie X la structure interne d’éprouvettes précédemment déformées, nous avons pu établir le lien entre la localisation de l’endommagement au sein de la mésostructure et les régions de concentration de contrainte que la simulation numérique avait mises en évidenceThis thesis is devoted to the characterization and the analysis of the mechanical properties of composite materials made of a plain weave glass fiber reinforcement and an acrylic resin (Elium®). Before the commercialization of the Elium resin in 2013, acrylics polymers were not used in the composite industry. In the experimental part of this thesis, we mainly focused on the sizing effect (surface treatment of the fibers to enhance the bonding between the matrix and the fibers) on the mechanical behavior of our composites. The characterizations were carried out through classical macroscopic mechanical tests (tensile, bending, shearing…) but using metrological tools for local analysis (full-field strain measurements, X ray micro-tomography, Scanning Electron Microscopy, Nano-indentation etc.). We were able to study strain and damage phenomena at local scales. Fatigue properties of the sizing were highlighted by heat build-up experiments. To analyze these measurements, an original data treatment has been developed which makes clear the benefit of an acrylic sizing in order to enhance the bonding between glass fibers and our acrylic matrix. In the theoretical part of this thesis, we studied the mechanical behaviour of our glass fiber plain weave/acrylic resin composite through a numerical simulation based on the CraFT spectral solver (Composite response and Fourier Transforms). Local stress and strain fields were obtained at the mesoscopic scale. The strain field analysis shows a periodic structure induced by the presence of the plain weave reinforcement. By a quantitative study, a good agreement between the numerical strain field obtained by CraFT and the 3D-DIC experimental strain measurements was found. The numerical stress field analysis reveals regions were a high local stress occurs. Comparing with X ray micro-tomography observationsof the internal structure of previously loaded composite sampleswe noticed that the damages occurring inside the mesostructure are totally correlated with the local stress concentration revealed by CraFT numerical simulations
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Clark, Richard L. "Altering the fiber-matrix interphase in semicrystalline polymer matrix composites." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12042009-020216/.
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Gonçalves, Flavia. "Fatores relacionados ao desenvolvimento de tensões de polimerização em compósitos experimentais contendo BisGMA, TEGDMA e BisEMA." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/23/23140/tde-13082007-154602/.
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Objetivo: avaliar a influência do conteúdo de BisGMA, TEGDMA e BisEMA sobre tensão de polimerização (spol), grau de conversão (GC), contração volumétrica (CV), módulo de elasticidade (E), escoamento (ES), taxa máxima de reação (RPmax) e incremento máximo de tensão (RSmax) e verificar as possíveis relações de dependência entre a tensão de polimerização e as demais variáveis. Material e métodos: Foram estudadas nove misturas, todas contendo 40% em peso de sílica coloidal, variando a concentração molar de BisGMA (33, 50 ou 66%) e o tipo de comonômero (TEGDMA, BisEMA ou ambos em partes iguais). spol foi determinada pela inserção do compósito (h=1mm) entre bastões de acrílico (r=3mm) fixados às garras de uma máquina universal de ensaios e dividindo-se a máxima força de contração registrada pela secção transversal dos bastões. CV foi mensurada em dilatômetro de mercúrio. E foi obtido através do teste de flexão em três pontos. Fragmentos de espécimes de flexão de cada grupo foram utilizados para análise do GC por FTRaman. O ES foi obtido pela aplicação de uma carga de 20N por 60s sobre o compósito não-polimerizado. RPmax foi determinada por calorimetria exploratória diferencial (DSC). RSmax foi calculado pela diferença entre dois valores de spol consecutivos. Os dados foram submetidos a ANOVA de dois fatores, teste de Tukey (a=0,05%) e análises de regressão. Resultados: A interação entre os fatores foi estatisticamente significante para todas as variáveis avaliadas (p<0,01), com exceção de GC onde apenas os fatores principais foram significantes (p<0,001). Em geral, composições com maior concentração de BisGMA e com o co-monômero BisEMA apresentaram menor GC e ES, o que se refletiu em menores valores para spol, CV e E. RPmax foi semelhante em todos os grupos, com exceção do compósito com 66%TEGDMA, que apresentou valor estatisticamente menor. Entretanto,. esse grupo apresentou o maior valor de RSmax. As análises de regressão evidenciaram forte relação direta de dependência da spol com GC (R2=0,830), ES (R2=0,896), CV (R2=0,690) e RSmax (R2=0,900). A correlação com o E foi fraca (R2=0,404) e com RPmax foi negativa (R2=0,667). Conclusões: Dentre as formulações avaliadas, compósitos contendo BisEMA e aqueles com maiores concentrações de BisGMA apresentaram, em geral, menor spol, GC, CV, ES e E. RPmax foi pouco afetada pela composição da matriz orgânica. spol mostrou maior relação de dependência com os fatores GC, CV e ES.Objective: To evaluate the influence of BisGMA, TEGDMA and TEGDMA content on polymerization stress (spol), degree of conversion (DC), volumetric shrinkage (VS), elastic modulus (E), flow, maximum polymerization rate (RPmax) and maximum stress rate (RSmax) and to establish the correlation between polymerization stress and the other variables. Materials and Methods: Nine resin mixtures were studied, varying the BisGMA molar concentration (33, 50 or 66%) and the co-monomer content (TEGDMA, BisEMA or both in equal parts). All blends received 40 wt % of colloidal silica. spol was determined by inserting the composite (h=1mm) between acrylic rods (r=3mm) fixed on the opposite ends of a universal testing machine, and dividing the maximum contraction force by the rods? cross section. VS was measured by mercury dilatometry. E was obtained by three-point bending test. Fragments of flexural specimens were used to analyze DC by FT-Raman. Flow was obtained applying load of 20N for 60s on the uncured composite. RPmax was determined by differential scanning calorimetry (DSC). RSmax was calculated by the difference between two consecutives spol values. Data were submitted to two-way ANOVA, Tukey´s test (a=0.05%) and regression analyses. Results: The interactions between factors were significant for all variables (p<0.01), except for DC, where only the main factors were significant (p<0.001). In general, composites with higher BisGMA concentration and those containing BisEMA showed lower DC and flow, which resulted in lower values of spol, VS and E. RPmax was similar for all groups, except for the 66%TEGDMA composite, which showed a statistically lower value. However, this group showed the highest value of RSmax. The regression analyses evidenced a strong direct dependence of spol to DC (R2=0.830), flow (R2=0.896), VS (R2=0.690) and RSmax (R2=0.900). The correlation with E was weak (R2=0.404) and with RPmax was negative (R2=0.667). Conclusion: For the monomer mixtures studied, composites with BisEMA and those with higher BisGMA concentration showed, in general, lower spol, DC, VS, flow and E. RPmax was almost insensitive to the organic matrix composition. spol showed stronger dependence with DC, VS and flow.
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Dubernet, Marion. "Mécanoluminescence de composites particulaires à matrice vitreuse." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S120/document.
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La mécanoluminescence (ML) est un phénomène physique qui se traduit par l’émission de lumière suite à l’application d’une contrainte mécanique. Dans le cadre de ce travail de thèse, les matériaux mécanoluminescents vont être utilisés afin de visualiser les contraintes qui peuvent être générées dans un verre lors d’une sollicitation mécanique. Nous avons élaboré un composite constitué de particules mécanoluminescentes SrAl2O4:Eu, Dy incorporées dans une matrice vitreuse. Nous nous sommes ensuite intéressés à l’origine et au mécanisme de ce phénomène en réalisant une étude mécanique sur le composite. Ces essais nous ont permis de développer un modèle empirique qui relie la contrainte à l’intensité émise. La structure cristalline des particules jouant un rôle clef dans la ML, nous avons également mené une étude théorique de cette structure, ce qui nous a permis de corréler les observations macroscopiques faites sur le composite aux phénomènes ayant lieu à une échelle atomiqueMechanoluminescence (ML) is the phenomenon of light emission generated by a mechanical loading. Mechanoluminescent materials were used to visualize the stress in glasses during mechanical loadings. A mechanoluminescent particulate glass composite was synthesized by incorporating SrAl2O4:Eu, Dy particles in a glass matrix for the first time. We performed a mechanical study on the composite to determine the origin and the mechanism of this phenomenon. We developed a theoretical model which accurately predicts the ML intensity changes induced by a complex mechanical loading. The crystal structure of the particles has a key role in the ML and we carried out a theoretical study of this structure to correlate the macroscopic observations made on the composite to the phenomena which occur at the atomic scale
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Samer, Nassim. "Synthèse réactive de Composites à Matrice Métallique." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1057/document.
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En raison de leur propriétés spécifiques élevées, par rapports aux alliages légers, les Composites à matrice métallique (CMM) représentent des matériaux d'intérêt pour des applications de haute technologie dans les domaines aéronautique et aérospatiale. Les CMM les plus couramment utilisés sont à renfort particulaire, ou PRMMC, et à matrice Al en raison de leur faible densité. Cette thèse porte sur la mise au point de PRMMC à renfort nanométrique par une voie de synthèse réactive globale. En raison des normes encadrant l’usage des nanomatériaux et visant à limiter l’exposition des usagers et de l’environnement, la manipulation de poudres de taille nanométrique est coûteuse et problématique dans le cadre d’un usage industriel. La nouvelle voie de synthèse qui a été développée dans le cadre de cette thèse a permis de démontrer la faisabilité de composites à matrice métallique et à renfort particulaire nanométrique, dimension moyenne de 30 nm, sans avoir recourt initialement à des poudres de taille nanométrique. Le procédé étudié consiste en une réaction chimique à haute température entre deux matériaux précurseurs qui conduit à la formation in-situ non seulement du renfort mais aussi de la matrice. Par rapport aux techniques de synthèse classiques, cette technique permet de synthétiser des nanoparticules in situ et d’en contrôler la taille. De plus, la matrice et le renfort étant co produits par la réaction à haute température, l’interface entre les deux phases est exempte de couches d’oxydes, ce qui lui assure une très bonne adhésion. Dans le cadre du projet ANR NanoTiCAl, la faisabilité de cette nouvelle méthode a été étudiée à travers le cas d'un composite à matrice aluminium renforcé par des particules de carbure de titane (TiC). Les synthèses ont été réalisées entre 900°C et 1000°C à partir d’un couple de précurseurs incluant le graphite et un aluminiure de titane (Al3Ti). Le composite obtenu, caractérisé par un taux de renfort élevé de 34wt.%, possède un module de Young de 106 GPa, un allongement maximal à la rupture de 6% ainsi qu’une énergie à rupture de l’ordre de 28 J.cm-3. Ces valeurs démontrent un compromis entre résistance et capacité d’endommagement original et particulièrement intéressant, jamais observé dans la littérature pour des composites d’une teneur en renfort aussi importante. La caractérisation fine de la microstructure du composite ainsi que du renfort TiC après extraction du composite massif, ont permis de mieux comprendre les mécanismes à l’oeuvre dans cette voie de synthèse réactive. Enfin, sur la base de la compréhension obtenue dans le cas du composite Al/TiC, des critères ont été identifiés permettant d’aller vers une généralisation de ce procédé de synthèse. La pertinence de cette généralisation a finalement pu être démontrée par quelques mises en application à d’autres systèmesMetal Matrix Composites (MMCs) have attracted research and industrial attentions as materials for high technological applications in the aeronautic and aerospace industry. The MMCs differ by their high specific mechanical properties compared to light weight alloys. The most commonly used are the Particulate Reinforcement Metal Matrix Composites (PRMMCs), especially the Al based matrices because of their low density.This thesis deals with the reactive synthesis of PRMMCs reinforced by nanoparticles. Because of the standards governing the use of nanomaterials to limit the exposure of users and environment, handling nanoscaled powders is very problematic and expensive in industry. Furthermore, the cost of this kind of processes is very high. This new synthesis route, developed during this thesis, shows the feasibility of PRMMCs reinforced by nanosized particles, with a mean size of 30 nm, without using any starting nanoparticles.The process consists in a chemical reaction at high temperature between precursor materials which leads to form both of the matrix and the reinforcement phase. Compared to conventional synthesis techniques as stir casting, this route allows to synthesis nanoparticles in-situ and to control their size. In addition, the matrix and the reinforcement, which are formed by a reaction at high temperature, have an interface free of oxide layers which assures a good adhesion.In the NanoTiCAl project, the feasibility of this new method is illustrated in the case of an aluminium based composite reinforced by titanium carbide (TiC). The synthesis were realized between 900°C and 1000°C from a couple of precursors including graphite and titanium aluminide (Al3Ti). The resulting composite, characterized by a high reinforcement ratio (34 wt.%), presents a Young’s modulus of 106 GPa, a maximum elongation of 6 % and a high toughness, about 28 J.cm-3. These values represent an uncommon compromise between strength and toughness never seen in the literature regarding to the high content of reinforcement.The characterization of the composite microstructure and of the reinforcement phase, after extraction of the solid composite, allowed a better understanding of the reaction mechanism during the reactive synthesis. Finally, based on our understanding of the Al-TiC composite, criteria have been identified to generalize this synthesis process. This generalization was demonstrated with success in other systems
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Ironside, K. I. "Damage in woven ceramic matrix composites." Thesis, University of Surrey, 1996. http://epubs.surrey.ac.uk/842778/.
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The mechanical behaviour of woven fabric-based continuous silicon carbide fibre reinforced Pyrex (SiC/Pyrex) and calcium alminosilicate (SiC/CAS) matrix composites under quasi-static and cyclic tensile loading has been investigated. Both a plain weave and a satin weave architecture were examined for each material type. Under quasi-static loading for all systems except the low temperature processed Pyrex system (which failed prematurely) a linear elastic region was observed up to an applied strain of 0.04-0.06%. Above this strain (the matrix microcracking threshold) a reduction in the composite modulus was seen. The reduction in composite stiffness is attributed to matrix microcracking, and the morphology of matrix microcracking was examined and quantified using an edge replication technique. In all systems the matrix microcrack density was seen to increase approximately linearly with increasing strain up to failure. The corresponding reduction in the composite modulus at failure was 40-50%. Associated with the damage there is hysteretic behaviour and an increasing residual strain. The strain to failure of the satin weave composites was higher than the plain weave composites. In the cyclic fatigue tests the number of cycles to failure decreased with increasing peak stress level. A progressive reduction in the composite modulus was seen with cycles even when the applied strain was below the matrix microcracking strain threshold. It is likely that at strains below this threshold there is non-interacting matrix microcracking which does not initially affect the composite modulus. However, on continued tensile fatigue cycling these microcracks grow through a possible sub-critical crack growth mechanism reducing the laminate modulus. A modified shear lag model was used to model the reduction in composite stiffness as a function of the measured matrix crack density. The woven composite was converted to an equivalent cross-ply sub-laminate on to which the matrix microcracks were superimposed. A model allowing for the presence of microcracks in both the matrix and transverse plies gave the best agreement between the experimental and predicted reduction in modulus.
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El-Gallab, Mariam S. "Machining of particulate metal matrix composites." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0030/NQ66206.pdf.
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Murphy, Angela Mary. "Clustering in particulate metal matrix composites." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242540.
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Wildan, Muhammad W. "Zirconia-matrix composites reinforced with metal." Thesis, University of Strathclyde, 2000. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21428.
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The aim of this study was to investigate a zirconia-matrix reinforced with metal powder (chromium, iron and stainless steel (AISI 316)) including processing, characterisation, and measurements of their properties (mechanical, thermal and electrical). Zirconia stabilised with 5.4 wt% Y₂0₃ (3 mol%) as the matrix was first studied and followed by an investigation of the effects of metal reinforcement on zirconia-matrix composites. Monolithic zirconia was pressureless sintered in air and argon to observe the effect of sintering atmosphere, while the composites were pressureless sintered in argon to avoid oxidation. Sintering was carried out at various temperatures for 1 hour and 1450°C was chosen to get almost fully dense samples. The density of the fired samples was measured using a mercury balance method and the densification behaviour was analysed using TMA (Thermo-mechanical Analysis). The TMA was also used to measure the coefficient of thermal expansion. In addition, thermal analysis using DTA and TGA was performed to observe reactions and phase transformations. Moreover, optical microscopy and SEM were used to observe the microstructures, XRD was used for phase identification, and mechanical properties including Vickers hardness, fracture toughness and bending strength were measured. The effect of thermal expansion mismatch on thermal stresses was also analysed and discussed. Finally, thermal diffusivity at room temperature and as a function of temperature was measured using a laser flash method, and to complete the study, electrical conductivity at room temperature was also measured. The investigation of monolithic zirconia showed that there was no significant effect of air and argon atmosphere during sintering on density, densification behaviour, microstructures, and properties (mechanical and thermal). Furthermore, the results were in good agreement with that reported by previous researchers. However, the presence of metal in the composites influenced the sintering behaviour and the densification process depends on the metal stability, reactivity, impurity, particle size, and volume fraction. Iron reacted with yttria (zirconia stabiliser), melted and reduced the densification temperature of monolithic zirconia, while chromium and AISI 316 did not significantly affect the densification temperature and did not react with either zirconia or yttria. AISI 316 melted during fabrication. Moreover, all of the metal reinforcements reduced the final shrinkage of monolithic zirconia. In terms of properties, the composites showed an increase in fracture toughness, and a reduction in Vickers hardness and strength with increasing reinforcement content. In addition, the thermal diffusivity of the composites showed an increase with reinforcement content for the zirconia/chromium and zirconia/iron composites, but not for the zirconia/AISI 316 composites due to intrinsic mircocracking. Furthermore, all the composites became electrically conductive with 20 vol% or more of reinforcement. It has been concluded that of those composites the zirconia/chromium system may be considered as having the best combination of properties and although further development is needed for such composites to be used in real applications in structural engineering, the materials may be developed based on these findings. In addition, these findings may be used in development of ceramic/metal joining as composite interlayers are frequently used.
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Zulfia, Anne. "Pressureless infiltration of aluminium matrix composites." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484253.
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Otani, T. "Corrosion behaviour of metal matrix composite." Thesis, University of Bath, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382471.
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Mohammadi-Aghdam, Mohammad. "Micromechanics of unidirectional metal matrix composites." Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297843.
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Wang, Aiguo. "Abrasive wear of metal matrix composites." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305516.
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Devlin, Brendan James. "The pultrusion of thermoplastic matrix composites." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260359.
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Dibelka, Jessica Anne. "Mechanics of Hybrid Metal Matrix Composites." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50579.
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The appeal of hybrid composites is the ability to create materials with properties which normally do not coexist such as high specific strength, stiffness, and toughness. One possible application for hybrid composites is as backplate materials in layered armor. Fiber reinforced composites have been used as backplate materials due to their potential to absorb more energy than monolithic materials at similar to lower weights through microfragmentation of the fiber, matrix, and fiber-matrix interface. Composite backplates are traditionally constructed from graphite or glass fiber reinforced epoxy composites. However, continuous alumina fiber-reinforced aluminum metal matrix composites (MMCs) have superior specific transverse and specific shear properties than epoxy composites. Unlike the epoxy composites, MMCs have the ability to absorb additional energy through plastic deformation of the metal matrix. Although, these enhanced properties may make continuous alumina reinforced MMCs advantageous for use as backplate materials, they still exhibit a low failure strain and therefore have low toughness. One possible solution to improve their energy absorption capabilities while maintaining the high specific stiffness and strength properties of continuous reinforced MMCs is through hybridization. To increase the strain to failure and energy absorption capability of a continuous alumina reinforced Nextel" MMC, it is laminated with a high failure strain Saffil® discontinuous alumina fiber layer. Uniaxial tensile testing of hybrid composites with varying Nextel" to Saffil® reinforcement ratios resulted in composites with non-catastrophic tensile failures and an increased strain to failure than the single reinforcement Nextel" MMC. The tensile behavior of six hybrid continuous and discontinuous alumina fiber reinforced MMCs are reported, as well as a description of the mechanics behind their unique behavior. Additionally, a study on the effects of fiber damage induced during processing is performed to obtain accurate as-processed fiber properties and improve single reinforced laminate strength predictions. A stochastic damage evolution model is used to predict failure of the continuous Nextel" fabric composite which is then applied to a finite element model to predict the progressive failure of two of the hybrid laminates.Ph. D.
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Coleman, Sarah L. "The corrosion of metal matrix composites." Thesis, University of Bath, 1991. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303434.
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Palmer, D. G. W. "The processing of intermetallic matrix composites." Thesis, University of Bath, 1997. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338451.
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DONNINI, RICCARDO. "Metal matrix composite: structure and technologies." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/868.
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I compositi a matrice metallica sono materiali aventi elevate potenzialità di applicazione, i cui punti critici riguardano soprattutto le tecnologie di produzione e le lavorazioni alle macchine utensili.
Un composito a matrice di titanio rinforzato con lunghe fibre unidirezionali in SiC, il Ti6Al4V-SiCf, è candidato per componenti di turbine aeronautiche soggette a medie temperature (fino a 600°C) per lunghi tempi di esposizione. Per questo ne sono state esaminate sia le reazioni di tipo microchimico, le quali accadono soprattutto nell’interfaccia fibra/matrice, sia le proprietà meccaniche. La microstruttura allo stato tal quale e dopo lunghi trattamenti termici (fino a 100 ore e 600°C) è stata esaminata mediante diffrazione ai raggi X (XRD), spettrometria elettronica (SEM/EDS), spettroscopia di fotoemissione (XPS) e spettroscopia Auger (AES). Il comportamento meccanico, anche qui sia allo stato tal quale che dopo trattamenti termici, è stato studiato attraverso prove ad indentazione strumentata (FIMEC), di modulo dinamico, prove di trazione e di fatica. Inoltre sono state eseguite prove di frizione interna per verificare il caratteristico comportamento anelastico del materiale, durante condizioni di elevato stato vibrazionale e di alta temperatura. Lo studio, sviluppato sullo stesso composito prodotto però mediante due processi di fabbricazione differenti come Hot Isostatic Pressure and Roll Diffusion Bonding, ha confermato l’idoneità del materiale alle applicazioni considerate.
Per quanto riguarda lo studio della lavorabilità, sono stati studiati, dal punto di vista dell’operazione di foratura, i materiali compositi a matrice di alluminio rinforzati a fibre corte o particolato, valutando le migliori condizioni di riduzione delle forze di taglio, soprattutto in funzione delle temperatura del pezzo da forare.Metal matrix composites are materials having high application potentiality, whose critical points regards especially production technology and machining. A titanium matrix composite reinforced by unidirectional SiC fibers, Ti6Al4V-SiCf , is candidate to components of aeronautical turbines subjected at middle temperatures (500-600°C) for long exposure time. It has been examined about the micro-chemical reactions, occurring especially on the fiber-matrix interface, and the mechanical properties. The microstructure, in as-fabricated condition and after long-term heat treatments simulating the work condition has been investigated by means of high-temperature X-ray diffraction (XRD), energy dispersion spectrometry (SEM/EDS), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The mechanical behaviour, in as-fabricated condition and after heat treatments, have been inspected by instrumented indentation (FIMEC), dynamic modulus, tensile and fatigue tests. Moreover, to the verify the characteristic anelastic phenomena for the composite, internal friction probes have been carried out by using a vibrating reed technique with electrostatic excitation and frequency modulation detection of flexural vibration. The study has been developed on the same composite produced by two different fabrication process, Hot Isostatic Pressure and Roll Diffusion Bonding, confirming the suitable of the material for the considered applications. About the composite machining, aluminium matrix composite reinforced by short fiber or particle has been studied about drilling operations, evaluating the better condition to reduce the cutting forces (thrust and torque), especially as function of the workpiece temperature (hot drilling)
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Shaterzadeh, Yazdi Mohsen. "Etude et modélisation physique et mécanique du comportement viscoélastique et plastique de composites particulaires à matrice polymère." Lyon, INSA, 1997. http://www.theses.fr/1997ISAL0092.
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L'objet de ce travail est de chercher à m1eux comprendre l'influence des interfaces et interphases (traitement de surface des renforts), et de la morphologie du matériau sur le comportement mécanique (viscoélastique et plastique) de composites particulaires à base de matrice polymère. Ainsi, en plus de la matrice à base de DGEBA/IPD, trois types de matériaux composites sont étudiés: - Composites à matrice DGEBA/IPD - billes de verres non traitées, - Composites à matrice DGEBA/IPD - billes de verres ensimées à base de Silane (interface), - Composites à matrice. DGEBA/IPD - billes de verres enrobées avec une couche d'élastomère CTBN-IPD-DGEBA (interphase). Les propriétés mécaniques de ces matériaux sont étudiées par les techniques de spectrométrie mécanique et de compression. L'analyse et l'interprétation des propriétés viscoélastiques sont basées d'une part sur la mobilité moléculaire, modèle physique développé par Perez et al, et d'autre part la méthode auto-cohérente (homogénéisation) défini par Hervé et Zaoui. L'apport de ce travail dans la compréhension des propriétés mécaniques (viscoélastique et plastique) des composites particulaires est double : i) Nous avons tenir compte dans le modèle auto-cohérent décrit par Hervé et Zaoui, de la morphologie réelle des composites. Le modèle ainsi complété permet de prédire correctement la réponse dynamique. Ii) Une tentative de modélisation pour mieux comprendre le comportement à grande déformation et à forte contrainte est développée dans ce travailThe aim of this work is to try to understand the influence of the interfaces and interphases (surface treatment of the reinforcements), and the morphology of the material on the mechanical behavior (viscoelastic and plastic) of particulate composites with a polymer matrix. So, adding to DGEBA/IPD matrix, three type of the composite materials have been studied: -Composites with DGEBA/IPD matrix- non treated glassy beads, -Composites with DGEBA/IPD matrix- aminosilane-treated fillers (interface), - Composites with DGEBA/IPD matrix- elastomer coated glassy beads based on a layer of CTBN-IPD-DGEBA (interphase), The mechanical properties of these materials have been studied by mechanical spectroscopy and by compression technics. The analysis and the interpretation of viscoelastic properties are based on the molecular mobility, physical model of the Perez and al. , and in the other hand on the self-consistent model (homogenisation) developed by Hervé and Zaoui. The contribution of this study in comprehension of the mechanical properties (viscoelastic and plastic) is double: i) considering the real morphology of the composites (spatial distribution of glass particles) in the self-consistent mode!. The model of Hervé and Zaoui was completed to prediction correctly the dynamics response. Ii) physical modelling of the polymeric matrix and mechanical modelling of the composites based on the local stress concentration for best comprehension of the mechanical behaviour on the large deformation and at high stress
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Rosetti, Yann. "Multiscale morphologies of epoxy-based composite matrices from combination of TP-tougheners." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0140.
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Les composites stratifiés à matrice organique thermodurcissable (TD) et renforts fibreux continus se sont progressivement imposés dans le monde de l’aéronautique depuis bientôt 50 ans. Ces matériaux, malgré de nombreux avantages ayant permis de remplacer les alliages métalliques précédemment utilisés, ont néanmoins un point faible majeur, à savoir une tolérance aux dommages limitée. De nombreuses solutions de renforcement ont vu le jour, dont l’ajout de polymères thermoplastiques (TP) présentant une ductilité supérieure à la matrice TD. Les travaux réalisés concernent une matrice représentative de composites stratifiés employés aujourd’hui. Elle est constituée d’un système époxy-amine menant à un réseau de haute Tg, ainsi que deux TP utilisés comme agents renforçants : un polyéthersulfone (PES) initialement soluble dans le système, et un polyamide (PA) sous forme de microparticules préformées. Un état de l’art sur les mélanges TD/TP cristallins et l’utilisation de TP comme agents renforçants dans les composites stratifiés est présenté en préambule des résultats expérimentaux. L’étude s’est focalisée sur le comportement de ces deux TP vis-à-vis du réseau époxy-amine en construction lors de la polymérisation. L’intérêt porte sur la compréhension des phénomènes reliant les différents composants du mélange entre eux. Dans un premier temps, le comportement du PES dans le système époxy-amine est étudié en fonction des conditions de polymérisation, à savoir le cycle de température appliqué. Le phénomène de séparation de phase induite par polymérisation (RIPS) ayant lieu étant en compétition avec la gélification du réseau TS, et ces deux phénomènes étant liés à la température, différents types de morphologie ont pu être obtenus. L’approche concernant le PA est différente. En effet, ce polymère initialement insoluble dans le système époxy-amine peut être compatibilisé après avoir réagi avec les monomères époxy. De plus, l’affinité physique entre le PA et le durcisseur aminé employé entraîne une modification du comportement du PA à la fusion. Des systèmes binaires modèles époxy-PA et amine-PA ont donc été étudiés pour bien découpler et comprendre toutes ces interactions. Enfin, les morphologies et propriétés résultantes du système époxy-amine modifié simultanément avec le PES et le PA ont été suivies et contrôlées grâce à un choix pertinent de différents cycles de polymérisation. La compréhension du développement d’un mélange si complexe, en termes de morphologie et de mécanismes réactionnels, a été rendue possible grâce aux études préliminaires sur systèmes modèlesFiber-reinforced thermosetting (TS) matrix-based composites, and more particularly laminates, have progressively imposed themselves in the aeronautic field for nearly 50 years. Nevertheless, despite numerous advantages making them an elegant solution to replace metallic alloys, such composites have a huge drawback: a low damage tolerance. Various toughening solutions have been developed, including the addition of thermoplastic (TP) polymers which exhibit a much higher ductility than the TS matrix. The present work relates on a representative matrix of currently considered laminates. It is constituted of an epoxy-amine system leading to a high Tg network, and two TP used as reinforcing agents: a polyethersulfone (PES) initially soluble in the system, and a polyamide (PA) preformed in micro-particles. A literature review about TS/semi-crystalline TP blends and TP reinforcement agents used in laminates is given previously to the experimental results. The study focuses on the behavior of these two TP in regard to the growing epoxy-amine network during its polymerization. The interest is put in the understanding of the phenomena linking all the matrix components together. In a first time the PES behavior in the epoxy-amine system dependence on curing conditions (i.e. the applied cure schedule) is studied. The reaction-induced phase separation (RIPS) phenomenon being competitive with the TS network gelation, and taking into account that both phenomena are temperature dependent, various types of morphologies were obtained. Apprehension of PA behavior is different. In fact, this polymer is initially soluble in the epoxy-amine system and may be compatibilized after chemical coupling with epoxy prepolymers. Moreover, physical affinities between PA and the considered amine hardener impact the PA melting behavior. Consequently, binary epoxy-PA and amine-PA model systems have been studied to uncouple and understand all these interactions. Finally, resulting morphologies and properties of the epoxy-amine system, simultaneously modified with both PES and PA, have been monitored and controlled thanks to a choice of suitable cure schedules. The understanding of the development of such a complicated system, in terms of morphologies and curing mechanisms, was made possible thanks to the preliminary studies on the model systems
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Pouzet, Sébastien. "Fabrication additive de composites à matrice titane par fusion laser de poudre projetée." Thesis, Paris, ENSAM, 2015. http://www.theses.fr/2015ENAM0051/document.
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Les composites à matrice titane (CMTi) sont des matériaux attractifs pour des applications aéronautiques, en raison de leurs performances mécaniques à haute température et de leur faible densité. La difficulté d’usiner ce type de matériaux rend les procédés de fabrication additive intéressants pour la fabrication de pièces complexes en trois dimensions. Cette étude porte sur l'élaboration de composites à matrice titane par le procédé de fabrication additive par fusion laser de poudre projetée. Dans un premier temps, différents types de poudres- renfort et de préparations de poudre ont été utilisés pour faciliter la mise en œuvre du procédé additif, dans le but d’obtenir des microstructures homogènes. Dans un second temps, l’étude s’est concentrée sur le mélange Ti-6Al-4V / B4C formant des renforts TiB et TiC par voie in-situ dans une matrice de Ti-6Al-4V. Les mécanismes de formation des microstructures obtenues ont pu être expliqués puis une étude des propriétés mécaniques (dureté, module d’Young et comportement sous une sollicitation en traction à chaud et à l’ambiante) a été réalisée afin d’évaluer l’effet du renforcement sur les propriétés mécaniques du matériau. Parmi les résultats importants ce cette étude, la présence de taux de carbone élevés en solution solide dans la matrice de titane a été évoqué comme étant le facteur prédominant dans l'augmentation des propriétés mécaniques avec le taux de B4CTitanium matrix composites are attractive materials for aeronautical applications, mainly because of their superior mechanical resistance at elevated temperature, combined with a low density. The critical machinability of such composites makes additive manufacturing processes particularly adapted for building complex 3D shapes. This study has been focused on the Direct Metal Deposition (DMD) of Metal matrix composites. In a first step, various powders and powder blends have been carried out in order to facilitate the DMD process and to obtain homogeneous microstructures. Following this, Ti-6Al-4V / B4C powder blends, allowing to obtain TiB + TiC particles distributed in the Ti matrix were more specifically considered. Metallurgical mechanisms involved in the formation of microstructures were identified prior to an investigation on mechanical properties at ambient and elevated temperature for various DMD process conditions and particle concentrations. Among the most interesting results of this study, the influence of a high carbon content solubilized in the Ti-matrix was considered as a dominant factor to explain the evolution of mechanical properties with increased amounts of reinforcements
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Schöneich, Marc. "Charakterisierung und Modellierung viskoelastischer Eigenschaften von kurzglasfaserverstärkten Thermoplasten mit Faser-Matrix Interphase." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0234/document.
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L’influence des propriétés microscopiques de l’interphase entre la matrice et les fibres sur le comportement mécanique macroscopique n’est pas suffisamment connue dans le domaine des polymères renforcés par fibres courtes. Dans le cadre de cette thèse, une étude systématique des propriétés géométriques et mécaniques de l’interphase est réalisée concernant la description des effets sur la réponse viscoélastique linéaire du composite. Dans ce contexte, les résultats présentés mettent l’accent sur l’interaction entre la modélisation micromécanique et la caractérisation expérimentale. D’une part, un nouveau modèle micromécanique en deux étapes est développé pour la description d’un composite anisotrope à trois phases avec interphases. D’autre part, les paramètres du matériau utilisés pour la modélisation micromécanique sont identifiés avec des méthodes expérimentales aux échelles micro- et macroscopiques. En comparaison des résultats expérimentaux avec les propriétés effectives calculées de matériau composite, une inférence peut être faite sur les propriétés mécaniques du composite à partir de celles de l’interphase. Par conséquent, une méthode inverse est proposée offrant un accès aux propriétés inconnues de l’interphase. Enfin, la combinaison de la modélisation micromécanique et des résultats expérimentaux permet une meilleure compréhension des propriétés mécaniques de l’interphase, qui n’étaient auparavant pas accessibles au moyen de seules approches expérimentalesIn order to improve the mechanical properties of short fiber composites, the fiber-matrix adhesion is decisive and depends strongly on the intersection region between the fiber and the matrix material. However, no perspicuous information about the influence or mechanical properties of the fiber-matrix interphase in short fiber reinforced thermoplastic composites is available. Thus, the present thesis aims for a systematic identification of the geometrical and mechanical impacts of an interphase on the linear-viscoelastic behavior in short glass fiber reinforced thermoplastics. Thereby, the performed investigations are focused on the interaction between micromechanical material modeling and experimental testing. On the one hand, a two-step modeling approach is developed for the realistic description of an entire three phase composite with interphase including anisotropic and linear-viscoelastic effects. On the other hand, the input of this model is provided by different experimental testing methods ranging from the micro- to the macroscale characterization of the composite and matrix material. By comparing these experimental results with the linear-viscoelastic modeling output, the impact of the interphase on the mechanical properties of the composite is accessible. Thus, it is shown that a realistic material modeling and experimental investigations are closely interlinked
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Lee, Jae-Kon. "Thermal cycling and creep resistance of metal matrix composites /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/7103.
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Kuriyama, Kazuya. "Joining of composites." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259744.
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