Dissertations / Theses on the topic 'Oxide Ceramic Matrix Composite'
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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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Marriner-Edwards, Cassian. "The development of fibre-reinforced ceramic matrix composites of oxide ceramic electrolyte." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:3af11d08-c0d8-429b-8eab-d2befc83ea74.
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Flammable solvents contained in liquid electrolytes pose a serious safety risk when used in lithium batteries. Oxide ceramic electrolytes are a safer alternative, but suffer from inadequate mechanical properties and ionic conductivity. Thin electrolyte layers resolve the issue of conductance, but accentuate the detrimental mechanical properties of oxide ceramics. The presented work has investigated oxide ceramic electrolyte reinforcement in composite electrolytes for all-solid-state batteries. Fabricating oxide ceramic electrolytes with engineered microstructure enabled development of a reinforced composite. This approach is based on the formation of 3D- porous ceramics via stereolithography printing of polymer templates from designed cubic, gyroid, diamond and bijel architectures. The microstructural parameters of templates were analysed and modified using computational techniques. Infiltration of the prepared 3D-porous electrolyte with polymeric-fibre reinforcement created the reinforced composite electrolyte. The prepared ceramic composite showed excellent reproduction of the template microstructure, good retention of ionic conductivity and enhanced mechanical properties. The final composite was composed of NASICON-type Li1.6Al0.6Ge1.4(PO4)3 oxide ceramic electrolyte and epoxy and aramid fibre reinforcement. The gyroid architecture was computationally determined as having the optimal stress transfer efficiency between two phases. The printed gyroid polymer template gave excellent pore microstructure reproduction in ceramic that had 3D-interconnected porosity, high relative density and the most uniform thickness distribution. The ceramic matrix porosity allowed for complete infiltration of reinforcement by aramid and epoxy forming the fibre-reinforced ceramic matrix composite. The interpenetrating composite microstructure with ceramic and epoxy gave a flexural strength increase of 45.65 MPa compared to the ceramic. Unfortunately, the infiltration procedure of aramid-epoxy reinforcement did not realise the full tensile strength potential of aramid fibres.
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Dearn, Sophie Clare. "Development of a novel oxide-oxide ceramic matrix composite for high temperature structural applications." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5924/.
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The introduction of ceramic matrix composites (CMCs) for structural applications in the hot section of a gas turbine provides many potential benefits over conventional alloy materials, including facilitating elevated operating temperatures. The development of an oxide-oxide CMC composed of commercially available Nextel 720 (3M) fibres within a porous alumina matrix was presented. A simple, low cost processing method involving slurry impregnation and subsequent consolidation and densification was developed, facilitating the production of dried pre-impregnated fabric (‘pre-preg’) that can be stored in ambient conditions. Detailed investigation into the effect of three types of PVA binder, the effect of 0-20wt% additions of an alumina precursor (ACH), the influence of a bimodal particle distribution and the effect of sintering at temperatures between 1100 and 1300°C on processing and mechanical properties was completed in order to optimise the material. The optimised composite material, composed of Nextel 720 fibres within a submicron alumina particle matrix with 10wt% ACH sintered at 1200°C, exhibited mean flexural strength >205MPa, short beam shear strength >12MPa and tensile strength >146MPa. These results were comparable to similar oxide CMCs previously reported, validating this material.
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Ludford, Nicholas Philip. "An investigation into the thermal aging of an all oxide ceramic matrix composite." Thesis, University of Surrey, 2005. http://epubs.surrey.ac.uk/843476/.
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The effect of thermal aging in air on a Nextel(TM) 720 aluminosilicate fibre reinforced alumina matrix material (N72O/AI2O3) has been investigated. Samples were aged at 1100oC for up to 4000 hours as well as for 200 hours at 1100°C, 1200°C, 1300°C, 1400°C and 1480°C. On completion of the thermal aging treatments, the microstructures of the samples were characterised, principally using scanning and transmission electron microscopy. The mechanical properties of the material, flexural strength, Young's modulus and relative toughness, after aging were investigated using three point flexural testing. The as-received material was found to contain many voids and a large quantity of cracking that are believed to arise from in-complete matrix infiltration and green body production, respectively, during manufacture. It was found that the material does not meet the original proposed design criteria for this class of material. Initial results indicate that the 1100°C thermal aging treatment for up to 2000 hours has no detectable effect on the microstructure or properties of the material. After aging at 1100°C for 4000 hours, changes were detected in the material suggesting that prolonged thermal exposure of the material does have an effect on its properties, specifically a reduction in sample thickness indicating that the matrix may have densified slightly and a small increase in modulus and loss of aluminium from the fibre. In contrast, much shorter exposures to higher temperatures lead to significant changes to the microstructure, principally in terms of the reduction in porosity and grain growth in the matrix regions and an embrittlement of the material from an aging temperature of 1300°C, such that the material behaved as a monolithic ceramic after aging at 1480°C. Aging at 1200°C and above was found to cause a progressive decrease in the material thickness indicating a densification of the material. The fibre architecture was found to restrict densification in the plane of the fibre reinforcement. The mechanical properties of the material aged for 200 hours at 1200°C appear unaffected by the thermal aging. The aging of material at 1300°C was found to increase the Young's modulus to a maximum value after aging at 1400°C. Aging at 1480°C appeared to cause a slight decrease in the Young's modulus of the material. Aging of the material at 1300°C and above was found to cause a continuing reduction in the flexural strength of the material until a minimum value was reached after aging at 1480°C. A change in the microstructure of the fibre was initially observed after aging at 1300°C and was more pronounced after aging at 1400°C and 1480"C. A progressive growth of elongated alumina grains in the fibres was observed to occur as the meta-stable aluminium-rich mullite transformed to a silicon-rich mullite within the fibre. After aging at 1480°C the fibre was also observed to contain significant quantities of porosity. Furthermore, the fibre reinforcement appears to have lost aluminium, possibly to the matrix. The results of this investigation have found that the material is stable for aging periods of 2000 hours at 1100°C and for up to 200 hours at 1200°C. Whilst aging regimes of over 2000 hours at 1100°C may be acceptable, evidence has been found to suggest that the material is changing.
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Mansour, Rabih. "Mode I Interlaminar Fracture Properties of Oxide and Non-Oxide Ceramic Matrix Composites." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1494248628194216.
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Vazquez, Calnacasco Daniel. "All-Oxide Ceramic Matrix Composites : Thermal Stability during Tribological Interactions with Superalloys." Thesis, Luleå tekniska universitet, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-85513.
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The challenges faced in today’s industry require materials capable of working in chemically aggressive environments at elevated temperature, which has fueled the development of oxidation resistant materials. All-Oxide Ceramic Matrix Composites (OCMC) are a promising material family due to their inherent chemical stability, moderate mechanical properties, and low weight. However, limited information exists regarding their behavior when in contact with other high-temperature materials such as superalloys. In this work three sets of tribological tests were performed: two at room temperature and one at elevated temperature (650 °C). The tests were performed in a pin-on-disk configuration testing Inconel 718 (IN-718) pins against disks made with an aluminosilicate geopolymeric matrix composite reinforced with alumina fibers (N610/GP). Two different loads were tested (85 and 425 kPa) to characterize the damage on both materials. Results showed that the pins experienced ~ 100 % wear increase when high temperature was involved, while their microstructure was not noticeably affected near the contact surface. After high temperature testing the OCMC exhibited mass losses two orders of magnitude higher than the pins and a sintering effect under its wear track, that led to brittle behavior. The debris generated consists of alumina and suggests a possible crystallization of the originally amorphous matrix which may destabilize the system. The data suggests that while the composite’s matrix is stable, wear will not develop uncontrollably. However, as soon as a critical load/temperature combination is attained the matrix is the first component to fail exposing the reinforcement to damage which drastically deteriorates the integrity of the component.
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Hunt, Michael Patrick. "Pressureless Densification of Alumina - Titanium Diboride Ceramic Matrix Composites." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/31326.
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The research focus was to determine diffusion mechanisms responsible for densification behavior of SHS produced Al2O3/TiB2 Ceramic Matrix Composites (CMCs). Previous research has shown SHS produced Al2O3/TiB2 composites exhibited unique microstructural properties that contributed to high strength, fracture toughness, and hardness properties. Pressureless densification of SHS produced Al2O3/TiB2 composites would provide a cost savings because the equipment for pressureless densification is less expensive and less complicated than equipment required for densification with pressure.
Models for sintering of CMCs and calculation of Sintering Time Constants (STC) were used to predict the densification behavior of the SHS produced Al2O3/TiB2 composite. The Levin, Dirnfeld, Shwam equation was used to determine the Rate Controlling Diffusion Mechanism (RCDM) and activation energy for sintering. X-Ray Diffraction (XRD) analysis of the as-milled reaction product powder revealed the presence of an aluminum borate (Al18B4O33) as a third phase, as well as, in pressureless heat treated samples. Based on experimental results and analysis, it seemed possible the Al18B4O33 compound may have formed by reaction of Al2O3 with TiB2 along their interfaces. Aluminum borates have been observed to form Al18B4O33 (s) + B2O3 (l) at temperatures above 1000°C. The RCDM for densification of SHS produced Al2O3/TiB2 was found to be liquid phase diffusion with volume diffusion also likely being active during densification. In addition, Al18B4O33 seemed to be the preferred compound formed during oxidation. Further research should be performed to control formation of Al18B4O33; as well as, on the oxidation behavior of the SHS produced Al2O3/TiB2.Master of Science
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AKRAM, MUHAMMAD YASIR. "Giunzione di compositi a matrice ceramica a base ossidica." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2751274.
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Shamsudin, Roslinda. "Directed melt oxidation of ceramic matrix composites : the effect of oxide dopants and particulate reinforcements." Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301283.
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Şahin, Erdem Çiftçioğlu Muhsin. "Synthesis and characterization of hydroxyapatite-alumina-zirconia biocomposites/." [s.l.]: [s.n.], 2006. http://library.iyte.edu.tr/tezler/master/malzemebilimivemuh/T000548.pdf.
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Thesis (Master)--İzmir Institute Of Technology, İzmir, 2006.Keywords: Hydroxiapatites, alumina ceramic, zirconium oxide, urea, precipitations. Includes bibliographical references (leaves. 73-75).
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Boutenel, Florian. "Comportement d’une matrice alumine-silice au cours de l’élaboration de composites à matrice céramique oxyde/oxyde." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2020. http://www.theses.fr/2020EMAC0011.
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Les composites à matrice céramique oxyde/oxyde peuvent être considérés pour des applications structurales opérant, en continu, sous environnement oxydant à des températures comprises entre 500°C et 900°C, comme c’est le cas dans les zones proches des moteurs d’avions. En particulier, les composites reposant sur une matrice associant de l’alumine et de la silice présentent un fort potentiel. En outre, la mise en œuvre de ces matériaux comprend plusieurs étapes dont deux sont essentielles : l’imprégnation du renfort fibreux par la suspension et le frittage de la matrice. Cette thèse s’intéresse à l’élaboration de composites à matrice céramique oxyde/oxyde utilisant une matrice alumine-silice. Celle-ci est issue d’une suspension aqueuse dans laquelle les deux espèces sont initialement présentes sous formes de particules. Aussi, l’objectif de ces travaux est d’étudier le comportement d’un tel système au cours des différentes étapes clés de la fabrication, c’est-à-dire d’établir les relations procédé/microstructure/propriétés, afin de proposer une composition optimale de la matrice au regard du procédé et des propriétés visées. En particulier, la proportion de silice sera un paramètre crucial. Tout d’abord, étant donné que la réussite de l’étape d’imprégnation repose sur la capacité de la suspension à s’écouler au sein de la structure fibreuse, une caractérisation rhéologique des suspensions d’oxydes a été menée. Le comportement rhéologique a été interprété sur la base des domaines de prédominance des différentes interactions au sein de la suspension. Aussi, l’influence des différentes caractéristiques des suspensions, comme la concentration volumique en particules et la proportion alumine-silice, a été examinée. Ensuite, le comportement de ce système au cours du frittage a été étudié puisque ce traitement thermique doit permettre, entre autres, d’aboutir à une microporosité respectueuse du concept de composites à matrice faible. Les mécanismes de frittage ont été identifiés tandis que l’influence des différents paramètres sur la cinétique a été qualifiée. Aussi, des liens avec les propriétés mécaniques de la matrice ont été établis. Enfin, des composites à renforts Nextel™ 610 et à matrice poreuse alumine-silice ont été mis en œuvre et caractérisésOxide/oxide ceramic matrix composites can be used for structural applications operating continuously at temperatures between 500°C and 900°C under oxidizing environments, such as in areas close to aircraft engines. In particular, composites based on a matrix combining alumina and silica are promising. In addition, the processing of these materials comprises several steps. Two of them are essential: the impregnation of the fibrous reinforcement with the suspension and the sintering of the matrix. This PhD thesis focuses on the processing of oxide/oxide ceramic matrix composites using an alumina-silica matrix. It is derived from an aqueous suspension in which the two species are initially present as particles. The aim of this work is to study the behaviour of such a system during the various stages of the manufacturing, i.e. to establish the relationships between processing/microstructure/properties, in order to propose an optimal composition of the matrix regarding the process and the required properties. In particular, the silica proportion will be a crucial parameter. Firstly, since the quality of the impregnation step is based on the ability of the suspension to flow within the fibrous structure, a rheological characterization of the oxide suspensions has been carried out. The rheological behavior has been interpreted on the basis of the domains of predominance of the different interactions within the suspension. Also, the influence of the various suspension characteristics, such as the solid fraction and the alumina-silica ratio, has been examined. Then, the behaviour of this system during the sintering has been studied since this thermal treatment should lead to a microporosity that respects the concept of weak matrix composites. The sintering mechanisms have been identified while the influence of the various parameters on the kinetics has been qualified. Also, relationships with the mechanical properties of the matrix have been established. Finally, composites with Nextel™ 610 reinforcements and a porous alumina-silica matrix have been fabricated and characterized
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Ben, Ramdane Camélia. "Etude et modélisation du comportement mécanique de CMC oxyde/oxyde." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0077/document.
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Les CMC oxyde/oxyde sont de bons candidats pour des applications thermostructurales. Le comportement mécanique et les mécanismes d’endommagement de deux composites alumine/alumine à renforts tissés bi- et tridimensionnels ont été étudiés et comparés. La microstructure de ces CMC à matrice faible a été caractérisée à partir de porosimétrie et de CND, tel que thermographie IR, scan ultrasonore et tomographie X, ce qui a permis de mettre en évidence la présence de défauts initiaux. Le comportement mécanique en traction, ainsi qu’en compression dansle cas du CMC à renfort bidimensionnel, dans la direction des fibres ainsi que dans la direction ±45°, aété étudié à température ambiante. Afin d’exploiter pleinement ces essais, nous avons eu recours à plusieurs méthodes d’extensométrie et de suivi d’endommagement, telles que la thermographie IR et l’émission acoustique. Les propriétés mécaniques à rupture ainsi que le module de Young du CMC à renfort bidimensionnel développé à l’Onera se sont avérées supérieures à celles disponibles dans la littérature. Les mécanismes d’endommagement des matériaux ont été déterminés à partir d’observations post mortem au MEB et d’essais in situ dans un MEB, ce qui a permis d’évaluer la nocivité des défauts initiaux. Enfin, l’étude du comportement mécanique de ces composites a permisde proposer un modèle d’endommagement tridimensionnel qui permettra de poursuivre le développement de ces matériaux grâce à du calcul de structure. A l’issue de cette thèse, des pistes d’amélioration des procédés d’élaboration et de choix d’instrumentation à utiliser pour les futures études, notamment en ce qui concerne le suivi d’endommagement, ont également été proposéesOxide/oxide CMCs are good candidates for thermostructural applications. Themechanical behaviour and damage mechanisms of two alumina/alumina composites with two andthree dimensional woven reinforcements were studied and compared. The microstructure of theseweak matrix CMCs was characterized by porosimetry and NDT methods, such as IR thermography,ultrasound scanning and X-ray tomography, which highlighted initial defects. The mechanicalbehaviour was studied through tensile tests, as well as compression tests in the case of the twodimensionalreinforced CMC. These tests were conducted at room temperature, in the fibres directionsand in the ±45° direction. In order to fully exploit these tests, several extensometry and damagemonitoring methods, such as IR thermography and acoustic emission, were used. Young’s moduli andmaximum stresses and strains of the two-dimensional reinforced CMC developed at Onera appearedto be higher than those available in the literature. The damage mechanisms of the materials weredetermined by post mortem SEM observations and in situ testing in a SEM, which made it possible toassess the nocivity of initial defects. Studying the mechanical behaviour of these composites finallyenabled the development of a three-dimensional damage model that will facilitate the furtherdevelopment of such materials, through finite element analysis. Finally, some improvements regardingthe manufacturing processes and the instrumentation for damage monitoring were suggested forfuture studies
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Rocabois, Philippe. "Stabilité thermochimique des composites céramiques base SiC : approche thermodynamique et expérimentale du système Si-O-C-N." Grenoble INPG, 1993. http://www.theses.fr/1993INPG0085.
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Les comportements experimentaux des materiaux de synthese contenant silicium, carbone et oxygene ou azote, a haute temperature, et leurs simulations thermodynamiques, presentent des desaccords quantitatifs importants qui peuvent etre expliques par des donnees thermodynamiques peu precises ou incompletes, ou par des cinetiques de reactions particulierement lentes. Pour lever toute ambiguite sur les donnees des composes cristallins, amorphes et gazeux du systeme si-c-n-o de nouvelles mesures d'enthalpie de formation ont ete effectuees par la technique des cellules d'effusion multiples couplee a la spectrometrie de masse. Il a ete mis en evidence que le sio(s) ne constitue pas une phase stable. La temperature de l'eutectique si+sic et les activites du silicium dans le liquide en equilibre avec sic ont ete mesurees. L'etude du ternaire si-n-o a permis de proposer une nouvelle valeur de l'enthalpie de formation de si#2n#2o. En plus des mesures de grandeurs thermodynamiques, l'etude de ces systemes a mis en evidence l'importance des cinetiques de reaction de decomposition (par exemple le faible coefficient d'evaporation de si#3n#4), ou entre phases solides (par exemple si+sio#2 ou sio#2+c). La prise en compte de la reduction des incertitudes sur les donnees thermodynamiques s'est revelee grandement insuffisante pour expliquer les desaccords entre le comportement des fibres et sa simulation. Le comportement de materiaux de synthese a base de sic et le comportement de melanges de phases connues ont ete etudies. Les resultats de ces experiences ont montre que les pressions mesurees de sio(g) et co(g) sont bien plus faibles que les pressions d'equilibre pour les materiaux dont la composition globale est dans le ternaire sic+sio#2+c. Les fibres sicn(o) (ex-pcsz) apparaissent plus stables que les fibres sico (ex-pcs). L'ensemble des resultats exposes peut etre exploite pour aider a expliquer et prevoir les traitements des fibres ceramiques en milieu industriel
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Grosskopf, Paul P. "Mechanical behavior of a ceramic matrix composite material." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42214.
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Monolithic ceramic materials have been used in industry for hundreds of years. These materials have proven their usefulness in many applications, yet, their potential for critical structural applications is limited. The existence of an imperfection in a monolithic ceramic on the order of several microns in size may be critical, resulting in catastrophic failure. To overcome this extreme sensitivity to sman material imperfections, reinforced ceramic materials have been developed. A ceramic matrix which has been reinforced with continuous fibers is not only less sensitive to microscopic flaws, but is also able to sustain significant damage without suffering catastrophic failure.
A borosilicate glass reinforced with several layers of plain weave silicon carbide cloth (Nicalon) has been studied. The mechanical testing which was performed included both flexural and tensile loading configurations. This testing was done not only to determine the material properties, but also to initiate a controlled amount of damage within each specimen.
Several nondestructive testing techniques, including acousto-ultrasonics (AU), were performed on the specimens periodically during testing. The AU signals were monitored through the use of an IBM compatible personal computer with a high speed data acquisition board. Software has been written which manipulates the AU signals in both the time and frequency domains, resulting in quantitative measures of the mechanical response of the material.
This paper will compare the measured AU parameters to both the mechanical test results and data from other nondestructive methods including ultrasonic C-scans and penetrant enhanced X-ray radiography.
Master of Science
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Davies, C. M. A. "Failure mechanisms in glass-ceramic matrix composite laminates." Thesis, University of Bath, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387305.
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Lyons, Jed S. "Micromechanical studies of crack growth in ceramic matrix composite." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/16086.
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Dunyak, Thomas John. "Properties and performance of a ceramic composite component." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-134634/.
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Bischoff, Matthew Lee. "CHARACTERIZATION OF CERAMIC MATRIX COMPOSITE MATERIALS USING MILLIMETER-WAVE TECHNIQUES." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1362655198.
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Trandel, Barbara Dawn. "Nondestructive evaluation of a high temperature ceramic matrix composite material." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-01312009-063125/.
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West, Grant. "Microstructure and mechanical performance of SiC/BMAS glass-ceramic matrix composite." Thesis, University of Warwick, 1997. http://wrap.warwick.ac.uk/66932/.
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A diverse range of microscopy techniques and mechanical testing methods have been used to characterize glass and glass-ceramic composites. The focus of the work has been a commercially available Barium Magnesium Aluminosilicate matrix reinforced by Tyranno SiC based yam type fibres. The mechanical behaviour has been related to the microstructure through use of models from the literature. The temperature range of study has been from room temperature to 1300°C in air. The microstructure of the BMAS(fyranno was a diphasic mixture of celsian and indialite/cordierite although the manufacturers intention was a monophasic bariumosumilite. The carbon rich interface was found to be thin (l0-15nm) but the composite displayed impressive strength when compared to similar glass-ceramic composites reported in the literature. The matrix could be converted to the equilibrium bariumosumilite phase by heating in an inert atmosphere at 1370°C (or possibly lower) but matrix elemental diffusion into the fibres is likely to impair fibre strength. Tensile failure was by conventional matrix microcracking with load transfer to the in line fibres. However the composite strength was found to be dependent upon the strain rate as was the microcracking threshold associated with cracking of the 0° plies. Failure of the UD BMAS(fyranno was by longitudinal splitting before the expected ultimate strength (from the 0,90° results) was reached. This was due to an apparent notch sensitivity in this fibre architecture, a trait not observed in the 2-D composite. Direct measurement methods were used to establish the interfacial shear strength and these were compared to various models. These were based on matrix cracking thresholds, matrix crack spacing and a relatively new method where an 'inelastic strain index' was found from loading and unloading curves or hysteresis loop widths. Greatest fidelity with the direct methods was found with the last of these models. As with all composites with carbon enriched interfaces oxidation of the interface and fibres was found to impair strength when tested in air at temperatures as low as 600°C and possibly below this when testing at lower strain rates. At high strain rates, near room-temperature-strengths were achieved, even at 1l00°C, as the degrading effects of the oxidizing environment had less time to act. Long term exposure at high temperatures (1200°C) was responsible for formation of an embrittled surface layer up to 70J.lm thick. Within this layer the fibres were severely degraded and strong bonding prevailed at the interface. At temperatures in excess of the expected fibre pyrolysis temperature, (l100°C), the composite was seen to shrink along the length of the fibre axis and dilate normal to it which was attributed to fibre instability. Stabilising the fibres by heat treatments at 1200°C for 24 hours was seen to improve the creep performance in terms of the total strain accumulated within the 100 hours of the creep tests. The creep was comparable to other commercial glass ceramics (CAS/Nicalon and BMAS/BN/SiC/Nicalon) indicating the dominance of fibre creep properties on those of the composite. Cycling of the creep load seemed to result in a greater embrittled depth from the surface but failure at 100MPa and 1200°C was not observed within 240 hours of testing. Other systems were investigated such as the CAS/Nicalon, MAS/Nicalon and AS/Nicalon. Of these the AS/Nicalon was used for modelling the creep behaviour since it represented a simple system where matrix creep was accompanied by elastic deformation of the fibres. A model from the literature was used to explain an apparent increase in the elastic modulus during load cycling at high temperature and also the lower strain accumulation seen during load cycling compared to conventional creep tests.
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Goff, Adam Carter. "Modeling and Synthesis of a Piezoelectric Ceramic-Reinforced Metal Matrix Composite." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/10143.
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A mathematical model has been created based on J.D. Eshelby's equivalent inclusion method that can predict the elastic modulus and damping capability in the form of Joule heat for any piezoelectric ceramic-reinforced metal matrix composite system. Specifically, barium titanate (BaTiO₃), lead titanate (PbTiO₃), and zinc oxide (ZnO) piezoelectric ceramics have been modeled as dispersed particles shaped as spheres, prolate spheroids, and discs within a host of common structural metallic matrices including 304 stainless steel, mild steel, aluminum, brass, copper, lead, magnesium, nickel, Ni-20wt%Cr, tin, titanium, Ti-6Al-4V(at%), and tungsten. Composite systems that were predicted to exhibit the greatest level of damping capacity include copper, aluminum, and magnesium matrices reinforced with PbTiO₃, BaTiO₃, and ZnO, in descending order of damping magnitude. In general, higher-conducting, lower-stiffness metallic matrices coupled with more-piezoelectric, higher-stiffness ceramic reinforcement resulted in the greatest level of predicted damping capability and enhanced composite elastic modulus. Additionally, a Ni-20wt%Cr-30v%BaTiO₃ composite has been created using mechanical alloying processing. Specifically, pure constituent powders were combined stoichiometrically in a SPEX milling vial utilizing a charge ratio of 4:1 and subsequently milled for 24 hours. Separate composite powder samples were then annealed in a hydrogen tube furnace at 400°C,
500°C, and 600°C for one and five hours at each temperature. X-ray diffraction was performed on the as-milled and the annealed powders revealing that each was composed of the starting constituents in the appropriate proportions. Representative powders were mounted and polished using common metallographic procedures and microstructures were examined by optical microscopy, scanning electron microscopy, and transmission electron microscopy. All of the powders exhibited a good dispersion of BaTiO₃ particles ranging in diameter from 1μm to about 25nm with no noticeable difference between the as-milled and the annealed powders.Master of Science
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King, Harry C. III. "Automation of CVI equipment for laminated matrix composite fabrication." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19509.
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Dev, Bodhayan. "Characterization of Ceramic/Glass Composite Seals for Solid Oxide Fuel Cells." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1400847202.
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Aldridge, Matthew. "Aspects of the processing, mechanical properties and thermal shock behaviour of a ductile particle toughened alumina." Thesis, University of Surrey, 1996. http://epubs.surrey.ac.uk/605/.
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Tang, Chao. "Modelling of Thermo-Mechanical Behaviour of Ceramic Matrix Composite Tows and Laminates." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509397.
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Pryce, A. W. "Matrix cracking and stress/strain behaviour of continuous fibre ceramic composite laminates." Thesis, University of Surrey, 1991. http://epubs.surrey.ac.uk/843150/.
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Matrix damage and its effects on mechanical properties have been examined for SiC (Nicalon1) fibre reinforced glass and glass ceramic matrix composites under quasi-static and fatigue loading conditions. Nicalon/Pyrex laminates of different lay-ups have been tested under quasi-static tension. The elastic moduli have been measured and matrix damage monitored as a function of applied strain. The mechanical properties are strongly influenced by the presence of crystalline regions in the matrix which promote microcracking. Laminated plate theory is used to provide bounds to the moduli of the laminates. For unidirectional and simple crossply Nicalon/CAS2 laminates the quasi-static stress/strain behaviour and associated matrix damage accumulation have been examined in detail. The damage development with applied stress was quantified by counts of crack density (in both longitudinal and transverse plies), stiffness loss and cumulative residual strain. The quasi static stress/strain behaviour during continuous tests (accumulating damage) and discontinuous tests (constant damage) have been modelled using a stress analysis based on Aveston, Cooper and Kelly (ACK) theory. The continuous stress/strain behaviour of (0/90) crossply laminates has been modelled using a shear-lag analysis developed previously to describe the transverse ply cracking behaviour of polymer matrix composites. The analysis is modified to account for longitudinal ply cracking. Matrix damage development in unidirectional and (0/90) crossply laminates under quasistatic cycling and high frequency fatigue loading have been studied. For unidirectional laminates stable stress/strain hysteresis loops were obtained during quasi-static cycling, corresponding to stable matrix damage states. These and similar loops obtained after high frequency fatigue are modelled using, the discontinuous stress/strain analysis. It is suggested that the effect of high frequency fatigue is to decrease the interfacial shear strength.
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Ham, Alexander. "High temperature erosive wear of a continuous fibre reinforced glass-ceramic matrix composite." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/804413/.
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Al-Joubory, Kassim M. "Fibre-matrix reaction in composite ceramics based on alumina, titania, and zirconia matrices." Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329508.
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Butts, Mark D. "Nondestructive examination of nicalon fiber composite preforms using x-ray tomographic microscopy." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/19959.
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Cottet, Arnaud J. "Modelling of ceramic matrix composite microstructure using a 2-D fractal spatial particle distribution." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/12928.
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GHOSH, DIPANKAR. "CRACK PROPAGATION AND FRACTURE RESISTANCE BEHAVIOR UNDER FATIGUE LOADING OF A CERAMIC MATRIX COMPOSITE." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1019491575.
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Hu, Yile, and Yile Hu. "Peridynamic Modeling of Fiber-Reinforced Composites with Polymer and Ceramic Matrix." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625367.
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This study focuses on developing novel modeling techniques for fiber-reinforced composites with polymer and ceramic matrix based on Peridynamic approach. To capture the anisotropic material behaviors of composites under quasi-static and dynamic loading conditions, a new peridynamic model for composite laminate and a modified peridynamic approach for non-uniform discretization are proposed in this study. In order to achieve the numerical implementation of the proposed model and approach, a mixed implicit-explicit solver based on GPU parallel computing is developed as well.
The new peridynamic model for composite laminates does not have any limitation in fiber orientation, material properties and stacking sequence. It can capture the expected orthotropic material properties and coupling behaviors in laminates with symmetric and asymmetric layups. Unlike the previous models, the new model enables the evaluation of stress and strain fields in each ply of the laminate. Therefore, it permits the use of existing stress- or strain-based failure criteria for damage prediction. The computation of strain energy stored at material points allows the energy-based failure criteria required for delamination propagation and fatigue crack growth. The capability of this approach is verified against benchmark solutions, and validated by comparison with the available experimental results for three laminate layups with an open hole under tension and compression.
The modified peridynamic approach for non-uniform discretization enables computational efficiency and removes the effect of geometric truncations in the simulation. This approach is a modification to the original peridynamic theory by splitting the strain energy associated with an interaction between two material points according to the volumetric ratio arising from the presence of non-uniform discretization and variable horizon. It also removes the requirement for correction of peridynamic material parameters due to surface effects. The accuracy of this approach is verified against the benchmark solutions, and demonstrated by considering cracking in nuclear fuel pellet subjected to a thermal load with non-uniform discretizations.
Unlike the previous peridynamic simulations which primarily employs explicit algorithm, this study introduces implicit algorithm to achieve peridynamic simulation under quasi-static loading condition. The Preconditioned Conjugate Gradient (PCG) and Generalized Minimal Residual (GMRES) algorithms are implemented with GPU parallel computing technology. Circulant preconditioner provides significant acceleration in the convergence of peridynamic analyses. To predict damage evolution, the simulation is continued with standard explicit algorithms. The validity and performance of this mixed implicit-explicit solver is established and demonstrated with benchmark tests.
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Chen, Makan. "A modified sol-gel route to fibre reinforced alumina and mullite composites." Thesis, University of Sheffield, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326846.
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Halverson, Howard Gerhard. "Durability of Ceramic Matrix Composites at Elevated Temperatures: Experimental Studies and Predictive Modeling." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/27834.
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In this work, the deformation and strength of an oxide/oxide ceramic matrix composite system under stress-rupture conditions were studied both experimentally and analytically. A rupture model for unidirectional composites which incorporates fiber strength statistics, fiber degradation, and matrix damage was derived. The model is based on a micromechanical analysis of the stress state in a fiber near a matrix crack and includes the effects of fiber pullout and global load sharing from broken to unbroken fibers. The parameters required to produce the deformation and lifetime predictions can all be obtained independently of stress-rupture testing through quasi-static tension tests and tests on the individual composite constituents. Thus the model is truly predictive in nature. The predictions from the model were compared to the results of an extensive experimental program. The model captures the trends in steady-state creep and tertiary creep but the lifetime predictions are extremely conservative. The model was further extended to the behavior of cross-ply or woven materials through the use of numeric representations of the fiber stresses as the fibers bridge matrix cracks. Comparison to experiments on woven materials demonstrated the relationship between the behavior of the unidirectional and cross-ply geometries. Finally, an empirical method for predicting the durability of materials which exhibit multiple damage modes is examined and compared to results of accurate Monte Carlo simulations. Such an empirical method is necessary for the durability analysis of large structural members with varying stress and temperature fields over individual components. These analyses typically require the use of finite element methods, but the extensive computations required in micromechanical models render them impractical. The simple method examined in this work, however, is shown to have applicability only over a narrow range of material properties.Ph. D.
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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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Kurtoglu, Aziz. "Aluminum Oxide And Titanium Diboride Reinforced Metal Matrix Composite And Its Mechanical Properties." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605381/index.pdf.
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This study is on the production and testing of an aluminum metal matrix composite. Metal Matrix Composites can be produced in several different ways. In this study, an aluminum matrix composite is produced by direct addition of the reinforcement ceramic into the liquid metal. The ceramic reinforcement for this process was a mixture of TiB2 and Al2O3 which was produced by means of a thermite reaction of reactants Al, B2O3 and TiO2 all in powder form with their respective stoichiometric amounts. This ceramic mixture was ground to fine powder size and then added to liquid aluminum in small percentages. After casting and taking samples of unreinforced alloy and reinforced alloys, their tensile strength and hardness as material properties were measured and compared. Another issue is the wetting of ceramic particles by molten Aluminum. The aim of the experiments in general is to find a better way to produce a composite material with desired mechanical properties.
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Smith, Craig Edward. "Monitoring Damage Accumulation In SiC/SiC Ceramic Matrix Composites Using Electrical Resistance." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1249917100.
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Herbst, Stephan. "Investigation of a ceramic metal matrix composite functional surface layer manufactured using gas tungsten arc welding." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/9191.
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Wear resistant surfaces with high toughness and impact resistant properties are to be created to improve the life cycle cost of brake discs for trains. A potential solution to this industrial problem is to use an arc cladding process. This work describes the application of gas tungsten arc welding (GTAW) for a structural ceramic Metal Matrix Composite (MMC) on steel. The structure of the two ceramics examined indicates the possibility of development of a wear resistant surface, which would extend the life of the brake disc. Silicon Carbide (SiC) and Tungsten Carbide (WC) ceramics were studied to embed them in a steel matrix by an advanced GTAW method. WC particles penetrated the liquid weld pool and also partially dissolved in the steel matrix, whereas, SiC because of the physical properties never penetrated deeper into the weld pool but segregated on the surface. Successful embedding and bonding of WC led to the decision to exercise an in-depth analysis of the bonding between the WC particles and the matrix. Chemical analysis of the matrix revealed more WC dissolution as compared to particle form within the clad. It was observed that WC reinforcement particles built a strong chemical bond with the steel matrix. This was shown by electron backscatter diffraction (EBSD) analysis. The hard clad layer composed of WC reinforced steel matrix gave an matching friction coefficient to high-strength steel in cold wear conditions through Pin-on-Disc wear and friction testing. A prototype railway brake disc was created with the established GTAW parameters to find out the difficulties of producing industrial scale components.
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Yang, Fan. "Oxidation and mechanical damage in unidirectional SiC/Si#N# composite at elevated temperatures." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/19057.
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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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MARCHISIO, SILVIA. "Composite Materials reinforced by Carbon Nanotubes." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2506164.
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The work of this Ph.D. thesis has been realised in the field of a promising and largely studied technological material: the carbon nanotubes (CNTs). Since 1991 a large number of attempts have been conducted, trying to exploit the outstanding potential of this carbonaceous material, in order to improve the properties of several matrices. The most important application is the production of polymer matrices composites (PMCs), but in last decades an increasing number of metal matrix ones (MMCs) have been presented and recently also ceramic matrix (CMCs) applications have been attempted. Despite massive efforts focused on CNTs-composites, the potential of employing this reinforcement materials has not yet been fully exploited. This lack is substantially due to the difficulties associated with the dispersion of entangled carbon nanotubes during processing and poor interfacial interaction between CNTs and matrix materials. Because of these reasons the very first aspect of this work has been the study of the dispersion state of nanotubes. The aim of the experiments was not only to obtain a good dispersion and distribution of the CNTs, but also to evaluate their dispersion grade. Indeed, due to their nanosize and to their carbonaceous nature, few simple experimental techniques result suitable for this purpose. The second part of the work consisted in the application of the carbon nanotubes to the production of new materials for technological applications, with improved mechanical properties. Three composite materials with different matrices have been designed, developed and produced: a polymer matrix composite, a ceramic matrix and a metal matrix one. For PMCs a polyvinyl butyral matrix has been used and the composites were obtained by a deeply studied technique: the tape casting technology. The same approach was also used in the case of CMCs: tape casted silicon carbide matrix composites reinforced by carbon nanotubes have been produced. Finally a third matrix has been experimented: MMCs were investigated starting from pure aluminium powders. For Al matrix composites a particular technique was used: the sintering was obtained starting from a powder metallurgy approach and exploiting electric current and pressure (Electric Current Assisted Sintering approach). For all the three different composite materials, after the development of the production route and the preparation of several specimens, a characterization step followed. The materials were characterized in terms of physical properties, morphology and microstructure, and mechanical behaviour.
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Turkyilmaz, Gokhan. "Processing And Assessment Of Aluminum Ceramic Fiber Reinforced Aluminum Metal Matrix Composite Parts For Automotive And Defense Applications." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610751/index.pdf.
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The aim of this study was to produce partially reinforced aluminum metal matrix
composite components by insertion casting technique and to determine the effects
of silicon content, fiber vol% and infiltration temperature on the mechanical
properties of inserts, which were the local reinforcement parts of the components.
Silicon content of alloys was selected as 7 wt% and 10 wt%. The reinforcement
material, i.e. Saffil fiber preforms, had three different fiber vol% of 20, 25 and 30
vol% respectively. The infiltration temperatures of composite specimens were fixed
as 750 °C and 800 °
C. In the first part of the thesis, physical and mechanical properties of composite specimens were determined according to the parameters of silicon content of the matrix alloy, infiltration temperature and vol% of the reinforcement phase. X-ray diffraction examination of fibers resulted as the fibers mainly composed of deltaalumina fibers and scanning electron microscopy analyses showed that fibers had planar isotropic condition for infiltration. Microstructural examination of composite specimens showed that appropriate fiber/matrix interface was created together with small amount of micro-porosities. Bending tests of the composites showed that as fiber vol% increases flexural strength of the composite increases. The highest strength obtained was 880.52 MPa from AlSi10Mg0.8 matrix alloy reinforced with 30 vol% Saffil fibers and infiltrated at 750 °
C. Hardness values were also increased by addition of Saffil fibers and the highest value was obtained as 191 HB from vertical to the fiber orientation of AlSi10Mg0.8 matrix alloy reinforced with 30 vol% Saffil fibers. Density measurement revealed that microporosities existed in the microstructure and the highest difference between the theoretical values and experimental values were observed in the composites of 30 vol% Saffil fiber reinforced ones for both AlSi7Mg0.8 and AlSi10Mg0.8 matrix alloys. In the second part of the experiments, insertion casting operation was performed. At casting temperature of 750 °
C, a good interface/component interface was obtained. Image analyses were also showed that there had been no significant fiber damage between the insert and the component.
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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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Miller, Ian Timothy. "Probabilistic finite element modeling of aerospace engine components incorporating time-dependent inelastic properties for ceramic matrix composite (CMC) materials." Akron, OH : University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1144941702.
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Thesis (M.S.)--University of Akron, Dept. of Mathematics, 2006."May, 2006." Title from electronic thesis title page (viewed 11/29/2007) Advisor, Vinod Arya; Co-Advisor, Ali Hajjafar; Faculty reader, Shantaram S. Pai; Department Chair, Kevin Kreider; Dean of the College, Ronald F. Levant; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Rajitrangson, Phitakphong. "Effect of surface conditioning methods on repair bond strength of microhybrid resin matrix composite." Connect to resource online, 2010. http://hdl.handle.net/1805/2138.
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Thesis (M.S.D.)--Indiana University School of Dentistry, 2010Title from PDF t. p. (viewed May 12, 2010) Advisor(s): Michael A. Cochran, Chair of the Research Committee, Jeffrey A. Platt, Bruce A. Matis, Carlos Gonzalez-Cabezas, Sopanis D. Cho. Curriculum vitae. Includes abstract. Includes bibliographical references (leaves 64-69).
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Mossor, Charles W. "Electrical Breakdown of Thermal Spray Alumina Ceramic Applied to AlSiC Baseplates Used in Power Module Packaging." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/33543.
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Thermal spray coatings offer new alternatives in the production of electronic power modules that use alumina ceramic as an isolation layer. Current processes use direct bond copper (DBC) soldered to a nickel plated copper heat spreader. A coefficient of thermal expansion (CTE) mismatch exists between copper and alumina and leads to reliability issues that arise due to product failure during thermal cycling and lifetime operation. The substitution of an AlSiC metal matrix composite (MMC) heat spreader baseplate addresses the problem of CTE mismatch and will reduce the number of product failures related to cracking and delamination caused by this pronounced mismatch in the thermal expansion coefficient..
The substitution of an AlSiC (MMC) heat spreader baseplate also allows the production process to be achieved with a fewer number of metallization layers. Thermal spray can apply alumina ceramic coatings directly to the AlSiC (MMC) baseplates. A reduction in process steps will lead to a reduction in manufacturing costs, the main driving objective in Microelectronics Industries.
Thermal spray coatings have a major problem since they have a porous microstructure which can trap undesired moisture. The moisture basically causes the coatings to have a lower dielectric breakdown voltage and a higher leakage current at normal operating voltages. This problem can be eliminated by manufacturing the electronic power modules in a controlled environment and packaging the devices in a hermetically sealed package.
This thesis analyzes the data obtained from direct-voltage dielectric breakdown and direct-voltage leakage current tests conducted on coupons manufactured using the thermal plasma spray coating process and the thermal high-velocity oxyfuel (HVOF) coating process. ASTM specifications defining appropriate testing procedures are used in testing the dielectric strength of these coupons.
Issues relating to the dielectric strength and dielectric leakage current are evaluated and validated at the Microelectronics Laboratory at Virginia Polytechnic Institute & State University. The objective to conduct this research study using plasma and HVOF alumina coatings as dielectric isolation layers is to support the Microelectronics Industries in developing a product with increased reliability at a lower manufacturing cost.Master of Science
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Fontaine, Florian. "Composites à matrice carbone-oxyde et carbone-nitrure : thermodynamique de l'élaboration et son impact sur les propriétés physico-chimiques, thermiques et mécaniques des composites." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14217/document.
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Les composites carbone/carbone présentent de propriétés thermomécaniques à hautes températures qui les rendent particulièrement adaptés à l’ablation ou à la friction. Leur sensibilité à l’oxydation dès 400°C a conduit à envisager leur dopage en éléments réfractaires inoxydables ou à température d’oxydation élevée. Le procédé sol-gel a permis d’introduire environ 1 % volumique d’oxyde ou de nitrure de titane ou d’aluminium dans leur matrice. Les nitrures sont obtenus par nitruration carbothermique des films d’oxydes. Deux types de sols ont été utilisés : des sols « standard » et des sols enrichis en saccharose. Le saccharose est ajouté pour prévenir la consommation du pyrocarbone lors de la nitruration. Il a par ailleurs une influence sur l’avancement de la nitruration. Les composites chargés sont ensuite densifiés par voie gazeuse, ce qui induit des transformations de phases prévues par la thermodynamique : les films de nitrure de titane sont partiellement carburés (formation de carbonitrure), et les films d’oxyde de titane sont réduits (formation d’oxycarbure). Les dépôts à base d’aluminium sont plus stables et ne subissent aucune transformation. La diffusivité thermique des composites réalisés est faiblement impactée par les charges introduites, alors que les résistances en traction/compression sont sensiblement augmentées. Par ailleurs, une rigidification des composites est observée. Leur cinétique d’oxydation est ralentie. Les composites enrichis en alumine et nitrure d’aluminium présentent des vitesses de perte de masse divisées par 2 par rapport à la référence C/C. Toutes ces propriétés sont liées directement ou non à la composition des sols, et plus particulièrement à sa teneur en saccharose. Il a en effet été montré que les sols qui en contiennent ont tendance à gélifier en surface du composite, ce qui gêne la diffusion des gaz précurseurs au cœur du composite lors de la densification. La porosité finale s’en trouve modifiée. Cette dernière a une influence non négligeable sur le comportement en compression, la diffusivité thermique et la cinétique d’oxydation des composites élaborésCarbon/carbon composites exhibit excellent mechanical and thermal properties at high temperature that make them espe-cially suitable for ablation or friction pieces. Their sensitivity toward oxidation above 400°C has lead to the will of doping them with refractory ceramics that are nonoxidizable or with a high oxidation temperature. The sol-gel process allowed to introduce 1 % in volume of titanium or aluminum oxide or nitride in the matrix. Nitrides are obtained by carbothermal nitridation of the oxide films. Two types of sols were used: the “standard” ones and those with extra sucrose. Sucrose is added to prevent pyrocarbon consumption during the nitridation. Furthermore, it was shown that it has an impact on the nitridation rate. Charged composites are then densified by Chemical Vapor Infiltration, which induces phases transforma-tions that were predicted by thermodynamics: titanium nitride films are partially carburized (formation of titanium carbonitride) and titanium dioxide films are reduced (formation of titanium oxycarbide). Aluminum-based films are more stable and don’t undergo any transformation. Thermal diffusivity of the as-synthesized composites is not much modified by the addition of these ceramics while the tensile and compressive strength are slightly increased. By the way, composites are hardened. Their oxidation kinetics is slowed down. Aluminum-rich composites exhibit a weight loss divided by two compared to the C/C reference. All those properties are directly, or not, linked to the composition of the sols, in particular to their sucrose content. Indeed, it was shown that sucrose-containing sols rather jellify on the surface of the composite, thus preventing the diffusion of precursor gases to the heart of the pieces. The final porosity is then modified. The porosity has an important impact on the compressive strength, thermal diffusivity and oxidation kinetics of the synthesized composites
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Gordon, Neal A. "Material Health Monitoring of SIC/SIC Laminated Ceramic Matrix Composites With Acoustic Emission And Electrical Resistance." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1414835900.
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Amirsardari, Z., and M. Salavati-Niasari. "Study on Microstructure and Ablation Properties of Graphene Oxide/Zirconium Diboride Nanoparticle/Carbon Fiber/Resol Nanocomposites." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42604.
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.The development of compatible additives for hot corrosion inhibition in high temperature application requires test methods which yield significant results on a short time scale. The present study aims at the evaluation of the effect of hot corrosion inhibiting model additives on the performance of an ablative phenolic resin using oxy-acetylene torch test which measure different properties. Thermogravimetric analysis (TGA) and field‐emission scanning electron microscopy (FESEM) in combination with energy disperse Xray (EDX) are used. Two kinds of corrosion inhibiting additives are employed: an inorganic inhibitor based on graphene oxide sheets (GO); a ceramic nanoparticle (ZrB2) with inhibiting properties. The results obtained show that hot corrosion inhibiting additives drastically modify the ablation and thermal stability. The experimental approach described in this paper should be useful for additive development in carbon fiber/phenolic composite because it yields a more durable product than can be obtained by neat composite of how a given additive affects the ablation performance in a hot corrosive environment.
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Hunt, Richard K. "A transmission electron microscope characterization of sodium sulfate hot corrosion of silicon carbide fiber-reinforced lithium aluminosilicate glass-ceramic matrix composite." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA286164.
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