Дисертації з теми "Ceramic Additive Manufacturing"
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Feilden, Ezra. "Additive manufacturing of ceramics and ceramic composites via robocasting." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/55940.
Повний текст джерелаZocca, Andrea [Verfasser]. "Additive manufacturing of porous ceramic structures from preceramic polymers / Andrea Zocca." Clausthal-Zellerfeld : Universitätsbibliothek Clausthal, 2016. http://d-nb.info/1093614021/34.
Повний текст джерелаSnelling, Jr Dean Andrew. "A Process for Manufacturing Metal-Ceramic Cellular Materials with Designed Mesostructure." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/51606.
Повний текст джерелаPh. D.
Snelling, Dean Andrew Jr. "A Process for Manufacturing Metal-Ceramic Cellular Materials with Designed Mesostructure." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51606.
Повний текст джерелаPh. D.
Page, Lindsay V. "Feasibility of Fused Deposition of Ceramics with Zirconia and Acrylic Binder." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1602.
Повний текст джерелаHofacker, Eva. "QUALITY IMPROVEMENT OF CERAMIC PARTS FORMEDICAL APPLICATIONS THROUGHOPTIMIZATION OF THE ADDITIVE MANUFACTURING ANDPOST-PROCESSING PROCESSES." Thesis, KTH, Industriell produktion, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226170.
Повний текст джерелаAdditiv tillverkning är fördelaktigt för medicinska tillämpningar där vävnader måste bytas ut eftersom additiv tillverkning möjliggör tillverkning av högkomplexa tredimensionella strukturer. I denna studie undersöktes additiv tillverkning och efterbehandlingsstegen av tillsatsframställda keramiska delar av ett specifikt material för vävnadsersättning för att optimera delarnas kvalitet. Visuell inspektion och mikroskopiska tekniker, vägning, dimensionella mätningar och böjningsböjningstest användes för resultatutvärderingen. Olika rengöringsmedel och metoder testades med det resultat att det aktuella rengöringsmedlet och metoden hade den bästa rengöringsytan. Med ändrad orientering på byggplattformen och ändrade stöd under additiv tillverkning och definierade positioner i ugnen under sintring förbättrades delarnas kvalitet klart, dvs delarna hade inte längre otaliga sprickor, inte varvade längre och hade en jämn yta. Efterhärdning med UV-ljus har visat sig ha en negativ inverkan på delarnas kvalitet. Test med olika sintringstemperaturer visade att sintringstemperaturen påverkar utseendet, graden av krympning, graden av fusion och böjhållfastheten hos delarna. Därför, beroende på den avsedda tillämpningen, måste sintringsparametrarna anges.
Pesce, Arianna. "3D printing of ceramic-based solid state energy conversion devices." Doctoral thesis, Universitat Autònoma de Barcelona, 2021. http://hdl.handle.net/10803/673218.
Повний текст джерелаEn las últimas décadas, las tecnologías de fabricación aditiva han logrado una amplia difusión, evolucionando desde los primeros prototipos hasta conseguir una extensa distribución comercial. Los materiales cerámicos son bien conocidos por su alta rigidez, fragilidad y tenacidad, que dificultan la consecución de formas complejas y hace extremadamente costosa su mecanización (gran consumo de herramientas o moldes para uso individual). La fabricación aditiva puede reducir el coste de fabricación y abrir nuevos diseños, con libertad de forma prácticamente total, no realizables mediante técnicas tradicionales. El primer paso de la investigación en este campo es la aplicación de la fabricación aditiva al campo de los materiales funcionales, donde los requisitos de propiedades estructurales, microestructurales, ópticas y eléctricas son superiores a los de las aplicaciones comerciales. En particular, la oportunidad de diseños complejos es interesante para aplicaciones en las que el área activa juega un papel importante en el rendimiento final, como en catálisis o en dispositivos electroquímicos. En estos casos, a menudo es necesario más de un material cerámico. Por este motivo es de un gran interés la impresión 3D de múltiples materiales, que permitiría la producción de dichos dispositivos con pasos de fabricación reducidos y, en consecuencia, reduciendo el coste. Esta tesis se centra en la impresión de dispositivos de geometrías complejas para probar las ventajas exclusivas de la fabricación aditiva, tanto en el campo de la catálisis como en la aplicación de pilas de combustible y electrolizadores. Para ello, el trabajo aborda el desarrollo de soportes imprimibles y la hibridación de dos tecnologías de impresión diferentes para producir todo el dispositivo en un solo paso: estereolitografía y robocasting. La estereolitografía (SLA) se caracteriza por obtener estructuras de alta densidad (> 90%) con gran resolución espacial, del orden de 25 µm en las tres direcciones. Se han producido electrolitos para celdas de óxido sólido (SOC) en zirconia estabilizada con itria al 3% y al 8% molar. Se produjeron pilas de botón incorporando materiales estándar de cátodo y ánodo sobre los electrolitos imprimidos, para caracterizar el rendimiento electroquímico. Después de haber demostrado que la tecnología SLA produce electrolitos adecuados con propiedades comparables a las producidas por la fabricación tradicional, se ha medido un incremento de rendimiento, coherente con el incremento de área activa, realizado mediante la corrugación del electrolito. Seguidamente, en esta tesis se exploró la posibilidad de implementar opciones multimaterial, necesarias para imprimir un dispositivo comercial basado en tecnología SOCs. Utilizando SLA como tecnología base, se agregó a la máquina un sistema de robocasting, logrando imprimir cinco materiales. Las pastas necesarias para la impresión por robocasting se han desarrollado íntegramente en el marco de esta tesis a partir de polvos cerámicos comerciales y componentes orgánicos, evaluando su reología y capacidad de curado; produciendo materiales de cátodo, ánodo e interconector. La hibridación de SLA con robocasting fue alcanzada satisfactoriamente, demostrando la posibilidad de imprimir apilamientos de capas de los diferentes componentes. El sinterizado conjunto de tales sistemas fue llevado a cabo, afrontando los retos de la calcinación conjunta de capas compuestas por distintos materiales. Las primeras celdas obtenidas utilizando este procedimiento fueron testadas. Aunque será necesaria una optimización para mejorar los rendimientos, estas celdas son la demostración de la posibilidad de fabricar dispositivos SOC mediante impresión 3D multimaterial. Finalmente, usando técnica de SLA se produjeron placas de microcanales, utilizadas como lecho para la reacción de metanización de CO2, demostrando su eficacia frente a la tecnología tradicional basada en acero inoxidable en términos de conversión de CO2. También se fabricó por primera vez un reactor de intercambio de calor con colectores integrados mediante impresión 3D.
In the last decades, additive manufacturing technologies (AM) have obtained a wider spreading, moving from the prototyping scale to the commercial distribution for some types of materials. The ceramic materials are well known for their high stiffness, brittleness and toughness, which make their processing limited in shape and extremely expensive (high consumption of tools or moulds for individual use). Additive manufacturing can reduce the cost of manufacturing and open new designs, near-free to shape, not realizable with subtracting manufacturing. Next step of the research in this field is the application of additive manufacturing to the field of functional materials, where the requirements of structural, microstructural, optical and electric properties are higher than for commercial applications. In particular the near-free design opportunity is particularly interesting for applications in which the area plays an important role on the final performance, such as in catalysis and for electrochemical devices. In these cases, often more than a ceramic material is necessary arising the interest of the scientific community to the multi-material possibility of 3D printing, to enable the production of such devices with reduced manufacturing steps and on consequence, reducing the cost. This thesis focuses on the printing of complex geometries devices to prove the unfair advantage of additive manufacturing, as in the catalysis field, as for fuel cells and electrolysis application. For this purpose, the work addresses on developing of printable media and hybridization of two different printing technologies to produce the entire device in a single step: stereo-lithography and robocasting. Stereo-lithography (SLA) offers the possibility of obtaining high-density structures (>90%) with high spatial resolution, in the order of 25 µm in the three directions. Electrolytes for Solid Oxide Cells (SOCs) have been produced in 3mol% and 8mol% yttria stabilized zirconia. Button cells were realized with state-of-the-art materials to characterize the electrochemical performance. At first, it was demonstrated that SLA technology is suitable to produce electrolytes with properties comparable with the ones produced by traditional manufacturing. The freedom of design, characteristic of the 3D printing, enables the increase of the performance according with the implement of the area. As a further step, the possibility of implementing multi-material options, necessary to print a commercial device based on SOCs technology, was explored in this thesis. Using SLA as a base, a robocasting system was added to the machine. In this way, a five-material 3D printer could be achieved. The required pastes for robocasting were integrally produced, mixing the ceramic commercial powders with organic materials in appropriate proportions and evaluating their rheology performance and curability. In this way, cathode, anode and interconnect layers were produced. The hybridization of SLA with robocasting was satisfactory achieved, demonstrating the possibility of printing stacks of layers of the different components. The co-sintering of such systems was conducted, facing the challenge of the simultaneous annealing of layers of different materials. The first cells using this procedure were obtained and tested. While still requiring optimization to improve their performances, these cells are the first-time demonstration of the feasibility of SOC devices by multi-material 3D printing. Micro-channel plates, used as bed for CO2 methanation reaction were produced with SLA, proving their efficiency compared with stainless steel ones in terms of CO2 conversion. A heat exchange reactor with integrated manifolds was produced by 3D printing for the first time.
Universitat Autònoma de Barcelona. Programa de Doctorat en Ciència de Materials
Hajiha, Reza. "A Novel Method in Additive Manufacturing of Titanium Matrix Composites with Ceramic Reinforcement by Thermal Decomposition of Aluminum Sulfate." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10838545.
Повний текст джерелаMetal matrix composites (MMCs) microstructure consists of a metallic alloy and a particular reinforcing component, ceramic in the case of this research. They are of high interest due to their high temperature strength, improved thermal stability, improved friction and wear resistant. Defining a low-cost additive manufacturing process that can fabricate high-quality MMC parts will combine the benefit of additive manufacturing and MMC together, which is highly desirable in today’s manufacturing.
This research introduces a novel method to fabricate MMC by introduction of uniformly distributed and dispersed ultra-fine ceramic particles within a metal substrate to form metal-ceramic composite during bulk sintering and to further develop three dimensional printing for fabrication of MMC structures reinforced by ceramic particles. This novel process is capable to fabricate metal-ceramic composite structures with a lower cost and shorter lead time in manufacturing compared to other existing additive manufacturing processes.
Myers, Kyle M. "Structure-Property Relationship of Binder Jetted Fused Silica Preforms to Manufacture Ceramic-Metallic Interpenetrating Phase Composites." Youngstown State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1464089607.
Повний текст джерелаOdinot, Julie. "Développement de la fabrication additive directe par DED-CLAD : de la poudre à la mise en forme de pièces céramiques denses." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN059.
Повний текст джерелаThis work, in partnership between the ONERA Materials and Composite Structure Department (DMSC) and IREPA Laser within the CLADIATOR project, is based on the study of direct additive manufacturing of dense ceramic materials by direct melt deposition (also known as laser cladding) process. This process enables high dimensions or even multi-materials part manufacturing.It will deal with the adaptation of raw materials (ceramic powders) to the existing machine, especially in the case of powder flowability and optical absorption. Indeed, the powder flowability enables its transportation up to the laser nozzle, while the optical absorption of the laser signal is necessary to allow its melting.In parallel, the existing machine also needs to be adapted to ceramic materials : the main difficulty of this work will be the occurence of cracks during the manufacturing. This phenomena is due to the local heating by the laser and the materials brittleness. That’s why some secondary heating solutions, before or after the melt, will have to be defined to decrease the thermal gradient in the material while processing. Those solutions will be discussed between Onera and Irepa Laser, based on FEM simulations established with COMSOL Multiphysics software.Finally, the elaboration process influence on the manufactured ceramics parts will be investigated with microscopy, mechanical and thermal characterization
Gariboldi, Maria Isabella. "Effect of calcium phosphate ceramic architectural features on the self-assembly of microvessels in vitro." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283005.
Повний текст джерелаMaillard, Mathilde. "Imprimabilité de pâtes céramiques par robocasting : Applications aux matériaux denses et multimatériaux." Thesis, Lyon, 2022. https://theses.insa-lyon.fr/publication/2022LYSEI035/these.pdf.
Повний текст джерелаThe main goal of this thesis is to elaborate dense single and multi-material ceramic parts with complex architectures. These architectures are realized using an additive manufacturing technology of extrusion of ceramic pastes through a fine syringe (DIW : robocasting). This research work is financed by the ANR CERAPIDE project, which aims to produce ceramic parts more quickly and with less energy consumption, from formulation to post heat treatment stages. Thus, the formulations of the pastes are optimized by adapting the additives and their quantities in order to obtain homogeneous pastes, without defects and having the rheological properties necessary for printing. Among other things, a ceramic paste must have be shear-thinning while having a high yield stress to be able to be printed by successive stacking of layers. The rheological control and the optimization of the formulations allow to print dense parts with improved mechanical properties. The change of additive allows to modify the topography of the dense parts and thus to modify the mechanical properties of the parts. The definition of printability of ceramic pastes is studied to understand the relationships between microstructural, environmental and technological properties. Finally, the printing parameters must be selected according to the final properties desired for the printed part. The understanding of all these parameters allows the development of alumina parts with an average stress at break of 350 MPa without polishing steps
Bazin, Tiphaine. "Synthèse, caractérisations structurales par spectroscopie et mise en forme d'hydroxyapatites dopées au cuivre ou au fer." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0118.
Повний текст джерелаHydroxyapatite (HA), with formula Ca10(PO4)6(OH)2, is one of the most used material in bone reconstruction. The improvement of its biological properties, in particular by doping with trace elements present in the body, is the subject of recent studies. Therefore, this work deals with the elaboration, structural characterizations from spectroscopy and shaping of copper- or iron-doped hydroxyapatite. Two synthesis routes have been considered: syntheses by aqueous co-precipitation led to the elaboration of pure HA phases doped with copper(II) or iron(III) stable at low temperature (≤ 600°C) while high temperature solid-state reactions led to the elaboration of pure HA phases doped with copper(I), iron(II) or iron(III) stable above 1100°C. These phases have been characterized by XRD and various spectroscopic techniques: FTIR, NMR, UV-vis-NIR, XPS, EPR, XANES-EXAFS and Mössbauer in order to evaluate the influence of the incorporation of the different transition elements into the apatitic structure and to determine the location of the doping element, its degree of oxidation, its coordination, as well as its local environment. The influence of copper and iron on the sinterability and densification of ceramics obtained by solid-state reaction and on the granular growth has been then established. In the case of copper-doped HA ceramics, the biocompatibility of the materials has been verified over a 5-day culture time using MC3T3-E1 cell line and the presence of copper does not seem to affect the cell differentiation onto the ceramic surface (up to 5.3 wt%). Finally, pre-sintered 2D films of the HA phase containing 0.8 wt% of copper have been shaped by selective laser sintering
Marchives, Yoann. "Development of 3D filter made by stereolithography." Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0073/document.
Повний текст джерелаEvery day, the data exchanges increase thanks to the new technologies. We can keep our files, our pictures, our videos online to have an access anywhere on the planet (for now). In this way, the data output of the telecommunication systems has to be increased in order to satisfy the more and more demanding users. One way to allow this is to increase the bandwidths of the different signals, making possible to transmit more data at the same time. In this work, we will develop wide bandpass filters dedicated to space telecommunications. For that purpose, we need them to be compact, with low insertion loss and a limited number of parts to assemble. Consequently, we are interested to use resonators made with ceramic materials that permits to reach such properties. Moreover, these materials are compatible with stereolithography, an additive manufacturing process. Such technology is here very useful for our purpose since its design freedom allows the creation of almost all kind of geometries. To realize such wide bandpass filters, we need strong couplings between the different resonators and also for the accesses, so we will present our studies focused on reaching these specific objectives. Then, we will present different designs of wide bandpass filter around 4GHz. After different generation of ceramic based components, we are be able to experimentally create a 60% bandwidth (even 100% for our last version) very compact bandpass filter filling the objectives of this PhD thesis
Mummareddy, Bhargavi. "Additive Manufacturing Processes for High-Performance Ceramics: Manufacturing - Mechanical and Thermal property Relationship." Youngstown State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1629131959379597.
Повний текст джерелаHagedorn, Yves-Christian [Verfasser]. "Additive manufacturing of high performance oxide ceramics via selective laser melting / Yves-Christian Hagedorn." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1051487862/34.
Повний текст джерелаValenová, Ludmila. "Optimalizace 3D tisku a post-processingu pokročilé keramiky na bázi kalcium fosfátu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442598.
Повний текст джерелаM'Barki, Amin. "3D Printed boehmite based objects." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1021/document.
Повний текст джерелаDirect Ink Writing is an additive manufacturing technique based on continuous layer-by-layer filament deposition. Mostly used to print porous structures, DIW of dense and strong ceramic objects remains an open challenge. However, the advantage of DIW resides in its ability to print multimaterial objects, offering the possibility to combine complex shaping to precise microstructural and functional control, from bioinspired materials, to novel composite structures.Our work focuses on using boehmite gels for DIW, an Al2O3 precursor, as a ceramic matrix to obtain different microstructures. Very small changes to the gels composition lead to completely different microstructures and hence, functional properties. By combining the microstructural versatility of boehmite gels with an understanding of rheology, we are able to print micro and macrocomposites with enhanced mechanical properties. Printing dense and strong ceramic objects starts with understanding the rheological properties that define a printable ink. Boehmite suspensions were ideal to correlate geometrical criteria with rheology and surface tension effects to provide a universal figure of merit for printability. We take advantage of the flow behavior inside DIW nozzles to align alumina platelets during printing. This provides the printed object with increased fracture toughness in the desired direction, with the ability to deviate the fracture propagation perpendicularly to the printing direction. A single object can thus be precisely designed, alternating between dense, strong layers, and directionally tough, fracture deviating layers, to combine the complexity of the shape with the tailoring of mechanical behavior
Moniz, da Silva Sancho Liliana. "Etude de l'interaction laser-matière pour la fabrication de pièces à haute valeur ajoutée en céramiques oxydes semi-transparentes par fusion laser sélective sur lit de poudre." Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLM060.
Повний текст джерелаSelective laser melting of oxide ceramics (Al2O3-ZrO2and Al2O3) is identified as a promising way to produce complex shaped parts with oriented fine microstructures, which would not be achievable by conventional sintering. These lightweight parts, presenting excellent resistance to creep at high temperature and oxidation, would appear as the answer to weight reduction and temperature increasing of turbojet engines, as compared to the usual metal parts coated with porous ceramics. The material/process coupling relies on the controlled addition of an absorber to pure ceramic powders, that compensate the quasi-transparency of these materials to Yb:YAG laser radiation. The effect on optical properties of process parameters, absorbent nature and content, compactness of the powder bed and their influence on manufacturing stability are identified. For this purpose, innovative radiative measurements in reflection and in transmission were carried out during manufacturing and for different operating conditions. These dynamic measurements through an integrating sphere provide information on the laser-material interaction mechanisms taking place in each media and they give access to optical material properties. These measurements enrich an analytical laser-matter interaction model based on the radiation attenuation by the Beer-Lambert law. This model gives a relation between melt pool dimensions, radiative propertiesof the different media (powder bed, substrate and liquid) along with the associated absorption coefficients, the process parameters and powder bed porosity. This model expresses also the apparent melted section within the powder bed, the section of the melted zone within the substrate and the consolidation section within the powder bed. Some of these calculated data are not measurable and usefully contribute to a consolidation model of the powder bed. This model takes into account the material exchanges observed between so-called bare zones (linked to the ejection of powder particles) and consolidation zones. Quantification of these particles exchanges, which have a strong impact on the LBM of these oxide ceramics, allows the definition of a specific manufacturing strategy that compensates for the bare zone formation while avoiding the formation of hot spots. These data collection enables the manufacturing of LBM ceramic oxide parts with reduced porosity and controlled micro-cracking
Wang, Xifan [Verfasser], Aleksander [Akademischer Betreuer] Gurlo, Aleksander [Gutachter] Gurlo, and Paolo [Gutachter] Colombo. "Photoinduced thiol-ene click chemistry assisted additive manufacturing and freeze casting of polymer-derived ceramics / Xifan Wang ; Gutachter: Aleksander Gurlo, Paolo Colombo ; Betreuer: Aleksander Gurlo." Berlin : Universitätsverlag der TU Berlin, 2019. http://d-nb.info/1196200122/34.
Повний текст джерелаVry, Sébastien. "Elaboration de céramiques hautes performances par voie polymère précéramique - Mise en forme par fabrication additive de type Digital Light Processing." Thesis, Université Grenoble Alpes, 2021. http://www.theses.fr/2021GRALI024.
Повний текст джерелаAdditive manufacturing technologies currently offer the opportunity to achieve complex geometries for a relatively wide material range, from polymers to metals, as well as for certain ceramics. The commercial offer of structural materials is still limited by technological obstacles generally associated with the compatibility between the forming process and the targetted material. In this thesis, a new way of study, still little explored in the literature, concerns the additive manufacturing by Digital Light Processing (DLP) of silicon carbide (SiC) ceramic, from preceramic polymers. In fact, the use of a SiC powder into a photosensitive formulation has limits in terms of charge rate, linked to the optical compatibility between this powder and the UV wavelength used during the layer-by-layer shaping. The use of polymers converting into ceramic, with suitable heat treatments, brings the possibility of improving the compatibility of the constituents at the working wavelength and allows the production of a ceramic of the SiC type. Two commercial preceramic polymers (a polysiloxane and a polycarbosilane) were selected and cross-linked at 200 ° C, followed by a pyrolysis treatment between 1000 and 1700 ° C, under argon. The microstructural changes, chemical compositions, as well as mechanical properties were studied. It appears that these polymer materials can be converted into polycrystalline SiC ceramic, with a residual carbon-rich secondary phase. Photopolymerizable formulations under UV exposure, containing a high load of preceramic polymer (from 25 to 75 wt.%), have been developed and studied in order to be able to shape a green object by DLP, which will then be converted into ceramic by heat treatment. Before additively manufacture parts, the reactivity of these formulations was characterized by varying the proportions of the constituents, including the initiator system and the incorporation of a UV photoabsorbent. The characterization of these formulations was mainly carried out by measuring the thickness of a monolayer polymerized under UV exposure, as well as by characterizing the photopolymerization kinetics by real time infrared spectroscopy. Finally, green parts were produced by DLP and were converted into ceramics and their mechanical properties and geometric integrity were characterized
Fan, Nai-Chung, and 范乃中. "Synthesis and Application of Ceramic Feedstocks for Additive Manufacturing." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/84976618719507644884.
Повний текст джерела國立臺灣大學
材料科學與工程學研究所
104
This research used previous formulation technique of ceramic/polymers, selecting two Al2O3 powders (α- and θ-Al2O3), kneading of several polymers with the ceramic powder, and extruding to produce various feedstocks of wire shape, which was used for 3D additive manufacturing, also known as 3D-printing (3DP). Four tasks were completed. First, the formulation of the feedstocks was conducted using PP as the major binder, replaced with some fractions of EVA, to improve the flexibility of the wires and reduce the chance of the fracture of the wire during 3D printing. The compatibility of PP and EVA was also investigated by grafting maleic acid (MA) on PP chain to reduce polarity difference between PP and EVA. The third task was to study the dispersion condition of the alumina powder in the feedstocks, and quantitatively investigated the influence by kneading sequences, solid content, and other processing parameters. After optimizing the processing conditions, the alumina parts could be densified to a density better than 97% theoretical density (T.D.). Finally, θ-Al2O3 feedstock was used to produce porous catalyst support. Ni-CeO2 nano-particles were evenly coated on the Al2O3 support, used to reform syngas. The CH4 in the syngas, which was gasified from biomass, was reformed to a content less than 1.0 vol% in optimized conditions.
Lee, I.-Chieh, and 李意婕. "Characterization of Ceramic Phononic Crystals Prepared with Additive Manufacturing." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/8g2dzd.
Повний текст джерела國立臺北科技大學
製造科技研究所
106
Phononic crystals (PC) are composed of two or more elastic materials arranged periodically. One of the important characteristics of PC is band gap within that frequency range elastic waves are not allowed to transmit. With the band gap, applications of PC include filters for body waves or surface acoustic waves. In recent years, additive manufacturing technique are widely employed to fabricate objects with complicated geometries like PC. In this study, ceramic PC samples are fabricated with additive manufacturing technique. Finite element analysis (FEA) is employed to predict band gaps of PC fabricated with traditional subtracted marching and the newly additive manufacturing technique. Experimental measurements with pulsed ultrasound technique together with fast Fourier Transform (FFT) and tone-bust frequency scanning are employed to measure band gaps. In general, measurement results agree well with the FEA results. Results of the research suggest a new PC fabrication method based on additive manufacturing technique.
Jheng, Yu-Ci, and 鄭郁騏. "Study on automation of Additive Manufacturing Apparatus for Ceramic Components." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/azh8ym.
Повний текст джерела國立臺北科技大學
機電整合研究所
102
Although galvanometer scanner possesses the advantages of fast scanning, the additive manufacturing equipment with a stationary galvanometer scanner can not build the large components is due to the limited working area and less capability of fabricating different component simultaneously. Furthermore, high cost is one of the shortcomings of the galvanometer scanner. Therefore, the aim of this paper is that designing the automation control system for a ceramic slurry-base rapid prototyping apparatus with the X-Y scanning mechanism to make up the deficiency of the galvanometer scanner. A rapid prototyping apparatus is constituted with a laser scanning system and layer coating system. The laser scanning system is based on the X-Y planar scanning, which uses a PC-Based Control Card [MC8141P (M)] with function of 4-axis interpolation, and a 4- axis motion control card [(PMC2)], to control the laser scanning systems and layer coating systems. By setting the parameters through the human –machine- interface, the commands are transmitted to the corresponding devices of the scanning system and coating system via a control panel to carry out the required motion. The laser scanning system is consisted of a 30 W CO2 laser, an optical system, and a X-Y mechanism driven by linear motion screw with two servo motors. The coating system is consisted of a elevating platform moved with a wedge assembly which is driven by a stepper motor to, a slurry feeding device, a coater and a coater cleaning device. In addition, the control panel includes a power supply system and a control signal panel systems. The power supply system supplies the require power. It includes no fuse breakers, power converters, etc. The control signal system will transmit control signals to the servo motor and stepping motor drivers, and feedback the signals to the servo motor control card. Through the human-machine-interface programmed with Microsoft VisualC + +2010, the X-Y scanning mechanism was verified by 2D patterns scanning. Eventually, 3D components were fabricated to verify the function of automation. The experimental results reveal that the constant lowing distance of the elevating platform can be achieved with the wedge mechanism driven by the stepping motor. By calculating the required slurry volume, the coating systems can obtain layers with good quality. The X-Y scanning mechanism not only can scan a larger area but also can achieve the component with high precision. After integrating the laser scanning systems and coating systems, the 3D parts can be built automatically through setting the parameters with the human-machine-interface.
Huang, Wei-Song, and 黃偉菘. "Study on Applying Laser Beam Shaper in Ceramic Additive Manufacturing." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/8y6y72.
Повний текст джерела國立臺北科技大學
機電整合研究所
104
Ceramic additive manufacturing is one of rapid prototyping technologies that can quickly create ceramic components. Previous processes used CO2 laser; the beam energy distribution is the Gaussian distribution. The profile of linear depth of the scanning corresponds to the Gaussian distribution. Due to the energy is concentrated at the center of the laser beam, the scanning depth reveals that the depth at both sides is smaller than that at the center. The scanning layer should be built with adjacent scanning lines with appropriate overlap. Therefore, a high linear overlap is necessary. However, the linear overlap will affect the time-taken of building a scanning layer. The aim of this study is to improve the building rate of the component with decreasing the useless energy to reduce the linear overlap. Eventually, the specimens was fabricated to verify the improvement. Firstly, the mechanism of the existing apparatus and control hardware and software were modified to achieve automatic fabrication. Secondly, transforming laser beam energy distribution from Gaussian distribution to Top-Hat type distribution by using beam shaper to obtain a wider scanning width, the linear overlap then can be reduced. The appropriate parameters for specimens fabrication can be obtained with adjusting the relative laser parameter, such as laser power, scanning speed, scanning hatch. Finally, the building rate was evaluated by specimens fabrication. The results revealed that, building rate of beam shaper isnt better than without beam shaper, when building small workpiece. However, according to the reasoning of results, building rate will significant increase when building large workpiece or increase laser power by using beam shaper.
Pai, Raikar Piyush Shrihari. "Extrusion Based Ceramic 3D Printing - Printer Development, Part Characterization, and Model-Based Systems Engineering Analysis." Thesis, 2020. http://hdl.handle.net/1805/24752.
Повний текст джерелаCeramics have been extensively used in aerospace, automotive, medical, and energy industries due to their unique combination of mechanical, thermal, and chemical properties. The objective of this thesis is to develop an extrusion based ceramic 3D printing process to digitally produce a casting mold. To achieve the objective, an in-house designed ceramic 3D printer was developed by converting a filament based plastic 3D printer. For mold making applications, zircon was selected because it is an ultra-high temperature ceramic with high toughness and good refractory properties. Additionally, alumina, bioglass, and zirconia slurries were formulated and used as the feedstock material for the ceramic 3D printer. The developed 3D printing system was used to demonstrate successful printing of special feature parts such as thin-walled high aspect ratio structures and biomimetically inspired complex structures. Also, proof of concept with regard to the application of 3D printing for producing zircon molds and casting of metal parts was also successfully demonstrated. To characterize the printed parts, microhardness test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were conducted. The zircon samples showed an increase in hardness value with an initial increase in heat treatment temperature followed by a drop due to the development of porosity in the microstructure, caused by the decomposition of the binder. The peak hardness value for zircon was observed to be 101±10 HV0.2. Similarly, the microhardness values of the other 3D printed ceramic specimens were observed to increase from 37±3 to 112±5 HV0.2 for alumina, 23±5 to 35±1 HV0.2 for bioglass, and 22±5 to 31±3 HV0.2 for zirconia, before and after the heat-treatment process, respectively. Finally, a system model for the ceramic 3D printing system was developed through the application of the model-based systems engineering (MBSE) approach using the MagicGrid framework. Through the system engineering effort, a logical level solution architecture was modeled, which captured the different system requirements, the system behaviors, and the system functionalities. Also, a traceability matrix for the system from a very abstract logical level to the definition of physical requirements for the subsystems was demonstrated.
Tsai, Jhih-Fong, and 蔡桎峰. "Study on the Feasibility of a New Additive Manufacturing Process and Apparatus for Fabricating Large-Scale Ceramic Components." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/n937sx.
Повний текст джерела國立臺北科技大學
製造科技研究所
104
Ceramic laser sintering (CLS) uses ceramic slurry to fabricate components. The green part is built in a green block after layer casting and selective laser sintering layer by layer. The inherent support is then removed by solution. Because diameter of laser beam is too small, laser scanning is time consuming when building a large component , so the building rate is poor. Study the feasibility of a new process with a modified device to fabricate the large-scale ceramic component is the aim of this research. Based on the process of 3DP, the binder which contains Polyvinyl alcohol (PVA) and phenolic resin, was selective sprayed on the green layer by a nozzle. A green block that contains green part was built after stacking the layers. Outside the sprayed area, the material played as the inherent supporting to support the component with overhang. A part of the existing rapid prototyping apparatus was modified to include the function of binder dispensing. The modified apparatus was employed to selectively spray binder layer by layer. After drying with heat, the green block was then be immersed in the solution. The workpiece was obtained when the supporting which surrounds the workpiece was collapsed. Experimental results revealed that the process is feasible. The workpiece can be completely built up and take out from the green block successfully. However, many details of the new process have to be improved and are worthy to be studied in the future.
(9741065), Piyush Shrihari Pai Raikar. "EXTRUSION BASED CERAMIC 3D PRINTING - PRINTER DEVELOPMENT, PART CHARACTERIZATION, AND MODEL-BASED SYSTEMS ENGINEERING ANALYSIS." Thesis, 2021.
Знайти повний текст джерелаCeramics have been extensively used in aerospace, automotive, medical, and energy industries due to their unique combination of mechanical, thermal, and chemical properties. The objective of this thesis is to develop an extrusion based ceramic 3D printing process to digitally produce a casting mold. To achieve the objective, an in-house designed ceramic 3D printer was developed by converting a filament based plastic 3D printer. For mold making applications, zircon was selected because it is an ultra-high temperature ceramic with high toughness and good refractory properties. Additionally, alumina, bioglass, and zirconia slurries were formulated and used as the feedstock material for the ceramic 3D printer.
The developed 3D printing system was used to demonstrate successful printing of special feature parts such as thin-walled high aspect ratio structures and biomimetically inspired complex structures. Also, proof of concept with regard to the application of 3D printing for producing zircon molds and casting of metal parts was also successfully demonstrated.
To characterize the printed parts, microhardness test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were conducted. The zircon samples showed an increase in hardness value with an initial increase in heat treatment temperature followed by a drop due to the development of porosity in the microstructure, caused by the decomposition of the binder. The peak hardness value for zircon was observed to be 101±10 HV0.2. Similarly, the microhardness values of the other 3D printed ceramic specimens were observed to increase from 37±3 to 112±5 HV0.2 for alumina, 23±5 to 35±1 HV0.2 for bioglass, and 22±5 to 31±3 HV0.2 for zirconia, before and after the heat-treatment process, respectively.
Finally, a system model for the ceramic 3D printing system was developed through the application of the model-based systems engineering (MBSE) approach using the MagicGrid framework. Through the system engineering effort, a logical level solution architecture was modeled, which captured the different system requirements, the system behaviors, and the system functionalities. Also, a traceability matrix for the system from a very abstract logical level to the definition of physical requirements for the subsystems was demonstrated.
Lopes, Filipa Daniela Pereira. "Processamento de pastas de alumina por robocasting." Master's thesis, 2018. http://hdl.handle.net/10316/86607.
Повний текст джерелаO interesse na impressão 3D tem crescido gradualmente de dia para dia, permitindo quer a otimização de muitos processos produtivos, quer a produção de peças com uma geometria cada vez mais complexa num menor espaço de tempo e, em alguns casos, com menores custos. Ao longo dos últimos anos, tem-se observado o desenvolvimento de novas técnicas de impressão 3D ou a otimização das técnicas já existentes. Assim, nesta dissertação pretende-se adaptar uma técnica já existente – robocasting – à produção de peças em alumina.Sendo a alumina um cerâmico técnico com boas propriedades (isolamento, funções químicas e resistência mecânica), neste estudo avalia-se a sua adequabilidade para o processo de impressão e as propriedades do material e das peças finais obtidas por este processo de conformação. Com base na bibliografia encontrada, optou-se por realizar um estudo com várias formulações agrupadas em dois sistemas (S e Z), associados aos diferentes aditivos usados, e com pós de duas granulometrias (0,4 μm e 4 μm). No sistema S elaboraram-se pastas de alumina com os aditivos: sacarose, álcool polivinílico e ácido oleico, enquanto que no sistema Z, as pastas foram preparadas com os aditivos: Zusoplast C92, Zusoplast 126/3, sacarose e ácido cítrico.Para estudar a adequabilidade das pastas elaboradas, avaliaram-se a humidade, a carga de sólidos, o comportamento reológico, a plasticidade, a adesão a superfícies, a dureza e a propensão para o envelhecimento. Por sua vez, para a caracterização dos materiais sinterizados obtidos, optou-se por avaliar a densificação (através da determinação das massas volúmicas e porosidades), a resistência mecânica e observação da sua estrutura interna por microscopia.Verificou-se que pastas adequadas para a impressão têm gamas muito restritas de propriedades, de forma a permitirem a impressão com boa adesão à plataforma e à manutenção da forma da peça durante a impressão. Além disso, verificou-se que a impressora não tem capacidade para imprimir pastas com viscosidades muito elevadas; pastas que apresentem uma viscosidade aparente de 6000 Pa.s a uma taxa de corte de 0,5 s-1 já oferecem muitas dificuldades para impressão às pressões utilizadas (até 7 bar).Ao nível das peças sinterizadas, observou-se que as características obtidas dependem essencialmente da capacidade de união entre os filamentos durante a impressão e da capacidade do pó cerâmico para densificar durante o tratamento térmico. A união dos filamentos é influenciada não só pelos aditivos usados, mas também pelos parâmetros da impressora, sendo que se deve garantir o esmagamento perfeito entre filamentos, nem insuficiente nem excessivo, de forma a evitar a existência de espaços vazios que dificultem a densificação ou a ocorrência de defeitos de forma, respetivamente. Por outro lado, verificou-se que a alumina mais fina permite alcançar densificações maiores e com maior crescimento de grão. Foi ainda possível observar que determinados aditivos podem promover a densificação, verificando-se que a utilização do Zusoplast C92 permite maior ligação entre partículas, originando peças mais densificadas. Os melhores resultados foram obtidos com duas das formulações, uma do sistema S e outra do sistema Z. A do sistema S – 9,9%(m/m) de sacarose, 0,4%(m/m) de álcool polivinílico e 2,0%(m/m) de ácido oleico – permitiu as melhores impressões, graças à sua menor viscosidade, sem que tal não comprometesse demasiado as propriedades finais das peças. A do sistema Z – 0,1%(m/m) de Zusoplast C92, 0,7%(m/m) de Zusoplast 126/3, 4,9%(m/m) de sacarose e 0,1%(m/m) de ácido cítrico, com a qual se alcançou as melhores densificações (Pt≈6%) e resistências (σfs≈150 MPa), tendo, no entanto, apresentado algumas dificuldades de impressão a baixas pressões.
The interest in the 3D printing has been growing every day, allowing not only the optimization of fabrication procedures but also the production of objects with a more complex geometry in less time and sometimes with less costs. In the last years, it was seen the development of new 3D printing technologies or the optimization of the ones that exist. In this way, the purpose of this dissertation is to adapt one of the existent technologies – robocasting – to the production of alumina objects.Being alumina a technical ceramic with good properties (isolation, chemical inertia and mechanical strength/hardness), this study aims to evaluate the printability of the ceramic body and the properties of the material and the final objects designed by this conformation process. According to the literature, different formulations were studied, grouped in two systems (S and Z), associating different additives, and alumina powders, with two different particle sizes (0,4 μm e 4 μm). For system S, the following additives were used: sucrose, polyvinyl alcohol and oleic acid, on the other hand, in system Z, the ceramic bodies were formulated with the additives: Zusoplast C92, Zusoplast 126/3, sucrose and citric acid. In order to analyse the suitability of the ceramic bodies, their humidity, solids content, rheological behaviour, plasticity, surface adhesion, rigidity and aging were evaluated. For the sintered objects characterization, the densification (through the density and porosity), the mechanical strength and internal structure (SEM) were assessed.It was verified that a good ceramic body for printing should fit a small range of properties, in order to allow a good surface adhesion and the shape maintenance during the printing process. Besides that, it was concluded that the 3D printer doesn’t work well with high viscosities; apparent viscosities above 6000 Pa.s at a shear strain of 0,5 s-1 induce printing difficulties at the allowed pressures (7 bar).The final characteristics of the sintered objects depended essentially on the filaments bonding during the printing process and on the capacity of the ceramic powder to densify during the sintering. The filaments bonding is not just influenced by the used additives but also by the 3D printer parameters, that must ensure the perfect crush between filaments, neither insufficient nor excessive, in order to avoid empty spaces that interfere in the densification or the occurrence of shape imperfections in the objects, respectively. On the other hand, it was verified that the alumina with smaller particle size allows higher densifications and grain growth. It was still possible to observe that some additives could enhance the densification, for example the utilization of Zusoplast C92 allows better bonding between the particles, producing more dense objects.The best results were obtained with two formulations, one of the system S and the other of the system Z. For the system S, the formulation with 9,9%wt of sucrose, 0,4%wt of polyvinyl alcohol and 2,0%wt of oleic acid provide the best printing, for its lower viscosity, without compromising too much the properties of the final objects. The one of the system Z, with 0,1%wt of Zusoplast C92, 0,7%wt of Zusoplast 126/3, 4,9%wt of sucrose and 0,1%wt of citric acid, achieved the best densification (Pt≈6%) and mechanical strength (σfs≈150 MPa), leading however to some difficulties during the printing at a low pressure (7 bar).
(8787950), William J. Costakis. "The Control of Microstructural and Crystallographic Orientation via Ceramic Forming Methods for Improved Sintered Transparency." Thesis, 2020.
Знайти повний текст джерелаTransparent alumina is a candidate material for ballistic applications where visible or infrared wavelength transmission is required. However, the transparency of polycrystalline alumina can be limited due to the rhombohedral crystal structure being inherently birefringent. Birefringence causes light scattering at grain boundaries and is detrimental to the transparency. It has been shown experimentally that the application of a high magnetic field during processing can lead to crystallographic alignment and the reduction of birefringent light scattering. This alignment method is effective but is limited in terms of scalability. This research addresses these limitations through the use of simple and cost-effective shear and elongational forming processes such as uniaxial warm pressing and direct ink writing (DIW) for the improvement of final sintered transparency. To further support the improvement of these processes as alternatives and to evaluate the possibility of using powder ratios to improve the alignment, this research will also investigate the sintering behavior during hot-pressing of equiaxed and platelet powders.
Platelet ceramic-filled thermoplastic blends were developed and formed into sheets through uniaxial warm pressing. The solids loading (30 – 40 vol.%) and platelet diameter (1.2 and 11μm) were varied to compare effects on viscosity, percent reduction, and final alignment. All ceramic- filled thermoplastic polymer blends exhibited pseudoplastic behavior. Crystallographic alignment of green body samples was quantified by the orientation parameter (r) and grain misalignment angle (full width at half maximum, FWHM) obtained from rocking curve analysis. Blends with 11μm diameter platelets displayed a higher temperature sensitivity constant, better flow properties, and higher alignment compared to blends with 1.2μm diameter platelets. Optimal samples produced with blends containing 30 vol.% of 11μm diameter platelets demonstrated an alignment of r = 0.251 +/- 0.017; FWHM = 11.16° +/- 1.16°. A sample with optimal alignment was hot-pressed to transparency and obtained an in-line transmission of 70.0% at 645nm. The final alignment of this pre-aligned hot-pressed sample (r = 0.254 +/- 0.008; FWHM = 11.38° +/- 0.54°) improved when compared to a non-pre-aligned sample (r = 0.283 +/- 0.005; FWHM = 13.40° +/- 0.38°).
Additionally, the use of direct ink writing, an additive manufacturing technique, as a viable alignment process for producing transparent alumina was investigated. Highly loaded (> 54 vol.%) equiaxed alumina suspensions were developed with platelet additions ranging from 0-20vol.% of the total solids loading. An increase in the amount of platelet powders from 5-20vol.% increased the dynamic yield stress from 104Pa to 169Pa and decreased in the equilibrium storage modulus from 17,036Pa to 13,816Pa. It was found that the DIW process significantly increased the alignment in one orientation when compared to samples cast from the same suspensions and this behavior may be connected to the rheological properties. Lastly, an optical analysis showed that sample developed with 5vol.% platelet suspensions had higher in-line transmission values across the visible spectrum when compared to samples developed with 20vol.% suspensions. A sample cast from a 5vol.% platelet suspensions had the lowest grain alignment but possessed an in-line transmission of 42.8% at 645nm, which was the highest of the samples produced in this study. An optical loss analysis showed, that this sample has the lowest backwards scattering losses due to residual porosity and this result was supported by the density data. It is suggested that the alignment of the DIW samples is more complex and a more advanced texture analysis will need to be conducted to properly characterize the grain alignment.
Lastly, the densification behavior of equiaxed and platelet powder ratios with no intentional pre-alignment was investigated. An initial sintering investigation identified the optimum maximum pressure selected for the hot-pressing process as 20MPa. Under the selected hot- pressing parameters, the effects of 0, 25, 50, 75, and 100wt.% equiaxed powder additions on the sintering behavior, optical properties, and grain alignment was investigated. The data showed that an increase in the amount of equiaxed powders decreased the initial powder compact displacements rate. Additionally, an increase in the wt.% equiaxed powders from 0wt% to 75wt% decreases the in-line transmission from 70.9% to 40.2%, respectively at 645nm. Lastly, an increase in the wt.% equiaxed powders from 0wt% to 75wt decreased the alignment from (r = 0.321 +/- 0.005; FWHM = 16.26° +/- 0.40°) to (r = 0.509 +/- 0.022; FWHM = 34.63° +/- 2.61°), respectively.
"Novel Materials and Processing Routes Using Alkali-activated Systems." Doctoral diss., 2019. http://hdl.handle.net/2286/R.I.54957.
Повний текст джерелаDissertation/Thesis
Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2019
Reis, Daniela Silva. "Processamento avançado de materiais cerâmicos: Aplicação de alumina em robocasting." Master's thesis, 2017. http://hdl.handle.net/10316/83013.
Повний текст джерелаThe present work is framed in the field of additive manufacturing, also known as 3D printing. The Robocasting technology, employed in this work, is one of the categories of additive manufacturing. It allows the processing of several types of materials, giving rise to a wide variety of items with complex geometries.The aim of this dissertation is to develop pastes of Al2O3 to apply in a Robocasting printer, the Wasp Extruder, in order to enable the printing of ceramic pieces at room temperature. The formulations are based on the cold mixture of a solvent, additives and the inorganic powder, being the final purpose the building of ceramic items with good properties, comparable to other objects produced by different AM technologies.Two different types of alumina pastes were selected to be studied. In the pastes of the 1st type, two different types of aluminium oxide with distinct particle size (D50 ≈ 4 µm and 0,7 µm) were tested. Either Zuzoplast C92 or arabic gum were used as a binder and the influence of a lubricant, glycerin, on the pastes was also tested. Water was always used as the solvent.For the 2nd type of pastes, only one type of aluminium oxide was used and water was kept as solvent. The major difference between this type of paste and the previous one is that, in this case, two binders, PVA and powdered sugar, were used in the same formulation. Moreover, an additional additive was used, oleic acid, with high affinity to alumina.The analysis of the rheological behaviour of the alumina pastes was carried out in a capillary rheometer (Thermo Haake Rheoflixer HT). A predominance of the pseudoplastic behaviour (where the viscosity decreases as the shear rate increases) was observed in the two types of formulations analysed. The viscosity increases as the particle size of the inorganic powder decreases. Several properties of sintered samples obtained from these two types of pastes were evaluated, with regard to their density, porosity and mechanical bending strength. Concerning the densification of the fabricated items, it is observed that the finest particles lead to a higher degree of packing, resulting in denser and less porous pieces. The values of the bending strength still are far from those that can be expected for the two types of pastes here studied.After characterizing the best pastes, these were tested in the Robocasting printer. Based on the results, it was observed that the best formulation for printing belongs to the 2nd type of paste. Notably, in spite of presenting good properties for application in the 3D printer, it gives rise to pieces with worse mechanical properties than the pastes of the 1st type.One of the aims of this work was achieved, the printing of Al2O3 pastes in the Robocasting printer. However, the pieces that were built do not exhibit yet the desired properties, namely in terms of densification level and strength. Therefore, further work will be needed for the optimization of conditions and tuning of formulations to achieve improved properties of the sintered items.
O presente trabalho insere-se na temática da fabricação aditiva ou também denominada de impressão 3D. A tecnologia robocasting está contida numa das categorias de fabricação aditiva e apresenta-se capaz de processar diferentes tipos de materiais e de originar uma ampla variedade de peças com geometrias complexas. Esta é a tecnologia usada no presente trabalho.O objetivo desta dissertação passa por desenvolver pastas em Al2O3 para aplicação numa impressora robocasting, a WASP Extruder, de maneira a que seja possível imprimir peças cerâmicas à temperatura ambiente. Estas formulações baseiam-se na mistura a frio de um solvente, aditivos e de um pó inorgânico, e deseja-se construir peças com boas propriedades, podendo ser comparadas com outros objetos originados por diferentes tecnologias AM.De acordo com o estudo prévio realizado optou-se por estudar dois tipos de pastas de alumina.Nas pastas do 1º tipo foram experimentados dois tipos de óxidos de alumínio com granulometrias distintas (D50 ≈ 4 µm e 0,7 µm). Como ligantes usou-se o Zuzoplast C92 ou a goma arábica, testando ainda a influência de um lubrificante nas pastas, a glicerina. Como solvente usou-se a água.Para o segundo tipo de pastas formuladas aplica-se apenas um tipo de óxido de alumínio, mantendo-se a água enquanto solvente. A grande distinção ente este tipo de pastas e o anterior é que, neste caso, são usados dois ligantes na mesma formulação, o PVA e o açúcar em pó, bem como um aditivo adicional, o ácido oleico, caracterizado pela sua grande afinidade com o pó inorgânico, alumina.Um dos principais pontos estudados nas formulações prende-se com a análise do comportamento reológico, tendo-se usado um reómetro capilar (Thermo Haake Rheoflixer HT). Verificou-se que o comportamento pseudoplástico (onde a viscosidade diminui com o aumento da taxa de corte) predomina entre os dois tipos de formulações analisadas. A viscosidade é tanto maior quanto menor a granulometria do pó inorgânico.Avaliaram-se ainda várias propriedades de provetes sinterizados obtidos com estes dois tipos de pastas, ao nível das massas volúmicas, porosidades e resistência mecânica à flexão. Relativamente à densificação das peças, verifica-se que as partículas mais finas conduzem a um maior grau de empacotamento, resultando peças mais densas e menos porosas. Os valores relativos às resistências à flexão alcançados ficam ainda muito aquém do espectável para ambos os tipos de pastas analisadas.Depois de caracterizadas as melhores pastas, testam-se na impressora robocasting. Com base nos resultados, verifica-se que a melhor formulação para impressão resulta do 2º tipo de pastas estudadas (Al1_PVA_A12). É de notar que apesar de apresentar boas propriedades para aplicação na impressora 3D, gera peças com piores propriedades mecânicas que as pastas do 1º tipo.Um dos objetivos do trabalho foi atingido, a impressão de Al2O3 em robocasting. No entanto, as peças construídas não possuem as propriedades desejadas, quer ao nível de densificação, quer ao nível da resistência, havendo ainda um longo caminho a percorrer.
Silva, António Miguel Rocha Raimundo. "Additive manufacturing of technical ceramics." Master's thesis, 2019. http://hdl.handle.net/10400.8/4021.
Повний текст джерелаMoreira, João Pedro Oliveira. "Fabrico aditivo cerâmico em arquitetura: metodologia computacional para definição de um sistema de colunas." Master's thesis, 2018. http://hdl.handle.net/1822/58352.
Повний текст джерелаNos dias de hoje não vemos apenas o processo de desenho em arquitetura mediado por ferramentas digitais, assistimos cada vez mais à experimentação e disseminação deste tipo de recursos em todos os estágios da construção, desde a concepção até à manufatura. Neste contexto, a associação de material cerâmico a fabrico aditivo representa, para a arquitetura, uma ampliação daquilo que é possível explorar através deste método e assim, devido às características do material, cria-se a possibilidade de explorar novas ideias e conceitos. O uso combinado de desenho computacional e fabrico digital em arquitetura apresenta um enorme potencial para melhorar e introduzir inovações ao desenho arquitetónico e ao ambiente construído. A associação destas ferramentas, permite não só explorar a produção em série de elementos singulares e personalizáveis, expandindo as potencialidades das técnicas tradicionais, mas também analisar determinados pressupostos, e com base neles, identificar a solução que melhor consegue atender a uma situação específica. A presente investigação procura avaliar a integração destas ferramentas digitais em arquitetura, incidindo especificamente sobre questões relacionadas com a produção de elementos estruturais personalizados, que se definem através de relações paramétricas de inspiração biomórfica, com recurso a fabrico aditivo cerâmico. Neste sentido, o caso de estudo procura desenvolver um sistema de componentes estruturais — um sistema de colunas — reticulados, personalizados e otimizados, com base em pressupostos definidos previamente. O processo de definição deste sistema é mediado por desenho computacional, implementando não só estratégias de análise e otimização estrutural, mas também características formais miméticas da natureza, criando um modelo que adapta os seus atributos formais, consoante os seus pressupostos e as restrições do material, resultando na definição de um conjunto de soluções que respondem ao problema de projeto proposto.
Nowadays, we not only see the design process in architecture mediated by digital tools, we also are increasingly witnessing the experimentation and dissemination of this type of resources at every stage of construction, from design to manufacturing. In this context, the association of ceramic material to additive manufacturing represents, for architecture, an extension of what can be exploited through this method, and thus, due to the characteristics of the material, it is possible to explore new ideas and concepts. The combined use of computational design and digital manufacturing in architecture presents an enormous potential to improve and introduce innovations in architectural design and the built environment. The association of these tools allows not only to explore the concept of standardized production of unique and customizable elements, expanding the potential of traditional techniques, but also allows an analysis of certain assumptions and, based on them, identify the solution that can best meet a specific situation. The present research aims to evaluate the integration of these digital tools in architecture, focusing specifically on issues related to the production of customized structural elements, which are defined through parametric relationships of biomorphic inspiration, using additive ceramic manufacturing. In this sense, the case study seeks to develop a system of reticulated, customized and optimized structural components, — a column system — based on previously defined assumptions. The process of defining this system is mediated by computational design, implementing not only structural and optimization analysis strategies, but also mimetic formal features of nature, creating a model that adapts its formal attributes, depending on its assumptions and the material constraints, resulting in the definition of a set of solutions that respond to the proposed design problem.
Carvalho, João António Nogueira. "Cerâmica 3D: sistemas digitais para a personalização do desenho e fabrico de componentes arquitetónicos." Master's thesis, 2018. http://hdl.handle.net/1822/54710.
Повний текст джерелаO surgimento e disseminação de tecnologias de fabrico aditivo, nomeadamente de impressão tridimensional, contribui para uma mudança de paradigma no processo de conceção e construção do projeto ao permitir que estas duas fases tradicionalmente autónomas se aproximem. Recentemente, tal como muitos outros materiais, a aplicação de cerâmica em tecnologias de fabrico digital expandiu consideravelmente os limites formais, performativos e funcionais que os elementos cerâmicos podem aportar para o contexto da construção e arquitetura. À implementação de processos de fabrico aditivo para a conceção de componentes arquitetónicos, associa-se ainda a possibilidade de produção em série de sistema personalizáveis. Graças a esta tecnologia, e com a integração de processos de desenho paramétrico, na conceção do projeto são criados sistemas que formulam várias soluções, selecionando aquela que melhor responde às necessidades do problema. Deste modo o desenvolvimento de componentes arquitetónicos cerâmicos poderá beneficiar destes dois fatores tendo em vista dar respostas a contextos específicos e objetivos multidisciplinares. Focando-se no desenho e produção de componentes arquitetónicos cerâmicos totalmente personalizados, esta investigação estuda os principais desafios que a integração de ferramentas de desenho e fabrico digital têm na prática da arquitetura. Com base em blocos hexagonais o principal caso de estudo da investigação consiste no desenvolvimento de um sistema de cobertura em abóbada que pretende auxiliar ao controlo da incidência solar. Esta otimização dá-se através da variação geométrica da estrutura interna dos blocos. O processo de projeto é mediado por um modelo paramétrico, considerando os dados climatéricos do local, resultando num sistema que adapta a geometria interna de cada um dos blocos em função da sua posição no conjunto, tornando-os mais ou menos permeáveis dependendo da relação espaço/tempo que se pretende sombrear.
The emergence and dissemination of additive manufacturing technologies, namely three-dimensional printing, contributes to a paradigm shift in the process of project design and construction by allowing these two traditionally autonomous phases to approach. Recently, like many other materials, the application of ceramics to digital manufacturing technologies has considerably expanded the formal, performative, and functional limits that ceramic elements can bring to the context of construction and architecture. The implementation of additive manufacturing processes for the design of architectural components also associates the possibility of serial production of customizable systems. Thanks to this technology, and with the integration of parametric design processes, in the design of the project are created systems that formulate various solutions, helping to select the one that best meets the needs of the problem. In this way the development of ceramic architectural components can benefit from these two factors in order to respond to specific contexts and multidisciplinary objectives. Focusing on the design and production of fully customized ceramic architectural components, this research studies the main challenges that the integration of digital design and manufacturing tools have in architectural practice. Based on hexagonal blocks, the main research case is the development of a dome cover system that aims to help control the solar incidence. This optimization takes place through the geometric variation of the internal structure of the blocks. The design process is mediated by a parametric model, taking into account the climacteric data of the site, resulting in a system that adapts the internal geometry of each one of the blocks by their position in the set, making them more or less permeable depending of the space / time ratio that we want to shade.
Vyatskikh, Andrey. "Additive Manufacturing of 3D Nano-Architected Metals and Ceramics." Thesis, 2020. https://thesis.library.caltech.edu/13722/12/Thesis%20Draft_v1.3.pdf.
Повний текст джерелаAdditive manufacturing (AM) represents a set of manufacturing processes that create complex 3D parts out of polymers, metals, and ceramics. AM of metals and ceramics is widely used to produce parts for aerospace, automotive, and medical applications. At the micro- and nano-scales, AM is poised to become the enabling technology for efficient 3D microelectromechanical systems (MEMS), 3D micro-battery electrodes, 3D electrically small antennae, micro-optical components, and photonics. Today, the minimum feature size for most commercially available metal and ceramic AM is limited to ~20-50 μm. Currently, no established processes can reliably produce complex 3D metal and ceramic parts with sub-micron features.
In this thesis, we first demonstrate a nanoscale metal AM process that can produce ~300 nm features out of nanocrystalline, nanoporous nickel using synthesized hybrid organic-inorganic materials, two-photon lithography, and pyrolysis. We study microstructure and mechanical properties of as-fabricated nickel architectures and compare their structural strength to established AM processes. We then show how this process can be extended to other metals and metalloids, including Mg, Ge, Si, and Ti.
This study extends further into nanoscale AM of transparent, high refractive index materials for micro-optics and photonic crystals. We develop an AM process to 3D print fully dense nanocrystalline rutile titanium dioxide (TiO₂) with feature dimensions down to ~120 nm. We carefully study and model the relationship between feature dimensions and process parameters to achieve a <2% variation in critical dimensions. We then use this understanding of the process to fabricate and study 3D dielectric photonic crystals with a full photonic bandgap in the infrared.
Finally, a microscale AM process of titanium dioxide is demonstrated for photocatalytic water treatment. We show how synthesized hybrid organic-inorganic materials can be applied for stereolithography to print TiO₂ architectures with 100 μm features. We use the developed 3D printing process to investigate the effect of 3D architecture on the efficiency of photocatalytic water treatment.
This work establishes a versatile and efficient pathway to create three-dimensional nano-architected metals and ceramics and to investigate their properties for applications in 3D MEMS, micro-optics, photonics, and photocatalysis.
Ku, Jung-Fan, and 古仲凡. "Study on slurry slot coater in additive manufacturing of ceramics." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/955259.
Повний текст джерела國立臺北科技大學
製造科技研究所
104
Ceramics have many excellent mechanical properties. But the ceramics are hard and brittle, which result in difficulty of forming and fabricating workpiece with complex shape. Ceramic additive manufacturing improves the drawbacks of the existing ceramic manufacturing processes. It can fabricate the complex ceramic components. The existing slurry-based additive manufacturing of ceramic can cast thinner layer than the layer casted with the powder-based processes to improve the step effect. Original slurry coater had the problem of un-uniform slurry distribution. Un-uniform distribution of water containing of the layer lead to the un-uniform time-taken of the layer drying was one of the disadvantages. The aim of this study is to achieve a proper coater to improve the aforementioned disadvantage through studying the relations of viscosity, slot width, distribution angle of the flow channel of the slot coater. Firstly, mold flow simulation was carried out by Flow-3D. The slurry behavior in the slot coater was simulated with related parameters to find the desirable distribution angle of the flow channel. Eventually, based on the experimental results, the physical coaters were fabricated to conduct slurry distribution and casting experiment, to verify simulation results. Experiment data was analyzed by ANOVA to explain the effect of experimental factor. The results revealed that, the simulation results is reliable. The quantitative slurry could be uniformly delivered to the outlet of the coater to achieve a perfect layer by a proper distribution angle obtained by the simulation. The same method can be employed to rapidly construct the coater for different ceramic slurry.