Extrusion-Based Ceramics Printing with Strictly-Continuous Deposition

International audienceWe propose a method for integrated tool path planning and support structuregeneration tailored to the specific constraints of extrusion-based ceramicsprinting. Existing path generation methods for thermoplastic materials relyon transfer moves to navigate between different print paths in a given layer.However, when printing with clay, these transfer moves can lead to severeartifacts and failure. Our method eliminates transfer moves altogether bygenerating deposition paths that are continuous within and across layers.Our algorithm is implemented as a sequential top-down pass through thelayer stack. In each layer, we detect points that require support, connectsupport points and model paths, and optimize the shape of the resultingcontinuous path with respect to length, smoothness, and distance to themodel. For each of these subproblems, we propose dedicated solutions thattake into account the fabrication constraints imposed by printable clay.We evaluate our method on a set of examples with multiple disconnectedcomponents and challenging support requirements. Comparisons to existingpath generation methods designed for thermoplastic materials show that ourmethod substantially improves print quality and often makes the differencebetween success and failure

From rapid prototyping to building in real scale: methodologies for upscaling additive manufacturing in architecture

The manufacture of architectural components mediated by computer-controlled Additive Manufacturing (AM) technologies has highlighted several positive aspects of their application, namely by enabling customised design solutions and high-performance complex geometries. Taking into account the experience of the Advanced Ceramics R&D Lab, in the production of small- / medium- scale prototypes, this paper explores the main variables and constraints of the production of real-scale architectural components. This information points to a set of procedures that should be avoided and others that should be privileged, allowing to anticipate how AM can contribute for the achievement of high performance components on a large scale.This work has the financial support of the Project Lab2PT – Landscapes, Heritage and Territory laboratory – AUR/04509 and FCT through national founds and when applicable of the FEDER cofinancing, in the aim of the new partnership agreement PT2020 and COMPETE2020 – POCI 01 0145FEDER 007528

Revisão sobre manufatura aditiva de materiais cerâmicos por extrusão de massas à base de argilas

This paper aims to present a state of the art of additive manufacturing (AM) of ceramic materials based on extrusion processes of clay pastes, reviewing the definitions and classifications of the AM field under current international standards. A general overview on the AM category ‘material extrusion’ is provided and the class ‘paste deposition modeling’ is proposed for those techniques based on the extrusion of pastes that are solidified by solvent vaporization, with the aim of distinguishing it from the class ‘fused deposition modeling’, which is applied to extruded polymers through temperature plasticization. Based on the survey of background information on 3D printing technology by ceramic paste extrusion, a classification and historization of the innovations in the development of this technology are proposed.O presente trabalho apresenta uma revisão do estado da arte de manufatura aditiva (MA) de materiais cerâmicos baseada nos processos de extrusão de massas à base de argilas, repassando as definições e a classificação do campo de MA de acordo com as normas internacionais. Descreve-se a categoria de MA ‘extrusão de material’ em aspectos gerais e propõe-se a classe ‘modelagem por deposição de pasta’ para as técnicas baseadas em extrusão de massas que solidificam por evaporação do solvente, com o intuito de diferenciar do termo ‘modelagem por deposição de material fundido’, que é utilizado para polímeros extrudados por meio de plastificação a quente. A partir do levantamento dos antecedentes da tecnologia de impressão 3D por extrusão de massas cerâmicas, propõe-se uma classificação e historização das inovações no desenvolvimento desta tecnologia.Fil: Ruscitti, Andrés Federico. Universidad Nacional de Lanús; ArgentinaFil: Tapia, Clara. Universidad Nacional de Lanús; ArgentinaFil: Rendtorff Birrer, Nicolás Maximiliano. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química; Argentin

Micro-extrusion of fine ceramic latticework

PhDMicroextrusion freeforming of ceramic lattices from high solids ceramic pastes is a method for forming complex multi-scale hierarchical porous structures. It has the advantages of low shrinkage stress, high sintered density and environmental compatibility. A user friendly graphical user interface (GUI) was created so that the micro-extrusion freeforming worktable could be made very easy to manipulate even for a beginner. A solvent-based approach to paste preparation for extrusion freeforming was established, involving selection of solvent, polymer and dispersant. The parameters in the process such as solid fraction in the paste, paste viscosity, extrusion rate, X, Y table velocity, filament diameter and the volatilization of the solvent were studied. A substrate material which provided sufficient adhesion to resist shrinkage efficiently and also allowed the extruded lattice to be easily detachable was selected. The extrusion pressure in the alumina paste was monitored and was found to be useful in predicting and optimizing the extrusion behaviour. Hydroxyapatite (HA)/ tricalcium phosphateTCP and alumina lattices were directly fabricated using 80-500 μm diameter filaments. This thesis reports the implementation of design and fabrication of these scaffolds for tissue engineering, band gap materials and micro-fluidic devices. Multi-scale hierarchical void structures were fabricated and tested in vivo for regenerative medical applications. A co-extrusion nozzle assemble was design to produce tubular alumina lattice

Geometric Modeling of Cellular Materials for Additive Manufacturing in Biomedical Field: A Review

Advances in additive manufacturing technologies facilitate the fabrication of cellular materials that have tailored functional characteristics. The application of solid freeform fabrication techniques is especially exploited in designing scaffolds for tissue engineering. In this review, firstly, a classification of cellular materials from a geometric point of view is proposed; then, the main approaches on geometric modeling of cellular materials are discussed. Finally, an investigation on porous scaffolds fabricated by additive manufacturing technologies is pointed out. Perspectives in geometric modeling of scaffolds for tissue engineering are also proposed

DESIGN STRATEGIES AND ADDITIVE MANUFACTURING OF 3D CUSTOMIZED SCAFFOLDS WITH OPTIMIZED PROPERTIES FOR CRANIOFACIAL TISSUE ENGINEERING

3D customized scaffolds for craniofacial tissue engineering were designed using advanced strategies and technologies. Specifically, reverse engineering, additive manufacturing, material selection, experimental and theoretical analyses were properly integrated. The focus was on: i) design strategies of 3D customized nanocomposite scaffolds for hard tissue regeneration; ii) an engineered design of 3D additive manufactured nanocomposite scaffolds with optimized properties; iii) an approach toward the design of 3D customized scaffolds for large cranial defects

Additive Manufacturing of CO2 sorbents for high-temperature Carbon Capture

openLaureando: Tessarolo Marco Titolo tesi: Additive Manufacturing of CO2 sorbents for high-temperature Carbon Capture Corso di Laurea: Ingegneria dei Materiali Relatrice: Franchin Giorgia Thermally activated hydrotalcites display great potential for Carbon Capture processes due to their ability to readily adsorb CO2 at temperatures as high as 300°C. Geopolymers are inorganic binders which couple a facile and low-cost synthesis route with excellent mechanical strength and porosity, making them promising matrix candidates for the immobilisation of active fillers. Various formulations of geopolymer-hydrotalcite composite monoliths with a well-defined macroporous structure were 3D printed through the Direct Ink Writing (DIW) technique, then characterized through compression testing, microscopy, FT-IR spectroscopy, XRD and CO2 adsorption tests. The difficult printing of potassium-based geopolymers required the use of carboxymethylcellulose as a rheological additive, whose removal with an appropriate thermal treatment was investigated to avoid performance loss in application. The composites, after thermal activation at 400°C, show high CO2 uptake which increases together with hydrotalcite content, with a better contribution of the K-based geopolymer matrices compared to their Na-based counterparts.Laureando: Tessarolo Marco Titolo tesi: Additive Manufacturing of CO2 sorbents for high-temperature Carbon Capture Corso di Laurea: Ingegneria dei Materiali Relatrice: Franchin Giorgia Thermally activated hydrotalcites display great potential for Carbon Capture processes due to their ability to readily adsorb CO2 at temperatures as high as 300°C. Geopolymers are inorganic binders which couple a facile and low-cost synthesis route with excellent mechanical strength and porosity, making them promising matrix candidates for the immobilisation of active fillers. Various formulations of geopolymer-hydrotalcite composite monoliths with a well-defined macroporous structure were 3D printed through the Direct Ink Writing (DIW) technique, then characterized through compression testing, microscopy, FT-IR spectroscopy, XRD and CO2 adsorption tests. The difficult printing of potassium-based geopolymers required the use of carboxymethylcellulose as a rheological additive, whose removal with an appropriate thermal treatment was investigated to avoid performance loss in application. The composites, after thermal activation at 400°C, show high CO2 uptake which increases together with hydrotalcite content, with a better contribution of the K-based geopolymer matrices compared to their Na-based counterparts

Topological Optimization Studies of Ceramic Scaffolds obtained by means of Advanced Additive Manufacturing

The work, carried out at the University of Padua and the Friedrich-Alexander-Universität Erlangen-Nürnberg, deals with the additive manufacturing of scaffolds by means of Direct Ink Writing technique, starting from pre-ceramic polymers and fillers

Synthesis and processing of MAX phases by Powder Injection Moulding and Additive Manufacturing

Mención Internacional en el título de doctorMAX phases are a family of ternary materials with a fixed stoichiometry and a general formula of Mn+1AXn, where M is a transition metal, A is generally an element of groups IIIA and IVA of the periodic table, X is either carbon or nitrogen and n a value between 1 and 3. Their nano-laminated structure gives these materials an unusual combination of (1) metallic properties, such as, good electrical and thermal conductivity, machinability, high damage tolerance; and (2) ceramic properties such as high rigidity, resistance to corrosion and oxidation and good mechanical properties at high temperatures. This unique combination of properties makes these materials very promising candidates for industrial applications with demanding conditions, which has prompted the study, design and development of these family of materials. Some of the conventional consolidation routes for MAX phases are pressureless sintering, hot pressing or spark plasma sintering, however they have limitation in the production of parts with complex shapes. In this work, the design and optimisation of the synthesis route was performed for different MAX phases with the aim of obtaining high purity powders studying the reaction mechanism during the synthesis. Ti3SiC2 and Cr2AlC MAX phases were selected for this work. The synthesis of these MAX phases was successfully carried out from different elemental powders (Ti, SiC, C, Cr and Al). In addition, the scalability of the powder production was achieved maintaining high phase purity while controlling the particle size distribution of the powders. To assess the quality of the powders produced, various conventional powder metallurgy processing routes were studied, such as pressureless sintering and hot pressing. For these samples, porosity measurements, mechanical properties (cyclic compression test) and wear behaviour were analysed, studying the influence of the processing route on the behaviour of the materials. In this context, the main challenge of this PhD is to demonstrate the viability of nonconventional processing techniques such as Powder Injection Moulding (PIM) and Composite Extrusion Modelling (CEM) for the production of near-net-shape MAX phase samples. These two technologies start from pelletised feedstocks and allow the production of samples with a higher freedom of design, reducing post-processing steps. The objective was to produce complex-shaped parts as well as increasing the application range of MAX phases, their reproducibility and production volume. For the successful production of MAX phase samples by PIM and CEM the selection of the binder system as well as the optimisation of the solid loading of the feedstocks is necessary and, for this purpose, the rheological properties of the materials were characterised. Two multicomponent binders were selected for this study, firstly, an environmentally-friendly binder consisting of a combination of a sustainable polymer (polyethylene glycol, PEG) and a biopolymer (cellulose acetate butyrate, CAB), and secondly, a binder composed of the same sustainable polymer (PEG) and polypropylene (PP). Porous MAX phases with tailored porosity were obtained by PIM processing, avoiding the use of spacer holder. Additive manufactured parts by CEM were also successfully produced, using the same feedstocks. Debinding and sintering processes were optimized in both cases. In conclusion, it was possible to obtain good quality parts with custom geometries through PIM and CEM for both Ti3SiC2 and Cr2AlC MAX phases, suitable for industrial applications with special requirements, such as catalytic devices, filters or as high temperature heat exchangers.Las fases MAX son una familia de materiales ternarios con una estequiometría fija y una fórmula general Mn+1AXn, donde M es un metal de transición, A es generalmente un elemento de los grupos IIIA y IVA de la tabla periódica, X es carbono o nitrógeno y n un valor entre 1 y 3. La estructura nano laminada de estos materiales proporcionan una combinación inusual de propiedades metálicas, tales como, buena conductividad eléctrica y térmica, fácil mecanizado y alta tolerancia al daño, y de propiedades cerámicas como alta rigidez, resistencia a la corrosión y oxidación y buenas propiedades mecánicas a altas temperaturas. Esta exclusiva combinación de propiedades ha hecho que las fases MAX sean considerados para aplicaciones industriales en las que se requieren condiciones exigentes, lo cual ha impulsado el estudio, diseño y desarrollo de esta familia de materiales. Algunas de las rutas convencionales de consolidación para este tipo de materiales son compactación y sinterización, prensado en caliente o spark plasma sintering, pero tienen limitaciones en la producción de piezas con formas complejas. En este trabajo, el diseño y optimización de las rutas de síntesis para diferentes fases MAX han sido estudiadas con el objetivo de obtener polvo con una alta pureza analizando los mecanismos de reacción durante la síntesis. Las fases MAX seleccionadas han sido Ti3SiC2 y Cr2AlC. La síntesis de estas fases MAX se ha llevado a cabo con éxito a partir de distintos polvos elementales (Ti, SiC, C, Cr y Al). Además, el escalado de la producción del polvo se logró manteniendo la alta pureza de las fases MAX procesadas controlando la distribución de tamaño de partícula. Con el objetivo de evaluar los polvos producidos, diversos procesados convencionales de la pulvimetalurgia fueron estudiados como, por ejemplo, presión y sinterización y hot pressing. Para las muestras consolidadas se estudió la porosidad, las propiedades mecánicas (compresión cíclica) y el comportamiento a desgaste, analizando la influencia de las rutas de procesamiento en el comportamiento de los materiales. En este contexto, el principal reto de esta Tesis Doctoral es la de demostrar la viabilidad de procesar fases MAX a través de rutas “no convencionales” como son el moldeo por inyección de polvos (PIM) y el Composite Extrusión Modelling (CEM). Todo esto para la fabricación de piezas near-net-shape de fases MAX. Estos dos tipos de procesado parten de feedstocks en forma de pellets permitiendo la producción de piezas con una mayor libertad de diseño, reduciendo posteriores etapas de postprocesado. El objetivo principal es fabricar piezas complejas y de esta manera aumentar los posibles campos de aplicación para las fases MAX, así como aumentar la reproducibilidad y el volumen de producción para estos materiales. Para la producción de fases MAX a través de PIM y CEM es necesario la selección adecuada de los polímeros que van a conformar el binder y, además, una optimización de la cantidad de sólido que se va a utilizar para la producción de feedstocks. Es por ello por lo que las propiedades reológicas de estos materiales han sido estudiadas en profundidad. Dos sistemas ligantes multicomponentes han sido utilizados para la producción de feedstocks. Por un lado, un binder respetuoso con el medioambiente compuesto por polietilenglicol (PEG) y un biopolímero (acetato butirato de celulosa, CAB). Por otro lado, se desarrolló otro sistema ligante con el mismo polímero sostenible (PEG) y polipropileno (PP). A través del procesamiento por PIM, se obtuvieron piezas con una porosidad a medida, evitando el uso de sistemas espaciadores. Por otro lado, se fabricaron con éxito piezas por manufactura aditiva a través de la tecnología CEM. Además, se optimizaron los procesos de debinding y sinterización de las piezas. Como conclusión, cabe destacar que mediante PIM y CEM fue posible obtener piezas de buena calidad con geometrías a medida tanto para la fase MAX Ti3SiC2 como para la fase Cr2AlC, aptas para aplicaciones industriales con requerimientos especiales como, por ejemplo, dispositivos catalíticos, filtros o como intercambiadores de calor de alta temperatura.Programa de Doctorado en Ciencia e Ingeniería de Materiales por la Universidad Carlos III de MadridPresidente: José Manuel Torralba Castelló.- Secretario: Javier Hidalgo García.- Vocal: Konstantina Lambrino