Obtención de cerámicos a base de caolín mediante el proceso de Freeze casting

(Eng) Freeze casting offers a tremendous opportunity to obtain bio-inspired synthetic materials that mimic microstructural characteristics of natural materials like bone and nacre. These natural materials display high strength and toughness; properties usually desired in synthetic engineering materials. The freeze casting process involves four basic steps. The ceramic slurry preparation consists of fine ceramic particles that are suspended in a fluid. In the current work, water based kaolin suspensions were prepared varying the volume fraction of ceramic particles. After the ceramic slurry is properly prepared, the slurry is frozen. The solidification process is often performed using directional freezing, which creates laminar pores, providing the microstructural characteristics of the final part. When a crystal is formed the frozen front moves the particles around it, allowing particles to agglomerate around the crystal, creating different types of pores. In the present study, freezing rates were varied. Subsequently, the samples have to be lyophilized in order to sublimate the frozen liquid phase. Sublimation is the transformation of a solid phase directly to the gas phase. As a result the lyophilized sample has a porous structure with a replica of the water crystals formed during freezing. As a final step, sintering of ceramics is performed. Results of the microstructural characteristics of the samples revealed that varying the volume fraction of ceramic particles and freezing rates have a direct influence on the pore characteristics, changing from circular to laminar pores.(Spa) El proceso de Freeze casting ofrece la oportunidad de obtener materiales sintéticos que imitan características microestructurales de materiales naturales como el hueso y el nácar. Estos materiales se caracterizan por presentar una buena combinación de resistencia y tenacidad; propiedades deseables en materiales sintéticos de ingeniería. El proceso de Freeze casting consiste en cuatro pasos. Primero, preparación de una suspensión coloidal de partículas cerámicas, en este trabajo se utilizaron suspensiones a base de caolín y agua con diferentes concentraciones de caolín. Luego de preparadas las suspensiones, se realizó un proceso de congelamiento direccional que brinda las características microestructurales de la parte final, obteniendo poros alineados debido a la formación direccional de los cristales de agua que mueven las partículas cerámicas alrededor de ellos, creando distintas tipologías de poros. En este trabajo se varió la velocidad de enfriamiento del proceso. Después de congelada la suspensión coloidal de partículas cerámicas se realizó un proceso de liofilización el cual cambia la fase sólida del agua, obtenida del proceso de congelamiento, a gas sin pasar por estado líquido, permitiendo que la parte mantenga la forma de los cristales de agua. Finalmente, se realiza el proceso de sinterizado. Resultados del análisis microestructural de las muestras obtenidas revela que la variación de la concentración de partículas cerámicas en la suspensión coloidal y la variación de la velocidad de enfriamiento en el proceso de solidificación tiene un efecto considerable sobre la microestructura obtenida. Las microestructuras varían desde poros columnares hasta poros esféricos

Freeze casted porous ceramics

Scientists have explored different manufacturing methods aiming at obtaining synthetic materials with controlled porosity, among them, Freeze Casting allows a control of the pore characteristics formed within the material by setting process variables like type of medium, particle size, solid content, inclusion of additives, freezing rate, etc. Despite of all the knowledge obtained about freeze casting, there still remain some questions to solve regarding processing-structure relationships, specifically the relations between cooling patterns during freezing and physical characteristics of the final material. The aim of this doctoral work is to understand the relations between cooling patterns during freezing and the structure at the macro and micro levels of the final freeze casted part. The current work comprises the development of a heat transfer model to efficiently and reliably predict the temperature evolution during freezing. In this way, it will be possible to recognize which are the process variables affecting the final pore morphology. The results of this work improved the fundamental knowledge of the process, serving as a tool to predict and control the microstructure obtained in the Freeze Casting process. The problem definition and goals of this work are presented in chapter 1. A brief description of the main literature on freeze casting is presented in chapter 2. The development of a numerical model that calculates the temperature distribution within the experiment domain was carried out in chapter 3. In chapter 4, an alumina tile was produced by freeze casting process in order to test the freezing device, coloidal suspension characteristics and sintering temperature of the sample. Additionally, an analytical model was proposed for predicting the thermal conductivity of the material. Chapter 5 evaluates the effect of solid content and freezing temperature on pore morphology and evaluates how these variables affect the temperature distribution within the experiment domain. Chapter 6 compares the steady solution of the numerical model and the pore morphology obtained experimentally under different process parameters. Finally, conclusions and future work for the study are presented in chapter 7

Nueva estrategia didáctica para fomentar la participación del alumnado en el proceso de aprendizaje en el ámbito de la tecnología farmacéutica (continuación)

Depto. de Farmacia Galénica y Tecnología AlimentariaFac. de FarmaciaFALSEsubmitte

Evaluation of the influence of the chemical composition and the time of fusion on the physical properties of the glass obtained from recycled bottle material

RESUMEN: Este estudio presenta la influencia de la composición química y el tiempo de fusión del vidrio reciclado de botella empleado como materia prima en el proceso de soplado a boca. Se planteó el diseño de experimentos empleando el método Taguchi considerando tres factores: Na2CO3, Na2SO4 y tiempo de permanencia del vidrio dentro del horno, para analizar el efecto sobre el diámetro y cantidad de burbujas, densidad, dureza, viscosidad y color. La formulación que presentó mejor desempeño son 10% Na2CO3, 0.5% Na2SO4 y un tiempo de fusión de 6 horas.ABSTRACT: This study presents the influence of the chemical composition and fusing time of recycled bottle glass used as raw material in the mouth-blowing process. The design of experiments was proposed using the Taguchi method considering three factors: Na2CO3, Na2SO4 and fusing time of the glass inside the furnace, to analyze the effect on the diameter and amount of bubbles, density, hardness, viscosity and color. The formulation that presented the best results are 10% Na2CO3, 0.5% Na2SO4, and a fusing time of 6 hours

Creación de un nuevo recurso educativo virtual para estudiantes de grado en Farmacia

Depto. de Farmacia Galénica y Tecnología AlimentariaFac. de FarmaciaFALSEsubmitte

Utilización de chamota posconsumo en la formulación de una pasta refractaria como sustitución de la alúmina

O desenvolvimento de materiais cerâmicos refratários é derivado de indústrias que utilizam altas temperaturas em seus processos. O uso de material pós-consumo para a formulação de pastas refratárias é de interesse para o desenvolvimento sustentável com impacto econômico e ambiental. O objetivo deste trabalho é estudar o efeito da adição de chamotte pós-consumo em uma pasta refratária como substituição de alumina. A chamotte foi obtida a partir de tijolos isolantes refratários porosos que cumpriram seu ciclo de vida na indústria cerâmica. Estes foram submetidos a um processo de trituração usando um moinho de bolas até passar pela malha 50. A chamotte foi caracterizada por difração de raios X. Quatro misturas foram formuladas e sinterizadas a 1600 °C. Foram avaliados cone cromático (ASTM C-24), densidade e porosidade (ASTM C-20), contração linear e dilatometria. Os resultados indicam que a adição de chamotte pós-consumo reduz o cone pirrométrico do refratário obtido, a amostra que não contém chamotte tem um cone maior que 36 e a amostra de maior conteúdo possui um cone de 32, adequado para uso como tijolo refratário Com a adição de chamotte, a densidade das amostrasaumentou e a porosidade e contração diminuíram. Finalmente, no teste de dilatometria, são evidenciadas alterações na curva dilatométrica, atribuídas a uma maior formação de fase  líquida e finas devido à contribuição da sílica e do K2O presente na chamotte.El desarrollo de los materiales cerámicos refractarios ha sido derivado de las industrias que utilizan altas temperaturas en sus procesos. El uso de material posconsumo para la formulación de pastas refractarias es de interés para el desarrollo sostenible con impacto económico y ambiental. El objetivo de este trabajo es estudiar el efecto de la adición de chamota posconsumo en una pasta refractaria como reemplazo de alúmina. La chamota fue obtenida a partir de ladrillos aislantes refractarios porosos que cumplieron su ciclo de vida en la industria cerámica. Estos fueron sometidos a un proceso de conminución utilizando un molino de bolas hasta llevarlo a pasante malla 50. La chamota se caracterizó mediante Fluorecencia de rayos X. Se formularon cuatro mezclas y se sinterizaron a 1600 ºC. Se evaluó el cono pirométrico (ASTM C-24), la densidad y la porosidad (ASTM C-20), la contracción lineal y dilatometría. Los resultados indican que la adición de chamota posconsumo disminuye el cono pirométrico del refractario obtenido; la muestra que no contiene chamota tiene un cono superior a 36 y la muestra de mayor contenido tiene un cono de 32, los cuales son adecuados para el uso como ladrillo refractario. Con la adición de chamota se aumentó la densidad de las muestras y se disminuyó la porosidad y la contracción. Finalmente, en el ensayo de dilatometría se evidencian cambios en la curva dilatometría que se atribuyen a una mayor formación de fase líquida y mulita, debido al aporte que hace la sílice y el K2O presentes en la chamota.The development of refractory ceramic materials has been derived from industries that use high temperatures in their processes. The use of post-consumer material for the formulation of refractory pastes is of interest for sustainable development with economic and environmental impact. The objective of this work is to study the effect of the addition of post-consumption chamotte in a refractory paste as an alumina replacement. The chamotte was obtained from porous refractory insulating bricks that fulfilled their life cycle in the ceramic industry. These were subjected to a comminution process using a ball mill until it was passed through 50 mesh. The chamotte was characterized by X-ray diffraction. Four mixtures were formulated and sintered at 1600 °C. Pyrometric cone (ASTM C-24), density and porosity (ASTMC-20), linear contraction and dilatometry were evaluated. The results indicate that the addition of postconsumption chamotte reduces the pyrometric cone of the refractory obtained, the sample that does not contain chamotte has a cone over 36 and the sample of higher content has a cone 32, which are suitable for use as a refractory brick. With the addition of chamotte, the density of the samples was increased and the porosity and contraction decreased. Finally, in the dilatometry test, changes in the dilatometric curve are evidenced, which are attributed to a greater formation of liquid phase and fines due to the contribution made by silica and K2O present in the chamotte

Informe preliminar. Propuesta de protección para la sierra de la mosca. Cáceres - Sierra de Fuentes

Presentamos este INFORME PRELIMINAR con el objetivo de impulsar una figura de protección para LA SIERRA DE LA MOSCA de Cáceres, para su justa valoración como espacio natural bien conservado, como forma de mantener a los ciudadanos cacereños concienciados con la importancia de sus recursos naturales y culturales, complementada con una serie de propuestas de usos y promoción social que la hagan más atractiva y eviten la amenaza del progresivo deterioro ecológico al que se encuentra hoy sometida esta zona periurbana.We present this PRELIMINARY REPORT with the aim of promoting a protection figure for LA SIERRA DE LA MOSCA of Cáceres, for its fair valuation as a well-conserved natural space, as a way of keeping the citizens of Cáceres aware of the importance of its natural and cultural resources, complemented with a series of proposals of uses and social promotion that make it more attractive and avoid the threat of the progressive ecological deterioration to which this periurban area is subjected today

A Case Study of available methodology for the identification of Vulnerable Ecosystems/Habitats in bottom deep-sea fisheries: Possibilities to apply this method in the NAFO Regulatory Area in order to select Marine Protected Areas

Information is critical to Ecosystem Approach and to research about Vulnerable Marine Ecosystems/Habitats (VME/Hs), fishing impacts on habitats and ad-hoc management measures are high-priority. Therefore, this paper presents the ECOVUL/ARPA Interdisciplinary Approach, a case study of methodology for the identification of VME/Hs in order to advise on conservation measures such as marine protected areas (MPAs). By means of an interactive process involving Conventional Fisheries Science, Geomorphology, Sedimentology and Benthic Ecology, the methodology developed under the ECOVUL/ARPA project, has been useful in order to contribute to define practical criteria to the identification of VME/Hs, to improve the knowledge about VME/Hs distribution and the adverse impacts of bottom trawl fisheries and to produce high quality advice on habitat protection. Applying an interdisciplinary approach, the project identified the deep-water bottom trawl fishery footprint on the Hatton Bank Western slope (NEAFC Regulatory Area), mapped the main fishing grounds and related seabed habitats and studied the interactions between fishing and cold-water corals. This approach was used to suggest, with high level of precision, the spatial limits of an area closed to bottom fishing, as an essential conservation measure to protect the cold-water corals in the framework of the Ecosystem Approach to Fisheries management. We present here the methods used, the main results obtained and discuss on the utility of this approach and the possibilities to apply it in the NAFO Regulatory Area, with the aim to advise on measures for reducing the interactions of bottom fishing with sensitive high-seas habitats and to contribute to implement the UNGA recommendations about habitat conservation

Creación de nuevo recurso educativo virtual para estudiantes de grado en Farmacia

Depto. de Farmacia Galénica y Tecnología AlimentariaFac. de FarmaciaFALSEsubmitte

Creación de un nuevo recurso educativo virtual para estudiantes de grado en Farmacia

Creación de un nuevo recurso educativo virtual para estudiantes de grado en Farmacia sobre la serialización de los medicamentos y los procesos de mezclado