Determinación de la microestructura y microanálisis (SEM/EDX) de vidrios procedentes de cuevas de Mallorca y Menorca

In recent years a field of research of growing interest has been the application of physico-chemical characterization methods on modern materials to the study of ancient materials found by the archaeologists. This new field on Materials Science is known as Archaeometry. Many questions about the origin and manufacture of ancient glasses can be solved by using the same methods of analysis and microstructure characterization applied normally to special and advanced glasses. The islands of Mallorca and Menorca, located in the Balearic archipelago in the Mediterranean sea, has long been a crossing place of cultures. Transparent, opal and coloured glasses have been found in various archaeological investigations carried out in these islands. In order to know the composition and microstructure of some of these glasses, an archaeometric study has been carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy and energy-dispersive X-ray analysis (SEM/EDX), differential thermal analysis (DTA), and hot stage optical microscopy (HSM) methods. The SEM/EDX average microanalysis results show that these glasses are deficient in sodium and highly enriched in Al2O3 and Fe2O3, their composition being in the range: 0.5-1.5 K2O, 8-10 CaO, 6-8 Al2O3, 6-8 Fe2O3, 74-76 SiO2 (wt%). Some of these glasses also contain high percentages of lead. Small quantities of TiO2, CuO and SO3 (0.5 %) have also been detected. Surface decoration and blue colour are other features of these ancient glasses, the surface of which, depicted by SEM, is highly altered with flaked and corroded microstructures.En los últimos años la aplicación de los métodos físicoquímicos de caracterización de materiales modernos al estudio de materiales antiguos es un campo de investigación de creciente interés para los arqueólogos. Este nuevo campo de investigación en Ciencia de los Materiales se viene denominando con el nombre de Arqueometría. Por lo tanto, muchas cuestiones sobre el origen y manufactura de los vidrios antiguos pueden resolverse usando los mismos métodos de análisis y de caracterización microestructural que se aplican normalmente a vidrios especiales o avanzados. La isla de Mallorca ha sido en el pasado un lugar de paso y de encuentro de diferentes culturas. Se han encontrado vidrios transparentes, opalescentes y coloreados en diferentes investigaciones arqueológicas llevadas a cabo en esta isla del Mediterráneo. Para conocer la composición y microestructura de algunos vidrios encontrados en cuevas de Mallorca y Menorca se ha realizado, pues, un estudio arqueo métrico por las técnicas de: Difracción de rayos X (DRX); microscopía electrónica de Transmisión (MET), microscopía electrónica de barrido y microanálisis por dispersión de energías de rayos X (MEB/EDX), análisis térmico diferencial (ATD) y microscopía de calefacción (HSM). Los resultados de MEB/EDX de microanálisis promedio muestran que estos vidrios son deficientes en sodio y altamente enriquecidos en Al2O3 y Fe2 O3 estando su composición en el intervalo: 0,5-1,5 K2O, 8-10 CaO, 6-8 Al2O3, 6-8 Fe2O3, 74-76 SiO2 (% peso). Algunos de estos vidrios también contienen un alto porcentaje de plomo. Se han detectado pequeñas cantidades de TiO2, CuO y SO3 (< 0,5%). La superficie decorada, el color azul y las otras características de estos vidrios que muestran su superficie altamente corroída por MEB han sido también analizados y discutidos

Glass-ceramic glazes for ceramic tiles – a review

Glass-ceramics are ceramic materials produced through controlled crystallisation (nucleation and crystal growth) of a parent glass. The great variety of compositions and the possibility of developing special microstructures with specific technological properties have allowed glass-ceramic materials to be used in a wide range of applications. One field for which glass-ceramics have been developed over the past two decades is that of glazes for ceramic tiles. Ceramic tiles are the most common building material for floor and wall coverings in Mediterranean countries. Glazed tiles are produced from frits (glasses quenched in water) applied on the surface of green tiles and subjected to a firing process. In the 1990s, there was growing interest in the development of frits that are able to crystallise on firing because of the need for improvement in the mechanical and chemical properties of glazed tiles. This review offers an extensive evaluation of the research carried out on glass-ceramic glazes used for covering and pavement ceramic tile is accomplished. The main crystalline phases (silicates and oxides) developed in glass-ceramic glazes have been considered. In addition, a section focused on glazes with specific functionality (photocatalytic, antibacterial and antifungal activity, or aesthetic superficial effects) is also includedThe authors want to thank Mr. R. Rincón for the kind assignment of the Ishtar gate photograph shown in Figure 4 and to Ms. D. Fernández and Mr. E. Fernández (Department of Library and Publications, IETcc-CSIC) for their assistance in compiling the references necessary for the completion of this review. R. Casasola is grateful to the Spanish National Research Council (CSIC) for her contract through the JAE Program (JAE Pre_08_00456). Financial support through the project MAT2006-05977 (Education and Science Spanish Ministry) is also recognised.Peer reviewe

Glass-ceramic glazes for ceramic tiles – a review

Glass-ceramics are ceramic materials produced through controlled crystallisation (nucleation and crystal growth) of a parent glass. The great variety of compositions and the possibility of developing special microstructures with specific technological properties have allowed glass-ceramic materials to be used in a wide range of applications. One field for which glass-ceramics have been developed over the past two decades is that of glazes for ceramic tiles. Ceramic tiles are the most common building material for floor and wall coverings in Mediterranean countries. Glazed tiles are produced from frits (glasses quenched in water) applied on the surface of green tiles and subjected to a firing process. In the 1990s, there was growing interest in the development of frits that are able to crystallise on firing because of the need for improvement in the mechanical and chemical properties of glazed tiles. This review offers an extensive evaluation of the research carried out on glass-ceramic glazes used for covering and pavement ceramic tile is accomplished. The main crystalline phases (silicates and oxides) developed in glass-ceramic glazes have been considered. In addition, a section focused on glazes with specific functionality (photocatalytic, antibacterial and antifungal activity, or aesthetic superficial effects) is also included.CSIC through the JAE Program (JAE Pre_08_00456). Financial support through the Education and Science Spanish Ministry through theproject MAT2006-05977Peer reviewe

Effect of microstructure on mechanical properties of porcelain stoneware

This work examines the effect of microstructure (aspect ratio of mullite crystals and proportion of crystalline and amorphous phases) as well as different physical features (bulk density, closed and open porosity and absolute density) on the mechanical properties of a standard porcelain stoneware composition (50% kaolinitic clay, 40% feldspar and 10% quartz) fired in the 1200–1300 °C temperature interval using a fast firing schedule. The mechanical behaviour was evaluated in terms of bending strength, Vickers microhardness, fracture toughness and Young's modulus. After viewing the results, it can be concluded that increased σf, Hv and E values were mainly due to open porosity, percentage of mullite phase and morphology of secondary mullite needles, whereas closed porosity and quartz particles have no influence on these properties.This research was supported by the Spanish Science and Technology Ministry (Projects MAT2000-1422 and MAT2003-2915). The authors gratefully acknowledge Compañía Europea de Arcillas, S.A. for providing raw materials. The authors thank IRICA from University of Castilla-La Mancha (Spain) for experimental assistance.Peer reviewe

Development of a new glass–ceramic by means of controlled vitrification and crystallisation of inorganic wastes from urban incineration

This paper reports the results of a study of the feasibility of recycling the solid residues from domiciliary waste incineration by producing a glass-ceramic. The major components of the raw material (TIRME F+L), which was from a Spanish domiciliary incinerator, were CaO, SiO2 and Al2O3 but nucleating agents, such as TiO2, P2O5, and Fe2O3 were also present in reasonable amounts. It was found that a relatively stable glass with suitable viscosity could be obtained by mixing 65 wt% TIRME F+L with 35 wt% glass cullet. The heat treatment required to crystallise the glass produced from this mixture, designated TIR65, was nucleation at 560°C for 35 min followed by crystal growth at 100°C for 120 min. The resulting glass-ceramic contained a number of crystalline phases, the most stable being clinoenstatite (MgSiO3), or perhaps a pyroxenic phase which incorporates Ca, Mg and Al in its composition, and åkermanite (Ca2MgSi2O7). The microstructure contained both fibre-like and dendritic crystals. The mechanical properties were acceptable for applications such as tiles for the building industry.Peer reviewe

Study of mullite formation in porcelain stoneware applying isoconversional and IKP methods

The growth process of mullite in a porcelain stoneware body has been studied under isoconversional, isokinetic relationship and invariant kinetic parameters. Activation energy for mullite crystallisation of over 589–628 kJ mol−1 and a Ln A over 50–59 min−1 was obtained. The model was Johnson–Melh–Avrami with n = 1.5. The model chosen implies quick nucleation and subsequent one or three-dimensional growth. Isoconversional methods show an independent activation energy variation in mid range conversion degrees. Lower and higher conversion degrees show different reactions in mullite formation. Results obtained with the methods employed here are in agreement with a previous paper where the Kissinger non-isothermal method and Ligero et al.approximation were appliedPeer reviewe

Nucleation and crystallisation kinetics of a Na-fluorrichterite based glass by differential scanning calorimetry (DSC)

The present paper shows the results of a nucleation and crystallisation study of a Na-fluorrichterite glass carried out by dynamic scanning calorimetry (DSC). The kinetic study was performed using different procedures (Kissinger, Matusita–Sakka and Kissinger–Akahira–Sunose (KAS) methods), and the Avrami parameter was determined from the Ozawa and Malek approximations and the Malek equation. The results have indicated the coexistence of surface and bulk crystallisation in the devitrification process of the studied glass. The kinetic study has shown that the activation energy of the crystallisation process is over 400 kJ/mol and that the mechanism proposed is a Johnson–Mehl–Avrami mechanism with n equal to 3, which implies that the crystallisation develops through the three-dimensional growth of crystals. The study of the variation of the activation energy with crystallisation using the KAS method has shown that the crystallisation process undergoes a multiple step mechanism, where the main part of the whole process corresponds to the three-dimensional growth of crystals. The mechanism proposed was confirmed by applying the Pérez-Maqueda et al. criterion.The authors would like to acknowledge Mrs. P. Díaz for the technical support of the experimental work. R. Casasola and J.M. Pérez express their gratitude to the Spanish National Research Council (CSIC) for their contract through the JAE Programme (JAEPre-08-00456 and JAEDoc-08-00362, respectively), co-financed by the European Social Fund.Peer reviewe

La educación de adultos en el marco universitario: los planes de formación de padres

[Resumen] El vertiginoso avance de la sociedad implica la necesidad de articular mecanismos que permitan una adaptación más adecuada de los ciudadanos a las nuevas exigencias sociales. Esto condiciona la labor de educar a las nuevas generaciones en la familia para posibilitar su incorporación a esta nueva dinámica social en continuo cambio. Ante esta situación, los padres manifiestan ciertas carencias formativas para afrontar la tarea de educar a sus hijos con criterios coherentes y eficaces. Desde el Área de Psicología Evolutiva de Facultad de Ciencias de la Educación de la UPSA se pretende dar respuesta a este tipo de necesidades formativas demandadas desarrollándose un Plan de Formación para Padres, que se contextualiza en la propia Universidad y tiene un carácter preventivo-educativo, siendo su núcleo fundamental la reflexión sobre las prácticas educativas en la familia. La finalidad de este proyecto ha sido ofrecer a los padres modelos adecuados en las prácticas educativas existentes y contribuir a la demanda de los centros escolares salmantinos para favorecer las relaciones familiaescuela. Además, con el fin de que los padres puedan asistir a las sesiones, el Plan se complementa con un Aula de Actividades Educativas Infantiles, donde se realizan diversas actividades lúdicas, contribuyendo a la socialización de los niños en un ambiente distendido[Abstract] The vertiginous advance of society involves the necessity to implement procedures that allow the citizens to able to adapt to the new social requirements. This fact determines the task of educating the new generations in the family to allow their inclusion to this new social dynamic which is constantly changing. In view of this situation, parents are showing certain lacks in their formation so as to face the task of educating their children with efficient and coherent criteria. In the Area of Evolutionary Psychology, belonging to the Faculty of Educational Sciences at the Pontifical University we try to provide a response to this kind or formative needs by developing a Plan for the Parents" Formation, which is set in the context of our University and which has a preventive-educational nature, being its basic aim to reflect on the educational practices in the family. " The purpose of this project is to offer the parents appropriate models in the existing educational practice and to contribute to the demand of the schools in Salamanca in order to favour the relation between the family and the school. Besides, so that parents can attend the sessions, this Plan is complemented with the establishment of a Classroom for Child Educational Activities, where varied ludic acti vities are carried out, contributing to the integration of children in society in the context of a relaxed environment

El Instituto Torroja a lo largo de su historia y la investigación en materiales vítreos y cerámicos

Publicado en: Boletín de la Sociedad Española de Cerámica y Vidrio, 44(2): 131-134 (2005).[ES] El Instituto de Ciencias de la Construcción Eduardo Torroja (IETcc) desde su fundación no sólo ha realizado a lo largo de su ya larga historia investigaciones y valiosas aportaciones científicas y técnicas en el campo de los materiales cerámicos y vidrios, sino que además fue uno de los principales fundadores de la actual Sociedad Española de Cerámica y Vidrio (SECV) con la destacada participación de D. Francisco Arredondo y Verdú. En los últimos once años esta línea de investigación se ha visto reforzada con la creación del Grupo y Laboratorio de Materiales Vítreos y Cerámicos, por lo que se realiza una revisión de la relación de este centro con este tipo de materiales, recordándose los investigadores y publicaciones que más destacaron en este campo. Se realiza finalmente un análisis de la situación actual y de las perspectivas de I+D+i en este tipo de materiales de construcción, haciendo especial énfasis en sus aplicaciones en fachadas ventiladas y del factor dinamizador de la investigación científica que implicará el reto tecnológico de la aplicación de plaquetas cerámicas en este tipo de fachadas.[EN] Ever since its inception and throughout its history, the Eduardo Torroja Institute for Construction Science of the CSIC (IETcc, CSIC) has conducted research in and made valuable scientific and technical contributions to the area of ceramic and glassy materials, and played a key role in the founding of the present Spanish Ceramic and Glass Society (SECV), under the leadership of Francisco Arredondo y Verdú. The creation in recent years of the Glassy and Ceramic Materials Group and Laboratory has reinforced this line of research. The present paper reviews the effort deployed by the Institute in connection with this type of materials, with a tribute to some of the most prominent publications in the field and their authors. Finally, it has been carried out a discussion of the nowadays situation and future prospects onf R+D+I in this type of construction materials, giving emphasis into the uses in vent façades, as well as the dynamic factor over the scientific research implied from the technological challenge of ceramic tiles in this constructive systems.Peer reviewe