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Mugoni C.,University of Modena and Reggio Emilia | Licciulli A.,University of Salento | Diso D.,Salentec Srl | Siligardi C.,University of Modena and Reggio Emilia
Ceramics International | Year: 2015

Lanthanum glass frits suitable for infiltration in pre-sintered alumina were developed in order to obtain innovative alumina-glass composites, which are promising materials for all-ceramic dental prosthetic restorations, such as single crowns and fixed partial dentures. Glass compositions belonging to the lanthanum-silicate-borate system were synthesized in order to reinforce and give an improved esthetic appearance to the pre-sintered Al2O3.Fifteen formulations, defined by using a mixture design approach, were melted and quenched in water at room temperature in order to obtain the frits. Those exhibiting the lower melting temperatures were tested for infiltration into Al2O3 to obtain Al2O3/glass composites. The frits and the composites were characterized by X-Ray diffraction, differential thermal analyses, hot stage microscopy, colorimetry (Hunter color scale) and scanning electron microscopy. The mechanical properties of the composites, in terms of flexure strength, were evaluated using a three-point bending tests. © 2015 Elsevier Ltd and Techna Group S.r.l. Source


Licciulli A.,University of Salento | Contaldi V.,University of Salento | Padmanabhan S.K.,University of Salento | Balakrishnan A.,Amrita Center for Nanosciences and Molecular Medicine | And 2 more authors.
Journal of the European Ceramic Society | Year: 2011

The present work describes the processing of alumina fiber reinforced alumina ceramic preforms consisting of chopped Al2O3 fibers (33wt%) and Al2O3 (67wt%) fine powders by slip casting. The preforms were pre-sintered in air at 1100°C for 1h. A lanthanum based glass was infiltrated into these preforms at 1250°C for 90min. Linear shrinkage (%) was studied before and after glass infiltration. Pre-sintered and infiltrated specimens were characterized by scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, porosimetry and flexural strength. The alumina preforms showed a narrow pore size distribution with an average pore size of ∼50nm. It was observed that introducing Al2O3 fibers into Al2O3 particulate matrix produced warp free preforms with minor shrinkage during pre-sintering and glass infiltration. It was observed that the infiltration process fills up the pores and considerably improves the strength and reliability of alumina preform. © 2010 Elsevier Ltd. Source


Pal S.,University of Salento | Diso D.,Salentec Srl | Franza S.,Salentec Srl | Licciulli A.,University of Salento | Rizzo L.,Costruzioni Solari
Journal of Materials Science | Year: 2013

Copper-manganese oxide (CuMnO x ) thin films are proposed as efficient and thermally stable selective solar absorbers. The coatings were deposited on aluminum, stainless steel, and glass substrates by dip-coating method from the alcoholic solution of the Cu and Mn nitrate. An organic filmogen was introduced in order to get better adherence with the substrate hence to get uniform films even for larger substrates. The coated films were dried and subsequently heat-treated at 500 C. X-ray diffraction spectra of the annealed film showed the formation of pure Cu-Mn oxide spinel structure (Cu 1.5Mn1.5O4) in the film. FTIR spectra show complete removal of the organic species after thermal treatment at 500 C. The solar absorptance and thermal emittance were calculated from the hemispherical reflectance spectra in the UV/Vis/NIR and IR range, respectively. The maximum visible absorptance with minimizing the infrared thermal emittance was optimized by controlling the thickness of the films, choosing substrates, and introducing a SiO2 overlayer. © 2013 Springer Science+Business Media New York. Source


Licciulli A.,University of Salento | Calia A.,CNR Institute of Archeological Heritage - Monuments and Sites | Lettieri M.,CNR Institute of Archeological Heritage - Monuments and Sites | Diso D.,Salentec Srl | And 4 more authors.
Journal of Sol-Gel Science and Technology | Year: 2011

The application of photocatalytic coatings on stone has been investigated for providing surface protection and self-cleaning properties. Sol-Gel and hydrothermal processes were used to synthesise TiO 2 colloidal suspensions and coatings with enhanced photocatalytic activity without any thermal curing of the coated stone. The stone was a porous limestone (apulian sedimentary carbonatic, calcite stone). Films and powders prepared from TiO 2 sols were studied using X-ray diffraction to evaluate the microstructure and identify rutile and anatase phases. A morphological and physical characterisation was carried out on coated and uncoated stone to establish the changes of appearance, colour, water absorption by capillarity and water vapour permeability. The photocatalytic activity of the coated surface was evaluated under UV irradiation through NO x and organics degradation tests. The performances of the synthesised TiO 2 sols were compared with commercial TiO 2 suspension. Since the coating doesn't need temperature treatments for activating the photocatalytic properties, the nano-crystalline hydrothermal TiO 2 sols seem good candidate for coating applications on stone that cannot be annealed after the coating application. © 2011 Springer Science+Business Media, LLC. Source


Licciulli A.,University of Salento | Laera A.M.,University of Salento | Pal S.,University of Salento | Franza S.,Salentec Srl | And 3 more authors.
Acta Horticulturae | Year: 2015

A synthetic strategy leading to the formation of highly crystalline and spherical TiO2 microspheres (TMS) is proposed. The microspheres were synthesized by means of spray drying process where a hydrothermally treated aqueous suspension containing TiO2 nanoparticles (about 6 nm in diameter) was fed into the atomizer of the spray dryer. Optimized control of sol concentration, flow rate, chamber temperature and nozzle pressure of the spray dryer led to the formation of highly crystalline and regular spherical shaped TiO2 microspheres in the range of 2-10 μm. TMS exhibits higher specific surface area as determined by the Brunauer- Emmett-Teller (BET) method. X-ray diffraction spectra show coexistence of anatase and rutile mixed phase with dominant anatase crystalline phase. Oxidation of ethylene under UV light irradiation has been achieved in the presence of TMS performed in an indigenously made closed Pyrex glass photocatalytic reactor. Source

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