Time filter

Source Type

Carriazo D.,CSIC - Institute of Materials Science | Pico F.,CSIC - National Center for Metallurgical Research | Gutierrez M.C.,CSIC - Institute of Materials Science | Rubio F.,Institute Ceramica y Vidrio ICV | And 2 more authors.
Journal of Materials Chemistry | Year: 2010

Three dimensional (3D) hierarchical porous (micro-, meso- and macro-porous) carbon monoliths (HCMs) have recently been proposed as promising supercapacitor electrodes. In this work, we have further explored the use of block-copolymers as templates for the preparation of HCMs via condensation of resorcinol and formaldehyde (RF) and subsequent carbonization. The resulting HCMs exhibited a textured morphology consisting of a bicontinuous macroporous carbon network built of interconnected microporous carbon colloids, as demonstrated by nitrogen adsorption/desorption isotherms, mercury porosimetry and electron microscopy, in both scanning and transmission mode. Such a texture favored the performance of HCMs as supercapacitor electrodes, reaching remarkable values of capacitance of up to 198 F g-1 (normalized by mass) and 34.5 μF cm -2 (normalized by BET surface area). The first electrolyte infiltration into the micropore (prior capacitance measurements) was demonstrated to play a crucial role in the achievement of large capacitance values. © 2010 The Royal Society of Chemistry.

Vicent M.,Jaume I University | Sanchez E.,Jaume I University | Santacruz I.,University of Malaga | Moreno R.,Institute Ceramica y Vidrio ICV
Journal of the European Ceramic Society | Year: 2011

This work deals with the dispersion and stabilisation of nanosized TiO2 particles in an aqueous medium as a first step in the preparation of spray-dried nanostructured powders.A colloidal route leading to the production of titania nanostructured feedstocks to obtain nanostructured powders was developed. The process was based on the production of homogeneous and concentrated TiO2 nanosuspensions dispersed in deionised water with a suitable control of pH and the use of an appropriate anionic dispersant. Concentrated suspensions could be obtained by mixing with an ultrasounds probe at different times depending on the dispersing conditions.Homogeneous suspensions prepared were then reconstituted by spray drying into free-flowing powders with an adequate granule size distribution for diverse purposes, such as atmospheric plasma spraying coatings. © 2011 Elsevier Ltd.

Munoz V.,CONICET | Pena P.,Institute Ceramica y Vidrio ICV | Martinez A.G.T.,CONICET
Ceramics International | Year: 2014

Alumina-magnesia-carbon refractories (AMC) are of great technological interest for their use as linings for iron and steelmaking ladles. In this paper, the methodology implemented for the physical, chemical and thermal characterization of AMC refractories is presented along with the obtained results. These results are essential for the study of the chemical and mechanical behavior of these materials, which the present work frames. AMC bricks comprise different amounts of alumina, sintered or electrofused magnesia, graphite and antioxidant additives bonded together with a phenolic resin. The variety of components, be they oxidic, metallic or polymeric in nature, and the complexity of the final microstructure and texture make characterizing these refractories a difficult task. In the present work, several complementary techniques were used in combination: X-ray fluorescence, plasma emission spectroscopy, gravimetry, X-ray diffraction, differential thermal and thermogrametric analyses, reflection optical microscopy and scanning electron microscopy, density and porosity measurements, dilatometric analysis and permanent linear change measurements. The results of these different techniques were analyzed separately and together in order to obtain a detailed description of each refractory in relation to its physical and chemical characteristics and thermal evolution. In addition, the characterization was completed by evaluating the mechanical properties at room temperature, such as the mechanical strength and Youngs modulus. © 2014 Elsevier Ltd and Techna Group S.r.l.

Gutierrez M.C.,CSIC - Institute of Materials Science | Rubio F.,Institute Ceramica y Vidrio ICV | Del Monte F.,CSIC - Institute of Materials Science
Chemistry of Materials | Year: 2010

Deep eutectic solvents (DES, a new class of ionic liquids) have been used as solvents to carry out the polycondensation of resorcinol-formaldehyde (RF). RF gels were characterized by FTIR and solid 13C NMR spectroscopy, and scanning electron microscopy. Solid 13C NMR spectroscopy demonstrated that the use of DES containing small amounts of water (those required to introduce formaldehyde in the solution) favored RF polycondensation as compared to that carried out in regular aqueous conditions (that is, in absence of DES). RF polycondensation also occurred in DES in its pure state (in this case, after lyophilization) albeit the reaction efficiency was difficult to evaluate given to partial elimination of formaldehyde. Carbonization of any of the RF gels obtained in DES (e.g., with or without water) resulted in the formation of monolithic carbons with conversion rates and carbon contents in range to and even slightly above those obtained in aqueous solutions. Finally, we took advantage of the excellent solvent properties of DES to suspend carbon nanotubes (CNTs) within the starting sol. Polycondensation of resorcinol and formaldehyde in DES also containing CNTs in suspension allowed the preparation of carbon-carbon nanotube RF gels and ultimately (i.e., after thermal treatment) carbon composites, having multiwall CNTs (MWCNTs) homogeneously distributed within the whole monolithic structure. © 2010 American Chemical Society.

Vicent M.,Jaume I University | Sanchez E.,Jaume I University | Moreno A.,Jaume I University | Moreno R.,Institute Ceramica y Vidrio ICV
Journal of the European Ceramic Society | Year: 2012

Nanosized TiO2 powder with an average primary size of ∼20nm and surface area of ∼50m2/g (Aeroxide® P25, Degussa-Evonik, Germany) was used as starting material. A colloidal titania suspension from the same supplier was also used (W740X). The dispersing conditions were studied as a function of pH, dispersant content, and solids loading. Well-dispersed TiO2 nanosuspensions with solids contents up to 30vol.% (62wt%) were obtained by dispersing the powder with 4wt% PAA. Suspensions with solids contents as high as 35vol.% were prepared by adding the TiO2 nanoparticles to the TiO2 colloidal suspension under optimised dispersing conditions.TiO2 powder reconstitution was performed by spray drying both types of nanosuspensions to obtain free-flowing micrometre-sized nanostructured granules. The spray-dried nanostructured TiO2 granules were deposited on austenitic stainless steel coupons using atmospheric plasma spraying. Coating microstructure and phase composition were characterised using scanning electron microscopy and X-ray diffraction techniques. © 2011 Elsevier Ltd.

Discover hidden collaborations