Artículos SCI
2023
2023
Reactividad de Sólidos
Touch-free reactive flash sintering of dense strontium hexaferrite permanent magnet
Jalali, SIA; Manchon-Gordon, AF; Chacartegui, R; Sanchez-Jimenez, PE; Blazquez, JS; Perejon, A; Raj, R; Pérez-Maqueda, LAJournal of the American Ceramic Society (2023)
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This work presents an extension of the touch-free flash sintering technique. In the proposed technique, chemical reaction and sintering occur in a single step, without the use of electrodes, in the presence of electric and magnetic fields. We show that a dense, single-phase strontium hexaferrite magnet can be produced from a mixture of commercial carbonate and oxide powders in a single step in a little more than a minute. This new technique implies significant reduction in energy and time consumption (primarily because of ultrafast processing) relative to conventional sintering.
Agosto, 2023 | DOI: 10.1111/jace.19389
Reactividad de Sólidos
Seville history insight through their construction mortars
Perez-Rodriguez, JL; Perez-Maqueda, LA; Franquelo, ML; Duran, AJournal of Thermal Analysis and Calorimetry, (2023)
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Seville is intimately linked to its historic role and extensive cultural heritage. The city has been occupied by Romans, Arabs and Christians, who built important historical buildings. Roman (first-second centuries) and Arabic (eleventh century) buildings, medieval Shipyard (thirteenth century), San Isidoro and Santa Maria de las Cuevas monasteries (fifteenth century), Santa Maria de las Cuevas (fifteenth century modified in eighteenth century), El Salvador Church (eighteenth century), the Royal Ordnance building (eighteenth century) and Santa Angela de la Cruz convent (twentieth century) performed with lining mortars, and mortars used in building stones (City Hall and Marchena Gate), all of them located in Seville (Spain), have been studied. Ninety-four mortar samples (employed as structural, plaster, coating) originally used or applied in restoration processes have been collected to perform an archaeometry study. The ratio of CO2 mass loss to hydraulic water (H2O) mass loss, and the mineralogical characterization by X-ray diffraction has been used to compare the mortars used in the different historical periods. Mainly hydraulic mortars were widely used in all these studied monuments as most mortars showed CO2/H2O ratios within the 4-10 range. Moreover, the thermal analysis curves also showed a broad temperature range for the thermal decomposition of the carbonate fraction of the mortars.
Julio, 2023 | DOI: 10.1007/s10973-023-12313-y
Química de Superficies y Catálisis
New 3D Printing Strategy for Structured Carbon Devices Fabrication
Delgado-Martin, G; Rodriguez, N; Dominguez, MI; Agamez-Pertuz, YY; Tejada, MM; Ruiz-Lopez, E; Ivanova, S; Centeno, MACatalysts, 13 (2023) 1039
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This work shows a new method for the preparation of 100% carbon-structured devices. The method is based on resorcinol-formaldehyde polymerization, using starch as a binder with the addition of a certain amount of external carbon source before polymerization. Molds obtained by 3D printing are used to shape the structured devices in the desired shape, and the ultimate pyrolysis step consolidates and produces the carbonaceous devices. The proposed method allows obtaining supports with different textural and surface properties varying the carbonaceous source, the solvent, or the pyrolysis conditions, among other factors. The as-obtained devices have demonstrated their usefulness as palladium supports for the gas-phase formic acid dehydrogenation reaction. The monolith shows a high conversion of formic acid (81% according to H-2 production) and a high selectivity towards hydrogen production at mild temperatures (80% at 423 K).
Julio, 2023 | DOI: 10.3390/catal13071039
Reactividad de Sólidos
Thermochemical energy storage using calcium magnesium acetates under low CO2 pressure conditions
Amghar, N; Jimenez, PES; Maqueda, LAP; Perejon, AJournal of Energy Storage, 63 (2023) 106958
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The calcium looping multicycle performance of CaO-based materials, derived from calcium magnesium acetates with different Mg content were tested under experimental conditions compatible with thermochemical energy storage. In order to reduce the sintering-induced decay in performance, calcination at an absolute CO2 pressure of 0.1 bar and 0.01 bar is implemented. CaO carbonation is performed at standard 1 bar CO2 conditions. The samples can be fully calcined in short residence times. Samples with MgO present high cycling stability, even when the MgO content is as low as 5 mol%. The effective conversion values lie within the range 0.88-0.84 over ten calcination/carbonation cycles, which provides an accumulated energy storage density of 90.9 GJ/m3. This outstanding reactivity is related with the microstructure of the sample after calcination composed of CaO nanoparticles that are highly reactive for carbonation.
Julio, 2023 | DOI: 10.1016/j.est.2023.106958
Nanotecnología en Superficies y Plasma
Setting a comprehensive strategy to face the runback icing phenomena
Mora, J et al.Surface & Coatings Technology, 465 (2023) 129585
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The development of anti-icing robust surfaces is a hot topic nowadays and particularly crucial in the aeronautics or wind energy sectors as ice accretion can compromise safety and power generation efficiency. However, the current performance of most anti-icing strategies has been proven insufficient for such demanding applications, particularly in large unprotected zones, which located downstream from thermally protected areas, may undergo secondary icing. Herein, a new testing methodology is proposed to evaluate accretion mechanisms and secondary icing phenomena through, respectively, direct impact and running-wet processes and systematically applied to anti-icing materials including commercial solutions and the latest trends in the state-of-the-art. Five categories of materials (hard, elastomeric, polymeric matrix, SLIPS and superhydrophobic) with up to fifteen formulations have been tested. This Round-Robin approach provides a deeper understanding of anti-icing mechanisms revealing the strengths and weaknesses of each material. The conclusion is that there is no single passive solution for anti-ice protection. Thus, to effectively protect a given real component, different tailored materials fitted for each particular zone of the system are required. For this selection, shape analysis of such a component and the impact characteristics of water droplets under real conditions are needed as schematically illustrated for aeronautic turbines.
Julio, 2023 | DOI: 10.1016/j.surfcoat.2023.129585
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