Browsing by Author "Lucci, Roberto"

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    Effect of TiO 2 content on Ni/TiO 2 composites electrodeposited on SS316L for hydrogen evolution reaction
    (Pergamon-Elsevier Science Ltd, 2021) Gómez, Melisa; Lucci, Roberto; Franceschini, Esteban; Lacconio, Gabriela
    Composite Ni/TiO2 catalysts have gained enormous interest in recent years in both electrocatalysis and photoelectrocatalysis for the generation of hydrogen. However, there are no systematic studies of the synthesis and characterization of these materials for applications in energy storage. In this work, three Ni/TiO2 catalysts were synthesized starting from nickel electrodeposition on AISI 316 L stainless steel with a modified Ni Watts bath, where different TiO2 contents have been added (0.1, 0.3, and 0.5% w/v). The mechanism of composite formation was studied at different electrodeposition times, in order to analyze the early periods of synthesis, reaching a chemically and structurally stable material after 45 min. It was found that all Ni/TiO2 catalysts present catalytic activity towards hydrogen genera tion, higher than that found by plating with a conventional Ni Watts. Particularly, the Ni/TiO2(0.3) catalyst presents increases in hydrogen formation efficiency of 75.3% and 67.8% at 298 K and 323 K, respectively
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    Estructuras de titanio porosas. Fabricación y caracterización.
    (Conamet/Sam., 2015) López Padilla, Roger; Oldani, Carlos; Grinschpun , Luciano; Lucci, Roberto; Roure, César
    It was studied the space particles process to obtain porous titanium structures, that consist in mixing the powders to be sintered with a component that volatilizes at low temperatures. In this case it was used the acid ammonium carbonate, which leaves gaps (pores) in the structure as it sublimates. There were obtained titanium compacts with open porosity between 35 % and 72 % and pore size between 200 mm and 300 mm. Moreover, there were performed initial studies to obtain titanium compacts with porosity gradient using sequential compaction, to obtain differentiated values of the elasticity modulus between the surface and the center, comparable to those observed in bone. The porous compacts obtained were characterized by optical and electron microscopy to evaluate the microstructure, and compression tests were performed to determine the values of yield strength and elastic modulus. The influence of the main process parameters were determined; percentage and size of the spacer particles, compaction pressure, sintering temperature and time, the values of elasticity modulus, yield strength and microstructure. The results indicates that it is possible to adjust the values of elastic modulus and yield strength of porous titanium compacts produced, so that resemble those with both trabecular and cortical bone. Additionally, it can be adjust the porosity achieved, to the values given in the literature as such as those that meet the needs of vascularization and transport of metabolic products that are critical in the formation of bone tissue. The pore size range reached is within the recommended values for a correct integration of the porous material in the bone, allowing good cell adhesion and migration.