Person: Larumbe Abuin, Silvia
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Larumbe Abuin
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Silvia
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Física
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Publication Open Access Multifunctional protective PVC-ZnO nanocomposite coatings deposited on aluminum alloys by electrospinning(MDPI, 2019) Iribarren Zabalegui, Álvaro; Rivero Fuente, Pedro J.; Berlanga Labari, Carlos; Larumbe Abuin, Silvia; Miguel, Adrián; Palacio, José F.; Rodríguez Trías, Rafael; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PRO-UPNA 18 (6107)This paper reports the use of the electrospinning technique for the synthesis of nanocomposite micro/nanofibers by combining a polymeric precursor with hydrophobic behavior like polyvinyl chloride (PVC) with nanoparticles of a corrosion inhibitor like ZnO. These electrospun fibers were deposited on substrates of the aluminum alloy 6061T6 until forming a coating around 100 m. The effect of varying the different electrospinning deposition parameters (mostly applied voltage and flow-rate) was exhaustively analyzed in order to optimize the coating properties. Several microscopy and analysis techniques have been employed, including optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Water contact angle (WCA) measurements have been carried out in order to corroborate the coating hydrophobicity. Finally, their corrosion behavior has been evaluated by electrochemical tests (Tafel curves and pitting potential measurements), showing a relevant improvement in the resultant corrosion resistance of the coated aluminum alloys.Publication Open Access Improved photocatalytic and antibacterial performance of Cr doped TiO2 nanoparticles(Elsevier, 2021) Gómez Polo, Cristina; Larumbe Abuin, Silvia; Gil Bravo, Antonio; Muñoz Labiano, Delia; Rodríguez Fernández, L.; Fernández Barquín, Luis; García-Prieto, Ana; Fernández-Gubieda, María Luisa; Muela, Alicia; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; CienciasThe effect of Cr and N doping in the adsorption capacity, photocatalytic properties and antibacterial response of TiO2 anatase nanoparticles is analyzed. The nanoparticles (N-TiO2, Cr-TiO2 and Cr/N-TiO2) were prepared by the sol-gel method. The structural (X-ray diffraction and TEM) and magnetic (SQUID magnetometry) characterization confirms the nanosized nature of the anatase nanoparticles and the absence of secondary phases. The enhancement of the adsorption capacity of the dye (methyl orange) on the surface of the catalysts for the Cr and Cr/N doped samples, together with the redshift of the UV-Vis absorbance spectra promote a high photocatalytic performance under visible light in these nanocatalysts. The culturability and viability of the Escherichia coli DH5α in a medium supplemented with the nanoparticles was characterized and compared with the evolution under visible light (both without and with nanoparticles). The results show that Cr-TiO2 nanoparticles under visible light display antibacterial activity that cannot be accounted by the toxicity of the nanoparticles alone. However the antibacterial effect is not observed in N-TiO2 and Cr/N-TiO2. The differences in the electrostatic charge (isoelectric point) and the degree of nanoparticle dispersion are invoked as the main origins of the different antibacterial response in the Cr-TiO2 nanoparticles.Publication Open Access Evaluation of functionalized coatings for the prevention of ice accretion by using icing wind tunnel tests(MDPI, 2020) Rivero Fuente, Pedro J.; Rodríguez Trías, Rafael; Larumbe Abuin, Silvia; Monteserín, María; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA1929Ice accretion presents serious safety issues, as airplanes are exposed to supercooled water droplets both on the ground and while flying through clouds in the troposphere. Prevention of icing is a main concern for both developers and users of aircraft. The successful solution of this problem implies the combination of active and passive methods and the use of advanced sensors for early detection of icing and monitoring of ice accretion and de-icing processes. This paper focuses on the development of passive solutions. These include advanced anti-icing coatings deposited by a variety of chemical methods including sol-gel, advanced paints based on polyester combined with fluorinated derivatives and applied by electrostatic spray deposition and conventional silicone-based paints modified by adding alumina nanoparticles. Water contact angle has been measured in all cases, demonstrating the hydrophobic character of the coatings. An ice accretion test has been carried out in a laboratory scale icing wind tunnel (IWT) located in a cold climate chamber. Three different studies have been undertaken: ice accretion measurement, durability of the anti-icing behavior after several icing/de-icing cycles and ice adhesion testing by means of the double lap shear test (DLST) methodology. All the studied coatings have shown significant anti-icing behavior which has been maintained, in some cases, beyond 25 cycles. Although these results are still far from any possible application for aeronautic components, they provide interesting insights for new developments and validate the laboratory scale tests.Publication Open Access Síntesis, caracterización y aplicaciones de nanoestructuras magnéticas basadas en óxidos de metales de transición(2014) Larumbe Abuin, Silvia; Gómez Polo, Cristina; Física; FisikaComo objetivo principal de esta tesis se plantea la preparación de sistemas híbridos constituídos por nanoestructuras del tipo NM@SiO2@X-TiO2 (NM: núcleo magnético; X: elemento dopante) con actividad fotocatalítica en el visible y capaces de ser recuperados del medio de reacción mediante la acción de un campo magnético externo. Además, existen una serie de aspectos complementarios que han surgido en el desarrollo del trabajo que presentan un claro interés tanto desde una perspectiva básica como aplicada: Síntesis 1.1 Síntesis de nanopartículas magnéticas de composición Fe3O4/NiFe2O4 recubiertas con SiO2: análisis de las condiciones de síntesis empleando el método sol-gel que den lugar a las propiedades estructurales y magnéticas deseadas. 1.2 Síntesis de nanopartículas de TiO2 dopadas con Fe/N: preparación de nanopartículas de TiO2 mediante el método sol-gel con propiedades fotocatalíticas óptimas (absorción en el visible). 1.3 Síntesis de nanoestructuras híbridas Fe3O4@SiO2@TiO2: preparación de nanoestructuras híbridas mediante el recubrimiento con óxido de titanio de nanopartículas magnéticas previamente sintetizadas empleando dos métodos de calcinación: calcinación convencional y mediante hipertermia magnética. Caracterización básica 2.1 Análisis de los efectos superficiales en las propiedades magnéticas de las nanopartículas ferrimagnéticas: estudio del efecto del tamaño nanométrico de las nanopartículas magnéticas en las propiedades magnéticas (reducción de la imanación de saturación, fenómenos de spin-glass y exchange bias). 2.2 Análisis del efecto de los dopantes y de la relación de hidrólisis en la temperatura de transición anatasa-rutilo: evaluación del efecto de los elementos dopantes (Fe,N) en la temperatura de transición anatasa-rutilo con el objeto de reducir la fracción de rutilo con fines aplicados. 2.3 Análisis del efecto de los dopantes en el espectro de absorción de las nanopartículas de TiO2: estudio de la modificación introducida por los dopantes en el espectro de absorción de las nanopartículas de óxido de titanio con el objetivo de obtener absorción en la zona del visible. 2.4 Análisis del efecto de los dopantes en la observación de ferromagnetismo a 300 K en las nanopartículas de TiO2: estudio desde un punto de vista básico de la introducción de elementos metálicos (Fe) y elementos no metálicos (N) en las propiedades magnéticas de la fase anatasa. Observación de ferromagnetismo a temperatura ambiente. Aplicaciones 3.1 Obtención de nanoestructuras híbridas Fe3O4@SiO2@TiO2 con actividad fotocatalítica en el visible: análisis de la actividad fotocatalítica de las estructuras híbridas preparadas para su utilización bajo radiación visible. 3.2 Obtención de nanoestructuras híbridas susceptibles de ser recuperadas mediante la aplicaciones de un campo magnético externo: evaluar si las nanoestructuras híbridas con actividad fotocatalítica en el visible además son susceptibles de ser recuperadas con un campo magnético externo para poder ser reutilizadas.Publication Open Access Fe-C nanoparticles obtained from thermal decomposition employing sugars as reducing agents(Elsevier, 2020) Cervera Gabalda, Laura María; Pérez de Landazábal Berganzo, José Ignacio; Garayo Urabayen, Eneko; Monteserín, María; Larumbe Abuin, Silvia; Martín, F.; Gómez Polo, Cristina; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaThe aim of the work is to present a comparative analysis (structural and magnetic) of Fe-C nanocomposites obtained by the thermal decomposition of sugars (fructose, glucose and sucrose) employing FeCl3 as Fe3+ precursor. The thermal decomposition was followed through Thermogravimetry (TGA) and Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, High Resolution Transmission Electron Microscopy (HRTEM) and Raman spectroscopy. The results indicate the reduction of Fe3+ under the performed thermal treatments and the achievement at high annealing temperatures of Fe-C nanostructures (coexistence of α-Fe and Fe3C nanoparticles surrounded by a carbon matrix). The magnetic characterization performed by dc SQUID magnetometry, shows an antiferromagnetic response in the initial stages of the decomposition process, and a ferromagnetic behavior linked to the Fe-based nanoparticles. The magnetic induction heating was analyzed through the ac hysteresis loops. Moderate Specific Absorption Rate (SAR) is obtained in Fe-C nanoparticles (~ 70 W/gFe), ascribed to the large nanoparticle size. The combination of porous carbon structure and ferromagnetic response of the Fe-C nanoparticles (i.e. local temperature increase under ac magnetic field) enlarge the emerging applications of these carbonaceous nanocomposites.Publication Open Access A comparative study of multifunctional coatings based on electrospun fibers with incorporated ZnO nanoparticles(MDPI, 2019) Rivero Fuente, Pedro J.; Iribarren Zabalegui, Álvaro; Larumbe Abuin, Silvia; Palacio, José F.; Rodríguez Trías, Rafael; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PRO-UPNA 18 (6107)In this work, polymeric fibers of polystyrene (PS) with incorporated ZnO nanoparticles have been deposited onto an aluminum alloy substrate (6061T6) by using the electrospinning technique. In order to optimize the deposition process, the applied voltage and flow rate have been evaluated in order to obtain micrometric electrospun fibers with a high average roughness and superhydrophobic behavior. Thermogravimetric analysis (TGA) has also been employed in order to corroborate the amount of ZnO incorporated into the electrospun fibers, whereas differential scanning calorimetry (DSC) has been performed in order to determine the glass transition temperature (Tg) of the polymeric electrospun fibers. In addition, a specific thermal treatment (Tg + 20 °C) of the synthesized electrospun fibers has been evaluated in the resultant corrosion resistance. A comparative study with previously reported results corresponding to polyvinyl chloride (PVC) fibers is carried out along this paper to show the changes in behavior due to the different compositions and fiber diameters. The coating has produced an important reduction of the corrosion current of the aluminum substrate in two orders of magnitude, showing also an important enhancement against pitting corrosion resistance. Finally, this deposition technique can be used as an innovative way for the design of both superhydrophobic and anticorrosive surfaces in one unique step over metallic substrates with arbitrary geometry.