Person:
Rodríguez Trías, Rafael

person.page.identifierURI

https://academica-e.unavarra.es/handle/2454/49886

Last Name

Rodríguez Trías

First Name

Rafael

person.page.departamento

Ingeniería

person.page.instituteName

InaMat2. Instituto de Investigación en Materiales Avanzados y Matemáticas

ORCID

0000-0003-0086-7547

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491

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Now showing 1 - 10 of 28

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; 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.
Open Access
An alternative methodology for the evaluation of photocatalytic activity of polymeric coatings by monitoring dye degradation
(MDPI, 2022) Sandúa Fernández, Xabier; Rivero Fuente, Pedro J.; Esparza Gorráiz, Joseba; Rodríguez Trías, Rafael; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
This work provides an alternative method for evaluating the photodegradation behaviour of different types of dyes such as Methylene Blue, Rhodamine B, Congo Red, Metanil Yellow, and Malachite Green. In this methodology, the coating is dyed with the chosen colorant and two beams of light are combined and channelled to a spot on the dyed coating through an optical fibre, the first one from an ultraviolet (UV) source (which is the responsible of activating photocatalysis) and the second one from a Visible light source, which is employed to monitor changes in colour along the time. The photocatalytic coating selected for testing this methodology consists of a mat of electrospun poly (acrylic acid) (PAA) fibres that acts as base film, furtherly coated by using layer-by-layer (LbL) assembly technique for the immobilization of two different photocatalytic metal oxide precursors (TiO2 and Fe2O3) nanoparticles. The morphological characterization of the samples has been implemented by means of scanning electron microscopy (SEM), confocal microscopy, and water contact angle measurements in order to analyse the resultant thickness, roughness, electrospun fibre diameter, and wettability. The experimental results clearly demonstrate the validity of the methodology to measure the photocatalytic activity in all dyed coatings, although significant differences have been observed depending on the selected dye.
Open Access
Visible light activation of gold nanoparticles embedded into titanium dioxide surface in electrospun polymeric coatings
(MDPI, 2024) Sandúa Fernández, Xabier; Rivero Fuente, Pedro J.; Calvopiña, Jonathan; Rodríguez Trías, Rafael; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
This work reports the development of a functional photocatalytic coating based on a combination of polymeric electrospun fibres and nanoparticles that is intended to be activated in the visible light range. In this sense, the resulting fibres can act as an effective matrix for the incorporation of titanium dioxide (TiO2) particles, which are covered by gold nanoparticles (AuNPs), in the outer surface of the metal oxide precursor. In the first step of the process, the optical properties of the nanoparticles were determined by UV-Vis spectroscopy. The extension of the visible absorption can be associated to the localized surface plasmon resonance (LSPR) of the metallic AuNPs. In addition, the resultant particle size distribution and average particle diameter was evaluated by dynamic light scattering (DLS) measurements. Furthermore, the phase composition and porosity of the functional particle powder were analysed by an XRD and N2 adsorption test. In the second step, these synthesized particles have been successfully immobilized into a PAA + β-CD electrospun fibre matrix by using the two different deposition methods of dip-coating and solution-casting, respectively. The morphological characterization of the samples was implemented by means of scanning electron microscopy (SEM), showing uniform and homogeneous, free-beaded fibres with a random distribution of the synthesized particles deposited onto the electrospun fibres. Then, the functional coatings were removed from the substrate, and a thermogravimetric (TGA) analysis was carried out for each sample in order to obtain the precursor mass immobilized in the coating. Once the overall mass of precursor was obtained, the percentage of TiO2 particles and AuNPs in the precursor was calculated by using inductively coupled plasma atomic emission spectrometry (ICP-AES). Finally, the photocatalytic activity of both functional solution and electrospun coatings were evaluated in terms of a gradual degradation of rhodamine B (RhB) dye after continuous exposition to a visible-light lamp.
Open Access
Icephobic and anticorrosion coatings deposited by electrospinning on aluminum alloys for aerospace applications
(MDPI, 2021) Vicente Gómara, Adrián; Rivero Fuente, Pedro J.; García, Paloma; Mora, Julio; Carreño, Francisco; Rodríguez Trías, Rafael; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería
Anti-icing or passive strategies have undergone a remarkable growth in importance as a complement for the de-icing approaches or active methods. As a result, many efforts for developing icephobic surfaces have been mostly dedicated to apply superhydrophobic coatings. Recently, a different type of ice-repellent structure based on slippery liquid-infused porous surfaces (SLIPS) has attracted increasing attention for being a simple and effective passive ice protection in a wide range of application areas, especially for the prevention of ice formation on aircrafts. In this work, the electrospinning technique has been used for the deposition of PVDF-HFP coatings on samples of the aeronautical alloy AA7075 by using a thickness control system based on the identification of the proper combination of process parameters such as the flow rate and applied voltage. In addition, the influence of the experimental conditions on the nanofiber properties is evaluated in terms of surface morphology, wettability, corrosion resistance, and optical transmittance. The experimental results showed an improvement in the micro/nanoscale structure, which optimizes the superhydro-phobic and anticorrosive behavior due to the air trapped inside the nanotextured surface. In addi-tion, once the best coating was selected, centrifugal ice adhesion tests (CAT) were carried out for two types of icing conditions (glaze and rime) simulated in an ice wind tunnel (IWT) on both as-deposited and liquid-infused coatings (SLIPs). The liquid-infused coatings showed a low water adhesion (low contact angle hysteresis) and low ice adhesion strength, reducing the ice adhesion four times with respect to PTFE (a well-known low-ice-adhesion material used as a reference).
Open Access
Chemical and mechanical stability of air annealed cathodic arc evaporated CrAlON coatings
(Elsevier, 2018) Almandoz Sánchez, Eluxka; García Fuentes, Gonzalo; Martínez de Bujanda Carasusán, Javier; Rodríguez Trías, Rafael; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería
This study reports the synthesis and characterization of ternary Cr-Al-O and quaternary Cr-Al-O-N coatings deposited by cathodic arc physical vapour deposition, for various nitrogen and oxygen mass flow ratios during the growth process. The composition, microstructure, indentation hardness and modulus of the films have been characterized by scanning electron microscopy, electron probe micro-analysis, X-ray diffraction, and nanoindentation techniques. The evolution of the microstructure and mechanical properties of the coatings after ambient air annealing from 800 °C up to 1100 °C have been investigated. As the oxygen to nitrogen mass flow increases, the as-deposited coatings exhibit lower hardness, higher roughness, lower crystallinity and a more marked columnar structure. At oxygen to nitrogen mass flow ratios bigger than 10/90, the coatings exhibit a stoichiometry of the type (CrAl)2+εO3−ε. Only the coatings with an oxygen to nitrogen mass flow ratio smaller than 10/90 retained nitrogen in their compositions. In all cases, the coatings developed a cubic fcc lattice structure. After annealing at 1100 °C the resulting microstructure showed a clear dependency upon the initial composition of the films. The evolution of the microstructure during the high temperature tests, as well as the analysis of the nanoindentation hardness, composition and thickness also provided valuable information about the combined effects of the thermal stability and the oxidation of the deposited coatings.
Open Access
Hydrophobic and corrosion behavior of sol-gel hybrid coatings based on the combination of TiO2 NPs and fluorinated chains for aluminum alloys protection
(MDPI, 2018) Rivero Fuente, Pedro J.; Maeztu Redin, Juan Deyo; Berlanga Labari, Carlos; Miguel, Adrián; Rodríguez Trías, Rafael; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, Navarre-PRO-UPNA18-6107-FRRRIO
In this work, layers of a sol-gel hybrid matrix doped with metal oxide nanoparticles (TiO2 NPs) have been deposited on flat samples of AA6061-T6 aluminum alloy using the dip-coating technique, with the aim of obtaining coatings with better anti-corrosive and hydrophobic properties. Two different organic modified silica alkoxides, namely 3-(glycidyloxypropyl)trimethoxysilane (GPTMS) and methyltriethoxysilane (MTEOS), have been used for an adequate entrapment of the metal oxide nanoparticles. In addition, a fluorinated metal-alkoxide precursor has also been added to the hybrid matrix in order to improve the hydrophobic behavior. The experimental results corroborate that the presence of these TiO2 NPs play an important role in the development of the sol-gel hybrid coatings. The water contact angle (WCA) measurements, as well as pencil hardness tests indicate that TiO2 NPs make a considerable increase in the resultant hydrophobicity possible, with better mechanical properties of the coatings. The coating thickness has been measured by cross-section scanning electron microscopy (SEM). In addition, a glow discharge optical emission spectroscopy (GD-OES) analysis has been carried out in order to corroborate the adequate entrapment of the TiO2 NPs into the sol-gel coatings. Finally, potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) have been performed in order to evaluate the corrosion resistance of the coatings. All the results provide insights into the efficacy of the developed sol-gel hybrid coatings for anticorrosive purposes with good mechanical properties.
Open Access
A comparative study in the design of TIO2 assisted photocatalytic coatings monitored by controlling hydrophilic behavior and rhodamine b degradation
(MDPI, 2023) Sandúa Fernández, Xabier; Rivero Fuente, Pedro J.; Conde, Ana; Esparza Gorráiz, Joseba; Rodríguez Trías, Rafael; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
This work presents a comparative study related to the photocatalytic efficiency associated with wettability measurements and organic dye degradation, as well as other relevant properties (i.e., corrosion resistance, roughness, wettability, and adhesion to a substrate). The photocatalytic precursors are titanium dioxide nanoparticles (TiO2 NPs) which are dispersed onto a polymeric electrospun fiber matrix by using three different deposition techniques such as electrospraying, spraying, and dip-coating, respectively. In this work, the host electrospun matrix is composed of poly(acrylic acid) fibers crosslinked with cyclodextrin (β-CD), which shows a good chemical affinity and stability with the other deposition techniques which are responsible for incorporating the TiO2 NPs. In order to evaluate the efficacy of each coating, the resultant photocatalytic activity has been monitored by two different tests. Firstly, the reduction in the water contact angle is appreciated, and secondly, the degradation of an organic dye (Rhodamine B) is observed under UV irradiation. In addition, the final roughness, adherence, and pitting corrosion potential have also been controlled in order to determine which solution provides the best combination of properties. Finally, the experimental results clearly indicate that the presence of TiO2 NPs deposited by the three techniques is enough to induce a super hydrophilic behavior after UV irradiation. However, there are notable differences in photocatalytic efficiency on the Rhodamine B as a function of the selected deposition technique.
Open Access
Electrospinning: a powerful tool to improve the corrosion resistance of metallic surfaces using nanofibrous coatings
(MDPI, 2020) Rivero Fuente, Pedro J.; Maeztu Redin, Juan Deyo; Rodríguez Trías, Rafael; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA1929
The use of surface engineering techniques to tune-up the composition of nanostructured thin-films for developing functional coatings with advanced properties is a hot topic within the scientific community. The control of the coating structure at the nanoscale level allows improving the intrinsic properties of the surface compared to bulk materials. A nanodeposition technique with increasing popularity in the field of nanotechnology is electrospinning. This technique permits the fabrication of long and continuous fibres on the micro-nano scale. The good control over fibre morphology combined with its simplicity, cost-effectiveness, easy exploitability and scalability make electrospinning a very interesting tool for technological applications. This review is focused on the use of the electrospinning technique to protect metallic surfaces against corrosion. Polymeric precursors, from natural or biodegradable to synthetic polymers and copolymers can be electrospun with an adequate control of the operational deposition parameters (applied voltage, flow rate, distance tip to collector) and the intrinsic properties of the polymeric precursor (concentration, viscosity, solvent). The electrospun fibres can be used as an efficient alternative to encapsulate corrosion inhibitors of different nature (inorganic or organic) as well as self-healing agents which can be released to reduce the corrosion rate in the metallic surfaces.
Open Access
Characterization of two iron bullets from the royal ammunition factory of Eugi (Spain)
(Technical Faculty, University of Belgrade, 2018) Zalakain Iriazabal, Iñaki; Berlanga Labari, Carlos; Álvarez Vega, Lucas; Rivero Fuente, Pedro J.; Valencia Monreal, Javier; Rodríguez Trías, Rafael; Mekanika, Energetika eta Materialen Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería Mecánica, Energética y de Materiales
In this work, a comparative analysis of two iron bullets found in The Royal Ammunition Factory of Eugi in Navarra (Spain) was performed. Both bullets presented a spherical shape with a relatively good state of preservation, belonging to the last years of the factory production (1766-1850). Several techniques such as microhardness, X-ray fluorescence (XRF), light (LM) and scanning electron microscopy (SEM), optical mission spectroscopy (OES) and energy dispersive X-ray spectroscopy (EDX) analysis were used in order to identify the manufacturing process of the two bullets. The analyses of the microstructures carried out by LM and SEM showed that one bullet was composed of white cast iron with a pearlitic matrix, steadite and graphite; while the other was composed of grey cast iron with a pearlitic matrix, graphite and a low amount of steadite. The chemical analysis of the bullets carried out by OES indicated significant differences in the amount of silicon and phosphorous. The variation in silicon content could suggest that the foundry temperature under oxidizing environment varied during the casting. The SEM and EDX analyses showed both bullets had manganese sulphide inclusions but only one of the bullets exhibited titanium and vanadium inclusions. The microhardness analyses carried out revealed Vickers hardness differences along the diameter. This variation could be explained by the differences in cooling rate along the diameter. Based on the physical characteristics of the bullets and on the obtained results, it can be concluded that one of the bullets could have been used as a grapeshot projectile and the other one as a bullet for ribauldequins. In addition, calcined ore and slag found in this factory were also analysed. The variation found in their chemical composition corroborated that the foundry temperature employed during the manufacturing process was low, the slag being enriched in Si, Al and Mn elements.
Open Access
Icephobic coating based on novel SLIPS made of infused PTFE fibers for aerospace application
(MDPI, 2024) Vicente Gómara, Adrián; Rivero Fuente, Pedro J.; Rehfeld, Nadine; Stake, Andreas; García, Paloma; Carreño, Francisco; Mora, Julio; Rodríguez Trías, Rafael; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA1929
The development of slippery surfaces has been widely investigated due to their excellent icephobic properties. A distinct kind of an ice-repellent structure known as a slippery liquid-infused porous surface (SLIPS) has recently drawn attention due to its simplicity and efficacy as a passive ice-protection method. These surfaces are well known for exhibiting very low ice adhesion values (τice < 20 kPa). In this study, pure Polytetrafluoroethylene (PTFE) fibers were fabricated using the electrospinning process to produce superhydrophobic (SHS) porous coatings on samples of the aeronautical alloy AA6061-T6. Due to the high fluorine–carbon bond strength, PTFE shows high resistance and chemical inertness to almost all corrosive reagents as well as extreme hydrophobicity and high thermal stability. However, these unique properties make PTFE difficult to process. For this reason, to develop PTFE fibers, the electrospinning technique has been used by an PTFE nanoparticles (nP PTFE) dispersion with addition of a very small amount of polyethylene oxide (PEO) followed with a sintering process (380 °C for 10 min) to melt the nP PTFE together and form uniform fibers. Once the porous matrix of PTFE fibers is attached, lubricating oil is added into the micro/nanoscale structure in the SHS in place of air to create a SLIPS. The experimental results show a high-water contact angle (WCA) ≈ 150° and low roll-off angle (αroll-off) ≈ 22° for SHS porous coating and a decrease in the WCA ≈ 100° and a very low αroll-off ≈ 15° for SLIPS coating. On one hand, ice adhesion centrifuge tests were conducted for two types of icing conditions (glaze and rime) accreted in an ice wind tunnel (IWT), as well as static ice at different ice adhesion centrifuge test facilities in order to compare the results for SHS, SLIPs and reference materials. This is considered a preliminary step in standardization efforts where similar performance are obtained. On the other hand, the ice adhesion results show 65 kPa in the case of SHS and 4.2 kPa of SLIPS for static ice and <10 kPa for rime and glace ice. These results imply a significant improvement in this type of coatings due to the combined effect of fibers PTFE and silicon oil lubricant.