Synthesis and Characterization of Reduced Graphene Oxide/ Polyaniline/Au Nanoparticles Hybrid Material for Energy Applications

In this work, synthesis and characterization of reduced graphene oxide/polyaniline/Au nanoparticles (GO/PANI/NpAu) as a hybrid capacitor are presented. Graphite oxide (GO) was synthesized by a modified Hummer’s method. Polyaniline was synthesized by chemical polymerization, and Au nanoparticles (NpAu) were added afterward. Fabrication of the electrodes consisted on the hybrid materials being deposited on carbon cloth electrodes. The chemical and structural properties of the electrode were characterized by high-resolution scanning electron microscopy (HRSEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X-R), and Raman spectroscopy; the results confirm the graphene reduction, the covalent functionalization, and formation of nanocomposites and also show the polyaniline grafted graphene. The performance and evaluation of the electrodes based on grapheme oxide (GO), polyaniline (PANI), GO-PANI, and GO/PANI/NpAu nanocomposites over carbon cloth, stainless steel, and copper have been obtained in 1 M H2SO4 solution, using electrochemical techniques namely: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). They showed that GO/PANI/NpAu gave higher specific capacitance (SC) and energy values than PANI, and GO/PANI, in the order of 160 F/g. The present study introduces new hybrid material for energy applications, from the evaluation of their electrical contributions

Hydrophobic Coatings for Corrosion Control of Aluminum Heat Exchangers

The production of thin films (nanocoatings) is a technological field with many applications to elaborate materials with new properties to be used as corrosion protection of traditional metals. Hydrophobicity is an example of such properties. In this chapter, an example of two hydrophobic corrosion coatings for possible use over aluminum heat exchanger geothermal power plants is discussed. Material substrate preparation, synthesis of hydrophobic sol‐gel nanocoating, characterization, and electrochemical evaluation as a function of time of immersion, which are compared to another commercial fluorinated compound, are presented. Good corrosion protection was found for both hydrophobic coatings for possible application in geothermal heat exchangers

Use of Silica Tubes as Nanocontainers for Corrosion Inhibitor Storage

A new alkyd paint anticorrosion smart coating was developed by using silica nanoparticles as corrosion inhibitor nanocontainers. Silica particles were mixed with the paint at different concentrations to study their performance and ensure their free transportation to the damaged metal. The filling up of silica particles was done preparing three solutions: distilled water, acetone, and a mixture of both, with Fe(NO3)3 and silica particles immersed in each of the solutions to adsorb the inhibitor. Acetone solution was the best alternative determined by weight gain analysis made with the inhibitor adsorbed in silica nanocontainers. Steel samples were painted with inhibitor silica nanocontainer coatings and immersed in an aqueous solution of 3% sodium chloride. Polarization curves and electrochemical noise techniques were used to evaluate the corrosion inhibitor system behavior. Good performance was obtained in comparison with samples without inhibitor nanocontainer coatin

Preparación y caracterización del complejo polianilina-fluconazol, como pigmento en un recubrimiento anticorrosivo

Se preparó una película protectora del proceso de corrosión del acero al carbono en medio neutro, utilizando la polianilina en su forma emeraldina base (PANIB) como matriz para dispersar un inhibidor (fluconazol). Para comprender el reconocimiento molecular en la formación de este complejo, se modeló computacionalmente la interacción de la emeraldina base con el fluconazol a partir de estudios de acoplamiento (docking). Después de la caracterización de los materiales mediante el modelo mencionado y técnicas como FTIR y DRX, se realizaron pruebas de Espectroscopia de Impedancia Electroquímica para evaluar la conducta protectora del complejo polianilina base-fluconazol (PANIB-F). Los resultados del modelo indicaron una débil interacción entre PANIB y el fluconazol, sin embargo, para efectos de protección del metal esto parece ser favorable.A protective film for mild Steel in neutral solution was prepared using polyaniline in its emeraldina base form (PANIB) as a matrix, in which, expired fluconazole as inhibitor was dispersed. In order to investigate the molecular recognition underlying this phenomenon (the formation of the complex), we developed a computational model for the interaction of the emeraldine base with fluconazole by docking analysis. The materials characterization was performed using FTIR and XRD techniques, and the anticorrosion behavior of the PANIB-F complex was studied at room temperature using electrochemical impedance spectroscopy. The docking model results indicated a weak interaction between PANI-B and fluconazole; however, for the metal protection purposes those results were favorable

Corrosión atmosférica tropical de Hierro Galvanizado en una atmósfera urbana leve, en el Valle de San José de Costa Rica

Costa Rica imports most of the metallic materials it uses. In construction, Galvanized Steel (GS) is one of the most used elements in urban areas, where atmospheric corrosion is the main problem of its environmental deterioration. The area of greatest population and economic activity in Costa Rica is the San José Valley, which has a tropical monsoon climate with low pollution, defined under ISO 9223 as light urban. The present study of the atmospheric corrosion of the GS, proposes a high correlation for simple linear models, with climatic parameters as main components and SO2 as secondary component. Seasonality and sampling sites are partially significant at the beginning of the oxidation process, but this effect is damped over time. The average corrosion rate after 2 years is in the order of 0.4 μm y-1, which represents a low level (C2 according to ISO 9223). Complex annual corrosion models, such as those indicated by ISO 9223, overestimate the real corrosion value.Costa Rica es un importador de la mayoría de los materiales metálicos que utiliza. En la construcción el Hierro Galvanizado (HG) es uno de los elementos de mayor uso en áreas urbanas, donde la corrosión atmosférica es el principal problema de su deterioro ambiental. El área de mayor población y actividad económica en Costa Rica es el Valle de San José, el cual tiene un clima tropical monzónico de baja contaminación, definido bajo la norma ISO 9223(2012) como urbano leve. El presente estudio de la corrosión atmosférica del HG, plantea una alta correlación para modelos lineales simples, con parámetros climáticos como principales componentes y SO2 como componente secundario. La estacionalidad y los sitios de muestreo son parcialmente significativos al inicio del proceso de oxidación, pero dicho efecto se amortigua con el tiempo. La velocidad de corrosión media luego de 2 años es del orden de 0.4 μm año-1, lo que representa un nivel bajo (C2 según la norma ISO 9223). Los modelos complejos de corrosión anual como los indicado por la norma ISO 9223, sobrestiman el valor de corrosión real.Universidad de Costa Rica/[804-B9-264]/UCR/Costa RicaCentro Nacional de Alta Tecnología/[CeNAT-VI-269-2017]/CeNAT/Costa RicaUniversidad Nacional/[UNA- SIA: 0600-17]/UNA/Costa RicaInstituto Tecnológico de Costa Rica/[ITCR-VIE 1490-021]/ITCR/Costa RicaMinisterio de Ciencia, Tecnología y Telecomunicaciones/[]/MICITT/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Electroquímica y Energía Química (CELEQ

Adsorption of Fe(NO) onto Activated Nylon-6,6 as a Container and a Possible “” Corrosion Inhibitor-containing System

Nylon-6,6 exhibits chemical, thermal and mechanical properties which include resistance to chemical attack, electrical insulating properties and degradation resistance. As a possible container, it can be used to manufacture a new family of active hybrid materials, coatings and corrosion inhibitor-containing systems. The release of encapsulated corrosion inhibitors is triggered by the corrosion process itself, which prevents the spontaneous leakage of such inhibitor and provides a quick response to changes in the service environment. With this in mind, nylon-6,6 pellets were activated using either γ-irradiation or chemical attack in alkaline solution. Better pore formation was achieved employing the latter method, with such pores being filled with adsorbed ferric nitrates. Electrochemical tests were undertaken to demonstrate the performance of the “ smart ” nature of the corrosion inhibitor system formed

Nylon/Graphene Oxide Electrospun Composite Coating

Graphite oxide is obtained by treating graphite with strong oxidizers. The bulk material disperses in basic solutions yielding graphene oxide. Starting from exfoliated graphite, different treatments were tested to obtain the best graphite oxide conditions, including calcination for two hours at 700°C and ultrasonic agitation in acidic, basic, or peroxide solutions. Bulk particles floating in the solution were filtered, rinsed, and dried. The graphene oxide obtained was characterized under SEM and FTIR techniques. On the other hand, nylon 6-6 has excellent mechanical resistance due to the mutual attraction of its long chains. To take advantage of the properties of both materials, they were combined as a hybrid material. Electrochemical cells were prepared using porous silica as supporting electrode of the electrospun nylon/graphene oxide films for electrochemical testing. Polarization curves were performed to determine the oxidation/reduction potentials under different acidic, alkaline, and peroxide solutions. The oxidation condition was obtained in KOH and the reduction in H2SO4 solutions. Potentiostatic oxidation and reduction curves were applied to further oxidize carbon species and then reduced them, forming the nylon 6-6/functionalized graphene oxide composite coating. Electrochemical impedance measurements were performed to evaluate the coating electrochemical resistance and compared to the silica or nylon samples

Producción de una aleación nanoestructurada FeAL mediante aleación mecánica y su caracterización microestructural

In this work, a Fe40Al alloy was produced by the mechanical alloying technique, from a mixture of elemental powders constituted by Fe and Al, using different milling times. The evolution of size and morphology of powders depending on the milling time was characterized by scanning electron microscopy. The X-Ray Diffraction technique was utilized in order to characterize the crystalline structure evolution depending on the milling time. The Fe40Al alloy with a body centered cubic crystal structure was formed at 20 h of milling time. Besides, this alloy acquired a disordered crystal structure with a Nano metric grain size. The Nano metric grain size of disordered Fe40Al alloy was decreased at the same time as the milling time transcurred, while its lattice parameter was increased.En este trabajo se elaboró la aleación Fe40Al mediante la técnica de aleación mecánica (AM) a partir de una mezcla de polvos elementales de Fe y Al, empleando distintos tiempos de molienda. Se caracterizó la evolución en tamaño y morfología de los polvos empleados en el proceso de AM en función del tiempo de molienda mediante la técnica de Microscopía Electrónica de Barrido (MEB). Se empleó la técnica de Difracción de Rayos X (DRX) para caracterizar la evolución de la estructura cristalina de las fases obtenidas en función del tiempo de molienda. La aleación Fe40Al con estructura cristalina desordenada del tipo cúbico centrado en el cuerpo se formó a las 20 h de molienda. El tamaño nano-métrico de grano correspondiente a la aleación desordenada Fe40Al se redujo con el transcurso del tiempo mientras que su parámetro de red se incrementó con el transcurso del tiempo de molienda

PRODUCTION OF FeAl NANOSTRUCTURED ALLOY BY MECHANICAL ALLOYING AND ITS MICROSTRUCTURAL CHARACTERIZATION

In this work, a Fe40Al alloy was produced by the mechanical alloying technique, from a mixture of elemental powders constituted by Fe and Al, using different milling times. The evolution of size and morphology of powders depending on the milling time was characterized by scanning electron microscopy. The X-Ray Diffraction technique was utilized in order to characterize the crystalline structure evolution depending on the milling time. The Fe40Al alloy with a body centered cubic crystal structure was formed at 20 h of milling time. Besides, this alloy acquired a disordered crystal structure with a Nano metric grain size. The Nano metric grain size of disordered Fe40Al alloy was decreased at the same time as the milling time transcurred, while its lattice parameter was increased