Alba Covelo

Corrosion Resistance of AA2024-T3 Coated with Graphene/Sol-Gel Films

Graphene is a two-dimensional network of carbon atoms with optimal thermal, electronic and chemical stability properties that promise different and versatile applications in various fields including the protection of metals from corrosion phenomena. For this reason in this paper graphene was employed and studied as an agent dopand incorporated into hybrid sol-gel coatings to enhance their resistance in saline media and to improve the durability of these films. Graphene was obtained by using an electrochemical method involving oxidation and reduction reactions in a sodium lauryl sulfate solution. On the other hand, the hybrid sol-gel was synthesized from the combination of inorganic and organic precursors, zirconium (IV) n-propoxide (TPOZ) and 3-glycidoxipropiltrimetoxysilane (GLYMO) respectively. In order to obtain the coating system (graphene/sol-gel) two different procedures were applied onto clean aluminum plates: a) the electrodeposition of graphene and b) the graphene-doped sol-gel coating. Differential scanning calorimetry, scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize the results, which demonstrate an improvement of the corrosion properties of the films with the incorporation of graphene compounds.

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.

Corrosion Behavior of Hybrid Sol-Gel Films Reinforced with Electrospun Nanofibers

The aim of this paper is to evaluate the efficiency of hybrid sol-gel coatings reinforced with electrospinning nanofibers doped with cerium nitrate and ceria particles to increase the corrosion properties of the coating. Poly(vinyl alcohol) solutions doped with cerium nitrate and ceria were electrospun onto clean commercial aluminum alloy AA2024-T3 plates and then coated with a hybrid sol-gel system using the dip-coating procedure. The hybrid materials synthesized via sol-gel chemistry were prepared from inorganic-organic precursors: zirconium (IV) propoxide and 3-glycidoxypropyltrimetoxysilane. The electrochemical impedance spectroscopy technique was applied to evaluate the electrochemical properties of the film whereas scanning electron microscopy and atomic force microscopy were employed to characterize the surface characteristics. The incorporation of nanofibers into the sol-gel system provides good barrier properties that increase the corrosion resistance of the aluminum at longer exposure times in saline media. This protection depends of the type of inhibitor loaded within the electrospun nanofibers.

Electrochemical Evaluation of a Recycled Copolymer Coating for Cultural Heritage Conservation Purposes

Acrylonitrile-butadiene-styrene (ABS) is a well-known discard product from the industry. This copolymer can be dissolved in organic solvents, and thin films can be created by immersion. Two requirements for coatings used for cultural heritage conservation purposes are transparency and reversibility, both fulfilled by ABS films. The aim of this work was to characterize the copolymer and to evaluate the electrochemical properties of ABS coatings applied to copper. Such performance was compared to that of a commercial varnish commonly used in conservation. The results indicate high protection values of the ABS film, generating a potential application for this waste material. The electrochemical techniques included electrochemical noise, impedance spectroscopy, and potentiodynamic polarization.