Browsing by Author "Solis, Roberto"

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    Alumoxane film for corrosion protection of 2024 aluminum alloy
    (2023) Vejar, Nelson; Rojas, Javier; Alvarado, Claudia; Solis, Roberto; Pineda, Fabiola; Sancy, Mamie; Munoz, Lisa; Paez, Maritza
    Alumoxane film on anodized 2024 was obtained using stearic acid to prevent corrosion in a chloride medium. A cleaning pretreatment was applied to the metal surface to improve the adhesion and formation of the alumoxane film using three different sprays, ethanol, water, and NaOH. Then a molten stearic acid was applied to form an alumoxane. The obtained films were characterized by X-ray photoelectron spectroscopy and glow discharge optical emission spectroscopy, and electrochemical techniques, such as linear sweep voltammetry and electrochemical impedance spectroscopy, evaluated the corrosion protection. The surface analyses suggested an interaction between the boehmite and stearic acid to form alumoxane, and the electrochemical results revealed that alumoxane film using ethanol significantly improved the protection against corrosion due to the formation of compact and homogeneous films with a hydrophobic characteristic for the 2024-T3 alloy. & COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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    Effects of laser surface modification on stainless steel 316L thin annular discs under radial and cartesian scans
    (2023) Gonzalez, Matias; Ramos Grez, Jorge; Jeria, Ignacio; Guerra, Carolina; Solis, Roberto; Carvajal, Linton
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    Influence of Bacillus safensis and Bacillus pumilus on the electrochemical behavior of 2024-T3 aluminum alloy
    (2022) Vejar, Nelson; Gutierrez, Sebastian; Tareelap, Napachat; Alvarado, Claudia; Solis, Roberto; Guerra, Carolina; Pineda, Fabiola; Sancy, Mamie; Paez, Maritza
    In this work, electrochemical techniques were employed to evaluate the contribution to the corrosion and corrosion inhibition of 2024-T3 aluminum alloy by two Gram-positive bacteria. In addition, polarized impedance was used to determine the microbial effect on the cathodic and anodic reactions. These microorganisms were collected from a tropical environment due to the favorable bacterial growth of this kind of climate. The alloy was exposed to the sterile medium and inoculated for up to 12 days evaluating the microbiological and electrochemical behavior. The results by linear scanning voltammetry showed that the B. safensis and B. pumilus caused a dual effect of increase and decrease currents, and through electrochemical impedance spectroscopy, showed in some cases, inductive loop, which could be associated with local corrosion and another case, an increasing impedance could be related to protection. In addition, a morphological characterization was performed by scanning electron microscopy before and after exposure, showing an increase in copper precipitation in the vicinity of the intermetallic phases by bacteria, attributed to local corrosion, but, in general, a significant effect of damages was not observed. (C) 2021 Elsevier B.V. All rights reserved.