51316-7789-Mixtures Of Acid And Natural Substances With Low Environmental Impact In The Production Of Anodized

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Product Number: 51316-7789-SG

ISBN: 7789 2016 CP

Author: Oladis de Rincón

Publication Date: 2016

Industry: Science of Corrosion

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In this work 57 anodized aluminum bath systems were evaluated, based on different organic acid mixtures (oxalic/O and citric/C), inorganic (sulfuric/S, phosphoric/P and boric/B) and additives with natural substances (Dividivi/A Tannin/B, Aloe Vera/C, Neem/D and Mango leaves/E). Different mixtures were made in order to optimize the parameters for generating the anodic film, such as current density and anodized time. Subsequently, resultant anodized layers were evaluated as per the following: thickness test, characteristics and composition of the film (SEM and EDX) and its resistance to corrosion by Linear Polarization Resistance, Anodic Polarization and Electrochemical Impedance Spectroscopy. After testing and analyzing the environmental impact of the system, among other variables, the top 8 anodized were selected to be evaluated by accelerated test under ISO(1) 11474 standard (15 months) and by field exposure at “La Voz” station (Paraguaná Peninsula/12 months), a highly aggressive marine environment. For the evaluation, monthly visual inspection and photographic records were performed, once concluded the exposure time, computer softwares were used to determine variables such as pitting density, percentage of etched surface and average pit size. This paper presents the results found at field level; where after an overall assessment, it was found that the mixture of oxalic/citric (MOC1) and the mixture of boric, oxalic and citric acids (MBOC) systems are the anodized with the best performance.

Key words: Downloadable, Corrosion, anodized, aluminum, natural substances