51314-4396-Evaluation of Corrosion Resistance of New Green Anodized Process

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Product Number: 51314-4396-SG

ISBN: 4396 2014 CP

Author: Oladis Trocónis de Rincón

Publication Date: 2014

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Aluminum is one of the most extensively used materials for industrial purposes in a number of applications and Venezuela is nowadays one of the bigger exporters of raw aluminum worldwide. One of the most important characteristics of this material is its high corrosion resistance because of a passive layer formation of aluminum oxides (Al2O3XH20); which thickness could increase by using anodizing processes improving its corrosion and erosion resistance. The most used anodized process on the industry was Chromic acid based which yield a high performance. However it has been try to be replaced with other process capable of the same outcome. Nowadays most of the anodizing is done on a sulfuric acid based system worldwide and locally; which as the aforementioned requires high energy consumption beside the cost of waste disposal. Therefore the present work has the aim to investigate on formulation of new electrolytes based on mixtures of different acids and natural substances environmentally friendly; which could improve manufacture and corrosion resistance of aluminum in highly aggressive marine environments. Different acid based electrolyte mixtures were initially evaluated (sulfuric oxalic boric phosphoric and citric acids) with and without additives of natural substances (Caesalpinia coriaria fruit commercial tannin aloe vera mango tree’s leaves and neem’s fruit) in a pilot scale production of anodized with a 5 µm minimum thickness. The samples were evaluated in 3.5 wt% NaCl using electrochemical techniques (i.e. Polarization resistance anodic Tafel polarization and EIS) in order to make an initial selection of those with higher corrosion resistance lower energy consumption in manufacture and more friendly with the environment. Then the chosen ones were subjected to further evaluation using SEM and an outdoor accelerated test (ISO 11474). This work will show a summary of the results which will allow to identify the best anodized obtained.