Effect of Anodization on the corrosion behavior of Aluminium Alloy in HCl acid and NaOH

Madakson P B,Bashir I G,Malik I A,Laminu S K

doi:10.5923/j.ijme.20120204.02

Madakson P B, Bashir I G + Show 2 more

Open Access

https://doi.org/10.5923/j.ijme.20120204.02

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Abstract

<b> </b>The effect of anodic oxidation on the corrosion behaviour of Aluminium alloy â7075â in two different media was investigated. The weight loss technique was used to determine the corrosion rate in 1.0M HCl and 1.0M NaOH solutions. These specimens were allowed to stay in the solutions for 504 hours with an interval of 72 hours weight loss measurement. The results shows that in both media, the normal corrosion rate profile of an initial steep rise in corrosion followed by subsequent fall was observed for both anodized and unanodized specimens but with severe attack on those specimens in 1.0M HCl. The anodized Al-Alloys in both solutions have lesser corrosion rate as compared to the unanodized Alloys. It was concluded that, Aluminium Alloy â7075â corrodes faster in 1.0M HCl than in 1.0M NaOH solution and that anodizing helps to reduce the corrosion rate of Al- Alloy in both media.

Highlights

New developments in the aircraft field are intimately related to the development and use of materials which are stronger, lighter, more corrosion resistant and more temperature resistant
The corrosion results and all measurements carried out are as shown in Tables1 to 4 and Figures 1 to 4
Discussion of results From figure 1 and 2, it can be observed that the corrosion rate of Aluminium alloy is greater in 1.0M HCl solution than in 1.0M NaOH solution

Summary

Introduction

New developments in the aircraft field are intimately related to the development and use of materials which are stronger, lighter, more corrosion resistant and more temperature resistant. One of the most important factors influencing corrosion is the difference in electrical potential of dissimilar metals when coupled together and immersed in an electrolyte This potential is due to the chemical natures of the anodic and cathodic regions. The most commonly used corrosion control methods include materials selection and design, using corrosion-resistant alloys, protective coatings; CP; use of special heat treatment ; corrosion inhibitors. The high corrosion resistance of aluminium is due to the self-protecting, thin, invisible oxide film that forms immediately on exposing surfaces to the atmosphere. Some of the electrolytes have little or no solvent action on the oxide coating so that very thining films usually known as barrier layer type coatings are formed, the thickmess of which is solely dependent on applied voltage These type of coatings are typically produced in solutions of borate, boric acid or titrate. Sulphuric acid is an example of electrolytes that as solvent action on the formed coating, porous film are formed as the oxidation process continues leading to the formation of relatively thick film.[9]

Experimental Techniques

Variable transformer

Electrolyte

Results and Discussion

Conclusions