Comparison study on the corrosion behavior of aluminum alloys in different acidic media

Abstract

Electrochemical study to compare the corrosion resistance of three different aluminum alloys (AA8011, AA4017 and AA1200) in organic acid solutions (nitric and acetic acids) was carried out. Polarization technique was used to determine the corrosion behavior of the alloys in the acid solutions, while potentiometric technique was used to study the passivity of the alloys over time. The surface analysis was carried out on the alloys’ surfaces to know the morphological changes that took place on the surface of the alloys using scanning electron microscopy (SEM). Alloy AA4017 showed the least tendency to pit in acetic acid solution with alloy AA8011 showing the highest susceptibility to pitting in the acidic solutions. All the alloys on the other hand showed high tendencies to pit in nitric acid solution. Considering the rate of corrosion of the alloys in both solutions, alloy AA8011 had corrosion rate of 0.0873 mm/yr., which was the highest in acetic acid solution, while alloy AA1200 had the least corrosion rate of 0.0045 mm/yr. in the solution. Meanwhile, alloy AA4017 exhibited the highest corrosion rate of 0.0552 mm/yr. and alloy AA1200 had the least corrosion rate of 0.0126 mm/yr. in nitric acid solution. These results showed that the AA4017 and AA1200 alloys corroded more in nitric acid solution than in acetic acid solution. Potentiometric test results showed the formation of more stable passive films in nitric acid than in acetic acid solution. The SEM micrographs showed pits formation on the alloys in all the acidic solutions.