Corrosion Behaviour of AA6063 Alloy in Acidic Chloride Conditions: Inhibition by Pennisetum glaucum Extract
摘要
The current study develops an understanding of the corrosion inhibition ability of Pennisetum glaucum (millet) extract in inhibiting the corrosion of AA6063 aluminium alloy in 1 M hydrochloric acid. Electrochemical measurements such as Tafel polarization, open circuit potential and linear sweep voltammetry were used to measure inhibition efficiency of the extract with varying concentrations (0.2–0.8 g) of the extract. The supplementation of millet extract was found to reduce corrosion as evidenced by decrease in corrosion current density (Icorr) from 1.11E-04 A/cm2 (blank) to 6.18E-05 A/cm2 for the highest concentration of the extract in the study (0.8 g). Within the same time, the corrosion rate diminished due to the higher concentration of extract, namely from 10.47 to 7.85 mm/yr. The corrosion inhibition concentration dependence revealed that the inhibitor conformed to Temkin adsorption isotherm with high Kads value of 14.1705 mol−1 implying strong adhesion of millet extract onto AA6063. The surface morphology analysis carried out using SEM/EDS supported the hypothesis with evidence of protective layer formation which reduced the corrosion attack. On top of that, when doing the mathematical optimization, it was also determined that the best inhibition condition occurred at the temperature of 32.4 °C and the inhibitor concentration of 0.224 g with the resulting corrosion rate of 2.399 mm/yr.