Electrochemical behaviour of AA6061 alloy in 1M hydrochloric acid using schiff base compounds as corrosion inhibitors

The corrosion inhibition properties of AA6061 Alloy in presence of 1M Hydrochloric Acid by Schiff base compounds namely N, N'-bis (Salicylidene)-1, 4-Diaminobutane (SDB) and N, N'-bis (3-Methoxy Salicylidene)-1, 4 Diaminobutane (MSDB) as corrosion inhibitors were investigated by weight loss, Potentiodynamic polarization(PDP), electrochemical impedance spectroscopy(EIS) and scanning electron microscopy (SEM). Potentiodynamic polarization study revealed that the two Schiff bases acted as mixed type inhibitors. The change in EIS parameters is indicative of adsorption of Schiff bases on aluminium alloys surface leading to formation of protective layer. The weight loss study showed that the inhibition efficiency of these compounds increases with increase in concentration and vary with solution temperature and immersion time. The results obtained from weight loss method, Tafel extrapolation technique and electrochemical impedance spectroscopy were in good agreement. The various thermodynamic parameters were also calculated to investigate the mechanism of corrosion inhibition. The effect of methoxy group on corrosion efficiency was observed from the results obtained between SDB and MSDB. The effectiveness of these inhibitors were in the order of MSDB>SDB. The adsorption of Schiff bases on AA6061 alloy surface in acid obeyed Langmuir adsorption isotherm. The surface characteristics of inhibited and uninhibited alloy samples were investigated by scanning electron microscopy (SEM).