ON THE CORROSION INHIBITION OF ALUMINIUM IN BICARBONATE BUFFER SOLUTIONS PART I: WEIGHT LOSS, POLARIZATION an‎d EDX STUDIES

The main object of this part is to investigate the corrosion inhibition of Al in weakly alkaline solutions(pH 8) by polyacrylic acid (PAA ; 12000 g mol-1) at 25 C by means of weight loss and potent iodynamicpolarization measurements, complemented with ex situ energy dispersive X-ray (EDX) examinations of the electrode surface. Measurements were carried out in bicarbonate buffer solution (pH 8) containing various concentrations of PAA. The results demonstrated that the inhibition effect of this polymer is due to its adsorption on Al surface. The isoelectric point (IEP) of aluminium oxide (pH = 9) seems to be animportant factor controlling corrosion inhibition and adsorption of the polymer. Polarization measurements showed that the polymer acts as a mixed-type inhibitor. The inhibition efficiency of the polymer increases with increasing its concentration. Results obtained from the chemical and electrochemical measurements are in good agreements. Studying the effect of temperature on the corrosion inhibition of Al and determination of the thermodynamic functions for both dissolution and adsorption processes will be the target of the second part of this work.