Comportement Électrochimique De L’alliage D’aluminium 2017a En Milieu Agressif En Présence Des Ions Chromates

Résumé: The study of the corrosion inhibition of 2017A aluminium alloy in 3.5% NaCl medium by sodium acetate compound was carried out using different electrochemical methods such as open circuit potential (ocp) measurements, polarization curves and electrochemical impedance spectroscopy (SIE). The influence of concentration, and immersion time on the corrosion behaviour were examined. The corrosion parameters determined from the polarization curves show that potasium potassium chromate compound inhibited corrosion of 2017A aluminium alloy in an agressive medium 3.5% NaCl. The maximum inhibition efficiency (E% = 94.52%.) was attained at 5 × 10–3 M. The results of polarization indicate that the inhibitor tested is cathodic-type affecting cathodic processes. The impedance spectra recorded at the ocp showed an increase of the polarization resistance in time. The results of the impedances are in agreement with the results of the currents of corrosion and the resistance of polarization which indicate the best resistance to corrosion in the case of the 5 × 10–2 M of sodium acetate. Optical micrographs clearly show the corrosion inhibiting effect of chromate ions on aluminum alloy 2017A and the detrimental effect of molybdate ions in aggressive NaCl (3.5%). This result is in agreement with the electrochemical results

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