Electrochemical influence of the nature and composition of halides on Al-12Si

Abstract

The aluminium alloy Al-12Si has been polarized by potentiodynamic method at 25 °C under magnetic stirring and in an aerated solution. Its electrochemical behaviour was tested first by varying the concentration of NaI or NaCl (10−4, 10−3, 10−2) added respectively to NaCl or NaI (10−3 M), and the pH of NaCl 10−3 M (pH = 2.3, 7.3, 10) when adding HCl or NaOH (i.e. the composition of the solution), then by incorporating different ions familiar to an industrial atmosphere (Cu2+, Zn2+, \( {\text{SO}}^{{2 - }}_{4} \), \( {\text{NO}}^{ - }_{3} \), \( {\text{PO}}^{{3 - }}_{4} \)) at 10−6 M to NaCl 10−3 M (i.e. the electrolyte nature). The use of the electrokinetic curves obtained allowed the access to the passivation (i pass , E rup and E rep ) and to the electrokinetic parameters (i corr , R p and P). They prove the behaviour dependence of the above alloy on the composition and nature of the electrolyte.