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 (Cu 2+, Zn 2+, SO 2- 4 NO - 3, 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. © 2007 Springer-Verlag