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

The aluminium alloy Al-12Si has been polarized by potentiodynamic method at 25 degrees 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(-1), 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+, SO42-, NO3-, PO43-) 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.